WIP: implement HandleEvent

Updates #1704

event/event.go

@@ -0,0 +1,28 @@
+// Copyright 2023 The Ebitengine Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package event
+
+type MouseMoveEvent struct {
+	X float64
+	Y float64
+}
+
+type MouseDownEvent struct {
+	// TODO
+}
+
+type MouseUpEvent struct {
+	// TODO
+}

examples/drag/main.go

@@ -16,6 +16,7 @@ package main
 
 import (
 	"bytes"
+	"flag"
 	"image"
 	"image/color"
 	_ "image/png"
@@ -25,6 +26,7 @@ import (
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
+	"github.com/hajimehoshi/ebiten/v2/event"
 	"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
 	"github.com/hajimehoshi/ebiten/v2/inpututil"
 )
@@ -38,6 +40,10 @@ const (
 	screenHeight = 480
 )
 
+var (
+	flagEvent = flag.Bool("event", false, "use HandleEvent")
+)
+
 // Sprite represents an image.
 type Sprite struct {
 	image      *ebiten.Image
@@ -117,6 +123,21 @@ func (t *TouchStrokeSource) IsJustReleased() bool {
 	return inpututil.IsTouchJustReleased(t.ID)
 }
 
+type MouseEventStrokeSource struct {
+	pressed        bool
+	x              float64
+	y              float64
+	isJustReleased bool
+}
+
+func (m *MouseEventStrokeSource) Position() (int, int) {
+	return int(m.x), int(m.y)
+}
+
+func (m *MouseEventStrokeSource) IsJustReleased() bool {
+	return m.isJustReleased
+}
+
 // Stroke manages the current drag state by mouse.
 type Stroke struct {
 	source StrokeSource
@@ -160,9 +181,12 @@ func (s *Stroke) Sprite() *Sprite {
 }
 
 type Game struct {
-	touchIDs []ebiten.TouchID
+	touchIDs    []ebiten.TouchID
-	strokes  map[*Stroke]struct{}
+	tickStrokes map[*Stroke]struct{}
-	sprites  []*Sprite
+	eventStroke *Stroke
+	sprites     []*Sprite
+
+	mouseEventStrokeSource MouseEventStrokeSource
 }
 
 var (
@@ -205,8 +229,8 @@ func NewGame() *Game {
 
 	// Initialize the game.
 	return &Game{
-		strokes: map[*Stroke]struct{}{},
+		tickStrokes: map[*Stroke]struct{}{},
-		sprites: sprites,
+		sprites:     sprites,
 	}
 }
 
@@ -234,11 +258,47 @@ func (g *Game) moveSpriteToFront(sprite *Sprite) {
 	g.sprites = append(g.sprites, sprite)
 }
 
+func (g *Game) HandleEvent(e any) {
+	if !*flagEvent {
+		return
+	}
+
+	switch e := e.(type) {
+	case event.MouseDownEvent:
+		g.mouseEventStrokeSource.pressed = true
+		g.mouseEventStrokeSource.isJustReleased = false
+	case event.MouseMoveEvent:
+		if g.mouseEventStrokeSource.pressed {
+			g.mouseEventStrokeSource.x = e.X
+			g.mouseEventStrokeSource.y = e.Y
+			if g.eventStroke == nil {
+				if sp := g.spriteAt(int(e.X), int(e.Y)); sp != nil {
+					g.eventStroke = NewStroke(&g.mouseEventStrokeSource, sp)
+				}
+			}
+		}
+	case event.MouseUpEvent:
+		g.mouseEventStrokeSource.pressed = false
+		g.mouseEventStrokeSource.isJustReleased = true
+	}
+
+	if g.eventStroke != nil {
+		g.eventStroke.Update()
+		if !g.eventStroke.sprite.dragged {
+			g.eventStroke = nil
+		}
+	}
+}
+
 func (g *Game) Update() error {
+	if *flagEvent {
+		return nil
+	}
+
 	if inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonLeft) {
 		if sp := g.spriteAt(ebiten.CursorPosition()); sp != nil {
 			s := NewStroke(&MouseStrokeSource{}, sp)
-			g.strokes[s] = struct{}{}
+			g.tickStrokes[s] = struct{}{}
 			g.moveSpriteToFront(sp)
 		}
 	}
@@ -246,15 +306,15 @@ func (g *Game) Update() error {
 	for _, id := range g.touchIDs {
 		if sp := g.spriteAt(ebiten.TouchPosition(id)); sp != nil {
 			s := NewStroke(&TouchStrokeSource{id}, sp)
-			g.strokes[s] = struct{}{}
+			g.tickStrokes[s] = struct{}{}
 			g.moveSpriteToFront(sp)
 		}
 	}
 
-	for s := range g.strokes {
+	for s := range g.tickStrokes {
 		s.Update()
 		if !s.sprite.dragged {
-			delete(g.strokes, s)
+			delete(g.tickStrokes, s)
 		}
 	}
 	return nil
@@ -277,6 +337,7 @@ func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
 }
 
 func main() {
+	flag.Parse()
 	ebiten.SetWindowSize(screenWidth, screenHeight)
 	ebiten.SetWindowTitle("Drag & Drop (Ebitengine Demo)")
 	if err := ebiten.RunGame(NewGame()); err != nil {

examples/paint/main.go

@@ -15,6 +15,7 @@
 package main
 
 import (
+	"flag"
 	"fmt"
 	"image"
 	"image/color"
@@ -24,6 +25,7 @@ import (
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/colorm"
 	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
+	"github.com/hajimehoshi/ebiten/v2/event"
 )
 
 const (
@@ -31,6 +33,10 @@ const (
 	screenHeight = 480
 )
 
+var (
+	flagEvent = flag.Bool("event", false, "use HandleEvent")
+)
+
 var (
 	brushImage *ebiten.Image
 )
@@ -70,6 +76,8 @@ type Game struct {
 	count   int
 
 	canvasImage *ebiten.Image
+
+	mousePressedByEvent bool
 }
 
 func NewGame() *Game {
@@ -80,14 +88,34 @@ func NewGame() *Game {
 	return g
 }
 
+func (g *Game) HandleEvent(e any) {
+	if !*flagEvent {
+		return
+	}
+
+	switch e := e.(type) {
+	case event.MouseDownEvent:
+		g.mousePressedByEvent = true
+	case event.MouseMoveEvent:
+		if g.mousePressedByEvent {
+			g.paint(g.canvasImage, int(e.X), int(e.Y))
+			g.count++
+		}
+	case event.MouseUpEvent:
+		g.mousePressedByEvent = false
+	}
+}
+
 func (g *Game) Update() error {
-	drawn := false
+	var drawn bool
 
 	// Paint the brush by mouse dragging
 	mx, my := ebiten.CursorPosition()
-	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
+	if !*flagEvent {
-		g.paint(g.canvasImage, mx, my)
+		if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
-		drawn = true
+			g.paint(g.canvasImage, mx, my)
+			drawn = true
+		}
 	}
 	g.cursor = pos{
 		x: mx,
@@ -142,6 +170,7 @@ func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
 }
 
 func main() {
+	flag.Parse()
 	ebiten.SetWindowSize(screenWidth, screenHeight)
 	ebiten.SetWindowTitle("Paint (Ebitengine Demo)")
 	if err := ebiten.RunGame(NewGame()); err != nil {

gameforui.go

@@ -114,6 +114,12 @@ func (g *gameForUI) NewScreenImage(width, height int) *ui.Image {
 	return g.screen.image
 }
 
+func (g *gameForUI) HandleEvent(event any) {
+	if h, ok := g.game.(EventHandler); ok {
+		h.HandleEvent(event)
+	}
+}
+
 func (g *gameForUI) Layout(outsideWidth, outsideHeight float64) (float64, float64) {
 	if l, ok := g.game.(LayoutFer); ok {
 		return l.LayoutF(outsideWidth, outsideHeight)

internal/graphicscommand/commandqueue.go

@@ -192,6 +192,9 @@ func (q *commandQueue) Flush(graphicsDriver graphicsdriver.Graphics, endFrame bo
 			}
 		}
 	}
+	/*if endFrame {
+		sync = true
+	}*/
 
 	logger := debug.SwitchLogger()
 

internal/ui/context.go

@@ -16,6 +16,7 @@ package ui
 
 import (
 	"math"
+	"sync"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/atlas"
 	"github.com/hajimehoshi/ebiten/v2/internal/clock"
@@ -33,6 +34,7 @@ type Game interface {
 	NewOffscreenImage(width, height int) *Image
 	NewScreenImage(width, height int) *Image
 	Layout(outsideWidth, outsideHeight float64) (screenWidth, screenHeight float64)
+	HandleEvent(event any)
 	UpdateInputState(fn func(*InputState))
 	Update() error
 	DrawOffscreen() error
@@ -40,7 +42,8 @@ type Game interface {
 }
 
 type context struct {
-	game Game
+	game    Game
+	inputCh chan any
 
 	updateCalled bool
 
@@ -55,12 +58,34 @@ type context struct {
 	isOffscreenModified bool
 
 	skipCount int
+
+	gameM sync.Mutex
 }
 
 func newContext(game Game) *context {
-	return &context{
+	c := &context{
-		game: game,
+		game:    game,
+		inputCh: make(chan any, 128),
 	}
+
+	// Create an independent goroutine from Update/Draw not to cause deadlock at (*UserInterface).readPixels.
+	go func() {
+		// TODO: Abort this loop when the game terminates.
+		for e := range c.inputCh {
+			e := e
+			func() {
+				c.gameM.Lock()
+				defer c.gameM.Unlock()
+				c.game.HandleEvent(e)
+			}()
+		}
+	}()
+
+	return c
+}
+
+func (c *context) sendInputEvent(event any) {
+	c.inputCh <- event
 }
 
 func (c *context) updateFrame(graphicsDriver graphicsdriver.Graphics, outsideWidth, outsideHeight float64, deviceScaleFactor float64, ui *UserInterface, swapBuffersForGL func()) error {
@@ -90,6 +115,18 @@ func (c *context) updateFrameImpl(graphicsDriver graphicsdriver.Graphics, update
 		return nil
 	}
 
+	if err := c.updateGameInFrame(graphicsDriver, updateCount, outsideWidth, outsideHeight, deviceScaleFactor, ui, forceDraw, swapBuffersForGL); err != nil {
+		return err
+	}
+
+	if err := atlas.SwapBuffers(graphicsDriver, swapBuffersForGL); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (c *context) updateGameInFrame(graphicsDriver graphicsdriver.Graphics, updateCount int, outsideWidth, outsideHeight float64, deviceScaleFactor float64, ui *UserInterface, forceDraw bool, swapBuffersForGL func()) (err error) {
 	debug.Logf("----\n")
 
 	if err := atlas.BeginFrame(graphicsDriver); err != nil {
@@ -101,13 +138,11 @@ func (c *context) updateFrameImpl(graphicsDriver graphicsdriver.Graphics, update
 			err = err1
 			return
 		}
-
-		if err1 := atlas.SwapBuffers(graphicsDriver, swapBuffersForGL); err1 != nil && err == nil {
-			err = err1
-			return
-		}
 	}()
 
+	c.gameM.Lock()
+	defer c.gameM.Unlock()
+
 	// ForceUpdate can be invoked even if the context is not initialized yet (#1591).
 	if w, h := c.layoutGame(outsideWidth, outsideHeight, deviceScaleFactor); w == 0 || h == 0 {
 		return nil

internal/ui/input_glfw.go

@@ -19,6 +19,7 @@ package ui
 import (
 	"math"
 
+	"github.com/hajimehoshi/ebiten/v2/event"
 	"github.com/hajimehoshi/ebiten/v2/internal/gamepad"
 	"github.com/hajimehoshi/ebiten/v2/internal/glfw"
 )
@@ -51,6 +52,35 @@ func (u *UserInterface) registerInputCallbacks() error {
 		return err
 	}
 
+	// For HandleEvent
+	if _, err := u.window.SetCursorPosCallback(func(w *glfw.Window, xpos float64, ypos float64) {
+		m, err := u.currentMonitor()
+		if err != nil {
+			u.setError(err)
+			return
+		}
+		x := dipFromGLFWPixel(xpos, m)
+		y := dipFromGLFWPixel(ypos, m)
+		x, y = u.context.clientPositionToLogicalPosition(x, y, m.deviceScaleFactor())
+		u.context.sendInputEvent(event.MouseMoveEvent{
+			X: x,
+			Y: y,
+		})
+	}); err != nil {
+		return err
+	}
+	if _, err := u.window.SetMouseButtonCallback(func(w *glfw.Window, button glfw.MouseButton, action glfw.Action, mods glfw.ModifierKey) {
+		// TODO: Use button and mods
+		switch action {
+		case glfw.Release:
+			u.context.sendInputEvent(event.MouseUpEvent{})
+		case glfw.Press:
+			u.context.sendInputEvent(event.MouseDownEvent{})
+		}
+	}); err != nil {
+		return err
+	}
+
 	return nil
 }
 

run.go

@@ -93,6 +93,10 @@ type LayoutFer interface {
 	LayoutF(outsideWidth, outsideHeight float64) (screenWidth, screenHeight float64)
 }
 
+type EventHandler interface {
+	HandleEvent(event any)
+}
+
 // FinalScreen represents the final screen image.
 // FinalScreen implements a part of Image functions.
 type FinalScreen interface {