Convert the coordinates in WebInputEvent To Viewport in InputRouter

content/browser/renderer_host/input/web_input_event_util.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.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "content/browser/renderer_host/input/web_input_event_util.h"
 
 #include <cmath>
@@ skipping 53 matching lines @@
     case ui::DomKeyLocation::RIGHT:
       return blink::WebInputEvent::IsRight;
     case ui::DomKeyLocation::NUMPAD:
       return blink::WebInputEvent::IsKeyPad;
     case ui::DomKeyLocation::STANDARD:
       break;
   }
   return static_cast<blink::WebInputEvent::Modifiers>(0);
 }
 
+scoped_ptr<blink::WebInputEvent> ConvertWebInputEventToViewport(

[Rick Byers, 2015/11/27 02:15:56]

nit: please add a TODO comment saying this mixing co-ordinate spaces in
WebInputEvent is temporary and a link to your doc for the long-term plan.

+    const blink::WebInputEvent& event,
+    float scale) {
+  scoped_ptr<blink::WebInputEvent> scaled_event;
+  if (scale == 1.f)
+    return scaled_event;
+  if (event.type == blink::WebMouseEvent::MouseWheel) {
+    blink::WebMouseWheelEvent* wheel_event = new blink::WebMouseWheelEvent;
+    scaled_event.reset(wheel_event);
+    *wheel_event = static_cast<const blink::WebMouseWheelEvent&>(event);

[tdresser, 2015/11/27 21:35:20]

Isn't there some way to avoid allocating an extra event?
Something like:

blink::WebMouseWheelEvent* wheel_event = static_cast<const
blink::WebMouseWheelEvent*>(&event);
scaled_event.reset(wheel_event);

[oshima, 2015/11/30 23:01:12]

I thought it's risky to modify const object, which is a member of
another (message) object, which may be used in different context.
I'm happy to change if this is safe, so please let me know.
If it's ok to modify the const object, I can (and should) just return the
pointer,
as the ownership cannot be transfered.

+    wheel_event->deltaX *= scale;
+    wheel_event->deltaY *= scale;
+    wheel_event->wheelTicksX *= scale;
+    wheel_event->wheelTicksY *= scale;

[tdresser, 2015/11/27 21:35:20]

Is this correct, or should we recompute wheelTicks here?

https://code.google.com/p/chromium/codesearch#chromium/src/components/html_vi...

[oshima, 2015/11/30 23:01:12]

If delta X needs to be scaled, so this needs to be scaled too, and it looks to
me that delta X needs to be scaled because the content has 2x size.

+  } else if (blink::WebInputEvent::isMouseEventType(event.type)) {
+    blink::WebMouseEvent* mouse_event = new blink::WebMouseEvent;
+    scaled_event.reset(mouse_event);
+    *mouse_event = static_cast<const blink::WebMouseEvent&>(event);
+    mouse_event->x *= scale;
+    mouse_event->y *= scale;
+    mouse_event->windowX = mouse_event->x;
+    mouse_event->windowY = mouse_event->y;
+    mouse_event->movementX *= scale;
+    mouse_event->movementY *= scale;
+  } else if (blink::WebInputEvent::isTouchEventType(event.type)) {
+    blink::WebTouchEvent* touch_event = new blink::WebTouchEvent;
+    scaled_event.reset(touch_event);
+    *touch_event = static_cast<const blink::WebTouchEvent&>(event);
+    for (unsigned i = 0; i < touch_event->touchesLength; i++) {
+      touch_event->touches[i].position.x *= scale;
+      touch_event->touches[i].position.y *= scale;
+      touch_event->touches[i].radiusX *= scale;
+      touch_event->touches[i].radiusY *= scale;
+    }
+  } else if (blink::WebInputEvent::isGestureEventType(event.type)) {
+    blink::WebGestureEvent* gesture_event = new blink::WebGestureEvent;
+    scaled_event.reset(gesture_event);
+    *gesture_event = static_cast<const blink::WebGestureEvent&>(event);
+    gesture_event->x *= scale;
+    gesture_event->y *= scale;
+    switch (gesture_event->type) {
+      case blink::WebInputEvent::GestureScrollUpdate:
+        gesture_event->data.scrollUpdate.deltaX *= scale;
+        gesture_event->data.scrollUpdate.deltaY *= scale;
+        break;
+      case blink::WebInputEvent::GestureScrollBegin:
+        gesture_event->data.scrollBegin.deltaXHint *= scale;
+        gesture_event->data.scrollBegin.deltaYHint *= scale;
+        break;
+
+      case blink::WebInputEvent::GesturePinchUpdate:
+        // Scale in pinch gesture is DSF agnostic.
+        break;
+
+      case blink::WebInputEvent::GestureDoubleTap:
+      case blink::WebInputEvent::GestureTap:
+      case blink::WebInputEvent::GestureTapUnconfirmed:
+        gesture_event->data.tap.width *= scale;
+        gesture_event->data.tap.height *= scale;
+        break;
+
+      case blink::WebInputEvent::GestureTapDown:
+        gesture_event->data.tapDown.width *= scale;
+        gesture_event->data.tapDown.height *= scale;
+        break;
+
+      case blink::WebInputEvent::GestureShowPress:
+        gesture_event->data.showPress.width *= scale;
+        gesture_event->data.showPress.height *= scale;
+        break;
+
+      case blink::WebInputEvent::GestureLongPress:
+      case blink::WebInputEvent::GestureLongTap:
+        gesture_event->data.longPress.width *= scale;
+        gesture_event->data.longPress.height *= scale;
+        break;
+
+      case blink::WebInputEvent::GestureTwoFingerTap:
+        gesture_event->data.twoFingerTap.firstFingerWidth *= scale;
+        gesture_event->data.twoFingerTap.firstFingerHeight *= scale;
+        break;
+
+      case blink::WebInputEvent::GestureFlingStart:
+        gesture_event->data.flingStart.velocityX *= scale;
+        gesture_event->data.flingStart.velocityY *= scale;
+        break;
+
+      // These event does not have location data.
+      case blink::WebInputEvent::GesturePinchBegin:
+      case blink::WebInputEvent::GesturePinchEnd:
+      case blink::WebInputEvent::GestureTapCancel:
+      case blink::WebInputEvent::GestureFlingCancel:
+      case blink::WebInputEvent::GestureScrollEnd:
+        break;
+
+      // TODO(oshima): Find out if ContextMenu needs to be scaled.
+      default:
+        break;
+    }
+  }
+  return scaled_event;
+}
+
 }  // namespace content