.gitignore

@@ -3,3 +3,4 @@ maps/
 bin/
 screenshot-*.png
 map-*.json
+pkg/wallpaper/*.png

balance/README.md

@@ -35,3 +35,7 @@ like `#FF00FF99` for 153 ($99) on the alpha channel.
   * `D_SCROLL_SPEED=8`: Canvas scroll speed when using the keyboard arrows
     in the Editor Mode, in pixels per tick.
   * `D_DOODAD_SIZE=100`: Default size when creating a new Doodad.
+
+Development booleans for unit tests (set to any non-empty value):
+
+* `T_WALLPAPER_PNG` for pkg/wallpaper to output PNG images.

cmd/doodle/main.go

@@ -7,6 +7,8 @@ import (
 	"git.kirsle.net/apps/doodle"
 	"git.kirsle.net/apps/doodle/balance"
 	"git.kirsle.net/apps/doodle/render/sdl"
+
+	_ "image/png"
 )
 
 // Build number is the git commit hash.

docs/Doodad Scripts.md

@@ -0,0 +1,66 @@
+# Doodad Scripting Engine
+
+Some ideas for the scripting engine for Doodads inside your level.
+
+# Architecture
+
+The script will be an "attached file" in the Doodad format as a special file
+named "index.js" as the entry point.
+
+Each Doodad will have its `index.js` script loaded into an isolated JS
+environment where it can't access any data about other Doodads or anything
+user specific. The `main()` function is called so the Doodad script can
+set itself up.
+
+The `main()` function should:
+
+* Initialize any state variables the Doodad wants to use in its script.
+* Subscribe to callback events that the Doodad is interested in catching.
+
+The script interacts with the Doodle application through an API broker object
+(a Go surface area of functions).
+
+# API Broker Interface
+
+```go
+type API interface {
+    // "Self" functions.
+    SetFrame(frame int)  // Set the currently visible frame in this Doodad.
+    MoveTo(render.Point)
+
+    // Game functions.k
+    EndLevel()  // Exit the current level with a victory
+
+    /************************************
+     * Event Handler Callback Functions *
+     ************************************/
+
+    // When we become visible on screen or disappear off the screen.
+    OnVisible()
+    OnHidden()
+
+    // OnEnter: the other Doodad has ENTIRELY entered our box. Or if the other
+    // doodad is bigger, they have ENTIRELY enveloped ours.
+    OnEnter(func(other Doodad))
+
+    // OnCollide: when we bump into another Doodad.
+    OnCollide(func(other Doodad))
+}
+```
+
+## Mockup Script
+
+```javascript
+function main() {
+  console.log("hello world");
+
+  // Register event callbacks.
+  Doodle.OnEnter(onEnter);
+}
+
+// onEnter: handle when another Doodad (like the player) completely enters
+// the bounding box of our Doodad. Example: a level exit.
+function onEnter(other) {
+
+}
+```

editor_scene.go

@@ -24,6 +24,7 @@ type EditorScene struct {
 	DoodadSize  int
 
 	UI *EditorUI
+	d  *Doodle
 
 	// The current level or doodad object being edited, based on the
 	// DrawingType.
@@ -43,6 +44,7 @@ func (s *EditorScene) Name() string {
 func (s *EditorScene) Setup(d *Doodle) error {
 	// Initialize the user interface. It references the palette and such so it
 	// must be initialized after those things.
+	s.d = d
 	s.UI = NewEditorUI(d, s)
 
 	// Were we given configuration data?
@@ -57,7 +59,7 @@ func (s *EditorScene) Setup(d *Doodle) error {
 	case enum.LevelDrawing:
 		if s.Level != nil {
 			log.Debug("EditorScene.Setup: received level from scene caller")
-			s.UI.Canvas.LoadLevel(s.Level)
+			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)
@@ -71,7 +73,7 @@ func (s *EditorScene) Setup(d *Doodle) error {
 			log.Debug("EditorScene.Setup: initializing a new Level")
 			s.Level = level.New()
 			s.Level.Palette = level.DefaultPalette()
-			s.UI.Canvas.LoadLevel(s.Level)
+			s.UI.Canvas.LoadLevel(d.Engine, s.Level)
 			s.UI.Canvas.ScrollTo(render.Origin)
 			s.UI.Canvas.Scrollable = true
 		}
@@ -154,7 +156,7 @@ func (s *EditorScene) LoadLevel(filename string) error {
 
 	s.DrawingType = enum.LevelDrawing
 	s.Level = level
-	s.UI.Canvas.LoadLevel(s.Level)
+	s.UI.Canvas.LoadLevel(s.d.Engine, s.Level)
 
 	// TODO: debug
 	for i, actor := range level.Actors {

level/json.go

@@ -48,6 +48,11 @@ func LoadJSON(filename string) (*Level, error) {
 		return m, fmt.Errorf("level.LoadJSON: JSON decode error: %s", err)
 	}
 
+	// Fill in defaults.
+	if m.Wallpaper == "" {
+		m.Wallpaper = DefaultWallpaper
+	}
+
 	// Inflate the chunk metadata to map the pixels to their palette indexes.
 	m.Chunker.Inflate(m.Palette)
 	m.Actors.Inflate()

level/page_type.go

@@ -0,0 +1,32 @@
+package level
+
+// PageType configures the bounds and wallpaper behavior of a Level.
+type PageType int
+
+// PageType values.
+const (
+	// Unbounded means the map can grow freely in any direction.
+	// - Only the repeat texture is used for the wallpaper.
+	Unbounded PageType = iota
+
+	// NoNegativeSpace means the map is bounded at the top left edges.
+	// - Can't scroll or visit any pixels in negative X,Y coordinates.
+	// - Wallpaper shows the Corner at 0,0
+	// - Wallpaper repeats the Top along the Y=0 plane
+	// - Wallpaper repeats the Left along the X=0 plane
+	// - The repeat texture fills the rest of the level.
+	NoNegativeSpace
+
+	// Bounded is the same as NoNegativeSpace but the level is imposing a
+	// maximum cap on the width and height of the level.
+	// - Can't scroll below X,Y origin at 0,0
+	// - Can't scroll past the bounded width and height of the level
+	Bounded
+
+	// Bordered is like Bounded except the corner textures are wrapped
+	// around the other edges of the level too.
+	// - 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
+)

level/types.go

@@ -8,6 +8,11 @@ import (
 	"git.kirsle.net/apps/doodle/render"
 )
 
+// Useful variables.
+var (
+	DefaultWallpaper = "notebook.png"
+)
+
 // Base provides the common struct keys that are shared between Levels and
 // Doodads.
 type Base struct {
@@ -33,6 +38,12 @@ type Level struct {
 	// properties (solid, fire, slippery, etc.)
 	Palette *Palette `json:"palette"`
 
+	// Page boundaries and wallpaper settings.
+	PageType  PageType `json:"pageType"`
+	MaxWidth  int64    `json:"boundedWidth"` // only if bounded or bordered
+	MaxHeight int64    `json:"boundedHeight"`
+	Wallpaper string   `json:"wallpaper"`
+
 	// Actors keep a list of the doodad instances in this map.
 	Actors ActorMap `json:"actors"`
 }
@@ -46,6 +57,11 @@ func New() *Level {
 		Chunker: NewChunker(balance.ChunkSize),
 		Palette: &Palette{},
 		Actors:  ActorMap{},
+
+		PageType:  NoNegativeSpace,
+		Wallpaper: DefaultWallpaper,
+		MaxWidth:  2550,
+		MaxHeight: 3300,
 	}
 }
 

pkg/wallpaper/texture.go

@@ -0,0 +1,76 @@
+package wallpaper
+
+// The methods that deal in cached Textures for Doodle.
+
+import (
+	"fmt"
+	"image"
+	"os"
+
+	"git.kirsle.net/apps/doodle/pkg/userdir"
+	"git.kirsle.net/apps/doodle/render"
+	"golang.org/x/image/bmp"
+)
+
+// CornerTexture returns the Texture.
+func (wp *Wallpaper) CornerTexture(e render.Engine) (render.Texturer, error) {
+	fmt.Println("CornerTex")
+	if wp.tex.corner == nil {
+		tex, err := texture(e, wp.corner, wp.Name+"c")
+		wp.tex.corner = tex
+		return tex, err
+	}
+	return wp.tex.corner, nil
+}
+
+// TopTexture returns the Texture.
+func (wp *Wallpaper) TopTexture(e render.Engine) (render.Texturer, error) {
+	if wp.tex.top == nil {
+		tex, err := texture(e, wp.top, wp.Name+"t")
+		wp.tex.top = tex
+		return tex, err
+	}
+	return wp.tex.top, nil
+}
+
+// LeftTexture returns the Texture.
+func (wp *Wallpaper) LeftTexture(e render.Engine) (render.Texturer, error) {
+	if wp.tex.left == nil {
+		tex, err := texture(e, wp.left, wp.Name+"l")
+		wp.tex.left = tex
+		return tex, err
+	}
+	return wp.tex.left, nil
+}
+
+// RepeatTexture returns the Texture.
+func (wp *Wallpaper) RepeatTexture(e render.Engine) (render.Texturer, error) {
+	if wp.tex.repeat == nil {
+		tex, err := texture(e, wp.repeat, wp.Name+"x")
+		wp.tex.repeat = tex
+		return tex, err
+	}
+	return wp.tex.repeat, nil
+}
+
+func texture(e render.Engine, img *image.RGBA, name string) (render.Texturer, error) {
+	filename := userdir.CacheFilename("wallpaper", name+".bmp")
+	if _, err := os.Stat(filename); os.IsNotExist(err) {
+		fh, err := os.Create(filename)
+		if err != nil {
+			return nil, fmt.Errorf("CornerTexture: %s", err.Error())
+		}
+		defer fh.Close()
+
+		err = bmp.Encode(fh, img)
+		if err != nil {
+			return nil, fmt.Errorf("CornerTexture: bmp.Encode: %s", err.Error())
+		}
+	}
+
+	texture, err := e.NewBitmap(filename)
+	if err != nil {
+		return nil, fmt.Errorf("CornerTexture: NewBitmap(%s): %s", filename, err.Error())
+	}
+	return texture, nil
+}

pkg/wallpaper/wallpaper.go

@@ -0,0 +1,143 @@
+package wallpaper
+
+import (
+	"image"
+	"image/draw"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"git.kirsle.net/apps/doodle/render"
+)
+
+// Wallpaper is a repeatable background image to go behind levels.
+type Wallpaper struct {
+	Name   string
+	Format string // image file format
+	Image  *image.RGBA
+
+	// Parsed values.
+	quarterWidth  int
+	quarterHeight int
+
+	// The four parsed images.
+	corner *image.RGBA // Top Left corner
+	top    *image.RGBA // Top repeating
+	left   *image.RGBA // Left repeating
+	repeat *image.RGBA // Main repeating
+
+	// Cached textures.
+	tex struct {
+		corner render.Texturer
+		top    render.Texturer
+		left   render.Texturer
+		repeat render.Texturer
+	}
+}
+
+// FromImage creates a Wallpaper from an image.Image.
+// If the renger.Engine is nil it will compute images but not pre-cache any
+// textures yet.
+func FromImage(e render.Engine, img *image.RGBA, name string) (*Wallpaper, error) {
+	wp := &Wallpaper{
+		Name:  name,
+		Image: img,
+	}
+	wp.cache(e)
+	return wp, nil
+}
+
+// FromFile creates a Wallpaper from a file on disk.
+// If the renger.Engine is nil it will compute images but not pre-cache any
+// textures yet.
+func FromFile(e render.Engine, filename string) (*Wallpaper, error) {
+	fh, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	img, format, err := image.Decode(fh)
+	if err != nil {
+		return nil, err
+	}
+
+	// Ugly hack: make it an image.RGBA because the thing we get tends to be
+	// an image.Paletted, UGH!
+	var b = img.Bounds()
+	rgba := image.NewRGBA(b)
+	for x := b.Min.X; x < b.Max.X; x++ {
+		for y := b.Min.Y; y < b.Max.Y; y++ {
+			rgba.Set(x, y, img.At(x, y))
+		}
+	}
+
+	wp := &Wallpaper{
+		Name:   strings.Split(filepath.Base(filename), ".")[0],
+		Format: format,
+		Image:  rgba,
+	}
+	wp.cache(e)
+	return wp, nil
+}
+
+// cache the bitmap images.
+func (wp *Wallpaper) cache(e render.Engine) {
+	// Zero-bound the rect cuz an image.Rect doesn't necessarily contain 0,0
+	var rect = wp.Image.Bounds()
+	if rect.Min.X < 0 {
+		rect.Max.X += rect.Min.X
+		rect.Min.X = 0
+	}
+	if rect.Min.Y < 0 {
+		rect.Max.Y += rect.Min.Y
+		rect.Min.Y = 0
+	}
+
+	// Our quarter rect size.
+	wp.quarterWidth = int(float64((rect.Max.X - rect.Min.X) / 2))
+	wp.quarterHeight = int(float64((rect.Max.Y - rect.Min.Y) / 2))
+	quarter := image.Rect(0, 0, wp.quarterWidth, wp.quarterHeight)
+
+	// Slice the image into the four corners.
+	slice := func(dx, dy int) *image.RGBA {
+		slice := image.NewRGBA(quarter)
+		draw.Draw(
+			slice,
+			image.Rect(0, 0, wp.quarterWidth, wp.quarterHeight),
+			wp.Image,
+			image.Point{dx, dy},
+			draw.Over,
+		)
+		return slice
+	}
+	wp.corner = slice(0, 0)
+	wp.top = slice(wp.quarterWidth, 0)
+	wp.left = slice(0, wp.quarterHeight)
+	wp.repeat = slice(wp.quarterWidth, wp.quarterHeight)
+
+}
+
+// QuarterSize returns the width and height of the quarter images.
+func (wp *Wallpaper) QuarterSize() (int, int) {
+	return wp.quarterWidth, wp.quarterHeight
+}
+
+// Corner returns the top left corner image.
+func (wp *Wallpaper) Corner() *image.RGBA {
+	return wp.corner
+}
+
+// Top returns the top repeating image.
+func (wp *Wallpaper) Top() *image.RGBA {
+	return wp.top
+}
+
+// Left returns the left repeating image.
+func (wp *Wallpaper) Left() *image.RGBA {
+	return wp.left
+}
+
+// Repeat returns the main repeating image.
+func (wp *Wallpaper) Repeat() *image.RGBA {
+	return wp.repeat
+}

pkg/wallpaper/wallpaper_test.go

@@ -0,0 +1,111 @@
+package wallpaper
+
+import (
+	"fmt"
+	"image"
+	"image/color"
+	"image/draw"
+	"image/png"
+	"os"
+	"testing"
+)
+
+func TestWallpaper(t *testing.T) {
+	var testFunc = func(width, height int) {
+		var (
+			qWidth  = width / 2
+			qHeight = height / 2
+			red     = color.RGBA{255, 0, 0, 255}
+			green   = color.RGBA{0, 255, 0, 255}
+			blue    = color.RGBA{0, 0, 255, 255}
+			pink    = color.RGBA{255, 0, 255, 255}
+		)
+
+		// Create a dummy image that is width*height and has the four
+		// quadrants laid out as solid colors:
+		// Red  | Green
+		// Blue | Pink
+		img := image.NewRGBA(image.Rect(0, 0, width, height))
+		draw.Draw(
+			// Corner: red
+			img, // dst Image
+			image.Rect(0, 0, qWidth, qHeight), // r Rectangle
+			image.NewUniform(red),             // src Image
+			image.Point{0, 0},                 // sp Point
+			draw.Over,                         // op Op
+		)
+		draw.Draw(
+			// Top: green
+			img,
+			image.Rect(qWidth, 0, width, qHeight),
+			image.NewUniform(green),
+			image.Point{qWidth, 0},
+			draw.Over,
+		)
+		draw.Draw(
+			// Left: blue
+			img,
+			image.Rect(0, qHeight, qWidth, height),
+			image.NewUniform(blue),
+			image.Point{0, qHeight},
+			draw.Over,
+		)
+		draw.Draw(
+			// Repeat: pink
+			img,
+			image.Rect(qWidth, qHeight, width, height),
+			image.NewUniform(pink),
+			image.Point{qWidth, qHeight},
+			draw.Over,
+		)
+
+		// Output as png to disk if you wanna see what's in it.
+		if os.Getenv("T_WALLPAPER_PNG") != "" {
+			fn := fmt.Sprintf("test-%dx%d.png", width, height)
+			if fh, err := os.Create(fn); err == nil {
+				defer fh.Close()
+				if err := png.Encode(fh, img); err != nil {
+					t.Errorf("err: %s", err)
+				}
+			}
+		}
+
+		wp, err := FromImage(nil, img, "dummy")
+		if err != nil {
+			t.Errorf("Couldn't create FromImage: %s", err)
+			t.FailNow()
+		}
+
+		// Check the quarter size is what we expected.
+		w, h := wp.QuarterSize()
+		if w != qWidth || h != qHeight {
+			t.Errorf(
+				"Got wrong quarter size: expected %dx%d but got %dx%d",
+				qWidth, qHeight,
+				w, h,
+			)
+		}
+
+		// Test the colors.
+		testColor := func(name string, img *image.RGBA, expect color.RGBA) {
+			if actual := img.At(5, 5); actual != expect {
+				t.Errorf(
+					"%s: expected color %v but got %v",
+					name,
+					expect,
+					actual,
+				)
+			}
+		}
+		testColor("Corner", wp.Corner(), red)
+		testColor("Top", wp.Top(), green)
+		testColor("Left", wp.Left(), blue)
+		testColor("Repeat", wp.Repeat(), pink)
+	}
+
+	testFunc(128, 128)
+	testFunc(128, 64)
+	testFunc(64, 128)
+	testFunc(12, 12)
+	testFunc(57, 39)
+}

play_scene.go

@@ -19,6 +19,7 @@ type PlayScene struct {
 	Level    *level.Level
 
 	// Private variables.
+	d       *Doodle
 	drawing *uix.Canvas
 
 	// Player character
@@ -32,6 +33,7 @@ func (s *PlayScene) Name() string {
 
 // Setup the play scene.
 func (s *PlayScene) Setup(d *Doodle) error {
+	s.d = d
 	s.drawing = uix.NewCanvas(balance.ChunkSize, false)
 	s.drawing.MoveTo(render.Origin)
 	s.drawing.Resize(render.NewRect(int32(d.width), int32(d.height)))
@@ -40,7 +42,7 @@ 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(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)
@@ -53,7 +55,7 @@ func (s *PlayScene) Setup(d *Doodle) error {
 	if s.Level == nil {
 		log.Debug("PlayScene.Setup: no grid given, initializing empty grid")
 		s.Level = level.New()
-		s.drawing.LoadLevel(s.Level)
+		s.drawing.LoadLevel(d.Engine, s.Level)
 	}
 
 	d.Flash("Entered Play Mode. Press 'E' to edit this map.")
@@ -161,7 +163,7 @@ func (s *PlayScene) LoadLevel(filename string) error {
 	}
 
 	s.Level = level
-	s.drawing.LoadLevel(s.Level)
+	s.drawing.LoadLevel(s.d.Engine, s.Level)
 	s.drawing.InstallActors(s.Level.Actors)
 	s.drawing.AddActor(s.Player)
 

render/functions.go

@@ -0,0 +1,69 @@
+package render
+
+// TrimBox helps with Engine.Copy() to trim a destination box so that it
+// won't overflow with the parent container.
+func TrimBox(src, dst *Rect, p Point, S Rect, thickness int32) {
+	// Constrain source width to not bigger than Canvas width.
+	if src.W > S.W {
+		src.W = S.W
+	}
+	if src.H > S.H {
+		src.H = S.H
+	}
+
+	// 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 - thickness) - (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 - thickness) - (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 + thickness
+		dst.W -= delta
+		src.X += delta
+	}
+	if dst.Y < p.Y {
+		delta := p.Y - dst.Y
+		dst.Y = p.Y + thickness
+		dst.H -= delta
+		src.Y += delta
+	}
+
+	// Trim the destination width so it doesn't overlap the Canvas border.
+	if dst.W >= S.W-thickness {
+		dst.W = S.W - thickness
+	}
+}

shell.go

@@ -206,6 +206,11 @@ func (s *Shell) Parse(input string) Command {
 
 // Draw the shell.
 func (s *Shell) Draw(d *Doodle, ev *events.State) error {
+	// Compute the line height we can draw.
+	lineHeight := balance.ShellFontSize + int(balance.ShellPadding)
+
+	// If the console is open, draw the console.
+	if s.Open {
 		if ev.EscapeKey.Read() {
 			s.Close()
 			return nil
@@ -246,11 +251,6 @@ func (s *Shell) Draw(d *Doodle, ev *events.State) error {
 
 		}
 
-	// Compute the line height we can draw.
-	lineHeight := balance.ShellFontSize + int(balance.ShellPadding)
-
-	// If the console is open, draw the console.
-	if s.Open {
 		// Cursor flip?
 		if d.ticks > s.cursorFlip {
 			s.cursorFlip = d.ticks + s.cursorRate

uix/canvas.go

@@ -2,6 +2,7 @@ package uix
 
 import (
 	"fmt"
+	"os"
 	"strings"
 
 	"git.kirsle.net/apps/doodle/balance"
@@ -9,6 +10,7 @@ import (
 	"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"
 )
@@ -32,6 +34,10 @@ type Canvas struct {
 	// 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
 
@@ -39,6 +45,9 @@ type Canvas struct {
 	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.
@@ -64,6 +73,7 @@ func NewCanvas(size int, editable bool) *Canvas {
 		Palette:    level.NewPalette(),
 		chunks:     level.NewChunker(size),
 		actors:     make([]*Actor, 0),
+		wallpaper:  &Wallpaper{},
 	}
 	w.setup()
 	w.IDFunc(func() string {
@@ -95,8 +105,27 @@ func (w *Canvas) Load(p *level.Palette, g *level.Chunker) {
 }
 
 // LoadLevel initializes a Canvas from a Level object.
-func (w *Canvas) LoadLevel(level *level.Level) {
+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.
@@ -262,6 +291,44 @@ func (w *Canvas) Present(e render.Engine, p render.Point) {
 		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 {
@@ -298,6 +365,8 @@ func (w *Canvas) Present(e render.Engine, p render.Point) {
 				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.
 			//

uix/canvas_wallpaper.go

@@ -0,0 +1,175 @@
+package uix
+
+import (
+	"git.kirsle.net/apps/doodle/level"
+	"git.kirsle.net/apps/doodle/pkg/wallpaper"
+	"git.kirsle.net/apps/doodle/render"
+)
+
+// Wallpaper configures the wallpaper in a Canvas.
+type Wallpaper struct {
+	pageType  level.PageType
+	maxWidth  int64
+	maxHeight int64
+	corner    render.Texturer
+	top       render.Texturer
+	left      render.Texturer
+	repeat    render.Texturer
+}
+
+// Valid returns whether the Wallpaper is configured. Only Levels should
+// have wallpapers and Doodads will have nil ones.
+func (wp *Wallpaper) Valid() bool {
+	return wp.repeat != nil
+}
+
+// PresentWallpaper draws the wallpaper.
+func (w *Canvas) PresentWallpaper(e render.Engine, p render.Point) error {
+	var (
+		wp       = w.wallpaper
+		S        = w.Size()
+		size     = wp.corner.Size()
+		Viewport = w.ViewportRelative()
+		origin   = render.Point{
+			X: p.X + w.Scroll.X + w.BoxThickness(1),
+			Y: p.Y + w.Scroll.Y + w.BoxThickness(1),
+		}
+		limit = render.Point{
+			// NOTE: we add + the texture size so we would actually draw one
+			// full extra texture out-of-bounds for the repeating backgrounds.
+			// This is cuz for scrolling we offset the draw spot on a loop.
+			X: origin.X + S.W - w.BoxThickness(1) + size.W,
+			Y: origin.Y + S.H - w.BoxThickness(1) + size.H,
+		}
+	)
+
+	// For tiled textures, compute the offset amount. If we are scrolled away
+	// from the Origin (0,0) we find out by how far (subtract full tile sizes)
+	// and use the remainder as an offset for drawing the tiles.
+	var dx, dy int32
+	if origin.X > 0 {
+		for origin.X > 0 && origin.X > size.W {
+			origin.X -= size.W
+		}
+		dx = origin.X
+		origin.X = 0
+	}
+	if origin.Y > 0 {
+		for origin.Y > 0 && origin.Y > size.H {
+			origin.Y -= size.H
+		}
+		dy = origin.Y
+		origin.Y = 0
+	}
+
+	// And capping the scroll delta in the other direction.
+	if limit.X < S.W {
+		limit.X = S.W
+	}
+	if limit.Y < S.H {
+		// TODO: slight flicker on bottom edge when scrolling down
+		limit.Y = S.H
+	}
+
+	// Tile the repeat texture.
+	for x := origin.X - size.W; x < limit.X; x += size.W {
+		for y := origin.Y - size.H; y < limit.Y; y += size.H {
+			src := render.Rect{
+				W: size.W,
+				H: size.H,
+			}
+			dst := render.Rect{
+				X: x + dx,
+				Y: y + dy,
+				W: src.W,
+				H: src.H,
+			}
+
+			// Trim the edges of the destination box, like in canvas.go#Present
+			render.TrimBox(&src, &dst, p, S, w.BoxThickness(1))
+
+			e.Copy(wp.repeat, src, dst)
+		}
+	}
+
+	// The left edge corner tiled along the left edge.
+	if wp.pageType > level.Unbounded {
+		for y := origin.Y; y < limit.Y; y += size.H {
+			src := render.Rect{
+				W: size.W,
+				H: size.H,
+			}
+			dst := render.Rect{
+				X: origin.X,
+				Y: y + dy,
+				W: src.W,
+				H: src.H,
+			}
+			render.TrimBox(&src, &dst, p, S, w.BoxThickness(1))
+			e.Copy(wp.left, src, dst)
+		}
+
+		// The top edge tiled along the top edge.
+		for x := origin.X; x < limit.X; x += size.W {
+			src := render.Rect{
+				W: size.W,
+				H: size.H,
+			}
+			dst := render.Rect{
+				X: x,
+				Y: origin.Y,
+				W: src.W,
+				H: src.H,
+			}
+			render.TrimBox(&src, &dst, p, S, w.BoxThickness(1))
+			e.Copy(wp.top, src, dst)
+		}
+
+		// The top left corner for all page types except Unbounded.
+		if Viewport.Intersects(size) {
+			src := render.Rect{
+				W: size.W,
+				H: size.H,
+			}
+			dst := render.Rect{
+				X: origin.X,
+				Y: origin.Y,
+				W: src.W,
+				H: src.H,
+			}
+			render.TrimBox(&src, &dst, p, S, w.BoxThickness(1))
+			e.Copy(wp.corner, src, dst)
+		}
+	}
+	return nil
+}
+
+// Load the wallpaper settings from a level.
+func (wp *Wallpaper) Load(e render.Engine, pageType level.PageType, v *wallpaper.Wallpaper) error {
+	wp.pageType = pageType
+	if tex, err := v.CornerTexture(e); err == nil {
+		wp.corner = tex
+	} else {
+		return err
+	}
+
+	if tex, err := v.TopTexture(e); err == nil {
+		wp.top = tex
+	} else {
+		return err
+	}
+
+	if tex, err := v.LeftTexture(e); err == nil {
+		wp.left = tex
+	} else {
+		return err
+	}
+
+	if tex, err := v.RepeatTexture(e); err == nil {
+		wp.repeat = tex
+	} else {
+		return err
+	}
+
+	return nil
+}