feat: expose window.invalidateShadow() (#32452)

Co-authored-by: Jeremy Rose <jeremya@chromium.org>
Co-authored-by: Darshan Sen <raisinten@gmail.com>

docs/api/browser-window.md

@@ -1565,6 +1565,13 @@ screen readers
 Sets a 16 x 16 pixel overlay onto the current taskbar icon, usually used to
 convey some sort of application status or to passively notify the user.
 
+#### `win.invalidateShadow()` _macOS_
+
+Invalidates the window shadow so that it is recomputed based on the current window shape.
+
+`BrowserWindows` that are transparent can sometimes leave behind visual artifacts on macOS.
+This method can be used to clear these artifacts when, for example, performing an animation.
+
 #### `win.setHasShadow(hasShadow)`
 
 * `hasShadow` boolean

shell/browser/api/electron_api_base_window.cc

@@ -639,6 +639,10 @@ std::string BaseWindow::GetBackgroundColor(gin_helper::Arguments* args) {
   return ToRGBHex(window_->GetBackgroundColor());
 }
 
+void BaseWindow::InvalidateShadow() {
+  window_->InvalidateShadow();
+}
+
 void BaseWindow::SetHasShadow(bool has_shadow) {
   window_->SetHasShadow(has_shadow);
 }
@@ -1259,6 +1263,7 @@ void BaseWindow::BuildPrototype(v8::Isolate* isolate,
       .SetMethod("isVisibleOnAllWorkspaces",
                  &BaseWindow::IsVisibleOnAllWorkspaces)
 #if BUILDFLAG(IS_MAC)
+      .SetMethod("invalidateShadow", &BaseWindow::InvalidateShadow)
       .SetMethod("_getAlwaysOnTopLevel", &BaseWindow::GetAlwaysOnTopLevel)
       .SetMethod("setAutoHideCursor", &BaseWindow::SetAutoHideCursor)
 #endif

shell/browser/api/electron_api_base_window.h

@@ -156,6 +156,7 @@ class BaseWindow : public gin_helper::TrackableObject<BaseWindow>,
   bool IsTabletMode() const;
   virtual void SetBackgroundColor(const std::string& color_name);
   std::string GetBackgroundColor(gin_helper::Arguments* args);
+  void InvalidateShadow();
   void SetHasShadow(bool has_shadow);
   bool HasShadow();
   void SetOpacity(const double opacity);

shell/browser/native_window.cc

@@ -421,6 +421,8 @@ void NativeWindow::SetParentWindow(NativeWindow* parent) {
   parent_ = parent;
 }
 
+void NativeWindow::InvalidateShadow() {}
+
 void NativeWindow::SetAutoHideCursor(bool auto_hide) {}
 
 void NativeWindow::SelectPreviousTab() {}

shell/browser/native_window.h

@@ -169,6 +169,7 @@ class NativeWindow : public base::SupportsUserData,
   virtual bool IsTabletMode() const;
   virtual void SetBackgroundColor(SkColor color) = 0;
   virtual SkColor GetBackgroundColor() = 0;
+  virtual void InvalidateShadow();
   virtual void SetHasShadow(bool has_shadow) = 0;
   virtual bool HasShadow() = 0;
   virtual void SetOpacity(const double opacity) = 0;

shell/browser/native_window_mac.h

@@ -94,6 +94,7 @@ class NativeWindowMac : public NativeWindow,
   bool IsKiosk() override;
   void SetBackgroundColor(SkColor color) override;
   SkColor GetBackgroundColor() override;
+  void InvalidateShadow() override;
   void SetHasShadow(bool has_shadow) override;
   bool HasShadow() override;
   void SetOpacity(const double opacity) override;

shell/browser/native_window_mac.mm

@@ -226,8 +226,8 @@ NativeWindowMac::NativeWindowMac(const gin_helper::Dictionary& options,
 
   NSUInteger styleMask = NSWindowStyleMaskTitled;
 
-  // Removing NSWindowStyleMaskTitled removes window title, which removes
-  // rounded corners of window.
+  // The NSWindowStyleMaskFullSizeContentView style removes rounded corners
+  // for frameless window.
   bool rounded_corner = true;
   options.Get(options::kRoundedCorners, &rounded_corner);
   if (!rounded_corner && !has_frame())
@@ -1061,6 +1061,10 @@ bool NativeWindowMac::HasShadow() {
   return [window_ hasShadow];
 }
 
+void NativeWindowMac::InvalidateShadow() {
+  [window_ invalidateShadow];
+}
+
 void NativeWindowMac::SetOpacity(const double opacity) {
   const double boundedOpacity = base::clamp(opacity, 0.0, 1.0);
   [window_ setAlphaValue:boundedOpacity];