fix: external resize hit targets for frameless windows on Windows (#50706)

shell/browser/native_window_views.cc

@@ -440,13 +440,11 @@ NativeWindowViews::NativeWindowViews(const int32_t base_window_id,
   if (window)
     window->AddPreTargetHandler(this);
 
-#if BUILDFLAG(IS_LINUX)
-  // We need to set bounds again after widget init for two reasons:
-  // 1. For CSD windows, user-specified bounds need  to be inflated by frame
-  //    insets, but the frame view isn't available at first.
-  // 2. The widget clamps bounds to fit the screen, but we want to allow
-  //    windows larger than the display.
-  SetBounds(gfx::Rect(GetPosition(), size), false);
+#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_WIN)
+  // The initial params.bounds was applied before the frame view existed, so
+  // non-client insets weren't accounted for and bounds need to be set again.
+  if (!GetRestoredFrameBorderInsets().IsEmpty())
+    SetBounds(gfx::Rect(GetPosition(), size), false);
 #endif
 }
 
@@ -906,7 +904,9 @@ gfx::Rect NativeWindowViews::GetNormalBounds() const {
   if (IsMaximized() && transparent())
     return restore_bounds_;
 #endif
-  return WidgetToLogicalBounds(widget()->GetRestoredBounds());
+  gfx::Rect bounds = widget()->GetRestoredBounds();
+  bounds.Inset(GetRestoredFrameBorderInsets());
+  return bounds;
 }
 
 void NativeWindowViews::SetContentSizeConstraints(
@@ -1676,17 +1676,24 @@ NativeWindowHandle NativeWindowViews::GetNativeWindowHandle() const {
 
 gfx::Rect NativeWindowViews::LogicalToWidgetBounds(
     const gfx::Rect& bounds) const {
+  // Use widget() directly since NativeWindowViews::IsMaximized() can
+  // call GetBounds and end up in a loop.
+  if (widget()->IsMaximized() || widget()->IsFullscreen())
+    return bounds;
+
   gfx::Rect widget_bounds(bounds);
   const gfx::Insets frame_insets = GetRestoredFrameBorderInsets();
   widget_bounds.Outset(
       gfx::Outsets::TLBR(frame_insets.top(), frame_insets.left(),
                          frame_insets.bottom(), frame_insets.right()));
-
   return widget_bounds;
 }
 
 gfx::Rect NativeWindowViews::WidgetToLogicalBounds(
     const gfx::Rect& bounds) const {
+  if (widget()->IsMaximized() || widget()->IsFullscreen())
+    return bounds;
+
   gfx::Rect logical_bounds(bounds);
   logical_bounds.Inset(GetRestoredFrameBorderInsets());
   return logical_bounds;

shell/browser/native_window_views.h

@@ -194,6 +194,7 @@ class NativeWindowViews : public NativeWindow,
   TaskbarHost& taskbar_host() { return taskbar_host_; }
   void UpdateThickFrame();
   void SetLayered();
+  bool has_thick_frame() const { return thick_frame_; }
 #endif
 
   SkColor overlay_button_color() const { return overlay_button_color_; }

shell/browser/ui/views/win_frame_view.cc

@@ -228,14 +228,15 @@ void WinFrameView::LayoutCaptionButtons() {
   int custom_height = window()->titlebar_overlay_height();
   int height = TitlebarHeight(custom_height);
 
-  // TODO(mlaurencin): This -1 creates a 1 pixel margin between the right
-  // edge of the button container and the edge of the window, allowing for this
-  // edge portion to return the correct hit test and be manually resized
-  // properly. Alternatives can be explored, but the differences in view
-  // structures between Electron and Chromium may result in this as the best
-  // option.
-  int variable_width =
-      IsMaximized() ? preferred_size.width() : preferred_size.width() - 1;
+  // Insets place the resize hit targets outside of the frame, so the caption
+  // buttons can go right at the edge. Without insets, the resize hit
+  // targets are inside the frame, and a 1px margin is needed to click and drag
+  // next to the button container. The margin can be removed if support is added
+  // for insets on non-thick frames.
+  int variable_width = !RestoredFrameBorderInsets().IsEmpty()
+                           ? preferred_size.width()
+                           : (IsMaximized() ? preferred_size.width()
+                                            : preferred_size.width() - 1);
   caption_button_container_->SetBounds(width() - preferred_size.width(),
                                        WindowTopY(), variable_width, height);
 
@@ -267,22 +268,33 @@ bool WinFrameView::GetShouldPaintAsActive() {
 gfx::Size WinFrameView::GetMinimumSize() const {
   if (!window_)
     return gfx::Size();
-  // Chromium expects minimum size to be in content dimensions on Windows
-  // because it adds the frame border automatically in OnGetMinMaxInfo.
+  // Chromium expects minimum size to be in content dimensions on Windows.
+  // If WidgetSizeIsClientSize() is true, it will account for frame borders and
+  // insets automatically.
   return window_->GetContentMinimumSize();
 }
 
 gfx::Size WinFrameView::GetMaximumSize() const {
   if (!window_)
     return gfx::Size();
-  // Chromium expects minimum size to be in content dimensions on Windows
-  // because it adds the frame border automatically in OnGetMinMaxInfo.
+  // See comment in GetMinimumSize().
   gfx::Size size = window_->GetContentMaximumSize();
   // Electron public APIs returns (0, 0) when maximum size is not set, but it
   // would break internal window APIs like HWNDMessageHandler::SetAspectRatio.
   return size.IsEmpty() ? gfx::Size(INT_MAX, INT_MAX) : size;
 }
 
+gfx::Insets WinFrameView::RestoredFrameBorderInsets() const {
+  if (window_->has_frame() || !window_->has_thick_frame() ||
+      !window_->IsResizable())
+    return {};
+
+  const int thickness =
+      display::win::GetScreenWin()->GetSystemMetricsInDIP(SM_CXSIZEFRAME) +
+      display::win::GetScreenWin()->GetSystemMetricsInDIP(SM_CXPADDEDBORDER);
+  return gfx::Insets::TLBR(0, thickness, thickness, thickness);
+}
+
 BEGIN_METADATA(WinFrameView)
 END_METADATA
 

shell/browser/ui/views/win_frame_view.h

@@ -36,6 +36,9 @@ class WinFrameView : public FramelessView {
   gfx::Size GetMinimumSize() const override;
   gfx::Size GetMaximumSize() const override;
 
+  // views::FramelessView:
+  gfx::Insets RestoredFrameBorderInsets() const override;
+
   WinCaptionButtonContainer* caption_button_container() {
     return caption_button_container_;
   }

shell/browser/ui/win/electron_desktop_window_tree_host_win.cc

@@ -89,24 +89,45 @@ bool ElectronDesktopWindowTreeHostWin::GetDwmFrameInsetsInPixels(
   return false;
 }
 
+bool ElectronDesktopWindowTreeHostWin::WidgetSizeIsClientSize() const {
+  // For both framed and frameless windows with resize insets (thick frames),
+  // this should return true so that the aura layer is sized to the client area
+  // rather than the full HWND, and so insets are accounted for when handling
+  // size/aspect ratio constraints.
+  if (native_window_view_->has_thick_frame())
+    return true;
+  return views::DesktopWindowTreeHostWin::WidgetSizeIsClientSize();
+}
+
 bool ElectronDesktopWindowTreeHostWin::GetClientAreaInsets(
     gfx::Insets* insets,
     int frame_thickness) const {
-  // Windows by default extends the maximized window slightly larger than
-  // current workspace, for frameless window since the standard frame has been
-  // removed, the client area would then be drew outside current workspace.
-  //
-  // Indenting the client area can fix this behavior.
-  if (IsMaximized() && !native_window_view_->has_frame()) {
-    // The insets would be eventually passed to WM_NCCALCSIZE, which takes
-    // the metrics under the DPI of _main_ monitor instead of current monitor.
-    //
-    // Please make sure you tested maximized frameless window under multiple
-    // monitors with different DPIs before changing this code.
+  if (!native_window_view_->has_frame()) {
     const int thickness = ::GetSystemMetrics(SM_CXSIZEFRAME) +
                           ::GetSystemMetrics(SM_CXPADDEDBORDER);
-    *insets = gfx::Insets::TLBR(thickness, thickness, thickness, thickness);
-    return true;
+
+    if (IsMaximized()) {
+      // Windows by default extends the maximized window slightly larger than
+      // current workspace, for frameless window since the standard frame has
+      // been removed, the client area would then be drew outside current
+      // workspace.
+      //
+      // Indenting the client area can fix this behavior.
+      //
+      // The insets would be eventually passed to WM_NCCALCSIZE, which takes
+      // the metrics under the DPI of _main_ monitor instead of current monitor.
+      //
+      // Please make sure you tested maximized frameless window under multiple
+      // monitors with different DPIs before changing this code.
+      *insets = gfx::Insets::TLBR(thickness, thickness, thickness, thickness);
+      return true;
+    } else if (native_window_view_->has_thick_frame() &&
+               native_window_view_->IsResizable()) {
+      // Grow the insets to support resize targets past the frame edge like in
+      // windows with standard frames.
+      *insets = gfx::Insets::TLBR(0, thickness, thickness, thickness);
+      return true;
+    }
   }
   return false;
 }

shell/browser/ui/win/electron_desktop_window_tree_host_win.h

@@ -40,6 +40,7 @@ class ElectronDesktopWindowTreeHostWin : public views::DesktopWindowTreeHostWin,
                     LRESULT* result) override;
   bool ShouldPaintAsActive() const override;
   bool GetDwmFrameInsetsInPixels(gfx::Insets* insets) const override;
+  bool WidgetSizeIsClientSize() const override;
   bool GetClientAreaInsets(gfx::Insets* insets,
                            int frame_thickness) const override;
   bool HandleMouseEventForCaption(UINT message) const override;