[windows] Improve fullscreen mode for frameless windows (#2279)

* Improve fullscreen mode for frameless windows
* Set Window background color in addition to WebView2 background color

v2/internal/frontend/desktop/windows/frontend.go

@@ -296,6 +296,9 @@ func (f *Frontend) WindowToggleMaximise() {
 func (f *Frontend) WindowUnmaximise() {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
+	if f.mainWindow.Form.IsFullScreen() {
+		return
+	}
 	f.mainWindow.Restore()
 }
 
@@ -312,6 +315,9 @@ func (f *Frontend) WindowMinimise() {
 func (f *Frontend) WindowUnminimise() {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
+	if f.mainWindow.Form.IsFullScreen() {
+		return
+	}
 	f.mainWindow.Restore()
 }
 
@@ -332,6 +338,8 @@ func (f *Frontend) WindowSetBackgroundColour(col *options.RGBA) {
 	}
 
 	f.mainWindow.Invoke(func() {
+		win32.SetBackgroundColour(f.mainWindow.Handle(), col.R, col.G, col.B)
+
 		controller := f.chromium.GetController()
 		controller2 := controller.GetICoreWebView2Controller2()
 

v2/internal/frontend/desktop/windows/winc/form.go

@@ -176,14 +176,15 @@ func (fm *Form) Fullscreen() {
 	if !w32.GetWindowPlacement(fm.hwnd, &fm.previousWindowPlacement) {
 		return
 	}
-	w32.SetWindowLong(fm.hwnd, w32.GWL_STYLE, fm.previousWindowStyle & ^uint32(w32.WS_OVERLAPPEDWINDOW))
+	// According to https://devblogs.microsoft.com/oldnewthing/20050505-04/?p=35703 one should use w32.WS_POPUP | w32.WS_VISIBLE
+	w32.SetWindowLong(fm.hwnd, w32.GWL_STYLE, fm.previousWindowStyle & ^uint32(w32.WS_OVERLAPPEDWINDOW) | (w32.WS_POPUP|w32.WS_VISIBLE))
+	fm.isFullscreen = true
 	w32.SetWindowPos(fm.hwnd, w32.HWND_TOP,
 		int(monitorInfo.RcMonitor.Left),
 		int(monitorInfo.RcMonitor.Top),
 		int(monitorInfo.RcMonitor.Right-monitorInfo.RcMonitor.Left),
 		int(monitorInfo.RcMonitor.Bottom-monitorInfo.RcMonitor.Top),
 		w32.SWP_NOOWNERZORDER|w32.SWP_FRAMECHANGED)
-	fm.isFullscreen = true
 }
 
 func (fm *Form) UnFullscreen() {
@@ -192,9 +193,9 @@ func (fm *Form) UnFullscreen() {
 	}
 	w32.SetWindowLong(fm.hwnd, w32.GWL_STYLE, fm.previousWindowStyle)
 	w32.SetWindowPlacement(fm.hwnd, &fm.previousWindowPlacement)
+	fm.isFullscreen = false
 	w32.SetWindowPos(fm.hwnd, 0, 0, 0, 0, 0,
 		w32.SWP_NOMOVE|w32.SWP_NOSIZE|w32.SWP_NOZORDER|w32.SWP_NOOWNERZORDER|w32.SWP_FRAMECHANGED)
-	fm.isFullscreen = false
 }
 
 func (fm *Form) IsFullScreen() bool {

v2/internal/frontend/desktop/windows/window.go

@@ -137,7 +137,7 @@ func (w *Window) Fullscreen() {
 }
 
 func (w *Window) UnFullscreen() {
-	if !w.IsFullScreen() {
+	if !w.Form.IsFullScreen() {
 		return
 	}
 	w.Form.UnFullscreen()
@@ -145,6 +145,14 @@ func (w *Window) UnFullscreen() {
 	w.SetMaxSize(w.maxWidth, w.maxHeight)
 }
 
+func (w *Window) Restore() {
+	if w.Form.IsFullScreen() {
+		w.UnFullscreen()
+	} else {
+		w.Form.Restore()
+	}
+}
+
 func (w *Window) SetMinSize(minWidth int, minHeight int) {
 	w.minWidth = minWidth
 	w.minHeight = minHeight
@@ -205,7 +213,6 @@ func (w *Window) WndProc(msg uint32, wparam, lparam uintptr) uintptr {
 			//}
 		}
 
-	// TODO move WM_DPICHANGED handling into winc
 	case 0x02E0: //w32.WM_DPICHANGED
 		newWindowSize := (*w32.RECT)(unsafe.Pointer(lparam))
 		w32.SetWindowPos(w.Handle(),
@@ -235,9 +242,10 @@ func (w *Window) WndProc(msg uint32, wparam, lparam uintptr) uintptr {
 			// shown. We still need the WS_THICKFRAME style to enable resizing from the frontend.
 			if wparam != 0 {
 				rgrc := (*w32.RECT)(unsafe.Pointer(lparam))
-
-				style := uint32(w32.GetWindowLong(w.Handle(), w32.GWL_STYLE))
-				if style&w32.WS_MAXIMIZE != 0 {
+				if w.Form.IsFullScreen() {
+					// In Full-Screen mode we don't need to adjust anything
+					w.chromium.SetPadding(edge.Rect{})
+				} else if w.IsMaximised() {
 					// If the window is maximized we must adjust the client area to the work area of the monitor. Otherwise
 					// some content goes beyond the visible part of the monitor.
 					// Make sure to use the provided RECT to get the monitor, because during maximizig there might be
@@ -268,6 +276,7 @@ func (w *Window) WndProc(msg uint32, wparam, lparam uintptr) uintptr {
 						}
 					}
 					w.chromium.SetPadding(edge.Rect{})
+					return 0
 				} else {
 					// This is needed to workaround the resize flickering in frameless mode with WindowDecorations
 					// See: https://stackoverflow.com/a/6558508
@@ -277,9 +286,8 @@ func (w *Window) WndProc(msg uint32, wparam, lparam uintptr) uintptr {
 					// therefore let's pad the content with 1px at the bottom.
 					rgrc.Bottom += 1
 					w.chromium.SetPadding(edge.Rect{Bottom: 1})
+					return 0
 				}
-
-				return 0
 			}
 		}
 	}