app: [Windows] add minimal support for devices with touch screens

The Windows Pointer API (https://learn.microsoft.com/en-us/windows/win32/api/_inputmsg/) was used to allow the detection of events when interacting with touch screens. This also opens the gates for supporting other types of input devices (e.g. pens and touchpads). Mouse events are now part of the pointer events (primary events trigger WM_POINTER<DOWN|UP>, whereas secondary ones vanilla WM_POINTERUPDATE, and cancellations WM_POINTERCAPTURECHANGED). A fourth and fifth button (usually found in modern mice) has also been added for completeness, though their integration in other OS-es shall be the objective of future patches. Signed-off-by: Marc <marc.leroy@samantree.com> Signed-off-by: Elias Naur <mail@eliasnaur.com>
2026-07-07 10:25:37 +00:00 · 2025-05-27 10:33:22 +02:00
parent 0eac4f2c6a
commit 809a6d0dc7
2 changed files with 239 additions and 87 deletions
@@ -36,10 +36,9 @@ type Win32ViewEvent struct {
 }

 type window struct {
-	hwnd        syscall.Handle
-	hdc         syscall.Handle
-	w           *callbacks
-	pointerBtns pointer.Buttons
+	hwnd syscall.Handle
+	hdc  syscall.Handle
+	w    *callbacks

 	// cursorIn tracks whether the cursor was inside the window according
 	// to the most recent WM_SETCURSOR.
@@ -175,6 +174,12 @@ func (w *window) init() error {
 	if err != nil {
 		return err
 	}
+	if err := windows.RegisterTouchWindow(hwnd, 0); err != nil {
+		return err
+	}
+	if err := windows.EnableMouseInPointer(1); err != nil {
+		return err
+	}
 	w.hdc, err = windows.GetDC(hwnd)
 	if err != nil {
 		windows.DestroyWindow(hwnd)
@@ -265,18 +270,32 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 				return 0
 			}
 		}
-	case windows.WM_LBUTTONDOWN:
-		w.pointerButton(pointer.ButtonPrimary, true, lParam, getModifiers())
-	case windows.WM_LBUTTONUP:
-		w.pointerButton(pointer.ButtonPrimary, false, lParam, getModifiers())
-	case windows.WM_RBUTTONDOWN:
-		w.pointerButton(pointer.ButtonSecondary, true, lParam, getModifiers())
-	case windows.WM_RBUTTONUP:
-		w.pointerButton(pointer.ButtonSecondary, false, lParam, getModifiers())
-	case windows.WM_MBUTTONDOWN:
-		w.pointerButton(pointer.ButtonTertiary, true, lParam, getModifiers())
-	case windows.WM_MBUTTONUP:
-		w.pointerButton(pointer.ButtonTertiary, false, lParam, getModifiers())
+	case windows.WM_POINTERDOWN, windows.WM_POINTERUP, windows.WM_POINTERUPDATE, windows.WM_POINTERCAPTURECHANGED:
+		pid := getPointerIDwParam(wParam)
+		pi, err := windows.GetPointerInfo(uint32(pid))
+		if err != nil {
+			panic(err)
+		}
+		switch msg {
+		case windows.WM_POINTERDOWN:
+			windows.SetCapture(w.hwnd)
+		case windows.WM_POINTERUP:
+			windows.ReleaseCapture()
+		}
+
+		kind := pointer.Move
+		switch pi.ButtonChangeType {
+		case windows.POINTER_CHANGE_FIRSTBUTTON_DOWN, windows.POINTER_CHANGE_SECONDBUTTON_DOWN, windows.POINTER_CHANGE_THIRDBUTTON_DOWN, windows.POINTER_CHANGE_FOURTHBUTTON_DOWN, windows.POINTER_CHANGE_FIFTHBUTTON_DOWN:
+			kind = pointer.Press
+		case windows.POINTER_CHANGE_FIRSTBUTTON_UP, windows.POINTER_CHANGE_SECONDBUTTON_UP, windows.POINTER_CHANGE_THIRDBUTTON_UP, windows.POINTER_CHANGE_FOURTHBUTTON_UP, windows.POINTER_CHANGE_FIFTHBUTTON_UP:
+			kind = pointer.Release
+		}
+
+		if (pi.PointerFlags&windows.POINTER_FLAG_CANCELED != 0) || (msg == windows.WM_POINTERCAPTURECHANGED) {
+			kind = pointer.Cancel
+		}
+
+		w.pointerUpdate(pi, pid, kind, lParam)
 	case windows.WM_CANCELMODE:
 		w.ProcessEvent(pointer.Event{
 			Kind: pointer.Cancel,
@@ -296,20 +315,9 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		np := windows.Point{X: int32(x), Y: int32(y)}
 		windows.ScreenToClient(w.hwnd, &np)
 		return w.hitTest(int(np.X), int(np.Y))
-	case windows.WM_MOUSEMOVE:
-		x, y := coordsFromlParam(lParam)
-		p := f32.Point{X: float32(x), Y: float32(y)}
-		w.ProcessEvent(pointer.Event{
-			Kind:      pointer.Move,
-			Source:    pointer.Mouse,
-			Position:  p,
-			Buttons:   w.pointerBtns,
-			Time:      windows.GetMessageTime(),
-			Modifiers: getModifiers(),
-		})
-	case windows.WM_MOUSEWHEEL:
+	case windows.WM_POINTERWHEEL:
 		w.scrollEvent(wParam, lParam, false, getModifiers())
-	case windows.WM_MOUSEHWHEEL:
+	case windows.WM_POINTERHWHEEL:
 		w.scrollEvent(wParam, lParam, true, getModifiers())
 	case windows.WM_DESTROY:
 		w.ProcessEvent(Win32ViewEvent{})
@@ -499,34 +507,28 @@ func (w *window) hitTest(x, y int) uintptr {
 	return windows.HTCLIENT
 }

-func (w *window) pointerButton(btn pointer.Buttons, press bool, lParam uintptr, kmods key.Modifiers) {
+func (w *window) pointerUpdate(pi windows.PointerInfo, pid pointer.ID, kind pointer.Kind, lParam uintptr) {
 	if !w.config.Focused {
 		windows.SetFocus(w.hwnd)
 	}

-	var kind pointer.Kind
-	if press {
-		kind = pointer.Press
-		if w.pointerBtns == 0 {
-			windows.SetCapture(w.hwnd)
-		}
-		w.pointerBtns |= btn
-	} else {
-		kind = pointer.Release
-		w.pointerBtns &^= btn
-		if w.pointerBtns == 0 {
-			windows.ReleaseCapture()
-		}
+	src := pointer.Touch
+	if pi.PointerType == windows.PT_MOUSE {
+		src = pointer.Mouse
 	}
+
 	x, y := coordsFromlParam(lParam)
-	p := f32.Point{X: float32(x), Y: float32(y)}
+	np := windows.Point{X: int32(x), Y: int32(y)}
+	windows.ScreenToClient(w.hwnd, &np)
+	p := f32.Point{X: float32(np.X), Y: float32(np.Y)}
 	w.ProcessEvent(pointer.Event{
 		Kind:      kind,
-		Source:    pointer.Mouse,
+		Source:    src,
 		Position:  p,
-		Buttons:   w.pointerBtns,
+		PointerID: pid,
+		Buttons:   getPointerButtons(pi),
 		Time:      windows.GetMessageTime(),
-		Modifiers: kmods,
+		Modifiers: getModifiers(),
 	})
 }

@@ -537,6 +539,12 @@ func coordsFromlParam(lParam uintptr) (int, int) {
 }

 func (w *window) scrollEvent(wParam, lParam uintptr, horizontal bool, kmods key.Modifiers) {
+	pid := getPointerIDwParam(wParam)
+	pi, err := windows.GetPointerInfo(uint32(pid))
+	if err != nil {
+		panic(err)
+	}
+
 	x, y := coordsFromlParam(lParam)
 	// The WM_MOUSEWHEEL coordinates are in screen coordinates, in contrast
 	// to other mouse events.
@@ -559,7 +567,7 @@ func (w *window) scrollEvent(wParam, lParam uintptr, horizontal bool, kmods key.
 		Kind:      pointer.Scroll,
 		Source:    pointer.Mouse,
 		Position:  p,
-		Buttons:   w.pointerBtns,
+		Buttons:   getPointerButtons(pi),
 		Scroll:    sp,
 		Modifiers: kmods,
 		Time:      windows.GetMessageTime(),
@@ -1005,3 +1013,45 @@ func (Win32ViewEvent) ImplementsEvent()     {}
 func (w Win32ViewEvent) Valid() bool {
 	return w != (Win32ViewEvent{})
 }
+
+// LOWORD (minwindef.h)
+func loWord(val uint32) uint16 {
+	return uint16(val & 0xFFFF)
+}
+
+// GET_POINTERID_WPARAM (winuser.h)
+func getPointerIDwParam(wParam uintptr) pointer.ID {
+	return pointer.ID(loWord(uint32(wParam)))
+}
+
+func getPointerButtons(pi windows.PointerInfo) pointer.Buttons {
+	var btns pointer.Buttons
+
+	if pi.PointerFlags&windows.POINTER_FLAG_FIRSTBUTTON != 0 {
+		btns |= pointer.ButtonPrimary
+	} else {
+		btns &^= pointer.ButtonPrimary
+	}
+	if pi.PointerFlags&windows.POINTER_FLAG_SECONDBUTTON != 0 {
+		btns |= pointer.ButtonSecondary
+	} else {
+		btns &^= pointer.ButtonSecondary
+	}
+	if pi.PointerFlags&windows.POINTER_FLAG_THIRDBUTTON != 0 {
+		btns |= pointer.ButtonTertiary
+	} else {
+		btns &^= pointer.ButtonTertiary
+	}
+	if pi.PointerFlags&windows.POINTER_FLAG_FOURTHBUTTON != 0 {
+		btns |= pointer.ButtonQuaternary
+	} else {
+		btns &^= pointer.ButtonQuaternary
+	}
+	if pi.PointerFlags&windows.POINTER_FLAG_FIFTHBUTTON != 0 {
+		btns |= pointer.ButtonQuinary
+	} else {
+		btns &^= pointer.ButtonQuinary
+	}
+
+	return btns
+}