Enable pinch-zoom telemetry on Mac

content/browser/renderer_host/input/synthetic_gesture_target_mac.mm

+// Copyright 2015 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.
+
+#include "content/browser/renderer_host/input/synthetic_gesture_target_mac.h"
+
+#include "base/mac/scoped_nsautorelease_pool.h"
+#include "content/browser/renderer_host/render_widget_host_impl.h"
+
+// Unlike some event APIs, Apple does not provide a way to programmatically
+// build a zoom event. To work around this, we leverage ObjectiveC's flexible
+// typing and build up an object with the right interface to provide a zoom
+// event.
+@interface SyntheticPinchEvent : NSObject
+
+// Populated based on desired zoom level.
+@property CGFloat magnification;
+@property NSPoint locationInWindow;
+@property NSEventType type;
+
+// Filled with default values.
+@property(readonly) CGFloat deltaX;
+@property(readonly) CGFloat deltaY;
+@property(readonly) NSEventModifierFlags modifierFlags;
+@property(readonly) NSTimeInterval timestamp;
+
+@end
+
+@implementation SyntheticPinchEvent
+
+@synthesize magnification = magnification_;
+@synthesize locationInWindow = locationInWindow_;
+@synthesize type = type_;
+@synthesize deltaX = deltaX_;
+@synthesize deltaY = deltaY_;
+@synthesize modifierFlags = modifierFlags_;
+@synthesize timestamp = timestamp_;
+
+- (id)initWithMagnification:(float)magnification
+           locationInWindow:(NSPoint)location {
+  self = [super init];
+  if (self) {
+    type_ = NSEventTypeMagnify;
+    magnification_ = magnification;
+    locationInWindow_ = location;
+
+    deltaX_ = 0;
+    deltaY_ = 0;
+    modifierFlags_ = 0;
+
+    // Default timestamp to current time.
+    timestamp_ = [[NSDate date] timeIntervalSince1970];
+  }
+
+  return self;
+}
+
++ (id)eventWithMagnification:(float)magnification
+            locationInWindow:(NSPoint)location {
+  SyntheticPinchEvent* event =
+      [[SyntheticPinchEvent alloc] initWithMagnification:magnification
+                                        locationInWindow:location];
+  return [event autorelease];
+}
+
+@end
+
+using blink::WebInputEvent;
+using blink::WebGestureEvent;
+
+namespace content {
+
+SyntheticGestureTargetMac::SyntheticGestureTargetMac(
+    RenderWidgetHostImpl* host,
+    RenderWidgetHostViewCocoa* cocoa_view)
+    : SyntheticGestureTargetBase(host), cocoa_view_(cocoa_view) {}
+
+void SyntheticGestureTargetMac::DispatchInputEventToPlatform(
+    const WebInputEvent& event) {
+  if (WebInputEvent::isGestureEventType(event.type)) {
+    // Create an autorelease pool so that we clean up any synthetic events we
+    // generate.
+    base::mac::ScopedNSAutoreleasePool pool;
+
+    const WebGestureEvent* gesture_event =
+        static_cast<const WebGestureEvent*>(&event);
+
+    switch (event.type) {
+      case WebInputEvent::GesturePinchBegin: {
+        id event = [SyntheticPinchEvent
+            eventWithMagnification:0.0f
+                  locationInWindow:NSMakePoint(gesture_event->x,
+                                               gesture_event->y)];
+        [cocoa_view_ beginGestureWithEvent:event];
+        return;
+      }
+      case WebInputEvent::GesturePinchEnd: {
+        id event = [SyntheticPinchEvent
+            eventWithMagnification:0.0f
+                  locationInWindow:NSMakePoint(gesture_event->x,
+                                               gesture_event->y)];
+        [cocoa_view_ endGestureWithEvent:event];
+        return;
+      }
+      case WebInputEvent::GesturePinchUpdate: {
+        id event = [SyntheticPinchEvent
+            eventWithMagnification:gesture_event->data.pinchUpdate.scale - 1.0f
+                  locationInWindow:NSMakePoint(gesture_event->x,
+                                               gesture_event->y)];
+        [cocoa_view_ magnifyWithEvent:event];
+        return;
+      }
+      default:
+        break;
+    }
+  }
+
+  // This event wasn't handled yet, forward to the base class.
+  SyntheticGestureTargetBase::DispatchInputEventToPlatform(event);
+}
+
+}  // namespace content