Abstract away all SDL logic into isolated package

cmd/doodle/main.go

@@ -5,6 +5,7 @@ import (
 	"runtime"
 
 	"git.kirsle.net/apps/doodle"
+	"git.kirsle.net/apps/doodle/render/sdl"
 )
 
 // Build number is the git commit hash.
@@ -31,7 +32,14 @@ func main() {
 		filename = args[0]
 	}
 
-	app := doodle.New(debug)
+	// SDL engine.
+	engine := sdl.New(
+		"Doodle v"+doodle.Version,
+		800,
+		600,
+	)
+
+	app := doodle.New(debug, engine)
 	if filename != "" {
 		if edit {
 			app.EditLevel(filename)

config.go

@@ -1,11 +1,12 @@
 package doodle
 
-import "github.com/veandco/go-sdl2/sdl"
+import "git.kirsle.net/apps/doodle/render"
 
 // Configuration constants.
 var (
 	DebugTextPadding int32 = 8
 	DebugTextSize          = 24
-	DebugTextColor         = sdl.Color{255, 153, 255, 255}
+	DebugTextColor         = render.SkyBlue
-	DebugTextOutline       = sdl.Color{0, 0, 0, 255}
+	DebugTextStroke        = render.Grey
+	DebugTextShadow        = render.Black
 )

doodle.go

@@ -7,8 +7,6 @@ import (
 	"git.kirsle.net/apps/doodle/events"
 	"git.kirsle.net/apps/doodle/render"
 	"github.com/kirsle/golog"
-	"github.com/veandco/go-sdl2/sdl"
-	"github.com/veandco/go-sdl2/ttf"
 )
 
 const (
@@ -25,6 +23,7 @@ const (
 // Doodle is the game object.
 type Doodle struct {
 	Debug  bool
+	Engine render.Engine
 
 	startTime time.Time
 	running   bool
@@ -34,15 +33,13 @@ type Doodle struct {
 	height    int32
 
 	scene Scene
-
-	window   *sdl.Window
-	renderer *sdl.Renderer
 }
 
 // New initializes the game object.
-func New(debug bool) *Doodle {
+func New(debug bool, engine render.Engine) *Doodle {
 	d := &Doodle{
 		Debug:     debug,
+		Engine:    engine,
 		startTime: time.Now(),
 		events:    events.New(),
 		running:   true,
@@ -59,44 +56,10 @@ func New(debug bool) *Doodle {
 
 // Run initializes SDL and starts the main loop.
 func (d *Doodle) Run() error {
-	// Initialize SDL.
+	// Set up the render engine.
-	log.Info("Initializing SDL")
+	if err := d.Engine.Setup(); err != nil {
-	if err := sdl.Init(sdl.INIT_EVERYTHING); err != nil {
 		return err
 	}
-	defer sdl.Quit()
-
-	// Initialize SDL_TTF.
-	log.Info("Initializing SDL_TTF")
-	if err := ttf.Init(); err != nil {
-		return err
-	}
-
-	// Create our window.
-	log.Info("Creating the Main Window")
-	window, err := sdl.CreateWindow(
-		"Doodle v"+Version,
-		sdl.WINDOWPOS_CENTERED,
-		sdl.WINDOWPOS_CENTERED,
-		d.width,
-		d.height,
-		sdl.WINDOW_SHOWN,
-	)
-	if err != nil {
-		return err
-	}
-	defer window.Destroy()
-	d.window = window
-
-	// Blank out the window in white.
-	log.Info("Creating the SDL Renderer")
-	renderer, err := sdl.CreateRenderer(window, -1, sdl.RENDERER_ACCELERATED)
-	if err != nil {
-		panic(err)
-	}
-	d.renderer = renderer
-	render.Renderer = renderer
-	defer renderer.Destroy()
 
 	// Set up the default scene.
 	if d.scene == nil {
@@ -105,31 +68,49 @@ func (d *Doodle) Run() error {
 
 	log.Info("Enter Main Loop")
 	for d.running {
+		start := time.Now() // Record how long this frame took.
 		d.ticks++
 
 		// Poll for events.
-		_, err := d.events.Poll(d.ticks)
+		ev, err := d.Engine.Poll()
 		if err != nil {
 			log.Error("event poll error: %s", err)
-			return err
+			d.running = false
+			break
 		}
 
-		// Draw a frame and log how long it took.
+		// Global event handlers.
-		start := time.Now()
+		if ev.EscapeKey.Pressed() {
-		err = d.scene.Loop(d)
+			log.Error("Escape key pressed, shutting down")
+			d.running = false
+			break
+		}
+
+		// Run the scene's logic.
+		err = d.scene.Loop(d, ev)
 		if err != nil {
 			return err
 		}
 
-		elapsed := time.Now().Sub(start)
+		// Draw the debug overlay over all scenes.
+		d.DrawDebugOverlay()
+
+		// Render the pixels to the screen.
+		err = d.Engine.Draw()
+		if err != nil {
+			log.Error("draw error: %s", err)
+			d.running = false
+			break
+		}
 
 		// 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
 			delay = uint32(TargetFPS - int(tmp))
 		}
-		sdl.Delay(delay)
+		d.Engine.Delay(delay)
 
 		// Track how long this frame took to measure FPS over time.
 		d.TrackFPS(delay)

editor_scene.go

@@ -9,7 +9,9 @@ import (
 	"time"
 
 	"git.kirsle.net/apps/doodle/draw"
+	"git.kirsle.net/apps/doodle/events"
 	"git.kirsle.net/apps/doodle/level"
+	"git.kirsle.net/apps/doodle/render"
 )
 
 // EditorScene manages the "Edit Level" game mode.
@@ -42,9 +44,7 @@ func (s *EditorScene) Setup(d *Doodle) error {
 }
 
 // Loop the editor scene.
-func (s *EditorScene) Loop(d *Doodle) error {
+func (s *EditorScene) Loop(d *Doodle, ev *events.State) error {
-	ev := d.events
-
 	// Taking a screenshot?
 	if ev.ScreenshotKey.Pressed() {
 		log.Info("Taking a screenshot")
@@ -53,8 +53,7 @@ func (s *EditorScene) Loop(d *Doodle) error {
 	}
 
 	// Clear the canvas and fill it with white.
-	d.renderer.SetDrawColor(255, 255, 255, 255)
+	d.Engine.Clear(render.White)
-	d.renderer.Clear()
 
 	// Clicking? Log all the pixels while doing so.
 	if ev.Button1.Now {
@@ -82,29 +81,25 @@ func (s *EditorScene) Loop(d *Doodle) error {
 		}
 	}
 
-	d.renderer.SetDrawColor(0, 0, 0, 255)
 	for i, pixel := range s.pixelHistory {
 		if !pixel.start && i > 0 {
 			prev := s.pixelHistory[i-1]
 			if prev.x == pixel.x && prev.y == pixel.y {
-				d.renderer.DrawPoint(pixel.x, pixel.y)
+				d.Engine.DrawPoint(
+					render.Black,
+					render.Point{pixel.x, pixel.y},
+				)
 			} else {
-				d.renderer.DrawLine(
+				d.Engine.DrawLine(
-					pixel.x,
+					render.Black,
-					pixel.y,
+					render.Point{pixel.x, pixel.y},
-					prev.x,
+					render.Point{prev.x, prev.y},
-					prev.y,
 				)
 			}
 		}
-		d.renderer.DrawPoint(pixel.x, pixel.y)
+		d.Engine.DrawPoint(render.Black, render.Point{pixel.x, pixel.y})
 	}
 
-	// Draw the FPS.
-	d.DrawDebugOverlay()
-
-	d.renderer.Present()
-
 	return nil
 }
 

events/events.go

@@ -1,12 +1,6 @@
 // Package events manages mouse and keyboard SDL events for Doodle.
 package events
 
-import (
-	"errors"
-
-	"github.com/veandco/go-sdl2/sdl"
-)
-
 // State keeps track of event states.
 type State struct {
 	// Mouse buttons.
@@ -15,6 +9,7 @@ type State struct {
 
 	// Screenshot key.
 	ScreenshotKey *BoolTick
+	EscapeKey     *BoolTick
 	Up            *BoolTick
 	Left          *BoolTick
 	Right         *BoolTick
@@ -31,6 +26,7 @@ func New() *State {
 		Button1:       &BoolTick{},
 		Button2:       &BoolTick{},
 		ScreenshotKey: &BoolTick{},
+		EscapeKey:     &BoolTick{},
 		Up:            &BoolTick{},
 		Left:          &BoolTick{},
 		Right:         &BoolTick{},
@@ -39,93 +35,3 @@ func New() *State {
 		CursorY:       &Int32Tick{},
 	}
 }
-
-// Poll for events.
-func (s *State) Poll(ticks uint64) (*State, error) {
-	for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
-		switch t := event.(type) {
-		case *sdl.QuitEvent:
-			return s, errors.New("quit")
-		case *sdl.MouseMotionEvent:
-			if DebugMouseEvents {
-				log.Debug("[%d ms] tick:%d MouseMotion  type:%d  id:%d  x:%d  y:%d  xrel:%d  yrel:%d",
-					t.Timestamp, ticks, t.Type, t.Which, t.X, t.Y, t.XRel, t.YRel,
-				)
-			}
-
-			// Push the cursor position.
-			s.CursorX.Push(t.X)
-			s.CursorY.Push(t.Y)
-			s.Button1.Push(t.State == 1)
-		case *sdl.MouseButtonEvent:
-			if DebugClickEvents {
-				log.Debug("[%d ms] tick:%d MouseButton  type:%d  id:%d  x:%d  y:%d  button:%d  state:%d",
-					t.Timestamp, ticks, t.Type, t.Which, t.X, t.Y, t.Button, t.State,
-				)
-			}
-
-			// Push the cursor position.
-			s.CursorX.Push(t.X)
-			s.CursorY.Push(t.Y)
-
-			// Is a mouse button pressed down?
-			if t.Button == 1 {
-				var eventName string
-				if DebugClickEvents {
-					if t.State == 1 && s.Button1.Now == false {
-						eventName = "DOWN"
-					} else if t.State == 0 && s.Button1.Now == true {
-						eventName = "UP"
-					}
-				}
-
-				if eventName != "" {
-					log.Debug("tick:%d  Mouse Button1 %s BEFORE: %+v",
-						ticks,
-						eventName,
-						s.Button1,
-					)
-					s.Button1.Push(eventName == "DOWN")
-					log.Debug("tick:%d  Mouse Button1 %s AFTER: %+v",
-						ticks,
-						eventName,
-						s.Button1,
-					)
-
-					// Return the event immediately.
-					return s, nil
-				}
-			}
-
-			// s.Button2.Push(t.Button == 3 && t.State == 1)
-		case *sdl.MouseWheelEvent:
-			if DebugMouseEvents {
-				log.Debug("[%d ms] tick:%d MouseWheel  type:%d  id:%d  x:%d  y:%d",
-					t.Timestamp, ticks, t.Type, t.Which, t.X, t.Y,
-				)
-			}
-		case *sdl.KeyboardEvent:
-			log.Debug("[%d ms] tick:%d Keyboard  type:%d  sym:%c  modifiers:%d  state:%d  repeat:%d\n",
-				t.Timestamp, ticks, t.Type, t.Keysym.Sym, t.Keysym.Mod, t.State, t.Repeat,
-			)
-			if t.Repeat == 1 {
-				continue
-			}
-
-			switch t.Keysym.Scancode {
-			case sdl.SCANCODE_F12:
-				s.ScreenshotKey.Push(t.State == 1)
-			case sdl.SCANCODE_UP:
-				s.Up.Push(t.State == 1)
-			case sdl.SCANCODE_LEFT:
-				s.Left.Push(t.State == 1)
-			case sdl.SCANCODE_RIGHT:
-				s.Right.Push(t.State == 1)
-			case sdl.SCANCODE_DOWN:
-				s.Down.Push(t.State == 1)
-			}
-		}
-	}
-
-	return s, nil
-}

fps.go

@@ -5,7 +5,6 @@ import (
 	"time"
 
 	"git.kirsle.net/apps/doodle/render"
-	"github.com/veandco/go-sdl2/sdl"
 )
 
 // Frames to cache for FPS calculation.
@@ -26,7 +25,7 @@ func (d *Doodle) DrawDebugOverlay() {
 		return
 	}
 
-	text := fmt.Sprintf(
+	label := fmt.Sprintf(
 		"FPS: %d (%dms)  (%d,%d)  S:%s  F12=screenshot",
 		fpsCurrent,
 		fpsSkipped,
@@ -34,20 +33,31 @@ func (d *Doodle) DrawDebugOverlay() {
 		d.events.CursorY.Now,
 		d.scene.Name(),
 	)
-	render.StrokedText(render.TextConfig{
+
-		Text:        text,
+	err := d.Engine.DrawText(
-		Size:        DebugTextSize,
+		render.Text{
+			Text:   label,
+			Size:   24,
 			Color:  DebugTextColor,
-		StrokeColor: DebugTextOutline,
+			Stroke: DebugTextStroke,
+			Shadow: DebugTextShadow,
+		},
+		render.Rect{
 			X: DebugTextPadding,
 			Y: DebugTextPadding,
-	})
+			W: d.width,
+			H: d.height,
+		},
+	)
+	if err != nil {
+		log.Error("DrawDebugOverlay: text error: %s", err.Error())
+	}
 }
 
 // TrackFPS shows the current FPS once per second.
 func (d *Doodle) TrackFPS(skipped uint32) {
 	fpsFrames++
-	fpsCurrentTicks = sdl.GetTicks()
+	fpsCurrentTicks = d.Engine.GetTicks()
 
 	// Skip the first second.
 	if fpsCurrentTicks < fpsInterval {

play_scene.go

@@ -3,7 +3,7 @@ package doodle
 import (
 	"git.kirsle.net/apps/doodle/events"
 	"git.kirsle.net/apps/doodle/level"
-	"github.com/veandco/go-sdl2/sdl"
+	"git.kirsle.net/apps/doodle/render"
 )
 
 // PlayScene manages the "Edit Level" game mode.
@@ -40,43 +40,31 @@ func (s *PlayScene) Setup(d *Doodle) error {
 }
 
 // Loop the editor scene.
-func (s *PlayScene) Loop(d *Doodle) error {
+func (s *PlayScene) Loop(d *Doodle, ev *events.State) error {
-	s.PollEvents(d.events)
+	s.movePlayer(ev)
 
 	// Apply gravity.
-
 	return s.Draw(d)
 }
 
 // Draw the pixels on this frame.
 func (s *PlayScene) Draw(d *Doodle) error {
 	// Clear the canvas and fill it with white.
-	d.renderer.SetDrawColor(255, 255, 255, 255)
+	d.Engine.Clear(render.White)
-	d.renderer.Clear()
 
-	d.renderer.SetDrawColor(0, 0, 0, 255)
 	for pixel := range s.canvas {
-		d.renderer.DrawPoint(pixel.x, pixel.y)
+		d.Engine.DrawPoint(render.Black, render.Point{pixel.x, pixel.y})
 	}
 
 	// Draw our hero.
-	d.renderer.SetDrawColor(0, 0, 255, 255)
+	log.Info("hero %s %+v", render.Magenta, render.Magenta)
-	d.renderer.DrawRect(&sdl.Rect{
+	d.Engine.DrawRect(render.Magenta, render.Rect{s.x, s.y, 16, 16})
-		X: s.x,
-		Y: s.y,
-		W: 16,
-		H: 16,
-	})
-
-	// Draw the FPS.
-	d.DrawDebugOverlay()
-	d.renderer.Present()
 
 	return nil
 }
 
-// PollEvents checks the event state and updates variables.
+// movePlayer updates the player's X,Y coordinate based on key pressed.
-func (s *PlayScene) PollEvents(ev *events.State) {
+func (s *PlayScene) movePlayer(ev *events.State) {
 	if ev.Down.Now {
 		s.y += 4
 	}

render/interface.go

@@ -0,0 +1,104 @@
+package render
+
+import (
+	"fmt"
+
+	"git.kirsle.net/apps/doodle/events"
+)
+
+// Engine is the interface for the rendering engine, keeping SDL-specific stuff
+// far away from the core of Doodle.
+type Engine interface {
+	Setup() error
+
+	// Poll for events like keypresses and mouse clicks.
+	Poll() (*events.State, error)
+	GetTicks() uint32
+
+	// Draw presents the current state to the screen.
+	Draw() error
+
+	// Clear the full canvas and set this color.
+	Clear(Color)
+	DrawPoint(Color, Point)
+	DrawLine(Color, Point, Point)
+	DrawRect(Color, Rect)
+	DrawText(Text, Rect) error
+
+	// Delay for a moment using the render engine's delay method,
+	// implemented by sdl.Delay(uint32)
+	Delay(uint32)
+
+	// Tasks that the Setup function should defer until tear-down.
+	Teardown()
+
+	Loop() error // maybe?
+}
+
+// Color holds an RGBA color value.
+type Color struct {
+	Red   uint8
+	Green uint8
+	Blue  uint8
+	Alpha uint8
+}
+
+func (c Color) String() string {
+	return fmt.Sprintf(
+		"Color<#%02x%02x%02x>",
+		c.Red, c.Green, c.Blue,
+	)
+}
+
+// Point holds an X,Y coordinate value.
+type Point struct {
+	X int32
+	Y int32
+}
+
+func (p Point) String() string {
+	return fmt.Sprintf("Point<%d,%d>", p.X, p.Y)
+}
+
+// Rect has a coordinate and a width and height.
+type Rect struct {
+	X int32
+	Y int32
+	W int32
+	H int32
+}
+
+func (r Rect) String() string {
+	return fmt.Sprintf("Rect<%d,%d,%d,%d>",
+		r.X, r.Y, r.W, r.H,
+	)
+}
+
+// Text holds information for drawing text.
+type Text struct {
+	Text   string
+	Size   int
+	Color  Color
+	Stroke Color // Stroke color (if not zero)
+	Shadow Color // Drop shadow color (if not zero)
+}
+
+func (t Text) String() string {
+	return fmt.Sprintf("Text<%s>", t.Text)
+}
+
+// Common color names.
+var (
+	Invisible = Color{}
+	White     = Color{255, 255, 255, 255}
+	Grey      = Color{153, 153, 153, 255}
+	Black     = Color{0, 0, 0, 255}
+	SkyBlue   = Color{0, 153, 255, 255}
+	Blue      = Color{0, 0, 255, 255}
+	Red       = Color{255, 0, 0, 255}
+	Green     = Color{0, 255, 0, 255}
+	Cyan      = Color{0, 255, 255, 255}
+	Yellow    = Color{255, 255, 0, 255}
+	Magenta   = Color{255, 0, 255, 255}
+	Pink      = Color{255, 153, 255, 255}
+)

render/sdl/canvas.go

@@ -0,0 +1,44 @@
+// Package sdl provides an SDL2 renderer for Doodle.
+package sdl
+
+import (
+	"git.kirsle.net/apps/doodle/render"
+	"github.com/veandco/go-sdl2/sdl"
+)
+
+// Clear the canvas and set this color.
+func (r *Renderer) Clear(color render.Color) {
+	if color != r.lastColor {
+		r.renderer.SetDrawColor(color.Red, color.Blue, color.Green, color.Alpha)
+	}
+	r.renderer.Clear()
+}
+
+// DrawPoint puts a color at a pixel.
+func (r *Renderer) DrawPoint(color render.Color, point render.Point) {
+	if color != r.lastColor {
+		r.renderer.SetDrawColor(color.Red, color.Blue, color.Green, color.Alpha)
+	}
+	r.renderer.DrawPoint(point.X, point.Y)
+}
+
+// DrawLine draws a line between two points.
+func (r *Renderer) DrawLine(color render.Color, a, b render.Point) {
+	if color != r.lastColor {
+		r.renderer.SetDrawColor(color.Red, color.Blue, color.Green, color.Alpha)
+	}
+	r.renderer.DrawLine(a.X, a.Y, b.X, b.Y)
+}
+
+// DrawRect draws a rectangle.
+func (r *Renderer) DrawRect(color render.Color, rect render.Rect) {
+	if color != r.lastColor {
+		r.renderer.SetDrawColor(color.Red, color.Green, color.Blue, color.Alpha)
+	}
+	r.renderer.DrawRect(&sdl.Rect{
+		X: rect.X,
+		Y: rect.Y,
+		W: rect.W,
+		H: rect.H,
+	})
+}

render/sdl/fps.go

@@ -0,0 +1,22 @@
+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

render/sdl/log.go

@@ -0,0 +1,15 @@
+package sdl
+
+import "github.com/kirsle/golog"
+
+var log *golog.Logger
+
+// Verbose debug logging.
+var (
+	DebugMouseEvents = false
+	DebugClickEvents = false
+)
+
+func init() {
+	log = golog.GetLogger("doodle")
+}

render/sdl/sdl.go

@@ -0,0 +1,203 @@
+// Package sdl provides an SDL2 renderer for Doodle.
+package sdl
+
+import (
+	"errors"
+	"time"
+
+	"git.kirsle.net/apps/doodle/events"
+	"git.kirsle.net/apps/doodle/render"
+	"github.com/veandco/go-sdl2/sdl"
+	"github.com/veandco/go-sdl2/ttf"
+)
+
+// Renderer manages the SDL state.
+type Renderer struct {
+	// Configurable fields.
+	title     string
+	width     int32
+	height    int32
+	startTime time.Time
+
+	// Private fields.
+	events   *events.State
+	window   *sdl.Window
+	renderer *sdl.Renderer
+	running  bool
+	ticks    uint64
+
+	// Optimizations to minimize SDL calls.
+	lastColor render.Color
+}
+
+// New creates the SDL renderer.
+func New(title string, width, height int32) *Renderer {
+	return &Renderer{
+		events: events.New(),
+		title:  title,
+		width:  width,
+		height: height,
+	}
+}
+
+// Teardown tasks when exiting the program.
+func (r *Renderer) Teardown() {
+	r.renderer.Destroy()
+	r.window.Destroy()
+	sdl.Quit()
+}
+
+// Setup the renderer.
+func (r *Renderer) Setup() error {
+	// Initialize SDL.
+	log.Info("Initializing SDL")
+	if err := sdl.Init(sdl.INIT_EVERYTHING); err != nil {
+		return err
+	}
+
+	// Initialize SDL_TTF.
+	log.Info("Initializing SDL_TTF")
+	if err := ttf.Init(); err != nil {
+		return err
+	}
+
+	// Create our window.
+	log.Info("Creating the Main Window")
+	window, err := sdl.CreateWindow(
+		r.title,
+		sdl.WINDOWPOS_CENTERED,
+		sdl.WINDOWPOS_CENTERED,
+		r.width,
+		r.height,
+		sdl.WINDOW_SHOWN,
+	)
+	if err != nil {
+		return err
+	}
+	r.window = window
+
+	// Blank out the window in white.
+	log.Info("Creating the SDL Renderer")
+	renderer, err := sdl.CreateRenderer(window, -1, sdl.RENDERER_ACCELERATED)
+	if err != nil {
+		panic(err)
+	}
+	r.renderer = renderer
+	render.Renderer = renderer
+
+	return nil
+}
+
+// GetTicks gets SDL's current tick count.
+func (r *Renderer) GetTicks() uint32 {
+	return sdl.GetTicks()
+}
+
+// Poll for events.
+func (r *Renderer) Poll() (*events.State, error) {
+	s := r.events
+	for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
+		switch t := event.(type) {
+		case *sdl.QuitEvent:
+			return s, errors.New("quit")
+		case *sdl.MouseMotionEvent:
+			if DebugMouseEvents {
+				log.Debug("[%d ms] tick:%d MouseMotion  type:%d  id:%d  x:%d  y:%d  xrel:%d  yrel:%d",
+					t.Timestamp, r.ticks, t.Type, t.Which, t.X, t.Y, t.XRel, t.YRel,
+				)
+			}
+
+			// Push the cursor position.
+			s.CursorX.Push(t.X)
+			s.CursorY.Push(t.Y)
+			s.Button1.Push(t.State == 1)
+		case *sdl.MouseButtonEvent:
+			if DebugClickEvents {
+				log.Debug("[%d ms] tick:%d MouseButton  type:%d  id:%d  x:%d  y:%d  button:%d  state:%d",
+					t.Timestamp, r.ticks, t.Type, t.Which, t.X, t.Y, t.Button, t.State,
+				)
+			}
+
+			// Push the cursor position.
+			s.CursorX.Push(t.X)
+			s.CursorY.Push(t.Y)
+
+			// Is a mouse button pressed down?
+			if t.Button == 1 {
+				var eventName string
+				if DebugClickEvents {
+					if t.State == 1 && s.Button1.Now == false {
+						eventName = "DOWN"
+					} else if t.State == 0 && s.Button1.Now == true {
+						eventName = "UP"
+					}
+				}
+
+				if eventName != "" {
+					log.Debug("tick:%d  Mouse Button1 %s BEFORE: %+v",
+						r.ticks,
+						eventName,
+						s.Button1,
+					)
+					s.Button1.Push(eventName == "DOWN")
+					log.Debug("tick:%d  Mouse Button1 %s AFTER: %+v",
+						r.ticks,
+						eventName,
+						s.Button1,
+					)
+
+					// Return the event immediately.
+					return s, nil
+				}
+			}
+
+			// s.Button2.Push(t.Button == 3 && t.State == 1)
+		case *sdl.MouseWheelEvent:
+			if DebugMouseEvents {
+				log.Debug("[%d ms] tick:%d MouseWheel  type:%d  id:%d  x:%d  y:%d",
+					t.Timestamp, r.ticks, t.Type, t.Which, t.X, t.Y,
+				)
+			}
+		case *sdl.KeyboardEvent:
+			log.Debug("[%d ms] tick:%d Keyboard  type:%d  sym:%c  modifiers:%d  state:%d  repeat:%d\n",
+				t.Timestamp, r.ticks, t.Type, t.Keysym.Sym, t.Keysym.Mod, t.State, t.Repeat,
+			)
+			if t.Repeat == 1 {
+				continue
+			}
+
+			switch t.Keysym.Scancode {
+			case sdl.SCANCODE_ESCAPE:
+				s.EscapeKey.Push(t.State == 1)
+			case sdl.SCANCODE_F12:
+				s.ScreenshotKey.Push(t.State == 1)
+			case sdl.SCANCODE_UP:
+				s.Up.Push(t.State == 1)
+			case sdl.SCANCODE_LEFT:
+				s.Left.Push(t.State == 1)
+			case sdl.SCANCODE_RIGHT:
+				s.Right.Push(t.State == 1)
+			case sdl.SCANCODE_DOWN:
+				s.Down.Push(t.State == 1)
+			}
+		}
+	}
+
+	return s, nil
+}
+
+// Draw a single frame.
+func (r *Renderer) Draw() error {
+	r.renderer.Present()
+	return nil
+}
+
+// Delay using sdl.Delay
+func (r *Renderer) Delay(time uint32) {
+	sdl.Delay(time)
+}
+
+// Loop is the main loop.
+func (r *Renderer) Loop() error {
+	return nil
+}

render/sdl/text.go

@@ -0,0 +1,81 @@
+package sdl
+
+import (
+	"git.kirsle.net/apps/doodle/render"
+	"github.com/veandco/go-sdl2/sdl"
+	"github.com/veandco/go-sdl2/ttf"
+)
+
+var fonts map[int]*ttf.Font = map[int]*ttf.Font{}
+
+// LoadFont loads and caches the font at a given size.
+func LoadFont(size int) (*ttf.Font, error) {
+	if font, ok := fonts[size]; ok {
+		return font, nil
+	}
+
+	font, err := ttf.OpenFont("./fonts/DejaVuSansMono.ttf", size)
+	if err != nil {
+		return nil, err
+	}
+	fonts[size] = font
+
+	return font, nil
+}
+
+// DrawText draws text on the canvas.
+func (r *Renderer) DrawText(text render.Text, rect render.Rect) error {
+	var (
+		font    *ttf.Font
+		surface *sdl.Surface
+		tex     *sdl.Texture
+		err     error
+	)
+
+	if font, err = LoadFont(text.Size); err != nil {
+		return err
+	}
+
+	write := func(dx, dy int32, color sdl.Color) {
+		if surface, err = font.RenderUTF8Blended(text.Text, color); err != nil {
+			return
+		}
+		defer surface.Free()
+
+		if tex, err = r.renderer.CreateTextureFromSurface(surface); err != nil {
+			return
+		}
+		defer tex.Destroy()
+
+		tmp := &sdl.Rect{
+			X: rect.X + dx,
+			Y: rect.Y + dy,
+			W: surface.W,
+			H: surface.H,
+		}
+		r.renderer.Copy(tex, nil, tmp)
+	}
+
+	// Does the text have a stroke around it?
+	if text.Stroke != render.Invisible {
+		color := ColorToSDL(text.Stroke)
+		write(-1, -1, color)
+		write(-1, 0, color)
+		write(-1, 1, color)
+		write(1, -1, color)
+		write(1, 0, color)
+		write(1, 1, color)
+		write(0, -1, color)
+		write(0, 1, color)
+	}
+
+	// Does it have a drop shadow?
+	if text.Shadow != render.Invisible {
+		write(1, 1, ColorToSDL(text.Shadow))
+	}
+
+	// Draw the text itself.
+	write(0, 0, ColorToSDL(text.Color))
+
+	return err
+}

render/sdl/utils.go

@@ -0,0 +1,21 @@
+package sdl
+
+import (
+	"git.kirsle.net/apps/doodle/render"
+	"github.com/veandco/go-sdl2/sdl"
+)
+
+// ColorToSDL converts Doodle's Color type to an sdl.Color.
+func ColorToSDL(c render.Color) sdl.Color {
+	return sdl.Color{c.Red, c.Green, c.Blue, c.Alpha}
+}
+
+// RectToSDL converts Doodle's Rect type to an sdl.Rect.
+func RectToSDL(r render.Rect) sdl.Rect {
+	return sdl.Rect{
+		X: r.X,
+		Y: r.Y,
+		W: r.W,
+		H: r.H,
+	}
+}

render/text.go

@@ -33,57 +33,3 @@ type TextConfig struct {
 	W           int32
 	H           int32
 }
-
-// StrokedText draws text with a stroke color around it.
-func StrokedText(t TextConfig) {
-	stroke := func(copy TextConfig, x, y int32) {
-		copy.Color = t.StrokeColor
-		copy.X += x
-		copy.Y += y
-		Text(copy)
-	}
-
-	stroke(t, -1, -1)
-	stroke(t, -1, 0)
-	stroke(t, -1, 1)
-
-	stroke(t, 1, -1)
-	stroke(t, 1, 0)
-	stroke(t, 1, 1)
-
-	stroke(t, 0, -1)
-	stroke(t, 0, 1)
-	Text(t)
-}
-
-// Text draws text on the renderer.
-func Text(t TextConfig) error {
-	var (
-		font    *ttf.Font
-		surface *sdl.Surface
-		tex     *sdl.Texture
-		err     error
-	)
-
-	if font, err = LoadFont(t.Size); err != nil {
-		return err
-	}
-
-	if surface, err = font.RenderUTF8Blended(t.Text, t.Color); err != nil {
-		return err
-	}
-	defer surface.Free()
-
-	if tex, err = Renderer.CreateTextureFromSurface(surface); err != nil {
-		return err
-	}
-	defer tex.Destroy()
-
-	Renderer.Copy(tex, nil, &sdl.Rect{
-		X: int32(t.X),
-		Y: int32(t.Y),
-		W: int32(surface.W),
-		H: int32(surface.H),
-	})
-	return nil
-}

scene.go

@@ -1,12 +1,14 @@
 package doodle
 
+import "git.kirsle.net/apps/doodle/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
 // state information.
 type Scene interface {
 	Name() string
 	Setup(*Doodle) error
-	Loop(*Doodle) error
+	Loop(*Doodle, *events.State) error
 }
 
 // Goto a scene. First it unloads the current scene.

scene/editor.go

@@ -0,0 +1,86 @@
+package scene
+
+import "git.kirsle.net/apps/doodle/events"
+
+// Editor is the drawing mode of the game where the user is clicking and
+// dragging to draw pixels.
+type Editor struct{}
+
+func (s *Editor) String() string {
+	return "Editor"
+}
+
+// Setup the scene.
+func (s *Editor) Setup() error {
+	return nil
+}
+
+// Loop the scene.
+func (s *Editor) Loop(ev *events.State) error {
+	// Taking a screenshot?
+	if ev.ScreenshotKey.Pressed() {
+		log.Info("Taking a screenshot")
+		d.Screenshot()
+		d.SaveLevel()
+	}
+
+	// Clear the canvas and fill it with white.
+	d.renderer.SetDrawColor(255, 255, 255, 255)
+	d.renderer.Clear()
+
+	// Clicking? Log all the pixels while doing so.
+	if ev.Button1.Now {
+		pixel := Pixel{
+			start: ev.Button1.Pressed(),
+			x:     ev.CursorX.Now,
+			y:     ev.CursorY.Now,
+			dx:    ev.CursorX.Now,
+			dy:    ev.CursorY.Now,
+		}
+
+		// Append unique new pixels.
+		if len(pixelHistory) == 0 || pixelHistory[len(pixelHistory)-1] != pixel {
+			// If not a start pixel, make the delta coord the previous one.
+			if !pixel.start && len(pixelHistory) > 0 {
+				prev := pixelHistory[len(pixelHistory)-1]
+				pixel.dx = prev.x
+				pixel.dy = prev.y
+			}
+
+			pixelHistory = append(pixelHistory, pixel)
+
+			// Save in the pixel canvas map.
+			d.canvas[pixel] = nil
+		}
+	}
+
+	d.renderer.SetDrawColor(0, 0, 0, 255)
+	for i, pixel := range pixelHistory {
+		if !pixel.start && i > 0 {
+			prev := pixelHistory[i-1]
+			if prev.x == pixel.x && prev.y == pixel.y {
+				d.renderer.DrawPoint(pixel.x, pixel.y)
+			} else {
+				d.renderer.DrawLine(
+					pixel.x,
+					pixel.y,
+					prev.x,
+					prev.y,
+				)
+			}
+		}
+		d.renderer.DrawPoint(pixel.x, pixel.y)
+	}
+
+	// Draw the FPS.
+	d.DrawDebugOverlay()
+
+	d.renderer.Present()
+
+	return nil
+}
+
+// Destroy the scene.
+func (s *Editor) Destroy() error {
+	return nil
+}

scene/log.go

@@ -0,0 +1,9 @@
+package scene
+
+import "github.com/kirsle/golog"
+
+var log *golog.Logger
+
+func init() {
+	log = golog.GetLogger("doodle")
+}

scene/scene.go

@@ -0,0 +1,67 @@
+package scene
+
+import (
+	"errors"
+	"fmt"
+
+	"git.kirsle.net/apps/doodle/events"
+)
+
+// Scene is an interface for the top level of a game mode. The game points to
+// one Scene at a time, and that Scene has majority control of the main loop,
+// and maintains its own state local to that scene.
+type Scene interface {
+	String() string // the scene's name
+	Setup() error
+	Loop() error
+	Destroy() error
+}
+
+// Manager is a type that provides context switching features to manage scenes.
+type Manager struct {
+	events *events.State
+	scene  Scene
+	ticks  uint64
+}
+
+// NewManager creates the new manager.
+func NewManager(events *events.State) Manager {
+	return Manager{
+		events: events,
+		scene:  nil,
+	}
+}
+
+// Go to a new scene. This tears down the existing scene, sets up the new one,
+// and switches control to the new scene.
+func (m *Manager) Go(scene Scene) error {
+	// Already running a scene?
+	if m.scene != nil {
+		if err := m.scene.Destroy(); err != nil {
+			return fmt.Errorf("couldn't destroy scene %s: %s", m.scene, err)
+		}
+		m.scene = nil
+	}
+
+	// Initialize the new scene.
+	m.scene = scene
+	return m.scene.Setup()
+}
+
+// Loop the scene manager. This is the game's main loop which runs all the tasks
+// that fall in the realm of the scene manager.
+func (m *Manager) Loop() error {
+	if m.scene == nil {
+		return errors.New("no scene loaded")
+	}
+
+	// Poll for events.
+	ev, err := m.events.Poll(m.ticks)
+	if err != nil {
+		log.Error("event poll error: %s", err)
+		return err
+	}
+	_ = ev
+
+	return m.scene.Loop()
+}