input: Implement Touches function (WIP) (#101)

input.go

@@ -35,6 +35,9 @@ func CursorPosition() (x, y int) {
 // IsMouseButtonPressed returns a boolean indicating whether mouseButton is pressed.
 //
 // This function is concurrent-safe.
+//
+// Note that touch events not longer affect this function's result as of 1.4.0-alpha.
+// Use Touches instead.
 func IsMouseButtonPressed(mouseButton MouseButton) bool {
 	return ui.CurrentInput().IsMouseButtonPressed(ui.MouseButton(mouseButton))
 }
@@ -78,3 +81,17 @@ func GamepadButtonNum(id int) int {
 func IsGamepadButtonPressed(id int, button GamepadButton) bool {
 	return ui.CurrentInput().IsGamepadButtonPressed(id, ui.GamepadButton(button))
 }
+
+type Touch interface {
+	ID() int
+	Position() (x, y int)
+}
+
+func Touches() []Touch {
+	t := ui.CurrentInput().Touches()
+	tt := make([]Touch, len(t))
+	for i := 0; i < len(tt); i++ {
+		tt[i] = t[i]
+	}
+	return tt
+}

internal/ui/input.go

@@ -28,6 +28,12 @@ type Input interface {
 	GamepadAxisNum(id int) int
 	GamepadButtonNum(id int) int
 	IsGamepadButtonPressed(id int, button GamepadButton) bool
+	Touches() []Touch
+}
+
+type Touch interface {
+	ID() int
+	Position() (x, y int)
 }
 
 type input struct {
@@ -36,16 +42,10 @@ type input struct {
 	cursorX            int
 	cursorY            int
 	gamepads           [16]gamePad
+	touches            []touch
 	m                  sync.RWMutex
 }
 
-type gamePad struct {
-	axisNum       int
-	axes          [16]float64
-	buttonNum     int
-	buttonPressed [256]bool
-}
-
 func CurrentInput() Input {
 	return currentInput
 }
@@ -103,3 +103,32 @@ func (i *input) IsGamepadButtonPressed(id int, button GamepadButton) bool {
 	}
 	return i.gamepads[id].buttonPressed[button]
 }
+
+func (in *input) Touches() []Touch {
+	t := make([]Touch, len(in.touches))
+	for i := 0; i < len(t); i++ {
+		t[i] = &in.touches[i]
+	}
+	return t
+}
+
+type gamePad struct {
+	axisNum       int
+	axes          [16]float64
+	buttonNum     int
+	buttonPressed [256]bool
+}
+
+type touch struct {
+	id int
+	x  int
+	y  int
+}
+
+func (t *touch) ID() int {
+	return t.id
+}
+
+func (t *touch) Position() (x, y int) {
+	return t.x, t.y
+}

internal/ui/input_js.go

@@ -112,3 +112,10 @@ func (i *input) updateGamepads() {
 		}
 	}
 }
+
+func (i *input) updateTouches(t []touch) {
+	i.m.Lock()
+	defer i.m.Unlock()
+	i.touches = make([]touch, len(t))
+	copy(i.touches, t)
+}

internal/ui/ui_js.go

@@ -112,6 +112,20 @@ func (u *userInterface) FinishRendering() error {
 	return nil
 }
 
+func touchEventToTouches(e *js.Object) []touch {
+	scale := currentUI.scale
+	j := e.Get("targetTouches")
+	t := make([]touch, j.Get("length").Int())
+	for i := 0; i < len(t); i++ {
+		jj := j.Call("item", i)
+		target := jj.Get("target")
+		t[i].id = jj.Get("identifier").Int()
+		t[i].x = (jj.Get("clientX").Int() - target.Get("left").Int()) / scale
+		t[i].y = (jj.Get("clientY").Int() - target.Get("top").Int()) / scale
+	}
+	return t
+}
+
 func initialize() (*opengl.Context, error) {
 	// Do nothing in node.js.
 	if js.Global.Get("require") != js.Undefined {
@@ -194,27 +208,18 @@ func initialize() (*opengl.Context, error) {
 		e.Call("preventDefault")
 	})
 
-	// Touch (emulating mouse events)
-	// TODO: Create indimendent touch functions
+	// Touch
 	canvas.Call("addEventListener", "touchstart", func(e *js.Object) {
 		e.Call("preventDefault")
-		currentInput.mouseDown(0)
-		touches := e.Get("changedTouches")
-		touch := touches.Index(0)
-		setMouseCursorFromEvent(touch)
+		currentInput.updateTouches(touchEventToTouches(e))
 	})
 	canvas.Call("addEventListener", "touchend", func(e *js.Object) {
 		e.Call("preventDefault")
-		currentInput.mouseUp(0)
-		touches := e.Get("changedTouches")
-		touch := touches.Index(0)
-		setMouseCursorFromEvent(touch)
+		currentInput.updateTouches(touchEventToTouches(e))
 	})
 	canvas.Call("addEventListener", "touchmove", func(e *js.Object) {
 		e.Call("preventDefault")
-		touches := e.Get("changedTouches")
-		touch := touches.Index(0)
-		setMouseCursorFromEvent(touch)
+		currentInput.updateTouches(touchEventToTouches(e))
 	})
 
 	// Gamepad