[Tracking Patch] Unified gesture detection

content/browser/renderer_host/input/gestures/zoom_manager.cc

+// Copyright 2014 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/gestures/zoom_manager.h"
+
+#include "base/auto_reset.h"
+#include "base/logging.h"
+#include "content/browser/renderer_host/input/gestures/motion_event.h"
+
+namespace content {
+
+ZoomManager::ZoomManager(ScaleGestureDetector::Config config,
+                         ScaleGestureDetector::OnScaleGestureListener* listener)
+    : listener_(listener),
+      permanently_ignore_detector_events_(false),
+      temporarily_ignore_detector_events_(false),
+      pinch_event_sent_(false) {
+  DCHECK(listener_);
+  multi_touch_detector_.reset(new ScaleGestureDetector(config, this));
+}
+
+ZoomManager::~ZoomManager() {}
+
+void ZoomManager::PassTouchEventThrough(const MotionEvent& event) {
+  base::AutoReset<bool> temporarily_ignore_detector_events(
+      &temporarily_ignore_detector_events_, true);
+  multi_touch_detector_->OnTouchEvent(event);
+}
+
+bool ZoomManager::ProcessTouchEvent(const MotionEvent& event) {
+  // TODO: Need to deal with multi-touch transition
+  bool in_gesture = IsScaleGestureDetectionInProgress();
+  bool result = multi_touch_detector_->OnTouchEvent(event);
+  if (!in_gesture && (event.GetActionMasked() == MotionEvent::ACTION_UP ||
+                      event.GetActionMasked() == MotionEvent::ACTION_CANCEL)) {
+    return false;
+  }
+  return result;
+}
+
+void ZoomManager::UpdateMultiTouchSupport(bool supports_multi_touch_zoom) {
+  // Note that returning false from onScaleBegin / onScale makes the
+  // gesture detector not to emit further scaling notifications
+  // related to this gesture. Thus, if detector events are enabled in
+  // the middle of the gesture, we don't need to do anything.
+  permanently_ignore_detector_events_ = !supports_multi_touch_zoom;
+}
+
+bool ZoomManager::IsScaleGestureDetectionInProgress() const {
+  return !permanently_ignore_detector_events_ &&
+         multi_touch_detector_->IsInProgress();
+}
+
+bool ZoomManager::OnScaleBegin(const ScaleGestureDetector& detector) {
+  if (IgnoreDetectorEvents())
+    return false;
+  pinch_event_sent_ = false;
+  // TODO(jdduke): Ignore single tap?
+  return true;
+}
+
+void ZoomManager::OnScaleEnd(const ScaleGestureDetector& detector) {
+  if (!pinch_event_sent_)
+    return;
+  listener_->OnScaleEnd(detector);
+  pinch_event_sent_ = false;
+}
+
+bool ZoomManager::OnScale(const ScaleGestureDetector& detector) {
+  if (IgnoreDetectorEvents())
+    return false;
+  // It is possible that OnScaleBegin() was never called when we reach here.
+  // This happens when webkit handles the 2nd touch down event. That causes
+  // ContentView to ignore the OnScaleBegin() call. And if webkit does not
+  // handle the touch move events afterwards, we will face a situation
+  // that OnScale() is called without any OnScaleBegin().
+  // To solve this problem, we call OnScaleBegin() here if it is never called.
+  if (!pinch_event_sent_) {
+    pinch_event_sent_ = true;
+    listener_->OnScaleBegin(detector);
+  }
+  listener_->OnScale(detector);
+  return true;
+}
+
+bool ZoomManager::IgnoreDetectorEvents() const {
+  return permanently_ignore_detector_events_ ||
+         temporarily_ignore_detector_events_;
+}
+
+}  // namespace content