Dragging panels near screen edge

ash/wm/panels/panel_window_resizer.cc

 // 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 "ash/wm/panels/panel_window_resizer.h"
 
 #include "ash/display/display_controller.h"
 #include "ash/launcher/launcher.h"
 #include "ash/screen_ash.h"
 #include "ash/shelf/shelf_types.h"
@@ skipping 46 matching lines @@
 }
 
 void PanelWindowResizer::Drag(const gfx::Point& location, int event_flags) {
   last_location_ = location;
   wm::ConvertPointToScreen(GetTarget()->parent(), &last_location_);
   bool destroyed = false;
   if (!did_move_or_resize_) {
     did_move_or_resize_ = true;
     StartedDragging();
   }
-  gfx::Point location_in_screen = location;
-  wm::ConvertPointToScreen(GetTarget()->parent(), &location_in_screen);
 
   // Check if the destination has changed displays.
   gfx::Screen* screen = Shell::GetScreen();
   const gfx::Display dst_display =
-      screen->GetDisplayNearestPoint(location_in_screen);
+      screen->GetDisplayNearestPoint(last_location_);
   if (dst_display.id() !=
       screen->GetDisplayNearestWindow(panel_container_->GetRootWindow()).id()) {
     // The panel is being dragged to a new display. If the previous container is
     // the current parent of the panel it will be informed of the end of drag
     // when the panel is reparented, otherwise let the previous container know
     // the drag is complete. If we told the panel's parent that the drag was
     // complete it would begin positioning the panel.
     if (GetTarget()->parent() != panel_container_)
       GetPanelLayoutManager(panel_container_)->FinishDragging();
     aura::RootWindow* dst_root = Shell::GetInstance()->display_controller()->
@@ skipping 107 matching lines @@
 
 void PanelWindowResizer::StartedDragging() {
   // Tell the panel layout manager that we are dragging this panel before
   // attaching it so that it does not get repositioned.
   if (panel_container_)
     GetPanelLayoutManager(panel_container_)->StartDragging(GetTarget());
   if (!was_attached_) {
     // Attach the panel while dragging placing it in front of other panels.
     GetTarget()->SetProperty(internal::kContinueDragAfterReparent, true);
     GetTarget()->SetProperty(internal::kPanelAttachedKey, true);
-    GetTarget()->SetDefaultParentByRootWindow(
-        GetTarget()->GetRootWindow(),
-        GetTarget()->GetBoundsInScreen());
+    gfx::Point start_location_in_screen(GetInitialLocation());

[flackr, 2013/06/19 15:16:49]

Add comment that we use the start location to make sure that it is reparented to
the same display as it was initially on. There may be a clearer way of ensuring
this (i.e. just passing the root window's bounds)

[varkha, 2013/06/19 15:49:22]

Done.

+    wm::ConvertPointToScreen(GetTarget()->parent(), &start_location_in_screen);
+    gfx::Rect near_start_location(start_location_in_screen, gfx::Size());
+    GetTarget()->SetDefaultParentByRootWindow(GetTarget()->GetRootWindow(),
+                                              near_start_location);

[flackr, 2013/06/19 15:16:49]

nit: Construct gfx::Rect in place for the parameter since it's only used once.

[varkha, 2013/06/19 15:49:22]

No need with using the root coordinates.

   }
 }
 
 void PanelWindowResizer::FinishDragging() {
   if (!did_move_or_resize_)
     return;
   if (GetTarget()->GetProperty(internal::kPanelAttachedKey) !=
       should_attach_) {
     GetTarget()->SetProperty(internal::kPanelAttachedKey, should_attach_);
     gfx::Rect near_last_location(last_location_, gfx::Size());
     GetTarget()->SetDefaultParentByRootWindow(GetTarget()->GetRootWindow(),
                                               near_last_location);
   }
   if (panel_container_)
     GetPanelLayoutManager(panel_container_)->FinishDragging();
 }
 
 void PanelWindowResizer::UpdateLauncherPosition() {
   if (panel_container_) {
     GetPanelLayoutManager(panel_container_)->launcher()->
         UpdateIconPositionForWindow(GetTarget());
   }
 }
 
 }  // namespace aura