Convert MouseEvents from DIPS to Pixels before passing it to surfaces for hittesting.

content/browser/renderer_host/render_widget_host_view_aura.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 "content/browser/renderer_host/render_widget_host_view_aura.h"
 
 #include <set>
 
 #include "base/auto_reset.h"
 #include "base/basictypes.h"
@@ skipping 62 matching lines @@
 #include "ui/compositor/compositor_vsync_manager.h"
 #include "ui/compositor/dip_util.h"
 #include "ui/events/blink/blink_event_util.h"
 #include "ui/events/event.h"
 #include "ui/events/event_utils.h"
 #include "ui/events/gesture_detection/gesture_configuration.h"
 #include "ui/events/gestures/gesture_recognizer.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/color_profile.h"
 #include "ui/gfx/display.h"
+#include "ui/gfx/geometry/dip_util.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/screen.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/touch_selection/touch_selection_controller.h"
 #include "ui/wm/public/activation_client.h"
 #include "ui/wm/public/scoped_tooltip_disabler.h"
 #include "ui/wm/public/tooltip_client.h"
 #include "ui/wm/public/transient_window_client.h"
 #include "ui/wm/public/window_types.h"
@@ skipping 402 matching lines @@
         GetSurfaceIdNamespace(), this);
   }
 
   bool overscroll_enabled = base::CommandLine::ForCurrentProcess()->
       GetSwitchValueASCII(switches::kOverscrollHistoryNavigation) != "0";
   SetOverscrollControllerEnabled(overscroll_enabled);
 
   selection_controller_client_.reset(
       new TouchSelectionControllerClientAura(this));
   CreateSelectionController();
+
+  const gfx::Display display =
+      gfx::Screen::GetScreenFor(window_)->GetDisplayNearestWindow(window_);
+  device_scale_factor_ = display.device_scale_factor();

[sadrul, 2015/11/03 18:00:00]

Note that at this point, |window_| hasn't been attached to a window-tree yet. So
GetDisplayNearestWindow() wouldn't necessarily give the right result. The better
place for this would be in the three InitAs* methods, where |window_| is
attached. In InitAsChild(), you should get the Display nearest |parent_view|. In
InitAsPopup() and InitAsFullscreen(), you should get the Display nearest
|window_| after the calls to ParentWindowWithContext(). That way, you start with
the correct DSF. In the ctor initialize-list, you should initialize
|device_scale_factor_| to some default value

[lfg, 2015/11/03 20:49:15]

Done. I've also added a DCHECK to make sure it's initialized before we use it.

 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewAura, RenderWidgetHostView implementation:
 
 bool RenderWidgetHostViewAura::OnMessageReceived(
     const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(RenderWidgetHostViewAura, message)
     IPC_MESSAGE_HANDLER(ViewHostMsg_SetNeedsBeginFrames,
@@ skipping 1361 matching lines @@
   NOTREACHED();
 }
 
 void RenderWidgetHostViewAura::OnDeviceScaleFactorChanged(
     float device_scale_factor) {
   if (!host_ || !window_->GetRootWindow())
     return;
 
   UpdateScreenInfo(window_);
 
+  device_scale_factor_ = device_scale_factor;
   const gfx::Display display = gfx::Screen::GetScreenFor(window_)->
       GetDisplayNearestWindow(window_);
   DCHECK_EQ(device_scale_factor, display.device_scale_factor());
   current_cursor_.SetDisplayInfo(display);
   SnapToPhysicalPixelBoundary();
 }
 
 void RenderWidgetHostViewAura::OnWindowDestroying(aura::Window* window) {
 #if defined(OS_WIN)
   HWND parent = NULL;
@@ skipping 271 matching lines @@
     window_->parent()->delegate()->OnMouseEvent(event);
   }
 
   if (!IsXButtonUpEvent(event))
     event->SetHandled();
 }
 
 uint32_t RenderWidgetHostViewAura::SurfaceIdNamespaceAtPoint(
     const gfx::Point& point,
     gfx::Point* transformed_point) {
-  cc::SurfaceId id =
-      delegated_frame_host_->SurfaceIdAtPoint(point, transformed_point);
+  gfx::Point point_in_pixels =
+      gfx::ConvertPointToPixel(device_scale_factor_, point);
+  cc::SurfaceId id = delegated_frame_host_->SurfaceIdAtPoint(point_in_pixels,
+                                                             transformed_point);
+  *transformed_point =
+      gfx::ConvertPointToDIP(device_scale_factor_, *transformed_point);

[sadrul, 2015/11/03 18:00:00]

Add a comment here to clarify that surface-hittest happens in device-pixels.

[lfg, 2015/11/03 20:49:16]

Done.

+
   // It is possible that the renderer has not yet produced a surface, in which
   // case we return our current namespace.
   if (id.is_null())
     return GetSurfaceIdNamespace();
   return cc::SurfaceIdAllocator::NamespaceForId(id);
 }
 
 void RenderWidgetHostViewAura::ProcessMouseEvent(
     const blink::WebMouseEvent& event) {
   host_->ForwardMouseEvent(event);
@@ skipping 710 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewBase, public:
 
 // static
 void RenderWidgetHostViewBase::GetDefaultScreenInfo(WebScreenInfo* results) {
   GetScreenInfoForWindow(results, NULL);
 }
 
 }  // namespace content