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>

app/internal/windows/windows.go

@@ -108,6 +108,74 @@ type MonitorInfo struct {
 	Flags    uint32
 }
 
+type POINTER_INPUT_TYPE int32
+
+const (
+	PT_POINTER  POINTER_INPUT_TYPE = 1
+	PT_TOUCH    POINTER_INPUT_TYPE = 2
+	PT_PEN      POINTER_INPUT_TYPE = 3
+	PT_MOUSE    POINTER_INPUT_TYPE = 4
+	PT_TOUCHPAD POINTER_INPUT_TYPE = 5
+)
+
+type POINTER_INFO_POINTER_FLAGS int32
+
+const (
+	POINTER_FLAG_NEW            POINTER_INFO_POINTER_FLAGS = 0x00000001
+	POINTER_FLAG_INRANGE        POINTER_INFO_POINTER_FLAGS = 0x00000002
+	POINTER_FLAG_INCONTACT      POINTER_INFO_POINTER_FLAGS = 0x00000004
+	POINTER_FLAG_FIRSTBUTTON    POINTER_INFO_POINTER_FLAGS = 0x00000010
+	POINTER_FLAG_SECONDBUTTON   POINTER_INFO_POINTER_FLAGS = 0x00000020
+	POINTER_FLAG_THIRDBUTTON    POINTER_INFO_POINTER_FLAGS = 0x00000040
+	POINTER_FLAG_FOURTHBUTTON   POINTER_INFO_POINTER_FLAGS = 0x00000080
+	POINTER_FLAG_FIFTHBUTTON    POINTER_INFO_POINTER_FLAGS = 0x00000100
+	POINTER_FLAG_PRIMARY        POINTER_INFO_POINTER_FLAGS = 0x00002000
+	POINTER_FLAG_CONFIDENCE     POINTER_INFO_POINTER_FLAGS = 0x00004000
+	POINTER_FLAG_CANCELED       POINTER_INFO_POINTER_FLAGS = 0x00008000
+	POINTER_FLAG_DOWN           POINTER_INFO_POINTER_FLAGS = 0x00010000
+	POINTER_FLAG_UPDATE         POINTER_INFO_POINTER_FLAGS = 0x00020000
+	POINTER_FLAG_UP             POINTER_INFO_POINTER_FLAGS = 0x00040000
+	POINTER_FLAG_WHEEL          POINTER_INFO_POINTER_FLAGS = 0x00080000
+	POINTER_FLAG_HWHEEL         POINTER_INFO_POINTER_FLAGS = 0x00100000
+	POINTER_FLAG_CAPTURECHANGED POINTER_INFO_POINTER_FLAGS = 0x00200000
+	POINTER_FLAG_HASTRANSFORM   POINTER_INFO_POINTER_FLAGS = 0x00400000
+)
+
+type POINTER_BUTTON_CHANGE_TYPE int32
+
+const (
+	POINTER_CHANGE_NONE              POINTER_BUTTON_CHANGE_TYPE = 0
+	POINTER_CHANGE_FIRSTBUTTON_DOWN  POINTER_BUTTON_CHANGE_TYPE = 1
+	POINTER_CHANGE_FIRSTBUTTON_UP    POINTER_BUTTON_CHANGE_TYPE = 2
+	POINTER_CHANGE_SECONDBUTTON_DOWN POINTER_BUTTON_CHANGE_TYPE = 3
+	POINTER_CHANGE_SECONDBUTTON_UP   POINTER_BUTTON_CHANGE_TYPE = 4
+	POINTER_CHANGE_THIRDBUTTON_DOWN  POINTER_BUTTON_CHANGE_TYPE = 5
+	POINTER_CHANGE_THIRDBUTTON_UP    POINTER_BUTTON_CHANGE_TYPE = 6
+	POINTER_CHANGE_FOURTHBUTTON_DOWN POINTER_BUTTON_CHANGE_TYPE = 7
+	POINTER_CHANGE_FOURTHBUTTON_UP   POINTER_BUTTON_CHANGE_TYPE = 8
+	POINTER_CHANGE_FIFTHBUTTON_DOWN  POINTER_BUTTON_CHANGE_TYPE = 9
+	POINTER_CHANGE_FIFTHBUTTON_UP    POINTER_BUTTON_CHANGE_TYPE = 10
+)
+
+type PointerInfo struct {
+	PointerType           POINTER_INPUT_TYPE
+	PointerId             uint32
+	FrameId               uint32
+	PointerFlags          POINTER_INFO_POINTER_FLAGS
+	SourceDevice          syscall.Handle
+	HwndTarget            syscall.Handle
+	PtPixelLocation       Point
+	PtHimetricLocation    Point
+	PtPixelLocationRaw    Point
+	PtHimetricLocationRaw Point
+	DwTime                uint32
+	HistoryCount          uint32
+	InputData             int32
+	DwKeyStates           uint32
+	PerformanceCount      uint64
+	ButtonChangeType      POINTER_BUTTON_CHANGE_TYPE
+}
+
 const (
 	TRUE = 1
 
@@ -269,7 +337,15 @@ const (
 	WM_NCHITTEST             = 0x0084
 	WM_NCCALCSIZE            = 0x0083
 	WM_PAINT                 = 0x000F
+	WM_POINTERCAPTURECHANGED = 0x024C
+	WM_POINTERDOWN           = 0x0246
+	WM_POINTERUP             = 0x0247
+	WM_POINTERUPDATE         = 0x0245
+	WM_POINTERWHEEL          = 0x024E
+	WM_POINTERHWHEEL         = 0x024F
 	WM_QUIT                  = 0x0012
+	WM_RBUTTONDOWN           = 0x0204
+	WM_RBUTTONUP             = 0x0205
 	WM_SETCURSOR             = 0x0020
 	WM_SETFOCUS              = 0x0007
 	WM_SHOWWINDOW            = 0x0018
@@ -277,8 +353,6 @@ const (
 	WM_STYLECHANGED          = 0x007D
 	WM_SYSKEYDOWN            = 0x0104
 	WM_SYSKEYUP              = 0x0105
-	WM_RBUTTONDOWN          = 0x0204
-	WM_RBUTTONUP            = 0x0205
 	WM_TIMER                 = 0x0113
 	WM_UNICHAR               = 0x0109
 	WM_USER                  = 0x0400
@@ -346,6 +420,7 @@ var (
 	_DestroyWindow               = user32.NewProc("DestroyWindow")
 	_DispatchMessage             = user32.NewProc("DispatchMessageW")
 	_EmptyClipboard              = user32.NewProc("EmptyClipboard")
+	_EnableMouseInPointer        = user32.NewProc("EnableMouseInPointer")
 	_GetWindowRect               = user32.NewProc("GetWindowRect")
 	_GetClientRect               = user32.NewProc("GetClientRect")
 	_GetClipboardData            = user32.NewProc("GetClipboardData")
@@ -355,6 +430,7 @@ var (
 	_GetMessage                  = user32.NewProc("GetMessageW")
 	_GetMessageTime              = user32.NewProc("GetMessageTime")
 	_GetMonitorInfo              = user32.NewProc("GetMonitorInfoW")
+	_GetPointerInfo              = user32.NewProc("GetPointerInfo")
 	_GetSystemMetrics            = user32.NewProc("GetSystemMetrics")
 	_GetWindowLong               = user32.NewProc("GetWindowLongPtrW")
 	_GetWindowLong32             = user32.NewProc("GetWindowLongW")
@@ -372,6 +448,7 @@ var (
 	_PostQuitMessage             = user32.NewProc("PostQuitMessage")
 	_ReleaseCapture              = user32.NewProc("ReleaseCapture")
 	_RegisterClassExW            = user32.NewProc("RegisterClassExW")
+	_RegisterTouchWindow         = user32.NewProc("RegisterTouchWindow")
 	_ReleaseDC                   = user32.NewProc("ReleaseDC")
 	_ScreenToClient              = user32.NewProc("ScreenToClient")
 	_ShowWindow                  = user32.NewProc("ShowWindow")
@@ -445,6 +522,31 @@ func CreateWindowEx(dwExStyle uint32, lpClassName uint16, lpWindowName string, d
 	return syscall.Handle(hwnd), nil
 }
 
+func GetPointerInfo(pointerId uint32) (PointerInfo, error) {
+	var info PointerInfo
+	r1, _, err := _GetPointerInfo.Call(uintptr(pointerId), uintptr(unsafe.Pointer(&info)))
+	if r1 == 0 {
+		return PointerInfo{}, fmt.Errorf("GetPointerInfo failed: %v", err)
+	}
+	return info, nil
+}
+
+func RegisterTouchWindow(hwnd syscall.Handle, flags uint32) error {
+	r1, _, err := _RegisterTouchWindow.Call(uintptr(hwnd), uintptr(flags))
+	if r1 == 0 {
+		return fmt.Errorf("RegisterTouchWindow failed: %v", err)
+	}
+	return nil
+}
+
+func EnableMouseInPointer(enable uint) error {
+	r1, _, err := _EnableMouseInPointer.Call(uintptr(enable))
+	if r1 == 0 {
+		return fmt.Errorf("EnableMouseInPointer failed: %v", err)
+	}
+	return nil
+}
+
 func DefWindowProc(hwnd syscall.Handle, msg uint32, wparam, lparam uintptr) uintptr {
 	r, _, _ := _DefWindowProc.Call(uintptr(hwnd), uintptr(msg), wparam, lparam)
 	return r

app/os_windows.go

@@ -39,7 +39,6 @@ type window struct {
 	hwnd syscall.Handle
 	hdc  syscall.Handle
 	w    *callbacks
-	pointerBtns pointer.Buttons
 
 	// 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:
+	case windows.WM_POINTERDOWN, windows.WM_POINTERUP, windows.WM_POINTERUPDATE, windows.WM_POINTERCAPTURECHANGED:
-		w.pointerButton(pointer.ButtonPrimary, true, lParam, getModifiers())
+		pid := getPointerIDwParam(wParam)
-	case windows.WM_LBUTTONUP:
+		pi, err := windows.GetPointerInfo(uint32(pid))
-		w.pointerButton(pointer.ButtonPrimary, false, lParam, getModifiers())
+		if err != nil {
-	case windows.WM_RBUTTONDOWN:
+			panic(err)
-		w.pointerButton(pointer.ButtonSecondary, true, lParam, getModifiers())
+		}
-	case windows.WM_RBUTTONUP:
+		switch msg {
-		w.pointerButton(pointer.ButtonSecondary, false, lParam, getModifiers())
+		case windows.WM_POINTERDOWN:
-	case windows.WM_MBUTTONDOWN:
+			windows.SetCapture(w.hwnd)
-		w.pointerButton(pointer.ButtonTertiary, true, lParam, getModifiers())
+		case windows.WM_POINTERUP:
-	case windows.WM_MBUTTONUP:
+			windows.ReleaseCapture()
-		w.pointerButton(pointer.ButtonTertiary, false, lParam, getModifiers())
+		}
+
+		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:
+	case windows.WM_POINTERWHEEL:
-		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:
 		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
+	src := pointer.Touch
-	if press {
+	if pi.PointerType == windows.PT_MOUSE {
-		kind = pointer.Press
+		src = pointer.Mouse
-		if w.pointerBtns == 0 {
-			windows.SetCapture(w.hwnd)
-		}
-		w.pointerBtns |= btn
-	} else {
-		kind = pointer.Release
-		w.pointerBtns &^= btn
-		if w.pointerBtns == 0 {
-			windows.ReleaseCapture()
-		}
 	}
+
 	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
+}