Switch to doing user-resizing via system for panels on Mac

chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/cocoa/panels/panel_window_controller_cocoa.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
@@ skipping 10 matching lines @@
 #import "chrome/browser/ui/cocoa/panels/panel_cocoa.h"
 #import "chrome/browser/ui/cocoa/panels/panel_titlebar_view_cocoa.h"
 #import "chrome/browser/ui/cocoa/panels/panel_utils_cocoa.h"
 #import "chrome/browser/ui/cocoa/tab_contents/favicon_util_mac.h"
 #import "chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.h"
 #import "chrome/browser/ui/cocoa/tabs/throbber_view.h"
 #include "chrome/browser/ui/panels/panel_bounds_animation.h"
 #include "chrome/browser/ui/panels/panel_collection.h"
 #include "chrome/browser/ui/panels/panel_constants.h"
 #include "chrome/browser/ui/panels/panel_manager.h"
+#include "chrome/browser/ui/panels/stacked_panel_collection.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/toolbar/encoding_menu_controller.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_view.h"
 #include "grit/ui_resources.h"
-#include "third_party/WebKit/public/web/WebCursorInfo.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/image/image.h"
-#include "webkit/common/cursors/webcursor.h"
 
 using content::WebContents;
 
 const int kMinimumWindowSize = 1;
 const double kBoundsAnimationSpeedPixelsPerSecond = 1000;
 const double kBoundsAnimationMaxDurationSeconds = 0.18;
 
-// Resize edge thickness, in screen pixels.
-const double kWidthOfMouseResizeArea = 4.0;
+// Edge thickness to trigger user resizing via system, in screen pixels.
+const double kWidthOfMouseResizeArea = 15.0;
 
 @interface PanelWindowControllerCocoa (PanelsCanBecomeKey)
 // Internal helper method for extracting the total number of panel windows
 // from the panel manager. Used to decide if panel can become the key window.
 - (int)numPanels;
 @end
 
 @implementation PanelWindowCocoaImpl
 // The panels cannot be reduced to 3-px windows on the edge of the screen
 // active area (above Dock). Default constraining logic makes at least a height
@@ skipping 41 matching lines @@
 // Ignore key events if window cannot become key window to fix problem
 // where keyboard input is still going into a minimized panel even though
 // the app has been deactivated in -[PanelWindowControllerCocoa deactivate:].
 - (void)sendEvent:(NSEvent*)anEvent {
   NSEventType eventType = [anEvent type];
   if ((eventType == NSKeyDown || eventType == NSKeyUp) &&
       ![self canBecomeKeyWindow])
     return;
   [super sendEvent:anEvent];
 }
-@end
 
-// Transparent view covering the whole panel in order to intercept mouse
-// messages for custom user resizing. We need custom resizing because panels
-// use their own constrained layout.
-@interface PanelResizeByMouseOverlay : NSView <MouseDragControllerClient> {
- @private
-   Panel* panel_;
-   base::scoped_nsobject<MouseDragController> dragController_;
-   base::scoped_nsobject<NSCursor> dragCursor_;
-   base::scoped_nsobject<NSCursor> eastWestCursor_;
-   base::scoped_nsobject<NSCursor> northSouthCursor_;
-   base::scoped_nsobject<NSCursor> northEastSouthWestCursor_;
-   base::scoped_nsobject<NSCursor> northWestSouthEastCursor_;
-   NSRect leftCursorRect_;
-   NSRect rightCursorRect_;
-   NSRect topCursorRect_;
-   NSRect bottomCursorRect_;
-   NSRect topLeftCursorRect_;
-   NSRect topRightCursorRect_;
-   NSRect bottomLeftCursorRect_;
-   NSRect bottomRightCursorRect_;
+- (void)mouseMoved:(NSEvent*)event {
+  // Cocoa does not support letting the application determine the edges that
+  // can trigger the user resizing. To work around this, we track the mouse
+  // location. When it is close to the edge/corner where the user resizing
+  // is not desired, we force the min and max size of the window to be same
+  // as current window size. For all other cases, we restore the min and max
+  // size.
+  PanelWindowControllerCocoa* controller =
+      base::mac::ObjCCast<PanelWindowControllerCocoa>([self windowController]);
+  NSRect frame = [self frame];
+  if ([controller canResizeByMouseAtCurrentLocation]) {
+    // Mac window server limits window sizes to 10000.
+    NSSize maxSize = NSMakeSize(10000, 10000);
+
+    // If the user is resizing a stacked panel by its bottom edge, make sure its
+    // height cannot grow more than what the panel below it could offer. This is
+    // because growing a stacked panel by y amount will shrink the panel below
+    // it by same amount and we do not want the panel below it being shrunk to
+    // be smaller than the titlebar.
+    Panel* panel = [controller panel];
+    NSPoint point = [NSEvent mouseLocation];
+    if (point.y < NSMinY(frame) + kWidthOfMouseResizeArea && panel->stack()) {
+      Panel* belowPanel = panel->stack()->GetPanelBelow(panel);
+      if (belowPanel && !belowPanel->IsMinimized()) {
+        maxSize.height = panel->GetBounds().height() +
+            belowPanel->GetBounds().height() - panel::kTitlebarHeight;
+      }
+    }
+
+    // Enable the user-resizing by setting both min and max size to the right
+    // values.
+    [self setMinSize:NSMakeSize(panel::kPanelMinWidth,
+                                panel::kPanelMinHeight)];
+    [self setMaxSize:maxSize];
+  } else {
+    // Disable the user-resizing by setting both min and max size to be same as
+    // current window size.
+    [self setMinSize:frame.size];
+    [self setMaxSize:frame.size];
+  }
+
+  [super mouseMoved:event];
 }
 @end
 
-namespace {
-NSCursor* LoadWebKitCursor(WebKit::WebCursorInfo::Type type) {
-    return WebCursor(WebCursor::CursorInfo(type)).GetNativeCursor();
-}
-}
-
-@implementation PanelResizeByMouseOverlay
-- (PanelResizeByMouseOverlay*)initWithFrame:(NSRect)frame panel:(Panel*)panel {
-  if ((self = [super initWithFrame:frame])) {
-    panel_ = panel;
-    dragController_.reset([[MouseDragController alloc] initWithClient:self]);
-
-    eastWestCursor_.reset(
-        [LoadWebKitCursor(WebKit::WebCursorInfo::TypeEastWestResize) retain]);
-    northSouthCursor_.reset(
-        [LoadWebKitCursor(WebKit::WebCursorInfo::TypeNorthSouthResize) retain]);
-    northEastSouthWestCursor_.reset(
-        [LoadWebKitCursor(WebKit::WebCursorInfo::TypeNorthEastSouthWestResize)
-        retain]);
-    northWestSouthEastCursor_.reset(
-        [LoadWebKitCursor(WebKit::WebCursorInfo::TypeNorthWestSouthEastResize)
-        retain]);
-  }
-  return self;
-}
-
-- (BOOL)acceptsFirstMouse:(NSEvent*)event {
-  return YES;
-}
-
-// |pointInWindow| is in window coordinates.
-- (panel::ResizingSides)edgeHitTest:(NSPoint)pointInWindow {
-  panel::Resizability resizability = panel_->CanResizeByMouse();
-  DCHECK_NE(panel::NOT_RESIZABLE, resizability);
-
-  NSPoint point = [self convertPoint:pointInWindow fromView:nil];
-  BOOL flipped = [self isFlipped];
-
-  if ((resizability & panel::RESIZABLE_TOP_LEFT) &&
-      NSMouseInRect(point, topLeftCursorRect_, flipped)) {
-    return panel::RESIZE_TOP_LEFT;
-  }
-  if ((resizability & panel::RESIZABLE_TOP_RIGHT) &&
-      NSMouseInRect(point, topRightCursorRect_, flipped)) {
-    return panel::RESIZE_TOP_RIGHT;
-  }
-  if ((resizability & panel::RESIZABLE_BOTTOM_LEFT) &&
-      NSMouseInRect(point, bottomLeftCursorRect_, flipped)) {
-    return panel::RESIZE_BOTTOM_LEFT;
-  }
-  if ((resizability & panel::RESIZABLE_BOTTOM_RIGHT) &&
-      NSMouseInRect(point, bottomRightCursorRect_, flipped)) {
-    return panel::RESIZE_BOTTOM_RIGHT;
-  }
-
-  if ((resizability & panel::RESIZABLE_LEFT) &&
-      NSMouseInRect(point, leftCursorRect_, flipped)) {
-    return panel::RESIZE_LEFT;
-  }
-  if ((resizability & panel::RESIZABLE_RIGHT) &&
-      NSMouseInRect(point, rightCursorRect_, flipped)) {
-    return panel::RESIZE_RIGHT;
-  }
-  if ((resizability & panel::RESIZABLE_TOP) &&
-      NSMouseInRect(point, topCursorRect_, flipped)) {
-    return panel::RESIZE_TOP;
-  }
-  if ((resizability & panel::RESIZABLE_BOTTOM) &&
-      NSMouseInRect(point, bottomCursorRect_, flipped)) {
-    return panel::RESIZE_BOTTOM;
-  }
-
-  return panel::RESIZE_NONE;
-}
-
-// NSWindow uses this method to figure out if this view is under the mouse
-// and hence the one to handle the incoming mouse event.
-// Since this view covers the whole panel, it is asked first.
-// See if this is the mouse event we are interested in (in the resize areas)
-// and return 'nil' to let NSWindow find another candidate otherwise.
-// |point| is in coordinate system of the parent view.
-- (NSView*)hitTest:(NSPoint)point {
-  // If panel is not resizable, let the mouse events fall through.
-  if (panel::NOT_RESIZABLE == panel_->CanResizeByMouse())
-    return nil;
-
-  NSPoint pointInWindow = [[self superview] convertPoint:point toView:nil];
-  return [self edgeHitTest:pointInWindow] == panel::RESIZE_NONE ? nil : self;
-}
-
-// Delegate these to MouseDragController, it will call back on
-// MouseDragControllerClient protocol.
-- (void)mouseDown:(NSEvent*)event {
-  [dragController_ mouseDown:event];
-}
-
-- (void)mouseDragged:(NSEvent*)event {
-  [dragController_ mouseDragged:event];
-}
-
-- (void)mouseUp:(NSEvent*)event {
-  [dragController_ mouseUp:event];
-}
-
-// MouseDragControllerClient protocol.
-
-- (void)prepareForDrag {
-  // If the panel is not resizable, hitTest should have failed and no mouse
-  // events should have come here.
-  DCHECK_NE(panel::NOT_RESIZABLE, panel_->CanResizeByMouse());
-
-  // Make sure the cursor stays the same during whole resize operation.
-  // The cursor rects normally do not guarantee the same cursor, since the
-  // mouse may temporarily leave the cursor rect area (or even the window) so
-  // the cursor will flicker. Disable cursor rects and grab the current cursor
-  // so we can set it on mouseDragged: events to avoid flicker.
-  [[self window] disableCursorRects];
-  dragCursor_.reset([[NSCursor currentCursor] retain]);
-}
-
-- (void)cleanupAfterDrag {
-  [[self window] enableCursorRects];
-  dragCursor_.reset();
-}
-
-- (void)dragStarted:(NSPoint)initialMouseLocation {
-  NSPoint initialMouseLocationScreen =
-      [[self window] convertBaseToScreen:initialMouseLocation];
-
-  panel_->manager()->StartResizingByMouse(
-      panel_,
-      cocoa_utils::ConvertPointFromCocoaCoordinates(initialMouseLocationScreen),
-      [self edgeHitTest:initialMouseLocation]);
-}
-
-- (void)dragProgress:(NSPoint)mouseLocation {
-  NSPoint mouseLocationScreen =
-      [[self window] convertBaseToScreen:mouseLocation];
-  panel_->manager()->ResizeByMouse(
-      cocoa_utils::ConvertPointFromCocoaCoordinates(mouseLocationScreen));
-
-  // Set the resize cursor on every mouse drag event in case the mouse
-  // wandered outside the window and was switched to another one.
-  // This does not produce flicker, seems the real cursor is updated after
-  // mouseDrag is processed.
-  [dragCursor_ set];
-}
-
-- (void)dragEnded:(BOOL)cancelled {
-  panel_->manager()->EndResizingByMouse(cancelled);
-}
-
-- (void)resetCursorRects {
-  panel::Resizability resizability = panel_->CanResizeByMouse();
-  if (panel::NOT_RESIZABLE == resizability)
-    return;
-
-  NSRect bounds = [self bounds];
-
-  // Left vertical edge.
-  if (resizability & panel::RESIZABLE_LEFT) {
-    leftCursorRect_ = NSMakeRect(
-        NSMinX(bounds),
-        NSMinY(bounds) + kWidthOfMouseResizeArea,
-        kWidthOfMouseResizeArea,
-        NSHeight(bounds) - 2 * kWidthOfMouseResizeArea);
-    [self addCursorRect:leftCursorRect_ cursor:eastWestCursor_];
-  }
-
-  // Right vertical edge.
-  if (resizability & panel::RESIZABLE_RIGHT) {
-    rightCursorRect_ = leftCursorRect_;
-    rightCursorRect_.origin.x = NSMaxX(bounds) - kWidthOfMouseResizeArea;
-    [self addCursorRect:rightCursorRect_ cursor:eastWestCursor_];
-  }
-
-  // Top horizontal edge.
-  if (resizability & panel::RESIZABLE_TOP) {
-    topCursorRect_ = NSMakeRect(NSMinX(bounds) + kWidthOfMouseResizeArea,
-                                NSMaxY(bounds) - kWidthOfMouseResizeArea,
-                                NSWidth(bounds) - 2 * kWidthOfMouseResizeArea,
-                                kWidthOfMouseResizeArea);
-    [self addCursorRect:topCursorRect_ cursor:northSouthCursor_];
-  }
-
-  // Top left corner.
-  if (resizability & panel::RESIZABLE_TOP_LEFT) {
-    topLeftCursorRect_ = NSMakeRect(NSMinX(bounds),
-                                    NSMaxY(bounds) - kWidthOfMouseResizeArea,
-                                    kWidthOfMouseResizeArea,
-                                    NSMaxY(bounds));
-    [self addCursorRect:topLeftCursorRect_ cursor:northWestSouthEastCursor_];
-  }
-
-  // Top right corner.
-  if (resizability & panel::RESIZABLE_TOP_RIGHT) {
-    topRightCursorRect_ = topLeftCursorRect_;
-    topRightCursorRect_.origin.x = NSMaxX(bounds) - kWidthOfMouseResizeArea;
-    [self addCursorRect:topRightCursorRect_ cursor:northEastSouthWestCursor_];
-  }
-
-  // Bottom horizontal edge.
-  if (resizability & panel::RESIZABLE_BOTTOM) {
-    bottomCursorRect_ = topCursorRect_;
-    bottomCursorRect_.origin.y = NSMinY(bounds);
-    [self addCursorRect:bottomCursorRect_ cursor:northSouthCursor_];
-  }
-
-  // Bottom right corner.
-  if (resizability & panel::RESIZABLE_BOTTOM_RIGHT) {
-    bottomRightCursorRect_ = topRightCursorRect_;
-    bottomRightCursorRect_.origin.y = NSMinY(bounds);
-    [self addCursorRect:bottomRightCursorRect_
-                 cursor:northWestSouthEastCursor_];
-  }
-
-  // Bottom left corner.
-  if (resizability & panel::RESIZABLE_BOTTOM_LEFT) {
-    bottomLeftCursorRect_ = bottomRightCursorRect_;
-    bottomLeftCursorRect_.origin.x = NSMinX(bounds);
-    [self addCursorRect:bottomLeftCursorRect_ cursor:northEastSouthWestCursor_];
-  }
-}
-@end
-
 // ChromeEventProcessingWindow expects its controller to implement the
 // BrowserCommandExecutor protocol.
 @interface PanelWindowControllerCocoa (InternalAPI) <BrowserCommandExecutor>
 
 // BrowserCommandExecutor methods.
 - (void)executeCommand:(int)command;
 
 @end
 
 @implementation PanelWindowControllerCocoa (InternalAPI)
@@ skipping 11 matching lines @@
       [base::mac::FrameworkBundle() pathForResource:@"Panel" ofType:@"nib"];
   if ((self = [super initWithWindowNibPath:nibpath owner:self])) {
     windowShim_.reset(window);
     animateOnBoundsChange_ = YES;
     canBecomeKeyWindow_ = YES;
     activationRequestedByPanel_ = NO;
   }
   return self;
 }
 
+- (Panel*)panel {
+  return windowShim_->panel();
+}
+
 - (void)awakeFromNib {
   NSWindow* window = [self window];
 
   DCHECK(window);
   DCHECK(titlebar_view_);
   DCHECK_EQ(self, [window delegate]);
 
   [self updateWindowLevel];
 
   [self updateWindowCollectionBehavior];
 
   [titlebar_view_ attach];
 
   // Set initial size of the window to match the size of the panel to give
   // the renderer the proper size to work with earlier, avoiding a resize
   // after the window is revealed.
   gfx::Rect panelBounds = windowShim_->panel()->GetBounds();
   NSRect frame = [window frame];
   frame.size.width = panelBounds.width();
   frame.size.height = panelBounds.height();
   [window setFrame:frame display:NO];
 
-  // Add a transparent overlay on top of the whole window to process mouse
-  // events - for example, user-resizing.
-  NSView* superview = [[window contentView] superview];
-  NSRect bounds = [superview bounds];
-  overlayView_.reset(
-      [[PanelResizeByMouseOverlay alloc] initWithFrame:bounds
-                                                 panel:windowShim_->panel()]);
-  // Set autoresizing behavior: glued to edges.
-  [overlayView_ setAutoresizingMask:(NSViewHeightSizable | NSViewWidthSizable)];
-  [superview addSubview:overlayView_ positioned:NSWindowAbove relativeTo:nil];
+  // MacOS will turn the user-resizing to the user-dragging if the direction of
+  // the dragging is orthogonal to the direction of the arrow cursor. We do not
+  // want this since it will bypass our dragging logic. The panel window is
+  // still draggable because we track and handle the dragging in our custom way.
+  [[self window] setMovable:NO];
+
+  [self updateTrackingArea];
 }
 
 - (void)updateWebContentsViewFrame {
   content::WebContents* webContents = windowShim_->panel()->GetWebContents();
   if (!webContents)
     return;
 
   // Compute the size of the web contents view. Don't assume it's similar to the
   // size of the contentView, because the contentView is managed by the Cocoa
   // to be (window - standard titlebar), while we have taller custom titlebar
@@ skipping 361 matching lines @@
 - (void)windowDidBecomeKey:(NSNotification*)notification {
   // We need to activate the controls (in the "WebView"). To do this, get the
   // selected WebContents's RenderWidgetHostView and tell it to activate.
   if (WebContents* contents = windowShim_->panel()->GetWebContents()) {
     if (content::RenderWidgetHostView* rwhv =
         contents->GetRenderWidgetHostView())
       rwhv->SetActive(true);
   }
 
   windowShim_->panel()->OnActiveStateChanged(true);
+
+  // Make the window user-resizable when it gains the focus.
+  [[self window] setStyleMask:
+      [[self window] styleMask] | NSResizableWindowMask];
 }
 
 - (void)windowDidResignKey:(NSNotification*)notification {
   // If our app is still active and we're still the key window, ignore this
   // message, since it just means that a menu extra (on the "system status bar")
   // was activated; we'll get another |-windowDidResignKey| if we ever really
   // lose key window status.
   if ([NSApp isActive] && ([NSApp keyWindow] == [self window]))
     return;
 
   [self onWindowDidResignKey];
+
+  // Make the window not user-resizable when it loses the focus. This is to
+  // solve the problem that the bottom edge of the active panel does not
+  // trigger the user-resizing if this panel stacks with another inactive
+  // panel at the bottom.
+  [[self window] setStyleMask:
+      [[self window] styleMask] & ~NSResizableWindowMask];
+}
+
+- (void)windowWillStartLiveResize:(NSNotification*)notification {
+  // Check if the user-resizing is allowed for the triggering edge/corner.
+  // This is an extra safe guard because we are not able to track the mouse
+  // movement outside the window and Cocoa could trigger the user-resizing
+  // when the mouse moves a bit outside the edge/corner.
+  if (![self canResizeByMouseAtCurrentLocation])
+    return;
+  userResizing_ = YES;
+  windowShim_->panel()->OnPanelStartUserResizing();
+}
+
+- (void)windowDidEndLiveResize:(NSNotification*)notification {
+  if (!userResizing_)
+    return;
+  userResizing_ = NO;
+
+  Panel* panel = windowShim_->panel();
+  panel->OnPanelEndUserResizing();
+
+  gfx::Rect newBounds =
+      cocoa_utils::ConvertRectFromCocoaCoordinates([[self window] frame]);
+  if (windowShim_->panel()->GetBounds() == newBounds)
+    return;
+  windowShim_->set_cached_bounds_directly(newBounds);
+
+  panel->IncreaseMaxSize(newBounds.size());
+  panel->set_full_size(newBounds.size());
+
+  panel->collection()->RefreshLayout();
+}
+
+- (NSSize)windowWillResize:(NSWindow*)sender toSize:(NSSize)newSize {
+  // As an extra safe guard, we avoid the user resizing if it is deemed not to
+  // be allowed (see comment in windowWillStartLiveResize).
+  if ([[self window] inLiveResize] && !userResizing_)
+    return [[self window] frame].size;
+  return newSize;
 }
 
 - (void)windowDidResize:(NSNotification*)notification {
   Panel* panel = windowShim_->panel();
+  if (userResizing_) {
+    panel->collection()->OnPanelResizedByMouse(
+        panel,
+        cocoa_utils::ConvertRectFromCocoaCoordinates([[self window] frame]));
+  }
+
+  [self updateTrackingArea];
+
   if (![self isAnimatingBounds] ||
       panel->collection()->type() != PanelCollection::DOCKED)

[Dmitry Titov, 2013/09/05 20:49:59]

This code seems like from another patch, this needs merging.

     return;
 
   // Remove the web contents view from the view hierarchy when the panel is not
   // taller than the titlebar. Put it back when the panel grows taller than
   // the titlebar. Note that RenderWidgetHostViewMac works for the case that
   // the web contents view does not exist in the view hierarchy (i.e. the tab
   // is not the main one), but it does not work well, like causing occasional
   // crashes (http://crbug.com/265932), if the web contents view is made hidden.
   //
   // This is needed when the docked panels are being animated. When the
@@ skipping 133 matching lines @@
 - (void)updateWindowCollectionBehavior {
   if (![self isWindowLoaded])
     return;
   NSWindowCollectionBehavior collectionBehavior =
       NSWindowCollectionBehaviorParticipatesInCycle;
   if (windowShim_->panel()->IsAlwaysOnTop())
     collectionBehavior |= NSWindowCollectionBehaviorCanJoinAllSpaces;
   [[self window] setCollectionBehavior:collectionBehavior];
 }
 
-- (void)enableResizeByMouse:(BOOL)enable {
-  if (![self isWindowLoaded])
-    return;
-  [[self window] invalidateCursorRectsForView:overlayView_];
+- (void)updateTrackingArea {
+  NSView* superview = [[[self window] contentView] superview];
+
+  if (trackingArea_.get())
+    [superview removeTrackingArea:trackingArea_.get()];
+
+  trackingArea_.reset(
+          [[CrTrackingArea alloc] initWithRect:[superview bounds]
+                                       options:NSTrackingInVisibleRect |
+                                               NSTrackingMouseMoved |
+                                               NSTrackingActiveInKeyWindow
+                                         owner:superview
+                                      userInfo:nil]);
+  [superview addTrackingArea:trackingArea_.get()];
 }
 
 - (void)showShadow:(BOOL)show {
   if (![self isWindowLoaded])
     return;
   [[self window] setHasShadow:show];
 }
 
 - (void)miniaturize {
   [[self window] miniaturize:nil];
 }
 
 - (BOOL)isMiniaturized {
   return [[self window] isMiniaturized];
 }
 
+- (BOOL)canResizeByMouseAtCurrentLocation {
+  panel::Resizability resizability = windowShim_->panel()->CanResizeByMouse();
+  NSRect frame = [[self window] frame];
+  NSPoint point = [NSEvent mouseLocation];
+
+  if (point.y < NSMinY(frame) + kWidthOfMouseResizeArea) {
+    if (point.x < NSMinX(frame) + kWidthOfMouseResizeArea &&
+        (resizability & panel::RESIZABLE_BOTTOM_LEFT) == 0) {
+      return NO;
+    }
+    if (point.x > NSMaxX(frame) - kWidthOfMouseResizeArea &&
+        (resizability & panel::RESIZABLE_BOTTOM_RIGHT) == 0) {
+      return NO;
+    }
+    if ((resizability & panel::RESIZABLE_BOTTOM) == 0)
+      return NO;
+  } else if (point.y > NSMaxY(frame) - kWidthOfMouseResizeArea) {
+    if (point.x < NSMinX(frame) + kWidthOfMouseResizeArea &&
+        (resizability & panel::RESIZABLE_TOP_LEFT) == 0) {
+      return NO;
+    }
+    if (point.x > NSMaxX(frame) - kWidthOfMouseResizeArea &&
+        (resizability & panel::RESIZABLE_TOP_RIGHT) == 0) {
+      return NO;
+    }
+    if ((resizability & panel::RESIZABLE_TOP) == 0)
+      return NO;
+  } else {
+    if (point.x < NSMinX(frame) + kWidthOfMouseResizeArea &&
+        (resizability & panel::RESIZABLE_LEFT) == 0) {
+      return NO;
+    }
+    if (point.x > NSMaxX(frame) - kWidthOfMouseResizeArea &&
+        (resizability & panel::RESIZABLE_RIGHT) == 0) {
+      return NO;
+    }
+  }
+  return YES;
+}
+
 // We have custom implementation of these because our titlebar height is custom
 // and does not match the standard one.
 - (NSRect)frameRectForContentRect:(NSRect)contentRect {
   // contentRect is in contentView coord system. We should add a titlebar on top
   // and then convert to the windows coord system.
   contentRect.size.height += panel::kTitlebarHeight;
   NSRect frameRect = [[[self window] contentView] convertRect:contentRect
                                                        toView:nil];
   return frameRect;
 }
 
 - (NSRect)contentRectForFrameRect:(NSRect)frameRect {
   NSRect contentRect = [[[self window] contentView] convertRect:frameRect
                                                        fromView:nil];
   contentRect.size.height -= panel::kTitlebarHeight;
   if (contentRect.size.height < 0)
     contentRect.size.height = 0;
   return contentRect;
 }
 
 @end