Bug 1809430 - Clean up ClientToWindowRect. r=cmartin,mstange

Make it return a margin from client area to window area, and add an
explicit function to get the size difference.

No behavior change.

Depends on D166428

Differential Revision: https://phabricator.services.mozilla.com/D166431

layout/generic/nsContainerFrame.cpp

@@ -869,16 +869,19 @@ void nsContainerFrame::SetSizeConstraints(nsPresContext* aPresContext,
   // The sizes are in inner window sizes, so convert them into outer window
   // sizes. Use a size of (200, 200) as only the difference between the inner
   // and outer size is needed.
-  LayoutDeviceIntSize windowSize =
-      aWidget->ClientToWindowSize(LayoutDeviceIntSize(200, 200));
-  if (constraints.mMinSize.width)
-    constraints.mMinSize.width += windowSize.width - 200;
-  if (constraints.mMinSize.height)
-    constraints.mMinSize.height += windowSize.height - 200;
-  if (constraints.mMaxSize.width != NS_MAXSIZE)
-    constraints.mMaxSize.width += windowSize.width - 200;
-  if (constraints.mMaxSize.height != NS_MAXSIZE)
-    constraints.mMaxSize.height += windowSize.height - 200;
+  const LayoutDeviceIntSize sizeDiff = aWidget->ClientToWindowSizeDifference();
+  if (constraints.mMinSize.width) {
+    constraints.mMinSize.width += sizeDiff.width;
+  }
+  if (constraints.mMinSize.height) {
+    constraints.mMinSize.height += sizeDiff.height;
+  }
+  if (constraints.mMaxSize.width != NS_MAXSIZE) {
+    constraints.mMaxSize.width += sizeDiff.width;
+  }
+  if (constraints.mMaxSize.height != NS_MAXSIZE) {
+    constraints.mMaxSize.height += sizeDiff.height;
+  }
 
   aWidget->SetSizeConstraints(constraints);
 }

widget/cocoa/nsCocoaWindow.h

@@ -249,7 +249,7 @@ class nsCocoaWindow final : public nsBaseWidget, public nsPIWidgetCocoa {
   virtual void SetFocus(Raise, mozilla::dom::CallerType aCallerType) override;
   virtual LayoutDeviceIntPoint WidgetToScreenOffset() override;
   virtual LayoutDeviceIntPoint GetClientOffset() override;
-  virtual LayoutDeviceIntSize ClientToWindowSize(const LayoutDeviceIntSize& aClientSize) override;
+  virtual LayoutDeviceIntMargin ClientToWindowMargin() override;
 
   virtual void* GetNativeData(uint32_t aDataType) override;
 

widget/cocoa/nsCocoaWindow.mm

@@ -2224,22 +2224,23 @@ LayoutDeviceIntPoint nsCocoaWindow::GetClientOffset() {
   NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntPoint(0, 0));
 }
 
-LayoutDeviceIntSize nsCocoaWindow::ClientToWindowSize(const LayoutDeviceIntSize& aClientSize) {
+LayoutDeviceIntMargin nsCocoaWindow::ClientToWindowMargin() {
   NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
 
   if (!mWindow) {
-    return LayoutDeviceIntSize(0, 0);
+    return {};
   }
 
+  NSRect clientNSRect = [mWindow contentLayoutRect];
+  NSRect frameNSRect = [mWindow frameRectForContentRect:clientNSRect];
+
   CGFloat backingScale = BackingScaleFactor();
-  LayoutDeviceIntRect r(0, 0, aClientSize.width, aClientSize.height);
-  NSRect rect = nsCocoaUtils::DevPixelsToCocoaPoints(r, backingScale);
+  const auto clientRect = nsCocoaUtils::CocoaRectToGeckoRectDevPix(clientNSRect, backingScale);
+  const auto frameRect = nsCocoaUtils::CocoaRectToGeckoRectDevPix(frameNSRect, backingScale);
 
-  NSRect maybeInflatedRect = [mWindow frameRectForContentRect:rect];
-  r = nsCocoaUtils::CocoaRectToGeckoRectDevPix(maybeInflatedRect, backingScale);
-  return r.Size();
+  return frameRect - clientRect;
 
-  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntSize(0, 0));
+  NS_OBJC_END_TRY_BLOCK_RETURN({});
 }
 
 nsMenuBarX* nsCocoaWindow::GetMenuBar() { return mMenuBar; }

widget/nsBaseWidget.cpp

@@ -567,6 +567,15 @@ nsIntSize nsIWidget::CustomCursorSize(const Cursor& aCursor) {
   return {width, height};
 }
 
+LayoutDeviceIntSize nsIWidget::ClientToWindowSizeDifference() {
+  auto margin = ClientToWindowMargin();
+  MOZ_ASSERT(margin.top >= 0, "Window should be bigger than client area");
+  MOZ_ASSERT(margin.left >= 0, "Window should be bigger than client area");
+  MOZ_ASSERT(margin.right >= 0, "Window should be bigger than client area");
+  MOZ_ASSERT(margin.bottom >= 0, "Window should be bigger than client area");
+  return {margin.LeftRight(), margin.TopBottom()};
+}
+
 RefPtr<mozilla::VsyncDispatcher> nsIWidget::GetVsyncDispatcher() {
   return nullptr;
 }

widget/nsBaseWidget.h

@@ -365,11 +365,6 @@ class nsBaseWidget : public nsIWidget, public nsSupportsWeakReference {
 
   nsPopupLevel PopupLevel() { return mPopupLevel; }
 
-  LayoutDeviceIntSize ClientToWindowSize(
-      const LayoutDeviceIntSize& aClientSize) override {
-    return aClientSize;
-  }
-
   // return true if this is a popup widget with a native titlebar
   bool IsPopupWithTitleBar() const {
     return (mWindowType == eWindowType_popup &&

widget/nsIWidget.h

@@ -1329,12 +1329,13 @@ class nsIWidget : public nsISupports {
   }
 
   /**
-   * Given the specified client size, return the corresponding window size,
-   * which includes the area for the borders and titlebar. This method
-   * should work even when the window is not yet visible.
+   * Returns the margins that are applied to go from client sizes to window
+   * sizes (which includes window borders and titlebar).
+   * This method should work even when the window is not yet visible.
    */
-  virtual LayoutDeviceIntSize ClientToWindowSize(
-      const LayoutDeviceIntSize& aClientSize) = 0;
+  virtual LayoutDeviceIntMargin ClientToWindowMargin() { return {}; }
+
+  LayoutDeviceIntSize ClientToWindowSizeDifference();
 
   /**
    * Dispatches an event to the widget

widget/windows/nsWindow.cpp

@@ -3871,27 +3871,31 @@ LayoutDeviceIntPoint nsWindow::WidgetToScreenOffset() {
   return LayoutDeviceIntPoint(point.x, point.y);
 }
 
-LayoutDeviceIntSize nsWindow::ClientToWindowSize(
-    const LayoutDeviceIntSize& aClientSize) {
+LayoutDeviceIntMargin nsWindow::ClientToWindowMargin() {
   if (mWindowType == eWindowType_popup && !IsPopupWithTitleBar()) {
-    return aClientSize;
+    return {};
   }
 
-  // Just use (200, 200) as the position
-  const LayoutDeviceIntPoint point(200, 200);
   if (mCustomNonClient) {
-    auto winRect = LayoutDeviceIntRect(point, aClientSize);
-    winRect.Inflate(NonClientSizeMargin(NormalWindowNonClientOffset()));
-    return winRect.Size();
+    return NonClientSizeMargin(NormalWindowNonClientOffset());
   }
 
-  RECT r;
-  r.left = point.x;
-  r.top = point.y;
-  r.right = point.x + aClientSize.width;
-  r.bottom = point.y + aClientSize.height;
-  ::AdjustWindowRectEx(&r, WindowStyle(), false, WindowExStyle());
-  return LayoutDeviceIntSize(r.right - r.left, r.bottom - r.top);
+  // Just use a dummy 200x200 at (200, 200) client rect as the rect.
+  RECT clientRect;
+  clientRect.left = 200;
+  clientRect.top = 200;
+  clientRect.right = 400;
+  clientRect.bottom = 400;
+
+  auto ToRect = [](const RECT& aRect) -> LayoutDeviceIntRect {
+    return {aRect.left, aRect.top, aRect.right - aRect.left,
+            aRect.bottom - aRect.top};
+  };
+
+  RECT windowRect = clientRect;
+  ::AdjustWindowRectEx(&windowRect, WindowStyle(), false, WindowExStyle());
+
+  return ToRect(windowRect) - ToRect(clientRect);
 }
 
 /**************************************************************

widget/windows/nsWindow.h

@@ -223,8 +223,7 @@ class nsWindow final : public nsBaseWidget {
   nsresult SetTitle(const nsAString& aTitle) override;
   void SetIcon(const nsAString& aIconSpec) override;
   LayoutDeviceIntPoint WidgetToScreenOffset() override;
-  LayoutDeviceIntSize ClientToWindowSize(
-      const LayoutDeviceIntSize& aClientSize) override;
+  LayoutDeviceIntMargin ClientToWindowMargin() override;
   nsresult DispatchEvent(mozilla::WidgetGUIEvent* aEvent,
                          nsEventStatus& aStatus) override;
   void EnableDragDrop(bool aEnable) override;

xpfe/appshell/AppWindow.cpp

@@ -437,9 +437,7 @@ static LayoutDeviceIntSize GetOuterToInnerSizeDifference(nsIWidget* aWindow) {
   if (!aWindow) {
     return LayoutDeviceIntSize();
   }
-  LayoutDeviceIntSize baseSize(200, 200);
-  LayoutDeviceIntSize windowSize = aWindow->ClientToWindowSize(baseSize);
-  return windowSize - baseSize;
+  return aWindow->ClientToWindowSizeDifference();
 }
 
 static CSSIntSize GetOuterToInnerSizeDifferenceInCSSPixels(