io/pointer: rename button names to reflect their meaning, not placement

For example, ButtonLeft may be the right-most button for a left-handed user.
Rename the button names to match their intended use.

This is an API change. Use the following commands to update your
projects:

    $ gofmt -r 'pointer.ButtonLeft -> pointer.ButtonPrimary' -w .
    $ gofmt -r 'pointer.ButtonRight -> pointer.ButtonSecondary' -w .
    $ gofmt -r 'pointer.ButtonMiddle -> pointer.ButtonTertiary' -w .

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/internal/window/os_android.go

@@ -523,13 +523,13 @@ func Java_org_gioui_GioView_onTouchEvent(env *C.JNIEnv, class C.jclass, handle C
 	var src pointer.Source
 	var btns pointer.Buttons
 	if jbtns&C.AMOTION_EVENT_BUTTON_PRIMARY != 0 {
-		btns |= pointer.ButtonLeft
+		btns |= pointer.ButtonPrimary
 	}
 	if jbtns&C.AMOTION_EVENT_BUTTON_SECONDARY != 0 {
-		btns |= pointer.ButtonRight
+		btns |= pointer.ButtonSecondary
 	}
 	if jbtns&C.AMOTION_EVENT_BUTTON_TERTIARY != 0 {
-		btns |= pointer.ButtonMiddle
+		btns |= pointer.ButtonTertiary
 	}
 	switch tool {
 	case C.AMOTION_EVENT_TOOL_TYPE_FINGER:

app/internal/window/os_js.go

@@ -382,13 +382,13 @@ func (w *window) pointerEvent(typ pointer.Type, dx, dy float32, e js.Value) {
 	jbtns := e.Get("buttons").Int()
 	var btns pointer.Buttons
 	if jbtns&1 != 0 {
-		btns |= pointer.ButtonLeft
+		btns |= pointer.ButtonPrimary
 	}
 	if jbtns&2 != 0 {
-		btns |= pointer.ButtonRight
+		btns |= pointer.ButtonSecondary
 	}
 	if jbtns&4 != 0 {
-		btns |= pointer.ButtonMiddle
+		btns |= pointer.ButtonTertiary
 	}
 	w.w.Event(pointer.Event{
 		Type:      typ,

app/internal/window/os_macos.go

@@ -200,13 +200,13 @@ func gio_onMouse(view C.CFTypeRef, cdir C.int, cbtns C.NSUInteger, x, y, dx, dy
 	}
 	var btns pointer.Buttons
 	if cbtns&(1<<0) != 0 {
-		btns |= pointer.ButtonLeft
+		btns |= pointer.ButtonPrimary
 	}
 	if cbtns&(1<<1) != 0 {
-		btns |= pointer.ButtonRight
+		btns |= pointer.ButtonSecondary
 	}
 	if cbtns&(1<<2) != 0 {
-		btns |= pointer.ButtonMiddle
+		btns |= pointer.ButtonTertiary
 	}
 	t := time.Duration(float64(ti)*float64(time.Second) + .5)
 	w := mustView(view)

app/internal/window/os_wayland.go

@@ -801,11 +801,11 @@ func gio_onPointerButton(data unsafe.Pointer, p *C.struct_wl_pointer, serial, t,
 	var btn pointer.Buttons
 	switch wbtn {
 	case BTN_LEFT:
-		btn = pointer.ButtonLeft
+		btn = pointer.ButtonPrimary
 	case BTN_RIGHT:
-		btn = pointer.ButtonRight
+		btn = pointer.ButtonSecondary
 	case BTN_MIDDLE:
-		btn = pointer.ButtonMiddle
+		btn = pointer.ButtonTertiary
 	default:
 		return
 	}

app/internal/window/os_windows.go

@@ -257,17 +257,17 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 			w.w.Event(e)
 		}
 	case windows.WM_LBUTTONDOWN:
-		w.pointerButton(pointer.ButtonLeft, true, lParam, getModifiers())
+		w.pointerButton(pointer.ButtonPrimary, true, lParam, getModifiers())
 	case windows.WM_LBUTTONUP:
-		w.pointerButton(pointer.ButtonLeft, false, lParam, getModifiers())
+		w.pointerButton(pointer.ButtonPrimary, false, lParam, getModifiers())
 	case windows.WM_RBUTTONDOWN:
-		w.pointerButton(pointer.ButtonRight, true, lParam, getModifiers())
+		w.pointerButton(pointer.ButtonSecondary, true, lParam, getModifiers())
 	case windows.WM_RBUTTONUP:
-		w.pointerButton(pointer.ButtonRight, false, lParam, getModifiers())
+		w.pointerButton(pointer.ButtonSecondary, false, lParam, getModifiers())
 	case windows.WM_MBUTTONDOWN:
-		w.pointerButton(pointer.ButtonMiddle, true, lParam, getModifiers())
+		w.pointerButton(pointer.ButtonTertiary, true, lParam, getModifiers())
 	case windows.WM_MBUTTONUP:
-		w.pointerButton(pointer.ButtonMiddle, false, lParam, getModifiers())
+		w.pointerButton(pointer.ButtonTertiary, false, lParam, getModifiers())
 	case windows.WM_CANCELMODE:
 		w.w.Event(pointer.Event{
 			Type: pointer.Cancel,

app/internal/window/os_x11.go

@@ -362,11 +362,11 @@ func (h *x11EventHandler) handleEvents() bool {
 			const scrollScale = 10
 			switch bevt.button {
 			case C.Button1:
-				btn = pointer.ButtonLeft
+				btn = pointer.ButtonPrimary
 			case C.Button2:
-				btn = pointer.ButtonMiddle
+				btn = pointer.ButtonTertiary
 			case C.Button3:
-				btn = pointer.ButtonRight
+				btn = pointer.ButtonSecondary
 			case C.Button4:
 				// scroll up
 				ev.Type = pointer.Scroll