app/internal/window: [windows] add icon support

That change adds the icon to the "window navbar".

Signed-off-by: Inkeliz <inkeliz@inkeliz.com>

app/internal/window/os_windows.go

@@ -70,6 +70,9 @@ var backends []gpuAPI
 // winMap maps win32 HWNDs to *windows.
 var winMap sync.Map
 
+// iconID is the ID of the icon in the resource file.
+const iconID = 1
+
 var resources struct {
 	once sync.Once
 	// handle is the module handle from GetModuleHandle.
@@ -130,11 +133,13 @@ func initResources() error {
 		return err
 	}
 	resources.cursor = c
+	icon, _ := windows.LoadImage(hInst, iconID, windows.IMAGE_ICON, 0, 0, windows.LR_DEFAULTSIZE|windows.LR_SHARED)
 	wcls := windows.WndClassEx{
 		CbSize:        uint32(unsafe.Sizeof(windows.WndClassEx{})),
 		Style:         windows.CS_HREDRAW | windows.CS_VREDRAW | windows.CS_OWNDC,
 		LpfnWndProc:   syscall.NewCallback(windowProc),
 		HInstance:     hInst,
+		HIcon:         icon,
 		LpszClassName: syscall.StringToUTF16Ptr("GioWindow"),
 	}
 	cls, err := windows.RegisterClassEx(&wcls)

app/internal/windows/windows.go

@@ -193,6 +193,19 @@ const (
 	GHND = 0x0042
 
 	CF_UNICODETEXT = 13
+	IMAGE_BITMAP   = 0
+	IMAGE_ICON     = 1
+	IMAGE_CURSOR   = 2
+
+	LR_CREATEDIBSECTION = 0x00002000
+	LR_DEFAULTCOLOR     = 0x00000000
+	LR_DEFAULTSIZE      = 0x00000040
+	LR_LOADFROMFILE     = 0x00000010
+	LR_LOADMAP3DCOLORS  = 0x00001000
+	LR_LOADTRANSPARENT  = 0x00000020
+	LR_MONOCHROME       = 0x00000001
+	LR_SHARED           = 0x00008000
+	LR_VGACOLOR         = 0x00000080
 )
 
 var (
@@ -221,6 +234,7 @@ var (
 	_GetMessageTime              = user32.NewProc("GetMessageTime")
 	_KillTimer                   = user32.NewProc("KillTimer")
 	_LoadCursor                  = user32.NewProc("LoadCursorW")
+	_LoadImage                   = user32.NewProc("LoadImageW")
 	_MonitorFromPoint            = user32.NewProc("MonitorFromPoint")
 	_MsgWaitForMultipleObjectsEx = user32.NewProc("MsgWaitForMultipleObjectsEx")
 	_OpenClipboard               = user32.NewProc("OpenClipboard")
@@ -438,6 +452,14 @@ func LoadCursor(curID uint16) (syscall.Handle, error) {
 	return syscall.Handle(h), nil
 }
 
+func LoadImage(hInst syscall.Handle, res uint32, typ uint32, cx, cy int, fuload uint32) (syscall.Handle, error) {
+	h, _, err := _LoadImage.Call(uintptr(hInst), uintptr(res), uintptr(typ), uintptr(cx), uintptr(cy), uintptr(fuload))
+	if h == 0 {
+		return 0, fmt.Errorf("LoadImageW failed: %v", err)
+	}
+	return syscall.Handle(h), nil
+}
+
 func monitorFromPoint(pt Point, flags uint32) syscall.Handle {
 	r, _, _ := _MonitorFromPoint.Call(uintptr(pt.X), uintptr(pt.Y), uintptr(flags))
 	return syscall.Handle(r)