[Remoting iOS] Basic viewport manipulation support

remoting/client/ios/client_gestures.mm

Index: remoting/client/ios/client_gestures.mm
diff --git a/remoting/client/ios/client_gestures.mm b/remoting/client/ios/client_gestures.mm
index 047e8ea8ac68dfa6a57972cd04dcddd7ea3c51fd..f667c68dbf84ea29364e58a910d4a3b3b16eb91e 100644
--- a/remoting/client/ios/client_gestures.mm
+++ b/remoting/client/ios/client_gestures.mm
@@ -10,7 +10,11 @@
 
 @implementation ClientGestures
 
-- (id)initWithView:(UIView*)view {
+- (instancetype)initWithView:(UIView*)view
+                    viewport:(remoting::DesktopViewport*)vp {
+  _view = view;
+  _viewport = vp;
+
   _inputScheme = HostInputSchemeTouch;
 
   _longPressRecognizer = [[UILongPressGestureRecognizer alloc]
@@ -99,11 +103,12 @@
 // Resize the view of the desktop - Zoom in/out.  This can occur during a Pan.
 - (IBAction)pinchGestureTriggered:(UIPinchGestureRecognizer*)sender {
   // LOG_TRACE(INFO) << "pinchGestureTriggered";
-  // if ([sender state] == UIGestureRecognizerStateChanged) {
-  //   [self applySceneChange:CGPointMake(0.0, 0.0) scaleBy:sender.scale];
-  //
-  //   sender.scale = 1.0;  // reset scale so next iteration is a relative ratio
-  // }
+  if ([sender state] == UIGestureRecognizerStateChanged) {
+    CGPoint pivot = [sender locationInView:_view];

[Yuwei, 2017/05/03 05:52:35]

I'm planning on creating a new C++ class to be shared with Android to handle
touch events, so eventually these code may be moved to that class and this class
may just become a pure adapter.

[nicholss, 2017/05/03 15:33:50]

Note this class is copy/paste from the original bad code. 

+    _viewport->ScaleDesktop(pivot.x, pivot.y, sender.scale);
+
+    sender.scale = 1.0;  // reset scale so next iteration is a relative ratio
+  }
 }
 
 - (IBAction)tapGestureTriggered:(UITapGestureRecognizer*)sender {
@@ -121,7 +126,19 @@
 
 // Change position of scene.  This can occur during a pinch or long press.
 // Or perform a Mouse Wheel Scroll.
+// TODO(yuweih): The comment above doesn't seem right. Non-panning gestures
+//     should be moved out of this method.
 - (IBAction)panGestureTriggered:(UIPanGestureRecognizer*)sender {
+  // TODO(yuweih): Need deceleration animation, probably in another class.
+  if ([sender state] == UIGestureRecognizerStateChanged &&
+      [sender numberOfTouches] == 1) {
+    CGPoint translation = [sender translationInView:_view];
+    _viewport->MoveDesktop(translation.x, translation.y);
+
+    // Reset translation so next iteration is relative
+    [sender setTranslation:CGPointZero inView:_view];
+  }
+
   // LOG_TRACE(INFO) << "panGestureTriggered";
   //   CGPoint translation = [sender translationInView:self.view];
   //   // If we start with 2 touches, and the pinch gesture is not in progress