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      1 // Copyright 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "content/browser/renderer_host/input/touch_action_filter.h"
      6 
      7 #include "third_party/WebKit/public/web/WebInputEvent.h"
      8 
      9 using blink::WebInputEvent;
     10 using blink::WebGestureEvent;
     11 
     12 namespace content {
     13 
     14 TouchActionFilter::TouchActionFilter() :
     15   drop_scroll_gesture_events_(false),
     16   allowed_touch_action_(TOUCH_ACTION_AUTO) {
     17 }
     18 
     19 bool TouchActionFilter::FilterGestureEvent(
     20     const WebGestureEvent& gesture_event) {
     21   // Filter for allowable touch actions first (eg. before the TouchEventQueue
     22   // can decide to send a touch cancel event).
     23   // TODO(rbyers): Add touch-action control over for pinch.  crbug.com/247566.
     24   switch(gesture_event.type) {
     25     case WebInputEvent::GestureScrollBegin:
     26       if (allowed_touch_action_ == TOUCH_ACTION_NONE)
     27         drop_scroll_gesture_events_ = true;
     28       // FALL THROUGH
     29     case WebInputEvent::GestureScrollUpdate:
     30       if (drop_scroll_gesture_events_)
     31         return true;
     32       break;
     33 
     34     case WebInputEvent::GestureScrollEnd:
     35     case WebInputEvent::GestureFlingStart:
     36       allowed_touch_action_ = content::TOUCH_ACTION_AUTO;
     37       if (drop_scroll_gesture_events_) {
     38         drop_scroll_gesture_events_ = false;
     39         return true;
     40       }
     41       break;
     42 
     43     default:
     44       // Gesture events unrelated to touch actions (panning/zooming) are left
     45       // alone.
     46       break;
     47   }
     48 
     49   return false;
     50 }
     51 
     52 void TouchActionFilter::OnSetTouchAction(
     53     content::TouchAction touch_action) {
     54   // For multiple fingers, we take the intersection of the touch actions for
     55   // all fingers that have gone down during this action.
     56   // TODO(rbyers): What exact multi-finger semantic do we want?  This is left
     57   // as implementation-defined in the pointer events specification.
     58   // crbug.com/247566.
     59   if (touch_action == content::TOUCH_ACTION_NONE)
     60     allowed_touch_action_ = content::TOUCH_ACTION_NONE;
     61 }
     62 
     63 }
     64