From 0ab90197a372bd49181affe9f4a15a8deebbdd41 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Tue, 6 Jan 2015 23:41:03 +0900
Subject: [PATCH] Implement IsMouseButtonPressed / CursorPosition in JS (#53)

---
 ebitenutil/debugprint.go |  4 ++--
 example/paint/main.go    | 12 +++++++++---
 internal/ui/input_js.go  | 28 ++++++++++++++++++++++++++++
 internal/ui/ui_js.go     | 23 +++++++++++++++++++++++
 4 files changed, 62 insertions(+), 5 deletions(-)

diff --git a/ebitenutil/debugprint.go b/ebitenutil/debugprint.go
index 7ad3b0d1b..8215aeb11 100644
--- a/ebitenutil/debugprint.go
+++ b/ebitenutil/debugprint.go
@@ -59,8 +59,8 @@ type debugPrintState struct {
 
 var defaultDebugPrintState = &debugPrintState{}
 
-func DebugPrint(r *ebiten.Image, str string) {
-	defaultDebugPrintState.DebugPrint(r, str)
+func DebugPrint(r *ebiten.Image, str string) error {
+	return defaultDebugPrintState.DebugPrint(r, str)
 }
 
 func (d *debugPrintState) drawText(rt *ebiten.Image, str string, x, y int, c color.Color) {
diff --git a/example/paint/main.go b/example/paint/main.go
index 53d2520c9..f9e471b14 100644
--- a/example/paint/main.go
+++ b/example/paint/main.go
@@ -47,12 +47,18 @@ func Update(screen *ebiten.Image) error {
 		op.ColorM.Scale(1.0, 0.25, 0.25, 1.0)
 		theta := 2.0 * math.Pi * float64(count%60) / 60.0
 		op.ColorM.Concat(ebiten.RotateHue(theta))
-		canvasRenderTarget.DrawImage(brushRenderTarget, op)
+		if err := canvasRenderTarget.DrawImage(brushRenderTarget, op); err != nil {
+			return err
+		}
 	}
 
-	screen.DrawImage(canvasRenderTarget, nil)
+	if err := screen.DrawImage(canvasRenderTarget, nil); err != nil {
+		return err
+	}
 
-	ebitenutil.DebugPrint(screen, fmt.Sprintf("(%d, %d)", mx, my))
+	if err := ebitenutil.DebugPrint(screen, fmt.Sprintf("(%d, %d)", mx, my)); err != nil {
+		return err
+	}
 	return nil
 }
 
diff --git a/internal/ui/input_js.go b/internal/ui/input_js.go
index 7acce39ae..aaccef39a 100644
--- a/internal/ui/input_js.go
+++ b/internal/ui/input_js.go
@@ -47,3 +47,31 @@ func (i *input) keyUp(key int) {
 	k := keyCodeToKey[key]
 	i.keyPressed[k] = false
 }
+
+func (i *input) mouseDown(button int) {
+	p := &i.mouseButtonPressed
+	switch button {
+	case 0:
+		p[MouseButtonLeft] = true
+	case 1:
+		p[MouseButtonMiddle] = true
+	case 2:
+		p[MouseButtonRight] = true
+	}
+}
+
+func (i *input) mouseUp(button int) {
+	p := &i.mouseButtonPressed
+	switch button {
+	case 0:
+		p[MouseButtonLeft] = false
+	case 1:
+		p[MouseButtonMiddle] = false
+	case 2:
+		p[MouseButtonRight] = false
+	}
+}
+
+func (i *input) mouseMove(x, y int) {
+	i.cursorX, i.cursorY = x, y
+}
diff --git a/internal/ui/ui_js.go b/internal/ui/ui_js.go
index e6adec405..a8ac04387 100644
--- a/internal/ui/ui_js.go
+++ b/internal/ui/ui_js.go
@@ -98,6 +98,19 @@ func init() {
 		code := e.Get("keyCode").Int()
 		currentInput.keyUp(code)
 	})
+	canvas.Set("onmousedown", func(e js.Object) {
+		defer e.Call("preventDefault")
+		button := e.Get("button").Int()
+		currentInput.mouseDown(button)
+	})
+	canvas.Set("onmouseup", func(e js.Object) {
+		defer e.Call("preventDefault")
+		button := e.Get("button").Int()
+		currentInput.mouseUp(button)
+	})
+	canvas.Set("oncontextmenu", func(e js.Object) {
+		defer e.Call("preventDefault")
+	})
 }
 
 func Start(width, height, scale int, title string) (actualScale int, err error) {
@@ -108,5 +121,15 @@ func Start(width, height, scale int, title string) (actualScale int, err error)
 	canvasStyle := canvas.Get("style")
 	canvasStyle.Set("left", "calc(50% - "+strconv.Itoa(width*scale/2)+"px)")
 	canvasStyle.Set("top", "calc(50% - "+strconv.Itoa(height*scale/2)+"px)")
+
+	canvas.Set("onmousemove", func(e js.Object) {
+		defer e.Call("preventDefault")
+		rect := canvas.Call("getBoundingClientRect")
+		x, y := e.Get("clientX").Int(), e.Get("clientY").Int()
+		x -= rect.Get("left").Int()
+		y -= rect.Get("top").Int()
+		currentInput.mouseMove(x/scale, y/scale)
+	})
+
 	return scale, nil
 }