[Remoting iOS] Basic viewport manipulation support

remoting/client/ios/app/host_view_controller.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/client/ios/app/host_view_controller.h"
 
 #import <GLKit/GLKit.h>
+#include <memory>
 
+#include "base/mac/bind_objc_block.h"
 #import "ios/third_party/material_components_ios/src/components/Buttons/src/MaterialButtons.h"
+#include "remoting/client/desktop_viewport.h"
+#import "remoting/client/ios/client_gestures.h"
 #import "remoting/client/ios/session/remoting_client.h"
 
 static const CGFloat kFabInset = 15.f;
 
 @interface HostViewController () {
   RemotingClient* _client;
   MDCFloatingButton* _floatingButton;
+
+  // DO NOT pass |_clientGestures| to other objects.
+  ClientGestures* _clientGestures;
+  std::unique_ptr<remoting::DesktopViewport> _viewport;
 }
 @end
 
 @implementation HostViewController
 
 - (id)initWithClient:(RemotingClient*)client {
   self = [super init];
   if (self) {
     _client = client;
   }
@@ skipping 37 matching lines @@
   [_client.displayHandler onSurfaceCreated:glView];
 
   // viewDidLayoutSubviews may be called before viewDidAppear, in which case
   // the surface is not ready and onSurfaceChanged will be no-op.
   // Call onSurfaceChanged here to cover that case.
   [_client.displayHandler onSurfaceChanged:glView.frame];
 }
 
 - (void)viewWillAppear:(BOOL)animated {
   [super viewWillAppear:animated];
-  ((GLKView*)self.view).enableSetNeedsDisplay = true;
+
+  _viewport.reset(new remoting::DesktopViewport());

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

I would rather see viewport be a part of the display handler and we ask the
display handler to translate and whatnot. I would like to minimize the amount of
logic in the native side as much as possible. 

[Yuwei, 2017/05/03 22:28:37]

I created a C++ GestureInterpreter in RemotingClient and moved the viewport
there. I put the viewport/GestureInterpreter in RemotingClient rather than the
display handler since it will also be used for injecting mouse clicks, etc.

+
+  _viewport->RegisterOnTransformationChangedCallback(
+      base::BindBlockArc(^(const remoting::ViewMatrix& matrix) {
+        [_client.displayHandler onPixelTransformationChanged:matrix];
+      }),
+      true);
+
+  _client.displayHandler.delegate = self;
+
+  _clientGestures =
+      [[ClientGestures alloc] initWithView:self.view viewport:_viewport.get()];
 }
 
 - (void)viewWillDisappear:(BOOL)animated {
   [super viewWillDisappear:animated];
+
+  // Explicitly free |client_gestures_| before |_viewport|. This only works if
+  // |_clientGestures| is only owned by this.
+  _clientGestures = nil;
+  _viewport.reset();
 }
 
 - (void)viewDidLayoutSubviews {
   [super viewDidLayoutSubviews];
 
-  [_client.displayHandler onSurfaceChanged:((GLKView*)self.view).frame];
+  CGRect surfaceFrame = ((GLKView*)self.view).frame;

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

No need to cast, frame comes from UIView.

[Yuwei, 2017/05/03 22:28:37]

Done.

+  [_client.displayHandler onSurfaceChanged:surfaceFrame];
+  _viewport->SetSurfaceSize(surfaceFrame.size.width, surfaceFrame.size.height);
 
-  const CGSize& btnSize = _floatingButton.frame.size;
+  CGSize btnSize = _floatingButton.frame.size;
   _floatingButton.frame =
       CGRectMake(self.view.frame.size.width - btnSize.width - kFabInset,
                  self.view.frame.size.height - btnSize.height - kFabInset,
                  btnSize.width, btnSize.height);
 }
 
+#pragma mark - GlDisplayHandlerDelegate
+- (void)canvasSizeChanged:(CGSize)size {

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

should have a space between the method and the pragma mark

[Yuwei, 2017/05/03 22:28:37]

Done.

+  _viewport->SetDesktopSize(size.width, size.height);
+}
+
 #pragma mark - Private
 
 - (void)didTap:(id)sender {
   // TODO(nicholss): The FAB is being used to close the window at the moment
   // just as a demo  as the integration continues. This will not be the case
   // in the final app.
   [self dismissViewControllerAnimated:YES completion:nil];
 }
 
 @end