[CRD iOS] Injecting scroll events w/ fling animation

remoting/ios/client_gestures.mm

 // Copyright 2017 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.
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 #import "remoting/ios/client_gestures.h"
 
@@ skipping 26 matching lines @@
   [view addGestureRecognizer:_panRecognizer];
 
   _flingRecognizer = [[UIPanGestureRecognizer alloc]
       initWithTarget:self
               action:@selector(flingGestureTriggered:)];
   _flingRecognizer.minimumNumberOfTouches = 1;
   _flingRecognizer.maximumNumberOfTouches = 1;
   _flingRecognizer.delegate = self;
   [view addGestureRecognizer:_flingRecognizer];
 
+  _scrollRecognizer = [[UIPanGestureRecognizer alloc]
+      initWithTarget:self
+              action:@selector(scrollGestureTriggered:)];
+  _scrollRecognizer.minimumNumberOfTouches = 2;
+  _scrollRecognizer.maximumNumberOfTouches = 2;
+  _scrollRecognizer.delegate = self;
+  [view addGestureRecognizer:_scrollRecognizer];
+
   _threeFingerPanRecognizer = [[UIPanGestureRecognizer alloc]
       initWithTarget:self
               action:@selector(threeFingerPanGestureTriggered:)];
   _threeFingerPanRecognizer.minimumNumberOfTouches = 3;
   _threeFingerPanRecognizer.maximumNumberOfTouches = 3;
   _threeFingerPanRecognizer.delegate = self;
   [view addGestureRecognizer:_threeFingerPanRecognizer];
 
   _pinchRecognizer = [[UIPinchGestureRecognizer alloc]
       initWithTarget:self
@@ skipping 23 matching lines @@
 
   _inputScheme = HostInputSchemeTouch;
 
   [_singleTapRecognizer requireGestureRecognizerToFail:_twoFingerTapRecognizer];
   [_twoFingerTapRecognizer
       requireGestureRecognizerToFail:_threeFingerTapRecognizer];
   [_pinchRecognizer requireGestureRecognizerToFail:_singleTapRecognizer];
   [_panRecognizer requireGestureRecognizerToFail:_singleTapRecognizer];
   [_threeFingerPanRecognizer
       requireGestureRecognizerToFail:_threeFingerTapRecognizer];
+  [_panRecognizer requireGestureRecognizerToFail:_scrollRecognizer];
 
   _edgeGesture = [[UIScreenEdgePanGestureRecognizer alloc]
       initWithTarget:self
               action:@selector(edgeGestureTriggered:)];
   //_edgeGesture.edges = UIRectEdgeLeft;
   _edgeGesture.delegate = self;
   [view addGestureRecognizer:_edgeGesture];
 
   _swipeGesture = [[UISwipeGestureRecognizer alloc]
       initWithTarget:self
@@ skipping 139 matching lines @@
 // panning.
 - (IBAction)flingGestureTriggered:(UIPanGestureRecognizer*)sender {
   if ([sender state] == UIGestureRecognizerStateEnded) {
     CGPoint velocity = [sender velocityInView:_view];
     if (velocity.x != 0 || velocity.y != 0) {
       _client.gestureInterpreter->OneFingerFling(velocity.x, velocity.y);
     }
   }
 }
 
+- (IBAction)scrollGestureTriggered:(UIPanGestureRecognizer*)sender {
+  if ([sender state] == UIGestureRecognizerStateEnded) {
+    CGPoint velocity = [sender velocityInView:_view];
+    _client.gestureInterpreter->ScrollWithVelocity(velocity.x, velocity.y);
+    return;
+  }
+
+  CGPoint scrollPoint = [sender locationInView:_view];
+  CGPoint translation = [sender translationInView:_view];
+  _client.gestureInterpreter->Scroll(scrollPoint.x, scrollPoint.y,
+                                     translation.x, translation.y);
+
+  // Reset translation so next iteration is relative
+  [sender setTranslation:CGPointZero inView:_view];
+}
+
 // Click-Drag mouse operation.  This can occur during a Pan.
 - (IBAction)longPressGestureTriggered:(UILongPressGestureRecognizer*)sender {
   CGPoint touchPoint = [sender locationInView:_view];
   remoting::GestureInterpreter::GestureState state;
   switch ([sender state]) {
     case UIGestureRecognizerStateBegan:
       state = remoting::GestureInterpreter::GESTURE_BEGAN;
       break;
     case UIGestureRecognizerStateChanged:
       state = remoting::GestureInterpreter::GESTURE_CHANGED;
@@ skipping 116 matching lines @@
       otherGestureRecognizer == _edgeGesture) {
     return YES;
   }
   // TODO(nicholss): If we return NO here, it dismisses the other reconizers.
   // As we add more types of reconizers, they need to be accounted for in the
   // above logic.
   return NO;
 }
 
 @end