app: [macOS] defer Window destroy to after window close

The windowWillClose callback is too soon to destroy our Window:
at least draw callbacks may be called after windowWillClose but
before the window is gone. This change moves cleanup to the
viewDidMoveToWindow callback where we're sure the NSView is no longer
active.

Fixes: https://todo.sr.ht/~eliasnaur/gio/466
Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/os_macos.go

@@ -186,6 +186,11 @@ static CFTypeRef layerForView(CFTypeRef viewRef) {
 	return (__bridge CFTypeRef)view.layer;
 }
 
+static CFTypeRef windowForView(CFTypeRef viewRef) {
+	NSView *view = (__bridge NSView *)viewRef;
+	return (__bridge CFTypeRef)view.window;
+}
+
 static void raiseWindow(CFTypeRef windowRef) {
 	NSWindow* window = (__bridge NSWindow *)windowRef;
 	[window makeKeyAndOrderFront:nil];
@@ -237,7 +242,6 @@ type ViewEvent struct {
 
 type window struct {
 	view        C.CFTypeRef
-	window      C.CFTypeRef
 	w           *callbacks
 	stage       system.Stage
 	displayLink *displayLink
@@ -305,7 +309,7 @@ func (w *window) WriteClipboard(s string) {
 }
 
 func (w *window) updateWindowMode() {
-	style := int(C.getWindowStyleMask(w.window))
+	style := int(C.getWindowStyleMask(C.windowForView(w.view)))
 	if style&C.NSWindowStyleMaskFullScreen != 0 {
 		w.config.Mode = Fullscreen
 	} else {
@@ -321,70 +325,71 @@ func (w *window) Configure(options []Option) {
 	w.updateWindowMode()
 	cnf := w.config
 	cnf.apply(cfg, options)
+	window := C.windowForView(w.view)
 
 	switch cnf.Mode {
 	case Fullscreen:
 		switch prev.Mode {
 		case Fullscreen:
 		case Minimized:
-			C.unhideWindow(w.window)
+			C.unhideWindow(window)
 			fallthrough
 		default:
 			w.config.Mode = Fullscreen
-			C.toggleFullScreen(w.window)
+			C.toggleFullScreen(window)
 		}
 	case Minimized:
 		switch prev.Mode {
 		case Minimized, Fullscreen:
 		default:
 			w.config.Mode = Minimized
-			C.hideWindow(w.window)
+			C.hideWindow(window)
 		}
 	case Maximized:
 		switch prev.Mode {
 		case Fullscreen:
 		case Minimized:
-			C.unhideWindow(w.window)
+			C.unhideWindow(window)
 			fallthrough
 		default:
 			w.config.Mode = Maximized
 			w.setTitle(prev, cnf)
-			if C.isWindowZoomed(w.window) == 0 {
+			if C.isWindowZoomed(window) == 0 {
-				C.zoomWindow(w.window)
+				C.zoomWindow(window)
 			}
 		}
 	case Windowed:
 		switch prev.Mode {
 		case Fullscreen:
-			C.toggleFullScreen(w.window)
+			C.toggleFullScreen(window)
 		case Minimized:
-			C.unhideWindow(w.window)
+			C.unhideWindow(window)
 		case Maximized:
 		}
 		w.config.Mode = Windowed
-		if C.isWindowZoomed(w.window) != 0 {
+		if C.isWindowZoomed(window) != 0 {
-			C.zoomWindow(w.window)
+			C.zoomWindow(window)
 		}
 		w.setTitle(prev, cnf)
 		if prev.Size != cnf.Size {
 			w.config.Size = cnf.Size
 			cnf.Size = cnf.Size.Div(int(screenScale))
-			C.setSize(w.window, C.CGFloat(cnf.Size.X), C.CGFloat(cnf.Size.Y))
+			C.setSize(window, C.CGFloat(cnf.Size.X), C.CGFloat(cnf.Size.Y))
 		}
 		if prev.MinSize != cnf.MinSize {
 			w.config.MinSize = cnf.MinSize
 			cnf.MinSize = cnf.MinSize.Div(int(screenScale))
-			C.setMinSize(w.window, C.CGFloat(cnf.MinSize.X), C.CGFloat(cnf.MinSize.Y))
+			C.setMinSize(window, C.CGFloat(cnf.MinSize.X), C.CGFloat(cnf.MinSize.Y))
 		}
 		if prev.MaxSize != cnf.MaxSize {
 			w.config.MaxSize = cnf.MaxSize
 			cnf.MaxSize = cnf.MaxSize.Div(int(screenScale))
-			C.setMaxSize(w.window, C.CGFloat(cnf.MaxSize.X), C.CGFloat(cnf.MaxSize.Y))
+			C.setMaxSize(window, C.CGFloat(cnf.MaxSize.X), C.CGFloat(cnf.MaxSize.Y))
 		}
 	}
 	if cnf.Decorated != prev.Decorated {
 		w.config.Decorated = cnf.Decorated
-		mask := C.getWindowStyleMask(w.window)
+		mask := C.getWindowStyleMask(window)
 		style := C.NSWindowStyleMask(C.NSWindowStyleMaskTitled | C.NSWindowStyleMaskResizable | C.NSWindowStyleMaskMiniaturizable | C.NSWindowStyleMaskClosable)
 		style = C.NSWindowStyleMaskFullSizeContentView
 		mask &^= style
@@ -395,12 +400,12 @@ func (w *window) Configure(options []Option) {
 			barTrans = C.YES
 			titleVis = C.NSWindowTitleHidden
 		}
-		C.setWindowTitlebarAppearsTransparent(w.window, barTrans)
+		C.setWindowTitlebarAppearsTransparent(window, barTrans)
-		C.setWindowTitleVisibility(w.window, titleVis)
+		C.setWindowTitleVisibility(window, titleVis)
-		C.setWindowStyleMask(w.window, mask)
+		C.setWindowStyleMask(window, mask)
-		C.setWindowStandardButtonHidden(w.window, C.NSWindowCloseButton, barTrans)
+		C.setWindowStandardButtonHidden(window, C.NSWindowCloseButton, barTrans)
-		C.setWindowStandardButtonHidden(w.window, C.NSWindowMiniaturizeButton, barTrans)
+		C.setWindowStandardButtonHidden(window, C.NSWindowMiniaturizeButton, barTrans)
-		C.setWindowStandardButtonHidden(w.window, C.NSWindowZoomButton, barTrans)
+		C.setWindowStandardButtonHidden(window, C.NSWindowZoomButton, barTrans)
 	}
 	w.w.Event(ConfigEvent{Config: w.config})
 }
@@ -410,25 +415,26 @@ func (w *window) setTitle(prev, cnf Config) {
 		w.config.Title = cnf.Title
 		title := stringToNSString(cnf.Title)
 		defer C.CFRelease(title)
-		C.setTitle(w.window, title)
+		C.setTitle(C.windowForView(w.view), title)
 	}
 }
 
 func (w *window) Perform(acts system.Action) {
+	window := C.windowForView(w.view)
 	walkActions(acts, func(a system.Action) {
 		switch a {
 		case system.ActionCenter:
-			r := C.getScreenFrame(w.window) // the screen size of the window
+			r := C.getScreenFrame(window) // the screen size of the window
 			sz := w.config.Size
 			x := (int(r.size.width) - sz.X) / 2
 			y := (int(r.size.height) - sz.Y) / 2
-			C.setScreenFrame(w.window, C.CGFloat(x), C.CGFloat(y), C.CGFloat(sz.X), C.CGFloat(sz.Y))
+			C.setScreenFrame(window, C.CGFloat(x), C.CGFloat(y), C.CGFloat(sz.X), C.CGFloat(sz.Y))
 		case system.ActionRaise:
-			C.raiseWindow(w.window)
+			C.raiseWindow(window)
 		}
 	})
 	if acts&system.ActionClose != 0 {
-		C.closeWindow(w.window)
+		C.closeWindow(window)
 	}
 }
 
@@ -531,7 +537,7 @@ func gio_onMouse(view, evt C.CFTypeRef, cdir C.int, cbtn C.NSInteger, x, y, dx,
 		if ok && w.config.Mode != Fullscreen {
 			switch act {
 			case system.ActionMove:
-				C.performWindowDragWithEvent(w.window, evt)
+				C.performWindowDragWithEvent(C.windowForView(w.view), evt)
 				return
 			}
 		}
@@ -781,14 +787,12 @@ func configFor(scale float32) unit.Metric {
 //export gio_onClose
 func gio_onClose(view C.CFTypeRef) {
 	w := mustView(view)
+	w.displayLink.Close()
 	w.w.Event(ViewEvent{})
 	deleteView(view)
 	w.w.Event(system.DestroyEvent{})
-	w.displayLink.Close()
 	C.CFRelease(w.view)
-	C.CFRelease(w.window)
 	w.view = 0
-	w.window = 0
 	w.displayLink = nil
 }
 
@@ -848,17 +852,18 @@ func newWindow(win *callbacks, options []Option) error {
 		}
 		errch <- nil
 		w.w = win
-		w.window = C.gio_createWindow(w.view, 0, 0, 0, 0, 0, 0)
+		window := C.gio_createWindow(w.view, 0, 0, 0, 0, 0, 0)
 		w.updateWindowMode()
 		win.SetDriver(w)
 		w.Configure(options)
 		if nextTopLeft.x == 0 && nextTopLeft.y == 0 {
 			// cascadeTopLeftFromPoint treats (0, 0) as a no-op,
 			// and just returns the offset we need for the first window.
-			nextTopLeft = C.cascadeTopLeftFromPoint(w.window, nextTopLeft)
+			nextTopLeft = C.cascadeTopLeftFromPoint(window, nextTopLeft)
 		}
-		nextTopLeft = C.cascadeTopLeftFromPoint(w.window, nextTopLeft)
+		nextTopLeft = C.cascadeTopLeftFromPoint(window, nextTopLeft)
-		C.makeKeyAndOrderFront(w.window)
+		// makeKeyAndOrderFront assumes ownership of our window reference.
+		C.makeKeyAndOrderFront(window)
 		layer := C.layerForView(w.view)
 		w.w.Event(ViewEvent{View: uintptr(w.view), Layer: uintptr(layer)})
 	})

app/os_macos.m

@@ -45,11 +45,6 @@ __attribute__ ((visibility ("hidden"))) CALayer *gio_layerFactory(void);
 	NSWindow *window = (NSWindow *)[notification object];
 	gio_onFocus((__bridge CFTypeRef)window.contentView, 0);
 }
-- (void)windowWillClose:(NSNotification *)notification {
-	NSWindow *window = (NSWindow *)[notification object];
-	window.delegate = nil;
-	gio_onClose((__bridge CFTypeRef)window.contentView);
-}
 @end
 
 static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFloat dy) {
@@ -86,6 +81,11 @@ static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFlo
 	layer.delegate = self;
 	return layer;
 }
+- (void)viewDidMoveToWindow {
+	if (self.window == nil) {
+		gio_onClose((__bridge CFTypeRef)self);
+	}
+}
 - (void)mouseDown:(NSEvent *)event {
 	handleMouse(self, event, MOUSE_DOWN, 0, 0);
 }
@@ -357,7 +357,6 @@ CFTypeRef gio_createWindow(CFTypeRef viewRef, CGFloat width, CGFloat height, CGF
 		NSView *view = (__bridge NSView *)viewRef;
 		[window setContentView:view];
 		[window makeFirstResponder:view];
-		window.releasedWhenClosed = NO;
 		window.delegate = globalWindowDel;
 		return (__bridge_retained CFTypeRef)window;
 	}