Ideas.md

@@ -222,11 +222,14 @@ Probably mostly DRM free. Will want some sort of account server early-on though.
 * The texture file will be a square (rectangular maybe ok) with four quadrants
   from which the textures will be extracted. For example if the overall image
   size was 100x100 pixels, it will be divided into the four 50x50 quadrants.
-  1. `TL`: Top left corner is the top left edge of the "page" the level is on
+  1. `Corner`: Top left corner is the top left edge of the "page" the level is on
-  2. `TR`: Top right corner is the repeated "top of page" texture.
+  2. `Top`: Top right corner is the repeated "top of page" texture.
-  3. `BL`: Bottom left corner is the repeated "left of page" texture.
+  3. `Left`: Bottom left corner is the repeated "left of page" texture.
-  4. `BR`: Bottom right corner is the repeated background texture that extends
+  4. `Repeat`: Bottom right corner is the repeated background texture that extends
      infinitely in all directions.
+* The Repeat texture is used all the time, and the other three are used when the
+  level type has boundaries (on the top and left edges in particular) to draw
+  decorative borders instead of the Repeat texture.
 * Levels will be able to choose a "page type" which controls how the wallpaper
   will be drawn and how the level boundaries may be constrained. There will be
   four options:
@@ -241,22 +244,14 @@ Probably mostly DRM free. Will want some sort of account server early-on though.
      wall.
   3. **Bounded:** The map has a fixed width and height and is bounded on all
      four edges.
-  4. **Bounded, Mirrored Wallpaper:** same as Bounded but with a different
+  4. **Bordered:** same as Bounded but the right and bottom edges are decorated
-     wallpaper behavior.
+     using mirrors of the top and left textures. This would look silly on notebook
-* The page types will have their own behaviors with how wallpapers are drawn:
+     paper (having an extra red line and blank margin) but would work for
-  * **Unbounded:** only the `BR` texture from the wallpaper is used, repeated
+     wrap-around textures like paper placemats.
-    infinitely in the X and Y directions. The top-left, top, and left edge
+  5. **Full Page:** special level type that treats the wallpaper image as a
-    textures are not used.
+     literal full page scan to be drawn on top of. The level is bounded by the
-  * **No Negative Space:** the `TL` texture is drawn at coordinate `(0,0)`.
+     literal dimensions of the wallpaper image which is drawn once instead of
-    To its right, the `TR` texture is repeated forever in the X direction, and
+     cut up and tiled as per the usual behavior.
-    along the left edge of the page, the `BL` texture is repeated in the Y
-    direction. The remaining whitespace on the page repeats the `BR` texture
-    infinitely.
-  * **Bounded:** same as No Negative Space.
-  * **Bounded, Mirrored Wallpaper:** same as No Negative Space, but all of the
-    _other_ corners and edges are textured too, with mirror images of the Top,
-    Top Left, and Left textures. This would look silly on the "ruled notebook"
-    texture, but could be useful to emborder the level with a fancy texture.
 * The game will come with a few built-in textures for levels to refer to by
   name. These textures don't need to be distributed with the map files themselves,
   as every copy of the game should include these (or a sensible fallback would
@@ -264,6 +259,24 @@ Probably mostly DRM free. Will want some sort of account server early-on though.
 * The map author can also attach their own custom texture that will be included
   inside the map file.
 
+### Default Wallpapers
+
+**notebook**: standard ruled notebook paper with a red line alone the Left
+dge and a blank margin along the Top, with a Corner and the blue lines
+aking up the Repeat in all directions.
+
+![notebook.png](../assets/wallpapers/notebook.png)
+
+**graph**: graph paper made up of a grid of light grey or blue lines.
+
+**dots**: graph paper made of dots at the intersections but not the lines in
+between.
+
+**legal**: yellow lined notebook paper (legal pad).
+
+**placemat**: a placemat texture with a wavy outline that emborders the map
+on all four sides. To be used with the Bordered level type.
+
 # Text Console
 
 * Create a rudimentary dev console for entering text commands in-game. It

Makefile

@@ -2,10 +2,11 @@ SHELL := /bin/bash
 
 VERSION=$(shell grep -e 'Version' doodle.go | head -n 1 | cut -d '"' -f 2)
 BUILD=$(shell git describe --always)
+BUILD_DATE=$(shell date -Iseconds)
 CURDIR=$(shell curdir)
 
 # Inject the build version (commit hash) into the executable.
-LDFLAGS := -ldflags "-X main.Build=$(BUILD)"
+LDFLAGS := -ldflags "-X main.Build=$(BUILD) -X main.BuildDate=$(BUILD_DATE)"
 
 # `make setup` to set up a new environment, pull dependencies, etc.
 .PHONY: setup

cmd/doodad/commands/convert.go

@@ -11,10 +11,10 @@ import (
 
 	"image/png"
 
-	"git.kirsle.net/apps/doodle"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/doodads"
+	"git.kirsle.net/apps/doodle/src"
-	"git.kirsle.net/apps/doodle/level"
+	"git.kirsle.net/apps/doodle/src/doodads"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/level"
 	"github.com/urfave/cli"
 	"golang.org/x/image/bmp"
 )

cmd/doodad/main.go

@@ -2,22 +2,38 @@
 package main
 
 import (
+	"fmt"
 	"log"
 	"os"
 	"sort"
+	"time"
 
-	"git.kirsle.net/apps/doodle"
 	"git.kirsle.net/apps/doodle/cmd/doodad/commands"
+	"git.kirsle.net/apps/doodle/src"
 	"github.com/urfave/cli"
 )
 
-var Build = "N/A"
+// Build number is the git commit hash.
+var (
+	Build     = "<dynamic>"
+	BuildDate string
+)
+
+func init() {
+	if BuildDate == "" {
+		BuildDate = time.Now().Format(time.RFC3339)
+	}
+}
 
 func main() {
 	app := cli.NewApp()
 	app.Name = "doodad"
 	app.Usage = "command line interface for Doodle"
-	app.Version = doodle.Version + " build " + Build
+	app.Version = fmt.Sprintf("%s build %s. Built on %s",
+		doodle.Version,
+		Build,
+		BuildDate,
+	)
 
 	app.Flags = []cli.Flag{
 		cli.BoolFlag{

cmd/doodle/main.go

@@ -1,59 +1,101 @@
 package main
 
 import (
-	"flag"
+	"fmt"
+	"log"
+	"os"
 	"runtime"
+	"sort"
+	"time"
 
-	"git.kirsle.net/apps/doodle"
+	"git.kirsle.net/apps/doodle/lib/render/sdl"
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/src"
-	"git.kirsle.net/apps/doodle/render/sdl"
+	"git.kirsle.net/apps/doodle/src/balance"
+	"github.com/urfave/cli"
 
 	_ "image/png"
 )
 
 // Build number is the git commit hash.
-var Build string
-
-// Command line args
 var (
-	debug   bool
+	Build     = "<dynamic>"
-	edit    bool
+	BuildDate string
-	guitest bool
 )
 
 func init() {
-	flag.BoolVar(&debug, "debug", false, "Debug mode")
+	if BuildDate == "" {
-	flag.BoolVar(&edit, "edit", false, "Edit the map given on the command line. Default is to play the map.")
+		BuildDate = time.Now().Format(time.RFC3339)
-	flag.BoolVar(&guitest, "guitest", false, "Enter the GUI Test scene.")
+	}
 }
 
 func main() {
 	runtime.LockOSThread()
-	flag.Parse()
 
-	args := flag.Args()
+	app := cli.NewApp()
-	var filename string
+	app.Name = "doodle"
-	if len(args) > 0 {
+	app.Usage = "command line interface for Doodle"
-		filename = args[0]
+	app.Version = fmt.Sprintf("%s build %s. Built on %s",
-	}
+		doodle.Version,
-
+		Build,
-	// SDL engine.
+		BuildDate,
-	engine := sdl.New(
-		"Doodle v"+doodle.Version,
-		balance.Width,
-		balance.Height,
 	)
 
-	app := doodle.New(debug, engine)
+	app.Flags = []cli.Flag{
-	app.SetupEngine()
+		cli.BoolFlag{
-	if guitest {
+			Name:  "debug, d",
-		app.Goto(&doodle.GUITestScene{})
+			Usage: "enable debug level logging",
-	} else if filename != "" {
+		},
-		if edit {
+		cli.BoolFlag{
-			app.EditFile(filename)
+			Name:  "edit, e",
-		} else {
+			Usage: "edit the map given on the command line (instead of play it)",
-			app.PlayLevel(filename)
+		},
-		}
+		cli.BoolFlag{
+			Name:  "guitest",
+			Usage: "enter the GUI Test scene on startup",
+		},
+	}
+
+	app.Action = func(c *cli.Context) error {
+		if c.Bool("version") {
+			fmt.Printf("This is Project Doodle, v%s build %s ",
+				doodle.Version,
+				Build,
+			)
+			return nil
+		}
+
+		var filename string
+		if c.NArg() > 0 {
+			filename = c.Args().Get(0)
+		}
+
+		// SDL engine.
+		engine := sdl.New(
+			"Doodle v"+doodle.Version,
+			balance.Width,
+			balance.Height,
+		)
+
+		game := doodle.New(c.Bool("debug"), engine)
+		game.SetupEngine()
+		if c.Bool("guitest") {
+			game.Goto(&doodle.GUITestScene{})
+		} else if filename != "" {
+			if c.Bool("edit") {
+				game.EditFile(filename)
+			} else {
+				game.PlayLevel(filename)
+			}
+		}
+		game.Run()
+		return nil
+	}
+
+	sort.Sort(cli.FlagsByName(app.Flags))
+	sort.Sort(cli.CommandsByName(app.Commands))
+
+	err := app.Run(os.Args)
+	if err != nil {
+		log.Fatal(err)
 	}
-	app.Run()
 }

doodads/player.go

@@ -1,81 +0,0 @@
-package doodads
-
-import (
-	"git.kirsle.net/apps/doodle/render"
-)
-
-// PlayerID is the Doodad ID for the player character.
-const PlayerID = "PLAYER"
-
-// Player is a special doodad for the player character.
-type Player struct {
-	point    render.Point
-	velocity render.Point
-	size     render.Rect
-	grounded bool
-}
-
-// NewPlayer creates the special Player Character doodad.
-func NewPlayer() *Player {
-	return &Player{
-		point: render.Point{
-			X: 100,
-			Y: 100,
-		},
-		size: render.Rect{
-			W: 32,
-			H: 32,
-		},
-	}
-}
-
-// ID of the Player singleton.
-func (p *Player) ID() string {
-	return PlayerID
-}
-
-// Position of the player.
-func (p *Player) Position() render.Point {
-	return p.point
-}
-
-// MoveBy a relative delta position.
-func (p *Player) MoveBy(by render.Point) {
-	p.point.X += by.X
-	p.point.Y += by.Y
-}
-
-// MoveTo an absolute position.
-func (p *Player) MoveTo(to render.Point) {
-	p.point = to
-}
-
-// Velocity returns the player's current velocity.
-func (p *Player) Velocity() render.Point {
-	return p.velocity
-}
-
-// Size returns the player's size.
-func (p *Player) Size() render.Rect {
-	return p.size
-}
-
-// Grounded returns if the player is grounded.
-func (p *Player) Grounded() bool {
-	return p.grounded
-}
-
-// SetGrounded sets if the player is grounded.
-func (p *Player) SetGrounded(v bool) {
-	p.grounded = v
-}
-
-// Draw the player sprite.
-func (p *Player) Draw(e render.Engine) {
-	e.DrawBox(render.RGBA(255, 255, 153, 255), render.Rect{
-		X: p.point.X,
-		Y: p.point.Y,
-		W: p.size.W,
-		H: p.size.H,
-	})
-}

lib/render/color.go

@@ -156,15 +156,15 @@ func (c *Color) UnmarshalJSON(b []byte) error {
 }
 
 // Add a relative color value to the color.
-func (c Color) Add(r, g, b, a int32) Color {
+func (c Color) Add(r, g, b, a int) Color {
 	var (
-		R = int32(c.Red) + r
+		R = int(c.Red) + r
-		G = int32(c.Green) + g
+		G = int(c.Green) + g
-		B = int32(c.Blue) + b
+		B = int(c.Blue) + b
-		A = int32(c.Alpha) + a
+		A = int(c.Alpha) + a
 	)
 
-	cap8 := func(v int32) uint8 {
+	cap8 := func(v int) uint8 {
 		if v > 255 {
 			v = 255
 		} else if v < 0 {
@@ -182,11 +182,22 @@ func (c Color) Add(r, g, b, a int32) Color {
 }
 
 // Lighten a color value.
-func (c Color) Lighten(v int32) Color {
+func (c Color) Lighten(v int) Color {
 	return c.Add(v, v, v, 0)
 }
 
 // Darken a color value.
-func (c Color) Darken(v int32) Color {
+func (c Color) Darken(v int) Color {
 	return c.Add(-v, -v, -v, 0)
 }
+
+// Transparentize adjusts the alpha level of a color.
+func (c Color) Transparentize(v int) Color {
+	return c.Add(0, 0, 0, int(v))
+}
+
+// SetAlpha sets the alpha value to a specific setting.
+func (c Color) SetAlpha(v uint8) Color {
+	c.Alpha = v
+	return c
+}

lib/render/interface.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"math"
 
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/src/events"
 )
 
 // Engine is the interface for the rendering engine, keeping SDL-specific stuff
@@ -125,7 +125,8 @@ func (r Rect) Add(other Rect) Rect {
 	}
 }
 
-// Add a point to move the rect.
+// Add (or subtract) a point to move the rect. This is usually the method you
+// want to use: negative Point values will subtract the rect's position.
 func (r Rect) AddPoint(other Point) Rect {
 	return Rect{
 		X: r.X + other.X,
@@ -135,6 +136,17 @@ func (r Rect) AddPoint(other Point) Rect {
 	}
 }
 
+// SubtractPoint is the inverse of AddPoint. Use this only if you need to
+// invert the Point being added.
+func (r Rect) SubtractPoint(other Point) Rect {
+	return Rect{
+		X: r.X - other.X,
+		Y: r.Y - other.Y,
+		W: r.W,
+		H: r.H,
+	}
+}
+
 // Text holds information for drawing text.
 type Text struct {
 	Text         string

lib/render/point.go

@@ -69,12 +69,21 @@ func (p Point) Inside(r Rect) bool {
 		(p.Y >= y1 && p.Y <= y2))
 }
 
-// Add (or subtract) the other point to your current point.
+// Add (or subtract) the other point to your current point. This is usually
+// the one you want: if the other Point has negative values it will subtract
+// them from this Point, or if they are positive it will add them.
 func (p *Point) Add(other Point) {
 	p.X += other.X
 	p.Y += other.Y
 }
 
+// Subtract is the inverse of Add. Use this if you want to force a subtraction
+// operation (i.e. to invert a Point before adding it).
+func (p *Point) Subtract(other Point) {
+	p.X -= other.X
+	p.Y -= other.Y
+}
+
 // MarshalText to convert the point into text so that a render.Point may be used
 // as a map key and serialized to JSON.
 func (p *Point) MarshalText() ([]byte, error) {

lib/render/point_test.go

@@ -4,7 +4,7 @@ import (
 	"strconv"
 	"testing"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 func TestPointInside(t *testing.T) {

lib/render/rect_test.go

@@ -4,7 +4,7 @@ import (
 	"strconv"
 	"testing"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 func TestIntersection(t *testing.T) {

lib/render/sdl/canvas.go

@@ -2,7 +2,7 @@
 package sdl
 
 import (
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 	"github.com/veandco/go-sdl2/sdl"
 )
 

lib/render/sdl/events.go

@@ -3,7 +3,7 @@ package sdl
 import (
 	"errors"
 
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/src/events" // XXX: break it up
 	"github.com/veandco/go-sdl2/sdl"
 )
 

lib/render/sdl/sdl.go

@@ -4,8 +4,8 @@ package sdl
 import (
 	"time"
 
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/events"
 	"github.com/veandco/go-sdl2/sdl"
 	"github.com/veandco/go-sdl2/ttf"
 )

lib/render/sdl/text.go

@@ -4,8 +4,8 @@ import (
 	"fmt"
 	"strings"
 
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/events"
 	"github.com/veandco/go-sdl2/sdl"
 	"github.com/veandco/go-sdl2/ttf"
 )

lib/render/sdl/texture.go

@@ -3,7 +3,7 @@ package sdl
 import (
 	"fmt"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 	"github.com/veandco/go-sdl2/sdl"
 )
 

lib/render/sdl/utils.go

@@ -1,7 +1,7 @@
 package sdl
 
 import (
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 	"github.com/veandco/go-sdl2/sdl"
 )
 

lib/ui/README.md

@@ -0,0 +1,8 @@
+# Doodle UI
+
+This is a UI toolkit designed for Doodle but made generally available.
+
+## Ties to Break
+
+lib/ui and lib/render both currently import doodle/src/events as their only
+dependency on Doodle. This module should be moved to a better common location.

lib/ui/button.go

@@ -4,8 +4,8 @@ import (
 	"errors"
 	"fmt"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/ui/theme"
+	"git.kirsle.net/apps/doodle/lib/ui/theme"
 )
 
 // Button is a clickable button.

lib/ui/check_button.go

@@ -4,8 +4,8 @@ import (
 	"fmt"
 	"strconv"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/ui/theme"
+	"git.kirsle.net/apps/doodle/lib/ui/theme"
 )
 
 // CheckButton implements a checkbox and radiobox widget. It's based on a

lib/ui/checkbox.go

@@ -1,6 +1,6 @@
 package ui
 
-import "git.kirsle.net/apps/doodle/render"
+import "git.kirsle.net/apps/doodle/lib/render"
 
 // Checkbox combines a CheckButton with a widget like a Label.
 type Checkbox struct {

lib/ui/frame.go

@@ -3,7 +3,7 @@ package ui
 import (
 	"fmt"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // Frame is a widget that contains other widgets.

lib/ui/frame_pack.go

@@ -1,6 +1,8 @@
 package ui
 
-import "git.kirsle.net/apps/doodle/render"
+import (
+	"git.kirsle.net/apps/doodle/lib/render"
+)
 
 // Pack provides configuration fields for Frame.Pack().
 type Pack struct {

lib/ui/functions.go

@@ -1,6 +1,6 @@
 package ui
 
-import "git.kirsle.net/apps/doodle/render"
+import "git.kirsle.net/apps/doodle/lib/render"
 
 // AbsolutePosition computes a widget's absolute X,Y position on the
 // window on screen by crawling its parent widget tree.

lib/ui/image.go

@@ -5,7 +5,7 @@ import (
 	"path/filepath"
 	"strings"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // ImageType for supported image formats.

lib/ui/label.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"strings"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // DefaultFont is the default font settings used for a Label.

lib/ui/supervisor.go

@@ -4,8 +4,8 @@ import (
 	"errors"
 	"sync"
 
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/events"
 )
 
 // Event is a named event that the supervisor will send.

lib/ui/theme/theme.go

@@ -1,6 +1,6 @@
 package theme
 
-import "git.kirsle.net/apps/doodle/render"
+import "git.kirsle.net/apps/doodle/lib/render"
 
 // Color schemes.
 var (
@@ -8,5 +8,5 @@ var (
 	ButtonHoverColor      = render.RGBA(200, 255, 255, 255)
 	ButtonOutlineColor    = render.Black
 
-	BorderColorOffset int32 = 40
+	BorderColorOffset = 40
 )

lib/ui/widget.go

@@ -1,8 +1,8 @@
 package ui
 
 import (
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/ui/theme"
+	"git.kirsle.net/apps/doodle/lib/ui/theme"
 )
 
 // BorderStyle options for widget.SetBorderStyle()

lib/ui/window.go

@@ -3,7 +3,7 @@ package ui
 import (
 	"fmt"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // Window is a frame with a title bar.

pkg/wallpaper/texture.go

@@ -7,8 +7,8 @@ import (
 	"image"
 	"os"
 
+	"git.kirsle.net/apps/doodle/lib/render"
 	"git.kirsle.net/apps/doodle/pkg/userdir"
-	"git.kirsle.net/apps/doodle/render"
 	"golang.org/x/image/bmp"
 )
 

pkg/wallpaper/wallpaper.go

@@ -7,7 +7,7 @@ import (
 	"path/filepath"
 	"strings"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // Wallpaper is a repeatable background image to go behind levels.

pkg/wallpaper/wallpaper_test.go

@@ -28,7 +28,7 @@ func TestWallpaper(t *testing.T) {
 		img := image.NewRGBA(image.Rect(0, 0, width, height))
 		draw.Draw(
 			// Corner: red
-			img, // dst Image
+			img,                               // dst Image
 			image.Rect(0, 0, qWidth, qHeight), // r Rectangle
 			image.NewUniform(red),             // src Image
 			image.Point{0, 0},                 // sp Point

render/sdl/fps.go

@@ -1,22 +0,0 @@
-package sdl
-
-import (
-	"git.kirsle.net/apps/doodle/level"
-)
-
-// Frames to cache for FPS calculation.
-const (
-	maxSamples = 100
-	TargetFPS  = 1000 / 60
-)
-
-var (
-	fpsCurrentTicks uint32 // current time we get sdl.GetTicks()
-	fpsLastTime     uint32 // last time we printed the fpsCurrentTicks
-	fpsCurrent      int
-	fpsFrames       int
-	fpsSkipped      uint32
-	fpsInterval     uint32 = 1000
-)
-
-var pixelHistory []level.Pixel

src/balance/debug.go

@@ -5,7 +5,7 @@ import (
 	"strconv"
 	"strings"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // Debug related variables that can toggle on or off certain features and
@@ -16,11 +16,11 @@ var (
 	 ***************/
 
 	// Debug overlay (FPS etc.) settings.
-	DebugFontFilename       = "./fonts/DejaVuSans-Bold.ttf"
+	DebugFontFilename = "./fonts/DejaVuSans.ttf"
-	DebugFontSize           = 15
+	DebugFontSize     = 16
-	DebugLabelColor         = render.MustHexColor("#FF9900")
+	DebugLabelColor   = render.MustHexColor("#FF9900")
-	DebugValueColor         = render.MustHexColor("#00CCFF")
+	DebugValueColor   = render.MustHexColor("#00CCFF")
-	DebugStrokeDarken int32 = 80
+	DebugStrokeDarken = 80
 
 	// Background color to use when exporting a drawing Chunk as a bitmap image
 	// on disk. Default is white. Setting this to translucent yellow is a great

src/balance/numbers.go

@@ -9,6 +9,16 @@ var (
 	// Speed to scroll a canvas with arrow keys in Edit Mode.
 	CanvasScrollSpeed int32 = 8
 
+	// Window scrolling behavior in Play Mode.
+	ScrollboxHoz      = 64 // horizontal pixels close to canvas border
+	ScrollboxVert     = 128
+	ScrollMaxVelocity = 24
+
+	// Player speeds
+	PlayerMaxVelocity  = 12
+	PlayerAcceleration = 2 // pixels / second / second
+	Gravity            = 2
+
 	// Default chunk size for canvases.
 	ChunkSize = 128
 

src/balance/shell.go

@@ -1,7 +1,7 @@
 package balance
 
 import (
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // Shell related variables.

src/balance/theme.go

@@ -1,8 +1,8 @@
 package balance
 
 import (
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/ui"
+	"git.kirsle.net/apps/doodle/lib/ui"
 )
 
 // Theme and appearance variables.

src/commands.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"strconv"
 
-	"git.kirsle.net/apps/doodle/enum"
+	"git.kirsle.net/apps/doodle/src/enum"
 )
 
 // Command is a parsed shell command.
@@ -22,6 +22,17 @@ func (c Command) Run(d *Doodle) error {
 		return nil
 	}
 
+	// Cheats :P
+	if c.Raw == "unleash the beast" {
+		if fpsDoNotCap {
+			d.Flash("Reset frame rate throttle to factory default %d FPS", TargetFPS)
+		} else {
+			d.Flash("Unleashing as many frames as we can render!")
+		}
+		fpsDoNotCap = !fpsDoNotCap
+		return nil
+	}
+
 	switch c.Command {
 	case "echo":
 		d.Flash(c.ArgsLiteral)

src/doodads/actor.go

@@ -1,8 +1,8 @@
 package doodads
 
 import (
-	"git.kirsle.net/apps/doodle/level"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/level"
 )
 
 // Actor is a reusable run-time drawing component used in Doodle. Actors are an
@@ -13,6 +13,9 @@ type Actor interface {
 	// Position and velocity, not saved to disk.
 	Position() render.Point
 	Velocity() render.Point
+	SetVelocity(render.Point)
+	Acceleration() int
+	SetAcceleration(int)
 	Size() render.Rect
 	Grounded() bool
 	SetGrounded(bool)
@@ -20,9 +23,6 @@ type Actor interface {
 	// Movement commands.
 	MoveBy(render.Point) // Add {X,Y} to current Position.
 	MoveTo(render.Point) // Set current Position to {X,Y}.
-
-	// Implement the Draw function.
-	Draw(render.Engine)
 }
 
 // GetBoundingRect computes the full pairs of points for the collision box

src/doodads/collision.go

@@ -1,8 +1,8 @@
 package doodads
 
 import (
-	"git.kirsle.net/apps/doodle/level"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/level"
 )
 
 // Collide describes how a collision occurred.
@@ -96,8 +96,15 @@ const (
 	Right
 )
 
-// CollidesWithGrid checks if a Doodad collides with level geometry.
+/*
-func CollidesWithGrid(d Actor, grid *level.Chunker, target render.Point) (*Collide, bool) {
+CollidesWithGrid checks if a Doodad collides with level geometry.
+
+The `target` is the point the actor wants to move to this tick.
+
+The `scroll` is the scroll offset of the canvas that is viewing the grid, so
+that collision geometry can be offset properly on screen.
+*/
+func CollidesWithGrid(d Actor, grid *level.Chunker, target render.Point, scroll render.Point) (*Collide, bool) {
 	var (
 		P = d.Position()
 		S = d.Size()
@@ -109,14 +116,14 @@ func CollidesWithGrid(d Actor, grid *level.Chunker, target render.Point) (*Colli
 		capHeight int32 // Stop vertical movement thru a ceiling
 		capLeft   int32 // Stop movement thru a wall
 		capRight  int32
-		hitLeft   bool // Has hit an obstacle on the left
+		capFloor  int32 // Stop movement thru the floor
-		hitRight  bool // or right
+		hitLeft   bool  // Has hit an obstacle on the left
-		hitFloor  bool
+		hitRight  bool  // or right
-		capFloor  int32
+		hitFloor  bool  // or floor
 	)
 
 	// Test all of the bounding boxes for a collision with level geometry.
-	if ok := result.ScanBoundingBox(GetBoundingRect(d), grid); ok {
+	if ok := result.ScanBoundingBox(GetBoundingRect(d).SubtractPoint(scroll), grid); ok {
 		// We've already collided! Try to wiggle free.
 		if result.Bottom {
 			if !d.Grounded() {
@@ -190,7 +197,7 @@ func CollidesWithGrid(d Actor, grid *level.Chunker, target render.Point) (*Colli
 			Y: point.Y,
 			W: S.W,
 			H: S.H,
-		}, grid); has {
+		}.SubtractPoint(scroll), grid); has {
 			if result.Bottom {
 				if !hitFloor {
 					hitFloor = true

src/doodads/doodad.go

@@ -1,9 +1,9 @@
 package doodads
 
 import (
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/level"
+	"git.kirsle.net/apps/doodle/src/balance"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/level"
 )
 
 // Doodad is a reusable component for Levels that have scripts and graphics.

src/doodads/drawing.go

@@ -0,0 +1,91 @@
+package doodads
+
+import (
+	"git.kirsle.net/apps/doodle/lib/render"
+	uuid "github.com/satori/go.uuid"
+)
+
+// Drawing is a Doodad Actor that is based on drawings made inside the game.
+type Drawing struct {
+	Doodad *Doodad
+
+	id       string
+	point    render.Point
+	velocity render.Point
+	accel    int
+	size     render.Rect
+	grounded bool
+}
+
+// NewDrawing creates a Drawing actor based on a Doodad drawing. If you pass
+// an empty ID string, it will make a random UUIDv4 ID.
+func NewDrawing(id string, doodad *Doodad) Drawing {
+	if id == "" {
+		id = uuid.Must(uuid.NewV4()).String()
+	}
+	return Drawing{
+		id:     id,
+		Doodad: doodad,
+		size:   doodad.Rect(),
+	}
+}
+
+// ID to get the Drawing ID.
+func (d *Drawing) ID() string {
+	return d.id
+}
+
+// Position returns the Drawing's position.
+func (d *Drawing) Position() render.Point {
+	return d.point
+}
+
+// Velocity returns the Drawing's velocity.
+func (d *Drawing) Velocity() render.Point {
+	return d.velocity
+}
+
+// SetVelocity to set the speed.
+func (d *Drawing) SetVelocity(v render.Point) {
+	d.velocity = v
+}
+
+// Acceleration returns the Drawing's acceleration.
+func (d *Drawing) Acceleration() int {
+	return d.accel
+}
+
+// SetAcceleration to set the acceleration.
+func (d *Drawing) SetAcceleration(v int) {
+	d.accel = v
+}
+
+// Size returns the Drawing's size.
+func (d *Drawing) Size() render.Rect {
+	return d.size
+}
+
+// Grounded returns whether the Drawing is standing on solid ground.
+func (d *Drawing) Grounded() bool {
+	return d.grounded
+}
+
+// SetGrounded sets the grounded state.
+func (d *Drawing) SetGrounded(v bool) {
+	d.grounded = v
+}
+
+// MoveBy a relative value.
+func (d *Drawing) MoveBy(by render.Point) {
+	d.point.Add(by)
+}
+
+// MoveTo an absolute world value.
+func (d *Drawing) MoveTo(to render.Point) {
+	d.point = to
+}
+
+// Draw the drawing.
+func (d *Drawing) Draw(e render.Engine) {
+
+}

src/doodads/dummy/dummy.go

@@ -0,0 +1,16 @@
+// Package dummy implements a dummy doodads.Drawing.
+package dummy
+
+import "git.kirsle.net/apps/doodle/src/doodads"
+
+// Drawing is a dummy doodads.Drawing that has no data.
+type Drawing struct {
+	doodads.Drawing
+}
+
+// NewDrawing creates a new dummy drawing.
+func NewDrawing(id string, doodad *doodads.Doodad) *Drawing {
+	return &Drawing{
+		Drawing: doodads.NewDrawing(id, doodad),
+	}
+}

src/doodads/dummy/player.go

@@ -0,0 +1,11 @@
+// Package dummy implements a dummy doodads.Drawing.
+package dummy
+
+import "git.kirsle.net/apps/doodle/src/doodads"
+
+// NewPlayer creates a dummy player object.
+func NewPlayer() *Drawing {
+	return &Drawing{
+		Drawing: doodads.NewDrawing("PLAYER", doodads.New(32)),
+	}
+}

src/doodle.go

@@ -5,16 +5,17 @@ import (
 	"strings"
 	"time"
 
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/enum"
+	"git.kirsle.net/apps/doodle/pkg/userdir"
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/src/balance"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/enum"
+	"git.kirsle.net/apps/doodle/src/events"
 	"github.com/kirsle/golog"
 )
 
 const (
 	// Version number.
-	Version = "0.0.1-alpha"
+	Version = "0.0.7-alpha"
 
 	// TargetFPS is the frame rate to cap the game to.
 	TargetFPS = 1000 / 60 // 60 FPS
@@ -147,13 +148,15 @@ func (d *Doodle) Run() error {
 		}
 
 		// Delay to maintain the target frames per second.
-		elapsed := time.Now().Sub(start)
-		tmp := elapsed / time.Millisecond
 		var delay uint32
-		if TargetFPS-int(tmp) > 0 { // make sure it won't roll under
+		if !fpsDoNotCap {
-			delay = uint32(TargetFPS - int(tmp))
+			elapsed := time.Now().Sub(start)
+			tmp := elapsed / time.Millisecond
+			if TargetFPS-int(tmp) > 0 { // make sure it won't roll under
+				delay = uint32(TargetFPS - int(tmp))
+			}
+			d.Engine.Delay(delay)
 		}
-		d.Engine.Delay(delay)
 
 		// Track how long this frame took to measure FPS over time.
 		d.TrackFPS(delay)
@@ -216,7 +219,7 @@ func (d *Doodle) EditDrawing(filename string) error {
 func (d *Doodle) PlayLevel(filename string) error {
 	log.Info("Loading level from file: %s", filename)
 	scene := &PlayScene{
-		Filename: filename,
+		Filename: userdir.LevelPath(filename),
 	}
 	d.Goto(scene)
 	return nil

src/draw/line.go

@@ -3,7 +3,7 @@ package draw
 import (
 	"math"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // Line is a generator that returns the X,Y coordinates to draw a line.

src/draw/line_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 
 	"git.kirsle.net/apps/doodle/draw"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 func TestLine(t *testing.T) {

src/editor_scene.go

@@ -7,12 +7,12 @@ import (
 	"os"
 	"strings"
 
-	"git.kirsle.net/apps/doodle/doodads"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/enum"
-	"git.kirsle.net/apps/doodle/events"
-	"git.kirsle.net/apps/doodle/level"
 	"git.kirsle.net/apps/doodle/pkg/userdir"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/doodads"
+	"git.kirsle.net/apps/doodle/src/enum"
+	"git.kirsle.net/apps/doodle/src/events"
+	"git.kirsle.net/apps/doodle/src/level"
 )
 
 // EditorScene manages the "Edit Level" game mode.
@@ -31,6 +31,11 @@ type EditorScene struct {
 	Level  *level.Level
 	Doodad *doodads.Doodad
 
+	// Custom debug overlay labels.
+	debTool       *string
+	debSwatch     *string
+	debWorldIndex *string
+
 	// Last saved filename by the user.
 	filename string
 }
@@ -42,6 +47,16 @@ func (s *EditorScene) Name() string {
 
 // Setup the editor scene.
 func (s *EditorScene) Setup(d *Doodle) error {
+	// Debug overlay labels.
+	s.debTool = new(string)
+	s.debSwatch = new(string)
+	s.debWorldIndex = new(string)
+	customDebugLabels = []debugLabel{
+		{"Pixel:", s.debWorldIndex},
+		{"Tool:", s.debTool},
+		{"Swatch:", s.debSwatch},
+	}
+
 	// Initialize the user interface. It references the palette and such so it
 	// must be initialized after those things.
 	s.d = d
@@ -60,6 +75,7 @@ func (s *EditorScene) Setup(d *Doodle) error {
 		if s.Level != nil {
 			log.Debug("EditorScene.Setup: received level from scene caller")
 			s.UI.Canvas.LoadLevel(d.Engine, s.Level)
+			s.UI.Canvas.InstallActors(s.Level.Actors)
 		} else if s.filename != "" && s.OpenFile {
 			log.Debug("EditorScene.Setup: Loading map from filename at %s", s.filename)
 			if err := s.LoadLevel(s.filename); err != nil {
@@ -106,6 +122,11 @@ func (s *EditorScene) Setup(d *Doodle) error {
 
 // Loop the editor scene.
 func (s *EditorScene) Loop(d *Doodle, ev *events.State) error {
+	// Update debug overlay labels.
+	*s.debTool = s.UI.Canvas.Tool.String()
+	*s.debSwatch = s.UI.Canvas.Palette.ActiveSwatch.Name
+	*s.debWorldIndex = s.UI.Canvas.WorldIndexAt(s.UI.cursor).String()
+
 	// Has the window been resized?
 	if resized := ev.Resized.Read(); resized {
 		w, h := d.Engine.WindowSize()
@@ -261,6 +282,5 @@ func (s *EditorScene) SaveDoodad(filename string) error {
 
 // Destroy the scene.
 func (s *EditorScene) Destroy() error {
-	debugWorldIndex = render.Origin
 	return nil
 }

src/editor_scene_debug.go

@@ -1,6 +1,6 @@
 package doodle
 
-import "git.kirsle.net/apps/doodle/uix"
+import "git.kirsle.net/apps/doodle/src/uix"
 
 // TODO: build flags to not include this in production builds.
 // This adds accessors for private variables from the dev console.

src/editor_ui.go

@@ -5,15 +5,15 @@ import (
 	"path/filepath"
 	"strconv"
 
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/doodads"
+	"git.kirsle.net/apps/doodle/lib/ui"
-	"git.kirsle.net/apps/doodle/enum"
-	"git.kirsle.net/apps/doodle/events"
-	"git.kirsle.net/apps/doodle/level"
 	"git.kirsle.net/apps/doodle/pkg/userdir"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/balance"
-	"git.kirsle.net/apps/doodle/ui"
+	"git.kirsle.net/apps/doodle/src/doodads"
-	"git.kirsle.net/apps/doodle/uix"
+	"git.kirsle.net/apps/doodle/src/enum"
+	"git.kirsle.net/apps/doodle/src/events"
+	"git.kirsle.net/apps/doodle/src/level"
+	"git.kirsle.net/apps/doodle/src/uix"
 )
 
 // Width of the panel frame.
@@ -163,11 +163,10 @@ func (u *EditorUI) Loop(ev *events.State) error {
 
 	// Update status bar labels.
 	{
-		debugWorldIndex = u.Canvas.WorldIndexAt(u.cursor)
 		u.StatusMouseText = fmt.Sprintf("Rel:(%d,%d)  Abs:(%s)",
 			ev.CursorX.Now,
 			ev.CursorY.Now,
-			debugWorldIndex,
+			*u.Scene.debWorldIndex,
 		)
 		u.StatusPaletteText = fmt.Sprintf("%s Tool",
 			u.Canvas.Tool,

src/editor_ui_doodad.go

@@ -7,12 +7,12 @@ package doodle
 import (
 	"fmt"
 
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/doodads"
+	"git.kirsle.net/apps/doodle/lib/ui"
 	"git.kirsle.net/apps/doodle/pkg/userdir"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/balance"
-	"git.kirsle.net/apps/doodle/ui"
+	"git.kirsle.net/apps/doodle/src/doodads"
-	"git.kirsle.net/apps/doodle/uix"
+	"git.kirsle.net/apps/doodle/src/uix"
 )
 
 // DraggableActor is a Doodad being dragged from the Doodad palette.

src/editor_ui_palette.go

@@ -1,9 +1,9 @@
 package doodle
 
 import (
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/ui"
-	"git.kirsle.net/apps/doodle/ui"
+	"git.kirsle.net/apps/doodle/src/balance"
 )
 
 // setupPaletteFrame configures the Color Palette tab for Edit Mode.

src/fps.go

@@ -4,10 +4,10 @@ import (
 	"fmt"
 	"strings"
 
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/doodads"
+	"git.kirsle.net/apps/doodle/lib/ui"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/balance"
-	"git.kirsle.net/apps/doodle/ui"
+	"git.kirsle.net/apps/doodle/src/doodads"
 )
 
 // Frames to cache for FPS calculation.
@@ -33,37 +33,72 @@ var (
 	fpsFrames       int
 	fpsSkipped      uint32
 	fpsInterval     uint32 = 1000
+	fpsDoNotCap     bool   // remove the FPS delay cap in Main Loop
 
-	// XXX: some opt-in WorldIndex variables for the debug overlay.
+	// Custom labels for scenes to add to the debug overlay view.
-	// This is the world pixel that the mouse cursor is over,
+	customDebugLabels []debugLabel
-	// the Cursor + Scroll position of the canvas.
-	debugWorldIndex render.Point
 )
 
+type debugLabel struct {
+	key      string
+	variable *string
+}
+
 // DrawDebugOverlay draws the debug FPS text on the SDL canvas.
 func (d *Doodle) DrawDebugOverlay() {
-	if !d.Debug || !DebugOverlay {
+	if !DebugOverlay {
 		return
 	}
 
+	var framesSkipped = fmt.Sprintf("(skip: %dms)", fpsSkipped)
+	if fpsDoNotCap {
+		framesSkipped = "uncapped"
+	}
+
 	var (
 		darken        = balance.DebugStrokeDarken
 		Yoffset int32 = 20 // leave room for the menu bar
-		Xoffset int32 = 5
+		Xoffset int32 = 20
 		keys          = []string{
-			"  FPS:",
+			"FPS:",
 			"Scene:",
-			"Pixel:",
 			"Mouse:",
 		}
 		values = []string{
-			fmt.Sprintf("%d   (skip: %dms)", fpsCurrent, fpsSkipped),
+			fmt.Sprintf("%d   %s", fpsCurrent, framesSkipped),
 			d.Scene.Name(),
-			debugWorldIndex.String(),
 			fmt.Sprintf("%d,%d", d.event.CursorX.Now, d.event.CursorY.Now),
 		}
 	)
 
+	// Insert custom keys.
+	for _, custom := range customDebugLabels {
+		keys = append(keys, custom.key)
+		if custom.variable == nil {
+			values = append(values, "<nil>")
+		} else if len(*custom.variable) == 0 {
+			values = append(values, `""`)
+		} else {
+			values = append(values, *custom.variable)
+		}
+	}
+
+	// Find the longest key.
+	var longest int
+	for _, key := range keys {
+		if len(key) > longest {
+			longest = len(key)
+		}
+	}
+
+	// Space pad the keys to align them.
+	for i, key := range keys {
+		if len(key) < longest {
+			key = strings.Repeat(" ", longest-len(key)) + key
+			keys[i] = key
+		}
+	}
+
 	key := ui.NewLabel(ui.Label{
 		Text: strings.Join(keys, "\n"),
 		Font: render.Text{
@@ -97,7 +132,7 @@ func (d *Doodle) DrawDebugOverlay() {
 
 // DrawCollisionBox draws the collision box around a Doodad.
 func (d *Doodle) DrawCollisionBox(actor doodads.Actor) {
-	if !d.Debug || !DebugCollision {
+	if !DebugCollision {
 		return
 	}
 

src/guitest_scene.go

@@ -3,10 +3,10 @@ package doodle
 import (
 	"fmt"
 
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/lib/ui"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/balance"
-	"git.kirsle.net/apps/doodle/ui"
+	"git.kirsle.net/apps/doodle/src/events"
 )
 
 // GUITestScene implements the main menu of Doodle.

src/level/actors.go

@@ -1,7 +1,7 @@
 package level
 
 import (
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 	uuid "github.com/satori/go.uuid"
 )
 

src/level/chunk.go

@@ -7,9 +7,9 @@ import (
 	"math"
 	"os"
 
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
 	"git.kirsle.net/apps/doodle/pkg/userdir"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/balance"
 	"github.com/satori/go.uuid"
 	"golang.org/x/image/bmp"
 )

src/level/chunk_map.go

@@ -5,7 +5,7 @@ import (
 	"errors"
 	"fmt"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // MapAccessor implements a chunk accessor by using a map of points to their

src/level/chunk_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 
 	"git.kirsle.net/apps/doodle/level"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // Test the high level Chunker.

src/level/chunker.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"math"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // Chunker is the data structure that manages the chunks of a level, and

src/level/chunker_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 
 	"git.kirsle.net/apps/doodle/level"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 func TestWorldSize(t *testing.T) {

src/level/page_type.go

@@ -28,5 +28,10 @@ const (
 	// - The wallpaper hoz mirrors Left along the X=Width plane
 	// - The wallpaper vert mirrors Top along the Y=Width plane
 	// - The wallpaper 180 rotates the Corner for opposite corners
-	Bordered
+	Bordered // TODO: to be implemented
+
+	// FullPage treats the wallpaper image as a literal full scan of a page.
+	// - The level boundaries are fixed to the wallpaper image's dimensions.
+	// - Used to e.g. scan in real letterhead paper and draw a map on it.
+	FullPage // TODO: to be implemented
 )

src/level/palette.go

@@ -1,7 +1,7 @@
 package level
 
 import (
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // DefaultPalette returns a sensible default palette.

src/level/swatch.go

@@ -3,7 +3,7 @@ package level
 import (
 	"fmt"
 
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/lib/render"
 )
 
 // Swatch holds details about a single value in the palette.

src/level/types.go

@@ -4,8 +4,8 @@ import (
 	"encoding/json"
 	"fmt"
 
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/balance"
 )
 
 // Useful variables.

src/main_scene.go

@@ -1,10 +1,10 @@
 package doodle
 
 import (
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/lib/ui"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/balance"
-	"git.kirsle.net/apps/doodle/ui"
+	"git.kirsle.net/apps/doodle/src/events"
 )
 
 // MainScene implements the main menu of Doodle.

src/play_scene.go

@@ -2,13 +2,15 @@ package doodle
 
 import (
 	"fmt"
+	"math"
 
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/doodads"
+	"git.kirsle.net/apps/doodle/src/balance"
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/src/doodads"
-	"git.kirsle.net/apps/doodle/level"
+	"git.kirsle.net/apps/doodle/src/doodads/dummy"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/events"
-	"git.kirsle.net/apps/doodle/uix"
+	"git.kirsle.net/apps/doodle/src/level"
+	"git.kirsle.net/apps/doodle/src/uix"
 )
 
 // PlayScene manages the "Edit Level" game mode.
@@ -21,8 +23,14 @@ type PlayScene struct {
 	d       *Doodle
 	drawing *uix.Canvas
 
+	// Custom debug labels.
+	debPosition   *string
+	debViewport   *string
+	debScroll     *string
+	debWorldIndex *string
+
 	// Player character
-	Player doodads.Actor
+	Player *uix.Actor
 }
 
 // Name of the scene.
@@ -33,6 +41,20 @@ func (s *PlayScene) Name() string {
 // Setup the play scene.
 func (s *PlayScene) Setup(d *Doodle) error {
 	s.d = d
+
+	// Initialize debug bound variables.
+	s.debPosition = new(string)
+	s.debViewport = new(string)
+	s.debScroll = new(string)
+	s.debWorldIndex = new(string)
+	customDebugLabels = []debugLabel{
+		{"Pixel:", s.debWorldIndex},
+		{"Player:", s.debPosition},
+		{"Viewport:", s.debViewport},
+		{"Scroll:", s.debScroll},
+	}
+
+	// Initialize the drawing canvas.
 	s.drawing = uix.NewCanvas(balance.ChunkSize, false)
 	s.drawing.MoveTo(render.Origin)
 	s.drawing.Resize(render.NewRect(int32(d.width), int32(d.height)))
@@ -41,20 +63,26 @@ func (s *PlayScene) Setup(d *Doodle) error {
 	// Given a filename or map data to play?
 	if s.Level != nil {
 		log.Debug("PlayScene.Setup: received level from scene caller")
-		s.drawing.LoadLevel(d.Engine, s.Level)
+		s.drawing.LoadLevel(s.d.Engine, s.Level)
+		s.drawing.InstallActors(s.Level.Actors)
 	} else if s.Filename != "" {
 		log.Debug("PlayScene.Setup: loading map from file %s", s.Filename)
 		s.LoadLevel(s.Filename)
 	}
 
-	s.Player = doodads.NewPlayer()
-
 	if s.Level == nil {
 		log.Debug("PlayScene.Setup: no grid given, initializing empty grid")
 		s.Level = level.New()
 		s.drawing.LoadLevel(d.Engine, s.Level)
+		s.drawing.InstallActors(s.Level.Actors)
 	}
 
+	player := dummy.NewPlayer()
+	s.Player = uix.NewActor(player.ID(), &level.Actor{}, player.Doodad)
+	s.Player.MoveTo(render.NewPoint(128, 128))
+	s.drawing.AddActor(s.Player)
+	s.drawing.FollowActor = s.Player.ID()
+
 	d.Flash("Entered Play Mode. Press 'E' to edit this map.")
 
 	return nil
@@ -62,6 +90,23 @@ func (s *PlayScene) Setup(d *Doodle) error {
 
 // Loop the editor scene.
 func (s *PlayScene) Loop(d *Doodle, ev *events.State) error {
+	// Update debug overlay variables.
+	*s.debWorldIndex = s.drawing.WorldIndexAt(render.NewPoint(ev.CursorX.Now, ev.CursorY.Now)).String()
+	*s.debPosition = s.Player.Position().String()
+	*s.debViewport = s.drawing.Viewport().String()
+	*s.debScroll = s.drawing.Scroll.String()
+
+	// Has the window been resized?
+	if resized := ev.Resized.Read(); resized {
+		w, h := d.Engine.WindowSize()
+		if w != d.width || h != d.height {
+			d.width = w
+			d.height = h
+			s.drawing.Resize(render.NewRect(int32(d.width), int32(d.height)))
+			return nil
+		}
+	}
+
 	// Switching to Edit Mode?
 	if ev.KeyName.Read() == "e" {
 		log.Info("Edit Mode, Go!")
@@ -72,8 +117,11 @@ func (s *PlayScene) Loop(d *Doodle, ev *events.State) error {
 		return nil
 	}
 
-	// s.drawing.Loop(ev)
 	s.movePlayer(ev)
+	if err := s.drawing.Loop(ev); err != nil {
+		log.Error("Drawing Loop: %s", err)
+	}
+
 	return nil
 }
 
@@ -86,9 +134,16 @@ func (s *PlayScene) Draw(d *Doodle) error {
 	s.drawing.Present(d.Engine, s.drawing.Point())
 
 	// Draw our hero.
-	s.Player.Draw(d.Engine)
+	{
+		d.Engine.DrawBox(render.RGBA(255, 255, 153, 255), render.Rect{
+			X: s.Player.Position().X,
+			Y: s.Player.Position().Y,
+			W: s.Player.Size().W,
+			H: s.Player.Size().H,
+		})
+	}
 
-	// Draw out bounding boxes.
+	// Draw our bounding boxes.
 	d.DrawCollisionBox(s.Player)
 
 	return nil
@@ -97,39 +152,49 @@ func (s *PlayScene) Draw(d *Doodle) error {
 // movePlayer updates the player's X,Y coordinate based on key pressed.
 func (s *PlayScene) movePlayer(ev *events.State) {
 	delta := s.Player.Position()
-	var playerSpeed int32 = 8
+	var playerSpeed = int32(balance.PlayerMaxVelocity)
-	var gravity int32 = 2
+	var gravity = int32(balance.Gravity)
+
+	var velocity render.Point
 
 	if ev.Down.Now {
-		delta.Y += playerSpeed
+		velocity.Y = playerSpeed
 	}
 	if ev.Left.Now {
-		delta.X -= playerSpeed
+		velocity.X = -playerSpeed
 	}
 	if ev.Right.Now {
-		delta.X += playerSpeed
+		velocity.X = playerSpeed
 	}
 	if ev.Up.Now {
-		delta.Y -= playerSpeed
+		velocity.Y = -playerSpeed
 	}
 
 	// Apply gravity.
 	// var onFloor bool
 
-	info, ok := doodads.CollidesWithGrid(s.Player, s.Level.Chunker, delta)
+	info, ok := doodads.CollidesWithGrid(s.Player, s.Level.Chunker, delta, s.drawing.Scroll)
 	if ok {
 		// Collision happened with world.
 	}
-	delta = info.MoveTo
+	_ = info.MoveTo
 
 	// Apply gravity if not grounded.
 	if !s.Player.Grounded() {
 		// Gravity has to pipe through the collision checker, too, so it
 		// can't give us a cheated downward boost.
-		delta.Y += gravity
+		velocity.Y += gravity
 	}
 
-	s.Player.MoveTo(delta)
+	// Cap the max speed.
+	if int(math.Abs(float64(velocity.X))) > balance.PlayerMaxVelocity {
+		velocity.X = int32(balance.PlayerMaxVelocity)
+	}
+	if int(math.Abs(float64(velocity.Y))) > balance.PlayerMaxVelocity {
+		velocity.Y = int32(balance.PlayerMaxVelocity)
+	}
+
+	s.Player.SetVelocity(velocity)
 }
 
 // LoadLevel loads a level from disk.
@@ -143,6 +208,7 @@ func (s *PlayScene) LoadLevel(filename string) error {
 
 	s.Level = level
 	s.drawing.LoadLevel(s.d.Engine, s.Level)
+	s.drawing.InstallActors(s.Level.Actors)
 
 	return nil
 }

src/scene.go

@@ -1,6 +1,8 @@
 package doodle
 
-import "git.kirsle.net/apps/doodle/events"
+import (
+	"git.kirsle.net/apps/doodle/src/events"
+)
 
 // Scene is an abstraction for a game mode in Doodle. The app points to one
 // scene at a time and that scene has control over the main loop, and its own
@@ -20,6 +22,9 @@ type Scene interface {
 
 // Goto a scene. First it unloads the current scene.
 func (d *Doodle) Goto(scene Scene) error {
+	// Reset any custom debug overlay entries.
+	customDebugLabels = []debugLabel{}
+
 	// Teardown existing scene.
 	if d.Scene != nil {
 		d.Scene.Destroy()

src/shell.go

@@ -5,10 +5,10 @@ import (
 	"fmt"
 	"strings"
 
-	"git.kirsle.net/apps/doodle/balance"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/lib/ui"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/balance"
-	"git.kirsle.net/apps/doodle/ui"
+	"git.kirsle.net/apps/doodle/src/events"
 	"github.com/robertkrimen/otto"
 )
 

src/uix/actor.go

@@ -0,0 +1,48 @@
+package uix
+
+import (
+	"git.kirsle.net/apps/doodle/lib/render"
+	"git.kirsle.net/apps/doodle/src/doodads"
+	"git.kirsle.net/apps/doodle/src/level"
+	uuid "github.com/satori/go.uuid"
+)
+
+// Actor is an object that marries together the three things that make a
+// Doodad instance "tick" while inside a Canvas:
+//
+// - uix.Actor is a doodads.Drawing so it fulfills doodads.Actor to be a
+//   dynamic object during gameplay.
+// - It has a pointer to the level.Actor indicating its static level data
+//   as defined in the map: its spawn coordinate and configuration.
+// - A uix.Canvas that can present the actor's graphics to the screen.
+type Actor struct {
+	doodads.Drawing
+	Actor  *level.Actor
+	Canvas *Canvas
+}
+
+// NewActor sets up a uix.Actor.
+// If the id is blank, a new UUIDv4 is generated.
+func NewActor(id string, levelActor *level.Actor, doodad *doodads.Doodad) *Actor {
+	if id == "" {
+		id = uuid.Must(uuid.NewV4()).String()
+	}
+
+	size := int32(doodad.Layers[0].Chunker.Size)
+	can := NewCanvas(int(size), false)
+	can.Name = id
+	can.actor = levelActor
+
+	// TODO: if the Background is render.Invisible it gets defaulted to
+	// White somewhere and the Doodad masks the level drawing behind it.
+	can.SetBackground(render.RGBA(0, 0, 1, 0))
+
+	can.LoadDoodad(doodad)
+	can.Resize(render.NewRect(size, size))
+
+	return &Actor{
+		Drawing: doodads.NewDrawing(id, doodad),
+		Actor:   levelActor,
+		Canvas:  can,
+	}
+}

src/uix/canvas.go

@@ -0,0 +1,289 @@
+package uix
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"git.kirsle.net/apps/doodle/lib/render"
+	"git.kirsle.net/apps/doodle/lib/ui"
+	"git.kirsle.net/apps/doodle/pkg/wallpaper"
+	"git.kirsle.net/apps/doodle/src/balance"
+	"git.kirsle.net/apps/doodle/src/doodads"
+	"git.kirsle.net/apps/doodle/src/events"
+	"git.kirsle.net/apps/doodle/src/level"
+)
+
+// Canvas is a custom ui.Widget that manages a single drawing.
+type Canvas struct {
+	ui.Frame
+	Palette *level.Palette
+
+	// Editable and Scrollable go hand in hand and, if you initialize a
+	// NewCanvas() with editable=true, they are both enabled.
+	Editable   bool // Clicking will edit pixels of this canvas.
+	Scrollable bool // Cursor keys will scroll the viewport of this canvas.
+
+	// Selected draw tool/mode, default Pencil, for editable canvases.
+	Tool Tool
+
+	// MaskColor will force every pixel to render as this color regardless of
+	// the palette index of that pixel. Otherwise pixels behave the same and
+	// the palette does work as normal. Set to render.Invisible (zero value)
+	// to remove the mask.
+	MaskColor render.Color
+
+	// Actor ID to follow the camera on automatically, i.e. the main player.
+	FollowActor string
+
+	// Debug tools
+	// NoLimitScroll suppresses the scroll limit for bounded levels.
+	NoLimitScroll bool
+
+	// Underlying chunk data for the drawing.
+	chunks *level.Chunker
+
+	// Actors to superimpose on top of the drawing.
+	actor  *level.Actor // if this canvas IS an actor
+	actors []*Actor
+
+	// Wallpaper settings.
+	wallpaper *Wallpaper
+
+	// When the Canvas wants to delete Actors, but ultimately it is upstream
+	// that controls the actors. Upstream should delete them and then reinstall
+	// the actor list from scratch.
+	OnDeleteActors func([]*level.Actor)
+	OnDragStart    func(filename string)
+
+	// Tracking pixels while editing. TODO: get rid of pixelHistory?
+	pixelHistory []*level.Pixel
+	lastPixel    *level.Pixel
+
+	// We inherit the ui.Widget which manages the width and height.
+	Scroll render.Point // Scroll offset for which parts of canvas are visible.
+}
+
+// NewCanvas initializes a Canvas widget.
+//
+// If editable is true, Scrollable is also set to true, which means the arrow
+// keys will scroll the canvas viewport which is desirable in Edit Mode.
+func NewCanvas(size int, editable bool) *Canvas {
+	w := &Canvas{
+		Editable:   editable,
+		Scrollable: editable,
+		Palette:    level.NewPalette(),
+		chunks:     level.NewChunker(size),
+		actors:     make([]*Actor, 0),
+		wallpaper:  &Wallpaper{},
+	}
+	w.setup()
+	w.IDFunc(func() string {
+		var attrs []string
+
+		if w.Editable {
+			attrs = append(attrs, "editable")
+		} else {
+			attrs = append(attrs, "read-only")
+		}
+
+		if w.Scrollable {
+			attrs = append(attrs, "scrollable")
+		}
+
+		return fmt.Sprintf("Canvas<%d; %s>", size, strings.Join(attrs, "; "))
+	})
+	return w
+}
+
+// Load initializes the Canvas using an existing Palette and Grid.
+func (w *Canvas) Load(p *level.Palette, g *level.Chunker) {
+	w.Palette = p
+	w.chunks = g
+
+	if len(w.Palette.Swatches) > 0 {
+		w.SetSwatch(w.Palette.Swatches[0])
+	}
+}
+
+// LoadLevel initializes a Canvas from a Level object.
+func (w *Canvas) LoadLevel(e render.Engine, level *level.Level) {
+	w.Load(level.Palette, level.Chunker)
+
+	// TODO: wallpaper paths
+	filename := "assets/wallpapers/" + level.Wallpaper
+	if _, err := os.Stat(filename); os.IsNotExist(err) {
+		log.Error("LoadLevel: %s", err)
+		filename = "assets/wallpapers/notebook.png" // XXX TODO
+	}
+
+	wp, err := wallpaper.FromFile(e, filename)
+	if err != nil {
+		log.Error("wallpaper FromFile(%s): %s", filename, err)
+	}
+
+	w.wallpaper.maxWidth = level.MaxWidth
+	w.wallpaper.maxHeight = level.MaxHeight
+	err = w.wallpaper.Load(e, level.PageType, wp)
+	if err != nil {
+		log.Error("wallpaper Load: %s", err)
+	}
+}
+
+// LoadDoodad initializes a Canvas from a Doodad object.
+func (w *Canvas) LoadDoodad(d *doodads.Doodad) {
+	// TODO more safe
+	w.Load(d.Palette, d.Layers[0].Chunker)
+}
+
+// SetSwatch changes the currently selected swatch for editing.
+func (w *Canvas) SetSwatch(s *level.Swatch) {
+	w.Palette.ActiveSwatch = s
+}
+
+// setup common configs between both initializers of the canvas.
+func (w *Canvas) setup() {
+	// XXX: Debug code.
+	if balance.DebugCanvasBorder != render.Invisible {
+		w.Configure(ui.Config{
+			BorderColor: balance.DebugCanvasBorder,
+			BorderSize:  2,
+			BorderStyle: ui.BorderSolid,
+		})
+	}
+}
+
+// Loop is called on the scene's event loop to handle mouse interaction with
+// the canvas, i.e. to edit it.
+func (w *Canvas) Loop(ev *events.State) error {
+	// Process the arrow keys scrolling the level in Edit Mode.
+	// canvas_scrolling.go
+	w.loopEditorScroll(ev)
+	if err := w.loopFollowActor(ev); err != nil {
+		log.Error("Follow actor: %s", err) // not fatal but nice to know
+	}
+	w.loopConstrainScroll()
+
+	// Move any actors.
+	for _, a := range w.actors {
+		if v := a.Velocity(); v != render.Origin {
+			// orig := a.Drawing.Position()
+			a.MoveBy(v)
+
+			// Keep them contained inside the level.
+			if w.wallpaper.pageType > level.Unbounded {
+				var (
+					orig   = w.WorldIndexAt(a.Drawing.Position())
+					moveBy render.Point
+					size   = a.Canvas.Size()
+				)
+
+				// Bound it on the top left edges.
+				if orig.X < 0 {
+					moveBy.X = -orig.X
+				}
+				if orig.Y < 0 {
+					moveBy.Y = -orig.Y
+				}
+
+				// Bound it on the right bottom edges. XXX: downcast from int64!
+				if w.wallpaper.maxWidth > 0 {
+					if int64(orig.X+size.W) > w.wallpaper.maxWidth {
+						var delta = int32(w.wallpaper.maxWidth - int64(orig.X+size.W))
+						moveBy.X = delta
+					}
+				}
+				if w.wallpaper.maxHeight > 0 {
+					if int64(orig.Y+size.H) > w.wallpaper.maxHeight {
+						var delta = int32(w.wallpaper.maxHeight - int64(orig.Y+size.H))
+						moveBy.Y = delta
+					}
+				}
+
+				if !moveBy.IsZero() {
+					a.MoveBy(moveBy)
+				}
+			}
+		}
+	}
+
+	// If the canvas is editable, only care if it's over our space.
+	if w.Editable {
+		cursor := render.NewPoint(ev.CursorX.Now, ev.CursorY.Now)
+		if cursor.Inside(ui.AbsoluteRect(w)) {
+			return w.loopEditable(ev)
+		}
+	}
+	return nil
+}
+
+// Viewport returns a rect containing the viewable drawing coordinates in this
+// canvas. The X,Y values are the scroll offset (top left) and the W,H values
+// are the scroll offset plus the width/height of the Canvas widget.
+//
+// The Viewport rect are the Absolute World Coordinates of the drawing that are
+// visible inside the Canvas. The X,Y is the top left World Coordinate and the
+// W,H are the bottom right World Coordinate, making this rect an absolute
+// slice of the world. For a normal rect with a relative width and height,
+// use ViewportRelative().
+//
+// The rect X,Y are the negative Scroll Value.
+// The rect W,H are the Canvas widget size minus the Scroll Value.
+func (w *Canvas) Viewport() render.Rect {
+	var S = w.Size()
+	return render.Rect{
+		X: -w.Scroll.X,
+		Y: -w.Scroll.Y,
+		W: S.W - w.Scroll.X,
+		H: S.H - w.Scroll.Y,
+	}
+}
+
+// ViewportRelative returns a relative viewport where the Width and Height
+// values are zero-relative: so you can use it with point.Inside(viewport)
+// to see if a World Index point should be visible on screen.
+//
+// The rect X,Y are the negative Scroll Value
+// The rect W,H are the Canvas widget size.
+func (w *Canvas) ViewportRelative() render.Rect {
+	var S = w.Size()
+	return render.Rect{
+		X: -w.Scroll.X,
+		Y: -w.Scroll.Y,
+		W: S.W,
+		H: S.H,
+	}
+}
+
+// WorldIndexAt returns the World Index that corresponds to a Screen Pixel
+// on the screen. If the screen pixel is the mouse coordinate (relative to
+// the application window) this will return the World Index of the pixel below
+// the mouse cursor.
+func (w *Canvas) WorldIndexAt(screenPixel render.Point) render.Point {
+	var P = ui.AbsolutePosition(w)
+	return render.Point{
+		X: screenPixel.X - P.X - w.Scroll.X,
+		Y: screenPixel.Y - P.Y - w.Scroll.Y,
+	}
+}
+
+// Chunker returns the underlying Chunker object.
+func (w *Canvas) Chunker() *level.Chunker {
+	return w.chunks
+}
+
+// ScrollTo sets the viewport scroll position.
+func (w *Canvas) ScrollTo(to render.Point) {
+	w.Scroll.X = to.X
+	w.Scroll.Y = to.Y
+}
+
+// ScrollBy adjusts the viewport scroll position.
+func (w *Canvas) ScrollBy(by render.Point) {
+	w.Scroll.Add(by)
+}
+
+// Compute the canvas.
+func (w *Canvas) Compute(e render.Engine) {
+
+}

src/uix/canvas_actors.go

@@ -0,0 +1,115 @@
+package uix
+
+import (
+	"fmt"
+
+	"git.kirsle.net/apps/doodle/lib/render"
+	"git.kirsle.net/apps/doodle/pkg/userdir"
+	"git.kirsle.net/apps/doodle/src/doodads"
+	"git.kirsle.net/apps/doodle/src/level"
+)
+
+// InstallActors adds external Actors to the canvas to be superimposed on top
+// of the drawing.
+func (w *Canvas) InstallActors(actors level.ActorMap) error {
+	w.actors = make([]*Actor, 0)
+	for id, actor := range actors {
+		doodad, err := doodads.LoadJSON(userdir.DoodadPath(actor.Filename))
+		if err != nil {
+			return fmt.Errorf("InstallActors: %s", err)
+		}
+
+		w.actors = append(w.actors, NewActor(id, actor, doodad))
+	}
+	return nil
+}
+
+// AddActor injects additional actors into the canvas, such as a Player doodad.
+func (w *Canvas) AddActor(actor *Actor) error {
+	w.actors = append(w.actors, actor)
+	return nil
+}
+
+// drawActors is a subroutine of Present() that superimposes the actors on top
+// of the level drawing.
+func (w *Canvas) drawActors(e render.Engine, p render.Point) {
+	var (
+		Viewport = w.ViewportRelative()
+		S        = w.Size()
+	)
+
+	// See if each Actor is in range of the Viewport.
+	for i, a := range w.actors {
+		if a == nil {
+			log.Error("Canvas.drawActors: null actor at index %d (of %d actors)", i, len(w.actors))
+			continue
+		}
+		var (
+			actor      = a.Actor     // Static Actor instance from Level file, DO NOT CHANGE
+			can        = a.Canvas    // Canvas widget that draws the actor
+			actorPoint = actor.Point // XXX TODO: DO NOT CHANGE
+			actorSize  = can.Size()
+		)
+
+		// Create a box of World Coordinates that this actor occupies. The
+		// Actor X,Y from level data is already a World Coordinate;
+		// accomodate for the size of the Actor.
+		actorBox := render.Rect{
+			X: actorPoint.X,
+			Y: actorPoint.Y,
+			W: actorSize.W,
+			H: actorSize.H,
+		}
+
+		// Is any part of the actor visible?
+		if !Viewport.Intersects(actorBox) {
+			continue // not visible on screen
+		}
+
+		drawAt := render.Point{
+			X: p.X + w.Scroll.X + actorPoint.X + w.BoxThickness(1),
+			Y: p.Y + w.Scroll.Y + actorPoint.Y + w.BoxThickness(1),
+		}
+		resizeTo := actorSize
+
+		// XXX TODO: when an Actor hits the left or top edge and shrinks,
+		// scrolling to offset that shrink is currently hard to solve.
+		scrollTo := render.Origin
+
+		// Handle cropping and scaling if this Actor's canvas can't be
+		// completely visible within the parent.
+		if drawAt.X+resizeTo.W > p.X+S.W {
+			// Hitting the right edge, shrunk the width now.
+			delta := (drawAt.X + resizeTo.W) - (p.X + S.W)
+			resizeTo.W -= delta
+		} else if drawAt.X < p.X {
+			// Hitting the left edge. Cap the X coord and shrink the width.
+			delta := p.X - drawAt.X // positive number
+			drawAt.X = p.X
+			// scrollTo.X -= delta // TODO
+			resizeTo.W -= delta
+		}
+
+		if drawAt.Y+resizeTo.H > p.Y+S.H {
+			// Hitting the bottom edge, shrink the height.
+			delta := (drawAt.Y + resizeTo.H) - (p.Y + S.H)
+			resizeTo.H -= delta
+		} else if drawAt.Y < p.Y {
+			// Hitting the top edge. Cap the Y coord and shrink the height.
+			delta := p.Y - drawAt.Y
+			drawAt.Y = p.Y
+			// scrollTo.Y -= delta // TODO
+			resizeTo.H -= delta
+		}
+
+		if resizeTo != actorSize {
+			can.Resize(resizeTo)
+			can.ScrollTo(scrollTo)
+		}
+		can.Present(e, drawAt)
+
+		// Clean up the canvas size and offset.
+		can.Resize(actorSize) // restore original size in case cropped
+		can.ScrollTo(render.Origin)
+	}
+}

src/uix/canvas_editable.go

@@ -1,10 +1,10 @@
 package uix
 
 import (
-	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/lib/render"
-	"git.kirsle.net/apps/doodle/level"
+	"git.kirsle.net/apps/doodle/lib/ui"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/events"
-	"git.kirsle.net/apps/doodle/ui"
+	"git.kirsle.net/apps/doodle/src/level"
 )
 
 // loopEditable handles the Loop() part for editable canvases.

src/uix/canvas_present.go

@@ -0,0 +1,171 @@
+package uix
+
+import (
+	"fmt"
+	"strings"
+
+	"git.kirsle.net/apps/doodle/lib/render"
+	"git.kirsle.net/apps/doodle/lib/ui"
+	"git.kirsle.net/apps/doodle/src/balance"
+)
+
+// Present the canvas.
+func (w *Canvas) Present(e render.Engine, p render.Point) {
+	var (
+		S        = w.Size()
+		Viewport = w.Viewport()
+	)
+	// w.MoveTo(p) // TODO: when uncommented the canvas will creep down the Workspace frame in EditorMode
+	w.DrawBox(e, p)
+	e.DrawBox(w.Background(), render.Rect{
+		X: p.X + w.BoxThickness(1),
+		Y: p.Y + w.BoxThickness(1),
+		W: S.W - w.BoxThickness(2),
+		H: S.H - w.BoxThickness(2),
+	})
+
+	// Draw the wallpaper.
+	if w.wallpaper.Valid() {
+		err := w.PresentWallpaper(e, p)
+		if err != nil {
+			log.Error(err.Error())
+		}
+	}
+
+	// Get the chunks in the viewport and cache their textures.
+	for coord := range w.chunks.IterViewportChunks(Viewport) {
+		if chunk, ok := w.chunks.GetChunk(coord); ok {
+			var tex render.Texturer
+			if w.MaskColor != render.Invisible {
+				tex = chunk.TextureMasked(e, w.MaskColor)
+			} else {
+				tex = chunk.Texture(e)
+			}
+			src := render.Rect{
+				W: tex.Size().W,
+				H: tex.Size().H,
+			}
+
+			// If the source bitmap is already bigger than the Canvas widget
+			// into which it will render, cap the source width and height.
+			// This is especially useful for Doodad buttons because the drawing
+			// is bigger than the button.
+			if src.W > S.W {
+				src.W = S.W
+			}
+			if src.H > S.H {
+				src.H = S.H
+			}
+
+			dst := render.Rect{
+				X: p.X + w.Scroll.X + w.BoxThickness(1) + (coord.X * int32(chunk.Size)),
+				Y: p.Y + w.Scroll.Y + w.BoxThickness(1) + (coord.Y * int32(chunk.Size)),
+
+				// src.W and src.H will be AT MOST the full width and height of
+				// a Canvas widget. Subtract the scroll offset to keep it bounded
+				// visually on its right and bottom sides.
+				W: src.W,
+				H: src.H,
+			}
+
+			// TODO: all this shit is in TrimBox(), make it DRY
+
+			// If the destination width will cause it to overflow the widget
+			// box, trim off the right edge of the destination rect.
+			//
+			// Keep in mind we're dealing with chunks here, and a chunk is
+			// a small part of the image. Example:
+			// - Canvas is 800x600 (S.W=800  S.H=600)
+			// - Chunk wants to render at 790,0 width 100,100 or whatever
+			//   dst={790, 0, 100, 100}
+			// - Chunk box would exceed 800px width (X=790 + W=100 == 890)
+			// - Find the delta how much it exceeds as negative (800 - 890 == -90)
+			// - Lower the Source and Dest rects by that delta size so they
+			//   stay proportional and don't scale or anything dumb.
+			if dst.X+src.W > p.X+S.W {
+				// NOTE: delta is a negative number,
+				// so it will subtract from the width.
+				delta := (p.X + S.W - w.BoxThickness(1)) - (dst.W + dst.X)
+				src.W += delta
+				dst.W += delta
+			}
+			if dst.Y+src.H > p.Y+S.H {
+				// NOTE: delta is a negative number
+				delta := (p.Y + S.H - w.BoxThickness(1)) - (dst.H + dst.Y)
+				src.H += delta
+				dst.H += delta
+			}
+
+			// The same for the top left edge, so the drawings don't overlap
+			// menu bars or left side toolbars.
+			// - Canvas was placed 80px from the left of the screen.
+			//   Canvas.MoveTo(80, 0)
+			// - A texture wants to draw at 60, 0 which would cause it to
+			//   overlap 20 pixels into the left toolbar. It needs to be cropped.
+			// - The delta is: p.X=80 - dst.X=60 == 20
+			// - Set destination X to p.X to constrain it there: 20
+			// - Subtract the delta from destination W so we don't scale it.
+			// - Add 20 to X of the source: the left edge of source is not visible
+			if dst.X < p.X {
+				// NOTE: delta is a positive number,
+				// so it will add to the destination coordinates.
+				delta := p.X - dst.X
+				dst.X = p.X + w.BoxThickness(1)
+				dst.W -= delta
+				src.X += delta
+			}
+			if dst.Y < p.Y {
+				delta := p.Y - dst.Y
+				dst.Y = p.Y + w.BoxThickness(1)
+				dst.H -= delta
+				src.Y += delta
+			}
+
+			// Trim the destination width so it doesn't overlap the Canvas border.
+			if dst.W >= S.W-w.BoxThickness(1) {
+				dst.W = S.W - w.BoxThickness(1)
+			}
+
+			e.Copy(tex, src, dst)
+		}
+	}
+
+	w.drawActors(e, p)
+
+	// XXX: Debug, show label in canvas corner.
+	if balance.DebugCanvasLabel {
+		rows := []string{
+			w.Name,
+
+			// XXX: debug options, uncomment for more details
+
+			// Size of the canvas
+			// fmt.Sprintf("S=%d,%d", S.W, S.H),
+
+			// Viewport of the canvas
+			// fmt.Sprintf("V=%d,%d:%d,%d",
+			// 	Viewport.X, Viewport.Y,
+			// 	Viewport.W, Viewport.H,
+			// ),
+		}
+		if w.actor != nil {
+			rows = append(rows,
+				fmt.Sprintf("WP=%s", w.actor.Point),
+			)
+		}
+		label := ui.NewLabel(ui.Label{
+			Text: strings.Join(rows, "\n"),
+			Font: render.Text{
+				FontFilename: balance.ShellFontFilename,
+				Size:         balance.ShellFontSizeSmall,
+				Color:        render.White,
+			},
+		})
+		label.SetBackground(render.RGBA(0, 0, 50, 150))
+		label.Compute(e)
+		label.Present(e, render.Point{
+			X: p.X + S.W - label.Size().W - w.BoxThickness(1),
+			Y: p.Y + w.BoxThickness(1),
+		})
+	}
+}

src/uix/canvas_scrolling.go

@@ -0,0 +1,187 @@
+package uix
+
+import (
+	"errors"
+	"fmt"
+
+	"git.kirsle.net/apps/doodle/lib/render"
+	"git.kirsle.net/apps/doodle/lib/ui"
+	"git.kirsle.net/apps/doodle/src/balance"
+	"git.kirsle.net/apps/doodle/src/events"
+	"git.kirsle.net/apps/doodle/src/level"
+)
+
+/*
+Loop() subroutine to scroll the canvas using arrow keys (for edit mode).
+
+If w.Scrollable is false this function won't do anything.
+
+Cursor keys will scroll the drawing by balance.CanvasScrollSpeed per tick.
+If the level pageType is constrained, the scrollable viewport will be
+constrained to fit the bounds of the level.
+
+The debug boolean `NoLimitScroll=true` will override the bounded level scroll
+restriction and allow scrolling into out-of-bounds areas of the level.
+*/
+func (w *Canvas) loopEditorScroll(ev *events.State) error {
+	if !w.Scrollable {
+		return errors.New("canvas not scrollable")
+	}
+
+	// Arrow keys to scroll the view.
+	scrollBy := render.Point{}
+	if ev.Right.Now {
+		scrollBy.X -= balance.CanvasScrollSpeed
+	} else if ev.Left.Now {
+		scrollBy.X += balance.CanvasScrollSpeed
+	}
+	if ev.Down.Now {
+		scrollBy.Y -= balance.CanvasScrollSpeed
+	} else if ev.Up.Now {
+		scrollBy.Y += balance.CanvasScrollSpeed
+	}
+	if !scrollBy.IsZero() {
+		w.ScrollBy(scrollBy)
+	}
+
+	return nil
+}
+
+/*
+Loop() subroutine to constrain the scrolled view to within a bounded level.
+*/
+func (w *Canvas) loopConstrainScroll() error {
+	if w.NoLimitScroll {
+		return errors.New("NoLimitScroll enabled")
+	}
+
+	var capped bool
+
+	// Constrain the top and left edges.
+	if w.wallpaper.pageType > level.Unbounded {
+		if w.Scroll.X > 0 {
+			w.Scroll.X = 0
+			capped = true
+		}
+		if w.Scroll.Y > 0 {
+			w.Scroll.Y = 0
+			capped = true
+		}
+	}
+
+	// Constrain the bottom and right for limited world sizes.
+	if w.wallpaper.maxWidth+w.wallpaper.maxHeight > 0 {
+		var (
+			// TODO: downcast from int64!
+			mw       = int32(w.wallpaper.maxWidth)
+			mh       = int32(w.wallpaper.maxHeight)
+			Viewport = w.Viewport()
+		)
+		if Viewport.W > mw {
+			delta := Viewport.W - mw
+			w.Scroll.X += delta
+			capped = true
+		}
+		if Viewport.H > mh {
+			delta := Viewport.H - mh
+			w.Scroll.Y += delta
+			capped = true
+		}
+	}
+
+	if capped {
+		return errors.New("scroll limited by level constraint")
+	}
+
+	return nil
+}
+
+/*
+Loop() subroutine for Play Mode to follow an actor in the camera's view.
+
+Does nothing if w.FollowActor is an empty string. Set it to the ID of an Actor
+to follow. If the actor exists, the Canvas will scroll to keep it on the
+screen.
+*/
+func (w *Canvas) loopFollowActor(ev *events.State) error {
+	// Are we following an actor?
+	if w.FollowActor == "" {
+		return nil
+	}
+
+	var (
+		P = w.Point()
+		S = w.Size()
+	)
+
+	// Find the actor.
+	for _, actor := range w.actors {
+		if actor.ID() != w.FollowActor {
+			continue
+		}
+
+		actor.Canvas.SetBorderSize(2)
+		actor.Canvas.SetBorderColor(render.Yellow)
+		actor.Canvas.SetBorderStyle(ui.BorderSolid)
+
+		var (
+			APosition = actor.Position() // relative to screen
+			APoint    = actor.Drawing.Position()
+			ASize     = actor.Drawing.Size()
+			scrollBy  render.Point
+		)
+
+		// Scroll left
+		if APosition.X-P.X <= int32(balance.ScrollboxHoz) {
+			var delta = APoint.X - P.X
+			if delta > int32(balance.ScrollMaxVelocity) {
+				delta = int32(balance.ScrollMaxVelocity)
+			}
+
+			if delta < 0 {
+				// constrain in case they're FAR OFF SCREEN so we don't flip back around
+				delta = -delta
+			}
+			scrollBy.X = delta
+		}
+
+		// Scroll right
+		if APosition.X >= S.W-ASize.W-int32(balance.ScrollboxHoz) {
+			var delta = S.W - ASize.W - int32(balance.ScrollboxHoz)
+			if delta > int32(balance.ScrollMaxVelocity) {
+				delta = int32(balance.ScrollMaxVelocity)
+			}
+			scrollBy.X = -delta
+		}
+
+		// Scroll up
+		if APosition.Y-P.Y <= int32(balance.ScrollboxVert) {
+			var delta = APoint.Y - P.Y
+			if delta > int32(balance.ScrollMaxVelocity) {
+				delta = int32(balance.ScrollMaxVelocity)
+			}
+
+			if delta < 0 {
+				delta = -delta
+			}
+			scrollBy.Y = delta
+		}
+
+		// Scroll down
+		if APosition.Y >= S.H-ASize.H-int32(balance.ScrollboxVert) {
+			var delta = S.H - ASize.H - int32(balance.ScrollboxVert)
+			if delta > int32(balance.ScrollMaxVelocity) {
+				delta = int32(balance.ScrollMaxVelocity)
+			}
+			scrollBy.Y = -delta
+		}
+
+		if scrollBy != render.Origin {
+			w.ScrollBy(scrollBy)
+		}
+
+		return nil
+	}
+
+	return fmt.Errorf("actor ID '%s' not found in level", w.FollowActor)
+}

src/uix/canvas_wallpaper.go

@@ -1,9 +1,9 @@
 package uix
 
 import (
-	"git.kirsle.net/apps/doodle/level"
+	"git.kirsle.net/apps/doodle/lib/render"
 	"git.kirsle.net/apps/doodle/pkg/wallpaper"
-	"git.kirsle.net/apps/doodle/render"
+	"git.kirsle.net/apps/doodle/src/level"
 )
 
 // Wallpaper configures the wallpaper in a Canvas.

uix/canvas.go

@@ -1,559 +0,0 @@
-package uix
-
-import (
-	"fmt"
-	"os"
-	"strings"
-
-	"git.kirsle.net/apps/doodle/balance"
-	"git.kirsle.net/apps/doodle/doodads"
-	"git.kirsle.net/apps/doodle/events"
-	"git.kirsle.net/apps/doodle/level"
-	"git.kirsle.net/apps/doodle/pkg/userdir"
-	"git.kirsle.net/apps/doodle/pkg/wallpaper"
-	"git.kirsle.net/apps/doodle/render"
-	"git.kirsle.net/apps/doodle/ui"
-)
-
-// Canvas is a custom ui.Widget that manages a single drawing.
-type Canvas struct {
-	ui.Frame
-	Palette *level.Palette
-
-	// Editable and Scrollable go hand in hand and, if you initialize a
-	// NewCanvas() with editable=true, they are both enabled.
-	Editable   bool // Clicking will edit pixels of this canvas.
-	Scrollable bool // Cursor keys will scroll the viewport of this canvas.
-
-	// Selected draw tool/mode, default Pencil, for editable canvases.
-	Tool Tool
-
-	// MaskColor will force every pixel to render as this color regardless of
-	// the palette index of that pixel. Otherwise pixels behave the same and
-	// the palette does work as normal. Set to render.Invisible (zero value)
-	// to remove the mask.
-	MaskColor render.Color
-
-	// Debug tools
-	// NoLimitScroll suppresses the scroll limit for bounded levels.
-	NoLimitScroll bool
-
-	// Underlying chunk data for the drawing.
-	chunks *level.Chunker
-
-	// Actors to superimpose on top of the drawing.
-	actor  *level.Actor // if this canvas IS an actor
-	actors []*Actor
-
-	// Wallpaper settings.
-	wallpaper *Wallpaper
-
-	// When the Canvas wants to delete Actors, but ultimately it is upstream
-	// that controls the actors. Upstream should delete them and then reinstall
-	// the actor list from scratch.
-	OnDeleteActors func([]*level.Actor)
-	OnDragStart    func(filename string)
-
-	// Tracking pixels while editing. TODO: get rid of pixelHistory?
-	pixelHistory []*level.Pixel
-	lastPixel    *level.Pixel
-
-	// We inherit the ui.Widget which manages the width and height.
-	Scroll render.Point // Scroll offset for which parts of canvas are visible.
-}
-
-// Actor is an instance of an actor with a Canvas attached.
-type Actor struct {
-	Actor  *level.Actor
-	Canvas *Canvas
-}
-
-// NewCanvas initializes a Canvas widget.
-//
-// If editable is true, Scrollable is also set to true, which means the arrow
-// keys will scroll the canvas viewport which is desirable in Edit Mode.
-func NewCanvas(size int, editable bool) *Canvas {
-	w := &Canvas{
-		Editable:   editable,
-		Scrollable: editable,
-		Palette:    level.NewPalette(),
-		chunks:     level.NewChunker(size),
-		actors:     make([]*Actor, 0),
-		wallpaper:  &Wallpaper{},
-	}
-	w.setup()
-	w.IDFunc(func() string {
-		var attrs []string
-
-		if w.Editable {
-			attrs = append(attrs, "editable")
-		} else {
-			attrs = append(attrs, "read-only")
-		}
-
-		if w.Scrollable {
-			attrs = append(attrs, "scrollable")
-		}
-
-		return fmt.Sprintf("Canvas<%d; %s>", size, strings.Join(attrs, "; "))
-	})
-	return w
-}
-
-// Load initializes the Canvas using an existing Palette and Grid.
-func (w *Canvas) Load(p *level.Palette, g *level.Chunker) {
-	w.Palette = p
-	w.chunks = g
-
-	if len(w.Palette.Swatches) > 0 {
-		w.SetSwatch(w.Palette.Swatches[0])
-	}
-}
-
-// LoadLevel initializes a Canvas from a Level object.
-func (w *Canvas) LoadLevel(e render.Engine, level *level.Level) {
-	w.Load(level.Palette, level.Chunker)
-
-	// TODO: wallpaper paths
-	filename := "assets/wallpapers/" + level.Wallpaper
-	if _, err := os.Stat(filename); os.IsNotExist(err) {
-		log.Error("LoadLevel: %s", err)
-		filename = "assets/wallpapers/notebook.png" // XXX TODO
-	}
-
-	wp, err := wallpaper.FromFile(e, filename)
-	if err != nil {
-		log.Error("wallpaper FromFile(%s): %s", filename, err)
-	}
-
-	w.wallpaper.maxWidth = level.MaxWidth
-	w.wallpaper.maxHeight = level.MaxHeight
-	err = w.wallpaper.Load(e, level.PageType, wp)
-	if err != nil {
-		log.Error("wallpaper Load: %s", err)
-	}
-}
-
-// LoadDoodad initializes a Canvas from a Doodad object.
-func (w *Canvas) LoadDoodad(d *doodads.Doodad) {
-	// TODO more safe
-	w.Load(d.Palette, d.Layers[0].Chunker)
-}
-
-// InstallActors adds external Actors to the canvas to be superimposed on top
-// of the drawing.
-func (w *Canvas) InstallActors(actors level.ActorMap) error {
-	w.actors = make([]*Actor, 0)
-	for id, actor := range actors {
-		log.Info("InstallActors: %s", id)
-
-		doodad, err := doodads.LoadJSON(userdir.DoodadPath(actor.Filename))
-		if err != nil {
-			return fmt.Errorf("InstallActors: %s", err)
-		}
-
-		size := int32(doodad.Layers[0].Chunker.Size)
-		can := NewCanvas(int(size), false)
-		can.Name = id
-		can.actor = actor
-		// TODO: if the Background is render.Invisible it gets defaulted to
-		// White somewhere and the Doodad masks the level drawing behind it.
-		can.SetBackground(render.RGBA(0, 0, 1, 0))
-		can.LoadDoodad(doodad)
-		can.Resize(render.NewRect(size, size))
-		w.actors = append(w.actors, &Actor{
-			Actor:  actor,
-			Canvas: can,
-		})
-	}
-	return nil
-}
-
-// SetSwatch changes the currently selected swatch for editing.
-func (w *Canvas) SetSwatch(s *level.Swatch) {
-	w.Palette.ActiveSwatch = s
-}
-
-// setup common configs between both initializers of the canvas.
-func (w *Canvas) setup() {
-	// XXX: Debug code.
-	if balance.DebugCanvasBorder != render.Invisible {
-		w.Configure(ui.Config{
-			BorderColor: balance.DebugCanvasBorder,
-			BorderSize:  2,
-			BorderStyle: ui.BorderSolid,
-		})
-	}
-}
-
-// Loop is called on the scene's event loop to handle mouse interaction with
-// the canvas, i.e. to edit it.
-func (w *Canvas) Loop(ev *events.State) error {
-	if w.Scrollable {
-		// Arrow keys to scroll the view.
-		scrollBy := render.Point{}
-		if ev.Right.Now {
-			scrollBy.X -= balance.CanvasScrollSpeed
-		} else if ev.Left.Now {
-			scrollBy.X += balance.CanvasScrollSpeed
-		}
-		if ev.Down.Now {
-			scrollBy.Y -= balance.CanvasScrollSpeed
-		} else if ev.Up.Now {
-			scrollBy.Y += balance.CanvasScrollSpeed
-		}
-		if !scrollBy.IsZero() {
-			w.ScrollBy(scrollBy)
-		}
-	}
-
-	// If the canvas is editable, only care if it's over our space.
-	if w.Editable {
-		cursor := render.NewPoint(ev.CursorX.Now, ev.CursorY.Now)
-		if cursor.Inside(ui.AbsoluteRect(w)) {
-			return w.loopEditable(ev)
-		}
-	}
-	return nil
-}
-
-// Viewport returns a rect containing the viewable drawing coordinates in this
-// canvas. The X,Y values are the scroll offset (top left) and the W,H values
-// are the scroll offset plus the width/height of the Canvas widget.
-//
-// The Viewport rect are the Absolute World Coordinates of the drawing that are
-// visible inside the Canvas. The X,Y is the top left World Coordinate and the
-// W,H are the bottom right World Coordinate, making this rect an absolute
-// slice of the world. For a normal rect with a relative width and height,
-// use ViewportRelative().
-//
-// The rect X,Y are the negative Scroll Value.
-// The rect W,H are the Canvas widget size minus the Scroll Value.
-func (w *Canvas) Viewport() render.Rect {
-	var S = w.Size()
-	return render.Rect{
-		X: -w.Scroll.X,
-		Y: -w.Scroll.Y,
-		W: S.W - w.Scroll.X,
-		H: S.H - w.Scroll.Y,
-	}
-}
-
-// ViewportRelative returns a relative viewport where the Width and Height
-// values are zero-relative: so you can use it with point.Inside(viewport)
-// to see if a World Index point should be visible on screen.
-//
-// The rect X,Y are the negative Scroll Value
-// The rect W,H are the Canvas widget size.
-func (w *Canvas) ViewportRelative() render.Rect {
-	var S = w.Size()
-	return render.Rect{
-		X: -w.Scroll.X,
-		Y: -w.Scroll.Y,
-		W: S.W,
-		H: S.H,
-	}
-}
-
-// WorldIndexAt returns the World Index that corresponds to a Screen Pixel
-// on the screen. If the screen pixel is the mouse coordinate (relative to
-// the application window) this will return the World Index of the pixel below
-// the mouse cursor.
-func (w *Canvas) WorldIndexAt(screenPixel render.Point) render.Point {
-	var P = ui.AbsolutePosition(w)
-	return render.Point{
-		X: screenPixel.X - P.X - w.Scroll.X,
-		Y: screenPixel.Y - P.Y - w.Scroll.Y,
-	}
-}
-
-// Chunker returns the underlying Chunker object.
-func (w *Canvas) Chunker() *level.Chunker {
-	return w.chunks
-}
-
-// ScrollTo sets the viewport scroll position.
-func (w *Canvas) ScrollTo(to render.Point) {
-	w.Scroll.X = to.X
-	w.Scroll.Y = to.Y
-}
-
-// ScrollBy adjusts the viewport scroll position.
-func (w *Canvas) ScrollBy(by render.Point) {
-	w.Scroll.Add(by)
-}
-
-// Compute the canvas.
-func (w *Canvas) Compute(e render.Engine) {
-
-}
-
-// Present the canvas.
-func (w *Canvas) Present(e render.Engine, p render.Point) {
-	var (
-		S        = w.Size()
-		Viewport = w.Viewport()
-	)
-	// w.MoveTo(p) // TODO: when uncommented the canvas will creep down the Workspace frame in EditorMode
-	w.DrawBox(e, p)
-	e.DrawBox(w.Background(), render.Rect{
-		X: p.X + w.BoxThickness(1),
-		Y: p.Y + w.BoxThickness(1),
-		W: S.W - w.BoxThickness(2),
-		H: S.H - w.BoxThickness(2),
-	})
-
-	// Constrain the scroll view if the level is bounded.
-	if w.Scrollable && !w.NoLimitScroll {
-		// Constrain the top and left edges.
-		if w.wallpaper.pageType > level.Unbounded {
-			if w.Scroll.X > 0 {
-				w.Scroll.X = 0
-			}
-			if w.Scroll.Y > 0 {
-				w.Scroll.Y = 0
-			}
-		}
-
-		// Constrain the bottom and right for limited world sizes.
-		if w.wallpaper.maxWidth > 0 && w.wallpaper.maxHeight > 0 {
-			var (
-				// TODO: downcast from int64!
-				mw = int32(w.wallpaper.maxWidth)
-				mh = int32(w.wallpaper.maxHeight)
-			)
-			if Viewport.W > mw {
-				delta := Viewport.W - mw
-				w.Scroll.X += delta
-			}
-			if Viewport.H > mh {
-				delta := Viewport.H - mh
-				w.Scroll.Y += delta
-			}
-		}
-	}
-
-	// Draw the wallpaper.
-	if w.wallpaper.Valid() {
-		err := w.PresentWallpaper(e, p)
-		if err != nil {
-			log.Error(err.Error())
-		}
-	}
-
-	// Get the chunks in the viewport and cache their textures.
-	for coord := range w.chunks.IterViewportChunks(Viewport) {
-		if chunk, ok := w.chunks.GetChunk(coord); ok {
-			var tex render.Texturer
-			if w.MaskColor != render.Invisible {
-				tex = chunk.TextureMasked(e, w.MaskColor)
-			} else {
-				tex = chunk.Texture(e)
-			}
-			src := render.Rect{
-				W: tex.Size().W,
-				H: tex.Size().H,
-			}
-
-			// If the source bitmap is already bigger than the Canvas widget
-			// into which it will render, cap the source width and height.
-			// This is especially useful for Doodad buttons because the drawing
-			// is bigger than the button.
-			if src.W > S.W {
-				src.W = S.W
-			}
-			if src.H > S.H {
-				src.H = S.H
-			}
-
-			dst := render.Rect{
-				X: p.X + w.Scroll.X + w.BoxThickness(1) + (coord.X * int32(chunk.Size)),
-				Y: p.Y + w.Scroll.Y + w.BoxThickness(1) + (coord.Y * int32(chunk.Size)),
-
-				// src.W and src.H will be AT MOST the full width and height of
-				// a Canvas widget. Subtract the scroll offset to keep it bounded
-				// visually on its right and bottom sides.
-				W: src.W,
-				H: src.H,
-			}
-
-			// TODO: all this shit is in TrimBox(), make it DRY
-
-			// If the destination width will cause it to overflow the widget
-			// box, trim off the right edge of the destination rect.
-			//
-			// Keep in mind we're dealing with chunks here, and a chunk is
-			// a small part of the image. Example:
-			// - Canvas is 800x600 (S.W=800  S.H=600)
-			// - Chunk wants to render at 790,0 width 100,100 or whatever
-			//   dst={790, 0, 100, 100}
-			// - Chunk box would exceed 800px width (X=790 + W=100 == 890)
-			// - Find the delta how much it exceeds as negative (800 - 890 == -90)
-			// - Lower the Source and Dest rects by that delta size so they
-			//   stay proportional and don't scale or anything dumb.
-			if dst.X+src.W > p.X+S.W {
-				// NOTE: delta is a negative number,
-				// so it will subtract from the width.
-				delta := (p.X + S.W - w.BoxThickness(1)) - (dst.W + dst.X)
-				src.W += delta
-				dst.W += delta
-			}
-			if dst.Y+src.H > p.Y+S.H {
-				// NOTE: delta is a negative number
-				delta := (p.Y + S.H - w.BoxThickness(1)) - (dst.H + dst.Y)
-				src.H += delta
-				dst.H += delta
-			}
-
-			// The same for the top left edge, so the drawings don't overlap
-			// menu bars or left side toolbars.
-			// - Canvas was placed 80px from the left of the screen.
-			//   Canvas.MoveTo(80, 0)
-			// - A texture wants to draw at 60, 0 which would cause it to
-			//   overlap 20 pixels into the left toolbar. It needs to be cropped.
-			// - The delta is: p.X=80 - dst.X=60 == 20
-			// - Set destination X to p.X to constrain it there: 20
-			// - Subtract the delta from destination W so we don't scale it.
-			// - Add 20 to X of the source: the left edge of source is not visible
-			if dst.X < p.X {
-				// NOTE: delta is a positive number,
-				// so it will add to the destination coordinates.
-				delta := p.X - dst.X
-				dst.X = p.X + w.BoxThickness(1)
-				dst.W -= delta
-				src.X += delta
-			}
-			if dst.Y < p.Y {
-				delta := p.Y - dst.Y
-				dst.Y = p.Y + w.BoxThickness(1)
-				dst.H -= delta
-				src.Y += delta
-			}
-
-			// Trim the destination width so it doesn't overlap the Canvas border.
-			if dst.W >= S.W-w.BoxThickness(1) {
-				dst.W = S.W - w.BoxThickness(1)
-			}
-
-			e.Copy(tex, src, dst)
-		}
-	}
-
-	w.drawActors(e, p)
-
-	// XXX: Debug, show label in canvas corner.
-	if balance.DebugCanvasLabel {
-		rows := []string{
-			w.Name,
-
-			// XXX: debug options, uncomment for more details
-
-			// Size of the canvas
-			// fmt.Sprintf("S=%d,%d", S.W, S.H),
-
-			// Viewport of the canvas
-			// fmt.Sprintf("V=%d,%d:%d,%d",
-			// 	Viewport.X, Viewport.Y,
-			// 	Viewport.W, Viewport.H,
-			// ),
-		}
-		if w.actor != nil {
-			rows = append(rows,
-				fmt.Sprintf("WP=%s", w.actor.Point),
-			)
-		}
-		label := ui.NewLabel(ui.Label{
-			Text: strings.Join(rows, "\n"),
-			Font: render.Text{
-				FontFilename: balance.ShellFontFilename,
-				Size:         balance.ShellFontSizeSmall,
-				Color:        render.White,
-			},
-		})
-		label.SetBackground(render.RGBA(0, 0, 50, 150))
-		label.Compute(e)
-		label.Present(e, render.Point{
-			X: p.X + S.W - label.Size().W - w.BoxThickness(1),
-			Y: p.Y + w.BoxThickness(1),
-		})
-	}
-}
-
-// drawActors superimposes the actors on top of the drawing.
-func (w *Canvas) drawActors(e render.Engine, p render.Point) {
-	var (
-		Viewport = w.ViewportRelative()
-		S        = w.Size()
-	)
-
-	// See if each Actor is in range of the Viewport.
-	for _, a := range w.actors {
-		var (
-			actor      = a.Actor     // Static Actor instance from Level file, DO NOT CHANGE
-			can        = a.Canvas    // Canvas widget that draws the actor
-			actorPoint = actor.Point // XXX TODO: DO NOT CHANGE
-			actorSize  = can.Size()
-		)
-
-		// Create a box of World Coordinates that this actor occupies. The
-		// Actor X,Y from level data is already a World Coordinate;
-		// accomodate for the size of the Actor.
-		actorBox := render.Rect{
-			X: actorPoint.X,
-			Y: actorPoint.Y,
-			W: actorSize.W,
-			H: actorSize.H,
-		}
-
-		// Is any part of the actor visible?
-		if !Viewport.Intersects(actorBox) {
-			continue // not visible on screen
-		}
-
-		drawAt := render.Point{
-			X: p.X + w.Scroll.X + actorPoint.X + w.BoxThickness(1),
-			Y: p.Y + w.Scroll.Y + actorPoint.Y + w.BoxThickness(1),
-		}
-		resizeTo := actorSize
-
-		// XXX TODO: when an Actor hits the left or top edge and shrinks,
-		// scrolling to offset that shrink is currently hard to solve.
-		scrollTo := render.Origin
-
-		// Handle cropping and scaling if this Actor's canvas can't be
-		// completely visible within the parent.
-		if drawAt.X+resizeTo.W > p.X+S.W {
-			// Hitting the right edge, shrunk the width now.
-			delta := (drawAt.X + resizeTo.W) - (p.X + S.W)
-			resizeTo.W -= delta
-		} else if drawAt.X < p.X {
-			// Hitting the left edge. Cap the X coord and shrink the width.
-			delta := p.X - drawAt.X // positive number
-			drawAt.X = p.X
-			// scrollTo.X -= delta // TODO
-			resizeTo.W -= delta
-		}
-
-		if drawAt.Y+resizeTo.H > p.Y+S.H {
-			// Hitting the bottom edge, shrink the height.
-			delta := (drawAt.Y + resizeTo.H) - (p.Y + S.H)
-			resizeTo.H -= delta
-		} else if drawAt.Y < p.Y {
-			// Hitting the top edge. Cap the Y coord and shrink the height.
-			delta := p.Y - drawAt.Y
-			drawAt.Y = p.Y
-			// scrollTo.Y -= delta // TODO
-			resizeTo.H -= delta
-		}
-
-		if resizeTo != actorSize {
-			can.Resize(resizeTo)
-			can.ScrollTo(scrollTo)
-		}
-		can.Present(e, drawAt)
-
-		// Clean up the canvas size and offset.
-		can.Resize(actorSize) // restore original size in case cropped
-		can.ScrollTo(render.Origin)
-	}
-}