Initial views touchui GestureRecognizer support

views/touchui/gesture_recognizer.cc

+// Copyright (c) 2011 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 "views/touchui/gesture_recognizer.h"
+
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "views/events/event.h"
+
+namespace {
+// TODO(Gajen): Make these configurable in sync with this CL http://code.google.
+//              com/p/chromium/issues/detail?id=100773.
+const double kMaximumTouchDownDurationInSecondsForClick = 0.8;
+const double kMinimumTouchDownDurationInSecondsForClick = 0.01;
+const double kMaximumSecondsBetweenDoubleClick = 0.7;
+const int kMaximumTouchMoveInPixelsForClick = 20;
+const float kMinFlickSpeedSquared = 550.f * 550.f;
+
+}  // namespace
+
+namespace views {
+
+////////////////////////////////////////////////////////////////////////////////
+// GestureRecognizer Public:
+
+GestureRecognizer::GestureRecognizer()
+    : first_touch_time_(0.0),
+      state_(GestureRecognizer::GS_NO_GESTURE),
+      last_touch_time_(0.0),
+      last_click_time_(0.0),
+      x_velocity_(0.0),
+      y_velocity_(0.0),
+      flags_(0) {
+  const unsigned int first_finger = 0;
+  const ui::EventType released = ui::ET_TOUCH_RELEASED;
+  const ui::EventType pressed = ui::ET_TOUCH_PRESSED;
+  const ui::EventType moved = ui::ET_TOUCH_MOVED;
+  const ui::EventType stationary = ui::ET_TOUCH_STATIONARY;
+  const ui::EventType cancelled = ui::ET_TOUCH_CANCELLED;
+
+  AddEdgeFunction(GS_NO_GESTURE, first_finger, pressed, false,
+                  &GestureRecognizer::TouchDown);
+  AddEdgeFunction(GS_PENDING_SYNTHETIC_CLICK, first_finger, cancelled, false,
+                  &GestureRecognizer::NoGesture);
+  AddEdgeFunction(GS_PENDING_SYNTHETIC_CLICK, first_finger, released, false,
+                  &GestureRecognizer::Click);
+  AddEdgeFunction(GS_PENDING_SYNTHETIC_CLICK, first_finger, moved, false,
+                  &GestureRecognizer::InClickOrScroll);
+  AddEdgeFunction(GS_PENDING_SYNTHETIC_CLICK, first_finger, stationary, false,
+                  &GestureRecognizer::InClickOrScroll);
+  AddEdgeFunction(GS_SCROLL, first_finger, moved, false,
+                  &GestureRecognizer::InScroll);
+  AddEdgeFunction(GS_SCROLL, first_finger, released, false,
+                  &GestureRecognizer::ScrollEnd);
+  AddEdgeFunction(GS_SCROLL, first_finger, cancelled, false,
+                  &GestureRecognizer::ScrollEnd);
+}
+
+GestureRecognizer::~GestureRecognizer() {
+}
+
+GestureRecognizer* GestureRecognizer::GetInstance() {
+  return Singleton<GestureRecognizer>::get();
+}
+
+GestureRecognizer::Gestures* GestureRecognizer::ProcessTouchEventForGesture(
+    const TouchEvent& event,
+    ui::TouchStatus status) {
+  if (status != ui::TOUCH_STATUS_UNKNOWN)
+    return false;  // The event was consumed by a touch sequence.
+
+  flags_ = event.flags();
+  scoped_ptr<Gestures> gestures(new Gestures());
+  UpdateValues(event);
+  GestureTransitionFunctionMap::iterator it =  edge_functions_.find(

[sky, 2011/11/15 16:54:44]

Is there a reason we need this level of complexity rather than a switch
statement?

[Gajen, 2011/11/16 15:08:41]

log n to O(1) can be achieved in switch case, but theoretically there could be
2^32 such switch states, So, I guess, its OK to have this.

[sky, 2011/11/16 16:27:34]

Theoretically we could, but will we? The current code has 8, do you envision
needing a lot more to warrant this level of complexity. I like the current
approach if you need to dynamically support various cases, but AFAICT that isn't
the case. As such, a switch statement is a lot simpler and easier to follow.

+      Signature(state_, event.identity(), event.type(), false));
+  if (edge_functions_.end() != it) {
+    GestureTransitionFunction ef = it->second;
+    ((*this).*ef)(event, gestures.get());
+  }
+  return gestures.release();
+}
+
+void GestureRecognizer::Reset() {
+  first_touch_time_ = 0.0;
+  state_ = GestureRecognizer::GS_NO_GESTURE;
+  last_touch_time_ = 0.0;
+  last_touch_position_.SetPoint(0, 0);
+  x_velocity_ = 0.0;
+  y_velocity_ = 0.0;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// GestureRecognizer Private:
+
+GestureRecognizer::TouchState GestureRecognizer::TouchEventTypeToTouchState(

[sky, 2011/11/15 16:54:44]

// static

[Gajen, 2011/11/16 15:08:41]

Done.

+    ui::EventType type) {
+  switch (type) {
+    case ui::ET_TOUCH_RELEASED: return TS_RELEASED;
+    case ui::ET_TOUCH_PRESSED: return TS_PRESSED;
+    case ui::ET_TOUCH_MOVED: return TS_MOVED;
+    case ui::ET_TOUCH_STATIONARY: return TS_STATIONARY;
+    case ui::ET_TOUCH_CANCELLED: return TS_CANCELLED;
+    default:
+      VLOG(1) << "Unknown Touch Event type";
+  }
+  return TS_UNKNOWN;
+}
+
+// Builds a signature. Signatures are assembled by joining together
+// multiple bits.
+// 1 LSB bit so that the computed signature is always greater than 0
+// 3 bits for the |type|.
+// 1 bit for |touch_handled|
+// 12 bits for |touch_id|
+// 15 bits for the |gesture_state|.
+unsigned int GestureRecognizer::Signature(GestureState gesture_state,
+                                unsigned int touch_id, ui::EventType type,
+                                bool touch_handled) {
+  CHECK((touch_id & 0xfff) == touch_id);
+  TouchState touch_state = TouchEventTypeToTouchState(type);
+  return 1 + ((touch_state & 0x7) << 1 | (touch_handled ? 1 << 4 : 0) |
+             ((touch_id & 0xfff) << 5) | (gesture_state << 17));
+}
+
+void GestureRecognizer::AddEdgeFunction(GestureState state,
+                                        unsigned int touch_id,
+                                        ui::EventType type,
+                                        bool touch_handled,
+                                        GestureTransitionFunction function) {
+  edge_functions_[Signature(state, touch_id, type, touch_handled)] = function;
+}
+
+bool GestureRecognizer::IsInClickTimeWindow() {
+  double duration(last_touch_time_ - first_touch_time_);
+  return duration >= kMinimumTouchDownDurationInSecondsForClick &&
+         duration < kMaximumTouchDownDurationInSecondsForClick;
+}
+
+bool GestureRecognizer::IsInSecondClickTimeWindow() {
+  double duration(last_touch_time_ - last_click_time_);
+  return duration < kMaximumSecondsBetweenDoubleClick;
+}
+
+bool GestureRecognizer::IsInsideManhattanSquare(const TouchEvent& event) {
+  int manhattanDistance = abs(event.x() - first_touch_position_.x()) +
+                          abs(event.y() - first_touch_position_.y());
+  return manhattanDistance < kMaximumTouchMoveInPixelsForClick;
+}
+
+bool GestureRecognizer::IsSecondClickInsideManhattanSquare(
+    const TouchEvent& event) {
+  int manhattanDistance = abs(event.x() - last_click_position_.x()) +
+                          abs(event.y() - last_click_position_.y());
+  return manhattanDistance < kMaximumTouchMoveInPixelsForClick;
+}
+
+bool GestureRecognizer::IsOverMinFlickSpeed() {
+  return (x_velocity_ * x_velocity_ + y_velocity_ * y_velocity_) >
+          kMinFlickSpeedSquared;
+}
+
+void GestureRecognizer::AppendTapDownGestureEvent(const TouchEvent& event,
+                                                  Gestures* gestures) {
+  gestures->push_back(linked_ptr<GestureEvent>(new GestureEvent(
+      ui::ET_GESTURE_TAP_DOWN,
+      first_touch_position_.x(),
+      first_touch_position_.y(),
+      event.flags(),
+      base::Time::FromDoubleT(last_touch_time_),
+      0.f, 0.f)));
+}
+
+void GestureRecognizer::AppendClickGestureEvent(const TouchEvent& event,
+                                                Gestures* gestures) {
+  gestures->push_back(linked_ptr<GestureEvent>(new GestureEvent(
+      ui::ET_GESTURE_TAP,
+      first_touch_position_.x(),
+      first_touch_position_.y(),
+      event.flags(),
+      base::Time::FromDoubleT(last_touch_time_),
+      0.f, 0.f)));
+}
+
+void GestureRecognizer::AppendDoubleClickGestureEvent(const TouchEvent& event,
+                                                      Gestures* gestures) {
+  gestures->push_back(linked_ptr<GestureEvent>(new GestureEvent(
+      ui::ET_GESTURE_DOUBLE_TAP,
+      first_touch_position_.x(),
+      first_touch_position_.y(),
+      event.flags(),
+      base::Time::FromDoubleT(last_touch_time_),
+      0.f, 0.f)));
+}
+
+void GestureRecognizer::AppendScrollGestureBegin(const TouchEvent& event,
+                                                 Gestures* gestures) {
+  gestures->push_back(linked_ptr<GestureEvent>(new GestureEvent(
+      ui::ET_GESTURE_SCROLL_BEGIN,
+      event.x(),
+      event.y(),
+      event.flags(),
+      base::Time::FromDoubleT(last_touch_time_),
+      0.f, 0.f)));
+}
+
+void GestureRecognizer::AppendScrollGestureEnd(const TouchEvent& event,
+                                               Gestures* gestures,
+                                               float x_velocity,
+                                               float y_velocity) {
+  gestures->push_back(linked_ptr<GestureEvent>(new GestureEvent(
+      ui::ET_GESTURE_SCROLL_END,
+      event.x(),
+      event.y(),
+      event.flags(),
+      base::Time::FromDoubleT(last_touch_time_),
+      x_velocity, y_velocity)));
+}
+
+void GestureRecognizer:: AppendScrollGestureUpdate(const TouchEvent& event,
+                                                   Gestures* gestures) {
+  float delta_x(event.x() - first_touch_position_.x());
+  float delta_y(event.y() - first_touch_position_.y());
+
+  gestures->push_back(linked_ptr<GestureEvent>(new GestureEvent(
+      ui::ET_GESTURE_SCROLL_UPDATE,
+      event.x(),
+      event.y(),
+      event.flags(),
+      base::Time::FromDoubleT(last_touch_time_),
+      delta_x, delta_y)));
+
+  first_touch_position_ = event.location();
+}
+
+void GestureRecognizer::UpdateValues(const TouchEvent& event) {
+  if (state_ != GS_NO_GESTURE && event.type() == ui::ET_TOUCH_MOVED) {
+    double interval(event.time_stamp().ToDoubleT() - last_touch_time_);
+    x_velocity_ = (event.x() - last_touch_position_.x()) / interval;
+    y_velocity_ = (event.y() - last_touch_position_.y()) / interval;
+  }
+  last_touch_time_ = event.time_stamp().ToDoubleT();
+  last_touch_position_ = event.location();
+  if (state_ == GS_NO_GESTURE) {
+    first_touch_time_ = last_touch_time_;
+    first_touch_position_ = event.location();
+    x_velocity_ = 0.0;
+    y_velocity_ = 0.0;
+  }
+}
+
+bool GestureRecognizer::Click(const TouchEvent& event, Gestures* gestures) {
+  bool gesture_added = false;
+  if (IsInClickTimeWindow() && IsInsideManhattanSquare(event)) {
+    gesture_added = true;
+    AppendClickGestureEvent(event, gestures);
+    if (IsInSecondClickTimeWindow() &&
+        IsSecondClickInsideManhattanSquare(event))
+      AppendDoubleClickGestureEvent(event, gestures);
+    last_click_time_ = last_touch_time_;
+    last_click_position_ = last_touch_position_;
+  }
+  Reset();
+  return gesture_added;
+}
+
+bool GestureRecognizer::InClickOrScroll(const TouchEvent& event,
+                                        Gestures* gestures) {
+  if (IsInClickTimeWindow() && IsInsideManhattanSquare(event)) {
+    SetState(GS_PENDING_SYNTHETIC_CLICK);
+    return false;
+  }
+  if (event.type() == ui::ET_TOUCH_MOVED && !IsInsideManhattanSquare(event)) {
+    AppendScrollGestureBegin(event, gestures);
+    AppendScrollGestureUpdate(event, gestures);
+    SetState(GS_SCROLL);
+    return true;
+  }
+  return false;
+}
+
+bool GestureRecognizer::InScroll(const TouchEvent& event, Gestures* gestures) {
+  AppendScrollGestureUpdate(event, gestures);
+  return true;
+}
+
+bool GestureRecognizer::NoGesture(const TouchEvent&, Gestures*) {
+  Reset();
+  return false;
+}
+
+bool GestureRecognizer::TouchDown(const TouchEvent& event, Gestures* gestures) {
+  AppendTapDownGestureEvent(event, gestures);
+  SetState(GS_PENDING_SYNTHETIC_CLICK);
+  return false;
+}
+
+bool GestureRecognizer::ScrollEnd(const TouchEvent& event, Gestures* gestures) {
+  if (IsOverMinFlickSpeed() && event.type() != ui::ET_TOUCH_CANCELLED)
+    AppendScrollGestureEnd(event, gestures, x_velocity_, y_velocity_);
+  else
+    AppendScrollGestureEnd(event, gestures, 0.f, 0.f);
+  SetState(GS_NO_GESTURE);
+  Reset();
+  return false;
+}
+
+}  // namespace views