ebiten: add additional MouseButtons (#2467)

Closes #2445

inpututil/inpututil.go

@@ -101,11 +101,7 @@ func (i *inputState) update() {
 	}
 
 	// Mouse
-	for _, b := range []ebiten.MouseButton{
-		ebiten.MouseButtonLeft,
-		ebiten.MouseButtonRight,
-		ebiten.MouseButtonMiddle,
-	} {
+	for b := ebiten.MouseButton(0); b <= ebiten.MouseButtonMax; b++ {
 		i.prevMouseButtonDurations[b] = i.mouseButtonDurations[b]
 		if ebiten.IsMouseButtonPressed(b) {
 			i.mouseButtonDurations[b]++

internal/glfw/const.go

@@ -54,6 +54,8 @@ const (
 	MouseButtonLeft   = MouseButton(0)
 	MouseButtonRight  = MouseButton(1)
 	MouseButtonMiddle = MouseButton(2)
+	MouseButton3      = MouseButton(3)
+	MouseButton4      = MouseButton(4)
 )
 
 const (

internal/ui/input_glfw.go

@@ -152,6 +152,8 @@ var glfwMouseButtonToMouseButton = map[glfw.MouseButton]MouseButton{
 	glfw.MouseButtonLeft:   MouseButtonLeft,
 	glfw.MouseButtonRight:  MouseButtonRight,
 	glfw.MouseButtonMiddle: MouseButtonMiddle,
+	glfw.MouseButton3:      MouseButton3,
+	glfw.MouseButton4:      MouseButton4,
 }
 
 // update must be called from the main thread.

internal/ui/input_js.go

@@ -129,6 +129,8 @@ var codeToMouseButton = map[int]MouseButton{
 	0: MouseButtonLeft,
 	1: MouseButtonMiddle,
 	2: MouseButtonRight,
+	3: MouseButton3,
+	4: MouseButton4,
 }
 
 func (i *Input) IsMouseButtonPressed(button MouseButton) bool {

internal/ui/ui.go

@@ -24,9 +24,15 @@ import (
 type MouseButton int
 
 const (
-	MouseButtonLeft MouseButton = iota
-	MouseButtonRight
-	MouseButtonMiddle
+	MouseButton0 MouseButton = iota
+	MouseButton1
+	MouseButton2
+	MouseButton3
+	MouseButton4
+
+	MouseButtonLeft   = MouseButton0
+	MouseButtonRight  = MouseButton1
+	MouseButtonMiddle = MouseButton2
 )
 
 type TouchID int

mousebuttons.go

@@ -26,4 +26,10 @@ const (
 	MouseButtonLeft   MouseButton = ui.MouseButtonLeft
 	MouseButtonRight  MouseButton = ui.MouseButtonRight
 	MouseButtonMiddle MouseButton = ui.MouseButtonMiddle
+	MouseButton0      MouseButton = ui.MouseButton0
+	MouseButton1      MouseButton = ui.MouseButton1
+	MouseButton2      MouseButton = ui.MouseButton2
+	MouseButton3      MouseButton = ui.MouseButton3
+	MouseButton4      MouseButton = ui.MouseButton4
+	MouseButtonMax    MouseButton = MouseButton4
 )