Set the coordinates of the synthetic touch event correctly in SyntheticGestureTargetAura

content/browser/renderer_host/input/synthetic_gesture_target_aura.cc

 // Copyright 2013 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/input/synthetic_gesture_target_aura.h"
 
 #include <stddef.h>
 
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_aura.h"
 #include "content/browser/renderer_host/ui_events_helper.h"
 #include "third_party/WebKit/public/platform/WebScreenInfo.h"
 #include "ui/aura/window.h"
+#include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/events/event_processor.h"
 #include "ui/events/event_utils.h"
 #include "ui/events/gesture_detection/gesture_configuration.h"
 
 using blink::WebTouchEvent;
 using blink::WebMouseWheelEvent;
 
 namespace content {
 
 SyntheticGestureTargetAura::SyntheticGestureTargetAura(
     RenderWidgetHostImpl* host)
     : SyntheticGestureTargetBase(host) {
   blink::WebScreenInfo screenInfo;
   host->GetWebScreenInfo(&screenInfo);
   device_scale_factor_ = screenInfo.deviceScaleFactor;
 }
 
 void SyntheticGestureTargetAura::DispatchWebTouchEventToPlatform(
     const WebTouchEvent& web_touch,
     const ui::LatencyInfo& latency_info) {
   TouchEventWithLatencyInfo touch_with_latency(web_touch, latency_info);
   for (size_t i = 0; i < touch_with_latency.event.touchesLength; i++) {
     touch_with_latency.event.touches[i].position.x *= device_scale_factor_;
     touch_with_latency.event.touches[i].position.y *= device_scale_factor_;
     touch_with_latency.event.touches[i].radiusX *= device_scale_factor_;
-    touch_with_latency.event.touches[i].radiusY *= device_scale_factor_;
+    touch_with_latency.event.touches[i].radiusY *= device_scale_factor_;;

[tdresser, 2016/08/24 12:27:48]

Remove extra ;

[lanwei, 2016/08/25 02:28:55]

Done.

   }
   ScopedVector<ui::TouchEvent> events;
   bool conversion_success = MakeUITouchEventsFromWebTouchEvents(
-      touch_with_latency, &events, LOCAL_COORDINATES);
+      touch_with_latency, &events, SCREEN_COORDINATES);

[bokan, 2016/08/24 15:56:57]

Why is this change needed? The call below to ConvertLocationToTarget seems to
imply we're going from one set of window coordinates to another, rather than any
screen coordinates. It happens that on Android screen coordinates are window
coordinates (perhaps off by the system toolbar) but I wonder if this breaks on
desktops.

[lanwei, 2016/08/25 02:28:55]

Actually for SyntheticTouchEvents, the screen position and position are set to
the same. like point.position.x = point.screenPosition.x = x;, so I guess it
would not make much difference.

[bokan, 2016/08/25 12:36:51]

Ugh, it looks like the synthetic gestures don't really set screen position
properly. That seems problematic to me but that's not a fault in this patch.
Anyway, I'd leave this as LOCAL_COORDINATES (as you currently have) since the
screen coordinates are sometimes set to 0. (e.g.
https://cs.chromium.org/chromium/src/content/common/input/synthetic_web_input...)

   DCHECK(conversion_success);
 
   aura::Window* window = GetWindow();
   aura::WindowTreeHost* host = window->GetHost();
+
+  // Synthetic touch events will be transformed here before send to

[tdresser, 2016/08/24 12:27:48]

before being sent to the EventProcessor

[lanwei, 2016/08/25 02:28:55]

Done.

+  // EventProcessor, so it should not be transformed again later in

[tdresser, 2016/08/24 12:27:49]

so they should not be transformed again later

[lanwei, 2016/08/25 02:28:55]

Done.

+  // WindowEventDispatcher.
+  host->dispatcher()->set_transform_events(false);
   for (ScopedVector<ui::TouchEvent>::iterator iter = events.begin(),
       end = events.end(); iter != end; ++iter) {
     (*iter)->ConvertLocationToTarget(window, host->window());
     ui::EventDispatchDetails details =
         host->event_processor()->OnEventFromSource(*iter);
     if (details.dispatcher_destroyed)
       break;
   }
 }
 
@@ skipping 106 matching lines @@
       ->min_distance_for_pinch_scroll_in_pixels();
 }
 
 aura::Window* SyntheticGestureTargetAura::GetWindow() const {
   aura::Window* window = render_widget_host()->GetView()->GetNativeView();
   DCHECK(window);
   return window;
 }
 
 }  // namespace content