Bug 1813554 - Clean-up CheckResizerEdge. r=stransky

No behavior change.

Differential Revision: https://phabricator.services.mozilla.com/D168282

widget/gtk/nsWindow.cpp

@@ -4291,45 +4291,52 @@ void nsWindow::OnLeaveNotifyEvent(GdkEventCrossing* aEvent) {
   DispatchInputEvent(&event);
 }
 
-bool nsWindow::CheckResizerEdge(LayoutDeviceIntPoint aPoint,
-                                GdkWindowEdge& aOutEdge) {
+Maybe<GdkWindowEdge> nsWindow::CheckResizerEdge(
+    const LayoutDeviceIntPoint& aPoint) {
   // We only need to handle resizers for PIP window.
   if (!mIsPIPWindow) {
-    return false;
+    return {};
   }
 
-  // Don't allow resizing maximized windows.
+  // Don't allow resizing maximized/fullscreen windows.
   if (mSizeMode != nsSizeMode_Normal) {
-    return false;
+    return {};
   }
 
 #define RESIZER_SIZE 15
-  int resizerSize = RESIZER_SIZE * GdkCeiledScaleFactor();
-  int topDist = aPoint.y;
-  int leftDist = aPoint.x;
-  int rightDist = mBounds.width - aPoint.x;
-  int bottomDist = mBounds.height - aPoint.y;
+  const int resizerSize = RESIZER_SIZE * GdkCeiledScaleFactor();
+  const int topDist = aPoint.y;
+  const int leftDist = aPoint.x;
+  const int rightDist = mBounds.width - aPoint.x;
+  const int bottomDist = mBounds.height - aPoint.y;
 
-  if (leftDist <= resizerSize && topDist <= resizerSize) {
-    aOutEdge = GDK_WINDOW_EDGE_NORTH_WEST;
-  } else if (rightDist <= resizerSize && topDist <= resizerSize) {
-    aOutEdge = GDK_WINDOW_EDGE_NORTH_EAST;
-  } else if (leftDist <= resizerSize && bottomDist <= resizerSize) {
-    aOutEdge = GDK_WINDOW_EDGE_SOUTH_WEST;
-  } else if (rightDist <= resizerSize && bottomDist <= resizerSize) {
-    aOutEdge = GDK_WINDOW_EDGE_SOUTH_EAST;
-  } else if (topDist <= resizerSize) {
-    aOutEdge = GDK_WINDOW_EDGE_NORTH;
-  } else if (leftDist <= resizerSize) {
-    aOutEdge = GDK_WINDOW_EDGE_WEST;
-  } else if (rightDist <= resizerSize) {
-    aOutEdge = GDK_WINDOW_EDGE_EAST;
-  } else if (bottomDist <= resizerSize) {
-    aOutEdge = GDK_WINDOW_EDGE_SOUTH;
-  } else {
-    return false;
+  if (topDist <= resizerSize) {
+    if (rightDist <= resizerSize) {
+      return Some(GDK_WINDOW_EDGE_NORTH_EAST);
+    }
+    if (leftDist <= resizerSize) {
+      return Some(GDK_WINDOW_EDGE_NORTH_WEST);
+    }
+    return Some(GDK_WINDOW_EDGE_NORTH);
   }
-  return true;
+
+  if (bottomDist <= resizerSize) {
+    if (leftDist <= resizerSize) {
+      return Some(GDK_WINDOW_EDGE_SOUTH_WEST);
+    }
+    if (rightDist <= resizerSize) {
+      return Some(GDK_WINDOW_EDGE_SOUTH_EAST);
+    }
+    return Some(GDK_WINDOW_EDGE_SOUTH);
+  }
+
+  if (leftDist <= resizerSize) {
+    return Some(GDK_WINDOW_EDGE_WEST);
+  }
+  if (rightDist <= resizerSize) {
+    return Some(GDK_WINDOW_EDGE_EAST);
+  }
+  return {};
 }
 
 template <typename Event>
@@ -4378,11 +4385,10 @@ void nsWindow::OnMotionNotifyEvent(GdkEventMotion* aEvent) {
     }
   }
 
-  GdkWindowEdge edge;
   const auto refPoint = GetRefPoint(this, aEvent);
-  if (CheckResizerEdge(refPoint, edge)) {
+  if (auto edge = CheckResizerEdge(refPoint)) {
     nsCursor cursor = eCursor_none;
-    switch (edge) {
+    switch (*edge) {
       case GDK_WINDOW_EDGE_NORTH:
         cursor = eCursor_n_resize;
         break;
@@ -4586,9 +4592,8 @@ void nsWindow::OnButtonPressEvent(GdkEventButton* aEvent) {
   }
 
   // Check to see if the event is within our window's resize region
-  GdkWindowEdge edge;
-  if (CheckResizerEdge(refPoint, edge)) {
-    gdk_window_begin_resize_drag(gtk_widget_get_window(mShell), edge,
+  if (auto edge = CheckResizerEdge(refPoint)) {
+    gdk_window_begin_resize_drag(gtk_widget_get_window(mShell), *edge,
                                  aEvent->button, aEvent->x_root, aEvent->y_root,
                                  aEvent->time);
     return;

widget/gtk/nsWindow.h

@@ -518,9 +518,10 @@ class nsWindow final : public nsBaseWidget {
                  LayoutDeviceIntSize aSize);
   void NativeMoveResizeWaylandPopup(bool aMove, bool aResize);
 
-  // Returns true if the given point (in device pixels) is within a resizer
-  // region of the window. Only used when drawing decorations client side.
-  bool CheckResizerEdge(LayoutDeviceIntPoint aPoint, GdkWindowEdge& aOutEdge);
+  // Returns a window edge if the given point (in device pixels) is within a
+  // resizer region of the window.
+  // Only used when drawing decorations client side.
+  mozilla::Maybe<GdkWindowEdge> CheckResizerEdge(const LayoutDeviceIntPoint&);
 
   GtkTextDirection GetTextDirection();