[Android] Perform eager gesture recognition on MotionEvents

content/browser/renderer_host/input/gesture_event_packet.cc

+// Copyright 2013 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/gesture_event_packet.h"
+
+#include "base/logging.h"
+#include "content/common/input/web_input_event_traits.h"

[tdresser, 2014/01/23 16:32:43]

Remove unused includes.

[jdduke (slow), 2014/01/23 22:52:34]

Done.

+
+using blink::WebGestureEvent;
+using blink::WebInputEvent;
+using blink::WebTouchEvent;
+using blink::WebTouchPoint;
+
+namespace content {
+namespace {
+
+bool IsTouchSequenceStart(const WebTouchEvent& event) {
+  if (event.type != WebInputEvent::TouchStart)
+    return false;
+  if (!event.touchesLength)
+    return false;
+  for (size_t i = 0; i < event.touchesLength; i++) {
+    if (event.touches[i].state != WebTouchPoint::StatePressed)
+      return false;
+  }
+  return true;
+}
+
+GestureEventPacket::GestureSource
+ToGestureSource(const WebTouchEvent& event) {
+  // TODO(jdduke): Use GestureTapDown as a new sequence marker?

[Rick Byers, 2014/01/23 20:45:29]

I think clearing using 'period when no touches are on the target window' as the
precise delimitation between sequences seems right to me.  This is what's
important to the user, and gestures are a higher level semantic above it (eg.
conceivably we could decide not to send GTD if we saw two fingers go down at
once in the same input frame, or that some other gesture event could come BEFORE
a GTD in a sequence).  So my vote is probably for removing this TODO and leaving
as-is.

[jdduke (slow), 2014/01/24 05:34:40]

Done.

+  return IsTouchSequenceStart(event) ? GestureEventPacket::TOUCH_BEGIN
+                                     : GestureEventPacket::TOUCH;
+}
+
+}  // namespace
+
+GestureEventPacket::GestureEventPacket()
+    : gesture_count_(0),
+      gesture_source_(GESTURE_SOURCE_DEFAULT) {}
+
+GestureEventPacket::GestureEventPacket(GestureSource source)
+    : gesture_count_(0),
+      gesture_source_(source) {}
+
+GestureEventPacket::~GestureEventPacket() {}
+
+void GestureEventPacket::Push(const blink::WebGestureEvent& gesture) {
+  CHECK_LT(gesture_count_, kMaxGesturesPerTouch);
+  gestures_[gesture_count_++] = gesture;
+}
+
+GestureEventPacket GestureEventPacket::FromTouch(const WebTouchEvent& event) {
+  return GestureEventPacket(ToGestureSource(event));
+}
+
+GestureEventPacket GestureEventPacket::FromGesture(
+    GestureSource source,
+    const WebGestureEvent& event) {
+  GestureEventPacket packet(source);
+  packet.Push(event);
+  return packet;
+}
+
+}  // namespace content