Touch emulator: allow multiple touch streams.

content/browser/renderer_host/input/touch_emulator.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/touch_emulator.h"
 
 #include "content/browser/renderer_host/input/motion_event_web.h"
 #include "content/browser/renderer_host/input/web_input_event_util.h"
 #include "content/common/input/web_touch_event_traits.h"
 #include "content/public/common/content_client.h"
@@ skipping 67 matching lines @@
   // We cannot cleanup properly in destructor, as we need roundtrip to the
   // renderer for ack. Instead, the owner should call Disable, and only
   // destroy this object when renderer is dead.
 }
 
 void TouchEmulator::ResetState() {
   last_mouse_event_was_move_ = false;
   last_mouse_move_timestamp_ = 0;
   mouse_pressed_ = false;
   shift_pressed_ = false;
-  touch_active_ = false;
+  emulated_stream_active_ = false;
+  native_stream_active_ = false;
   suppress_next_fling_cancel_ = false;
   pinch_scale_ = 1.f;
   pinch_gesture_active_ = false;
 }
 
 void TouchEmulator::Enable(bool allow_pinch) {
   if (!enabled_) {
     enabled_ = true;
     ResetState();
   }
@@ skipping 41 matching lines @@
             kMouseMoveDropIntervalSeconds)
       return true;
 
     last_mouse_event_was_move_ = true;
     last_mouse_move_timestamp_ = mouse_event.timeStampSeconds;
   } else {
     last_mouse_event_was_move_ = false;
   }
 
   if (mouse_event.type == WebInputEvent::MouseDown)
     mouse_pressed_ = true;

[jdduke (slow), 2014/07/15 19:43:03]

Is the mouse_pressed_ variable redundant with |emulated_stream_active_|?

[dgozman, 2014/07/16 09:05:03]

mouse_pressed_ is a generation flag, we always send events to gesture provider
while it is |true|.

emulated_stream_active_ is a forwarding flag. We may not send event further, but
still have to ack them to gesture provider.

They should be separate.

   else if (mouse_event.type == WebInputEvent::MouseUp)
     mouse_pressed_ = false;
 
   UpdateShiftPressed((mouse_event.modifiers & WebInputEvent::ShiftKey) != 0);
 
   if (FillTouchEventAndPoint(mouse_event) &&
       gesture_provider_.OnTouchEvent(MotionEventWeb(touch_event_))) {
-    client_->ForwardTouchEvent(touch_event_);
+    ForwardTouchEventToClient();
   }
 
   // Do not pass mouse events to the renderer.
   return true;
 }
 
 bool TouchEmulator::HandleMouseWheelEvent(const WebMouseWheelEvent& event) {
   if (!enabled_)
     return false;
 
   // Send mouse wheel for easy scrolling when there is no active touch.
-  return touch_active_;
+  return emulated_stream_active_;
 }
 
 bool TouchEmulator::HandleKeyboardEvent(const WebKeyboardEvent& event) {
   if (!enabled_)
     return false;
 
   if (!UpdateShiftPressed((event.modifiers & WebInputEvent::ShiftKey) != 0))
     return false;
 
   if (!mouse_pressed_)
     return false;
 
   // Note: The necessary pinch events will be lazily inserted by
   // |OnGestureEvent| depending on the state of |shift_pressed_|, using the
   // scroll stream as the event driver.
   if (shift_pressed_) {
     // TODO(dgozman): Add secondary touch point and set anchor.
   } else {
     // TODO(dgozman): Remove secondary touch point and anchor.
   }
 
   // Never block keyboard events.
   return false;
 }
 
-bool TouchEmulator::HandleTouchEventAck(InputEventAckState ack_result) {
-  const bool event_consumed = ack_result == INPUT_EVENT_ACK_STATE_CONSUMED;
-  gesture_provider_.OnTouchEventAck(event_consumed);
-  // TODO(dgozman): Disable emulation when real touch events are available.
+bool TouchEmulator::HandleTouchEvent(const blink::WebTouchEvent& event) {
+  // Block native event when emulated touch stream is active.
+  // Do not allow middle-sequence event to pass through, if start was blocked.
+  if (native_stream_active_ ||

[jdduke (slow), 2014/07/15 19:43:03]

Hmm, maybe split out the conditional? 

if (!emulated_stream_active_ &&
    WebTouchEventTraits::IsTouchSequenceStart(event))) {
  native_stream_active_ = true;
}

return !native_stream_active_;


Actually, maybe that's not any better...

[dgozman, 2014/07/16 09:05:03]

This code have changed now.

+      (!emulated_stream_active_ &&
+       WebTouchEventTraits::IsTouchSequenceStart(event))) {
+    native_stream_active_ = true;
+    return false;
+  }
   return true;
 }
 
+void TouchEmulator::ForwardTouchEventToClient() {
+  // Block emulated event when native touch stream is active.
+  // Do not allow middle-sequence event to pass through, if start was blocked.
+  if (emulated_stream_active_ ||
+      (!native_stream_active_ &&
+       WebTouchEventTraits::IsTouchSequenceStart(touch_event_))) {
+    emulated_stream_active_ = true;
+    client_->ForwardEmulatedTouchEvent(touch_event_);
+  } else {
+    // Block emulated stream and ack immediately.
+    gesture_provider_.OnTouchEventAck(true);

[jdduke (slow), 2014/07/15 19:43:03]

Nit: For readability maybe add something like

const bool event_consumed = true;
gesture_provider_.OnTouchEventAck(event_consumed);

[dgozman, 2014/07/16 09:05:03]

Done.

+  }
+}
+
+bool TouchEmulator::HandleTouchEventAck(
+    const blink::WebTouchEvent& event, InputEventAckState ack_result) {
+  if (emulated_stream_active_) {
+    if (WebTouchEventTraits::IsTouchSequenceEnd(event))
+      emulated_stream_active_ = false;
+
+    const bool event_consumed = ack_result == INPUT_EVENT_ACK_STATE_CONSUMED;
+    gesture_provider_.OnTouchEventAck(event_consumed);
+    return true;
+  }
+
+  DCHECK(native_stream_active_);
+  if (WebTouchEventTraits::IsTouchSequenceEnd(event))
+    native_stream_active_ = false;
+  return false;
+}
+
 void TouchEmulator::OnGestureEvent(const ui::GestureEventData& gesture) {
   WebGestureEvent gesture_event =
       CreateWebGestureEventFromGestureEventData(gesture);
 
   switch (gesture_event.type) {
     case WebInputEvent::Undefined:
       NOTREACHED() << "Undefined WebInputEvent type";
       // Bail without sending the junk event to the client.
       return;
 
@@ skipping 47 matching lines @@
       suppress_next_fling_cancel_ = false;
       break;
 
     default:
       // Everything else goes through.
       client_->ForwardGestureEvent(gesture_event);
   }
 }
 
 void TouchEmulator::CancelTouch() {
-  if (!touch_active_)
+  if (!emulated_stream_active_)
     return;
 
   WebTouchEventTraits::ResetTypeAndTouchStates(
       WebInputEvent::TouchCancel,
       (base::TimeTicks::Now() - base::TimeTicks()).InSecondsF(),
       &touch_event_);
-  touch_active_ = false;
   if (gesture_provider_.OnTouchEvent(MotionEventWeb(touch_event_)))
-    client_->ForwardTouchEvent(touch_event_);
+    ForwardTouchEventToClient();
 }
 
 void TouchEmulator::UpdateCursor() {
   if (!enabled_)
     client_->SetCursor(pointer_cursor_);
   else
     client_->SetCursor(InPinchGestureMode() ? pinch_cursor_ : touch_cursor_);
 }
 
 bool TouchEmulator::UpdateShiftPressed(bool shift_pressed) {
@@ skipping 55 matching lines @@
   if (mouse_event.type != WebInputEvent::MouseDown &&
       mouse_event.type != WebInputEvent::MouseMove &&
       mouse_event.type != WebInputEvent::MouseUp) {
     return false;
   }
 
   WebInputEvent::Type eventType;
   switch (mouse_event.type) {
     case WebInputEvent::MouseDown:
       eventType = WebInputEvent::TouchStart;
-      touch_active_ = true;
       break;
     case WebInputEvent::MouseMove:
       eventType = WebInputEvent::TouchMove;
       break;
     case WebInputEvent::MouseUp:
       eventType = WebInputEvent::TouchEnd;
-      touch_active_ = false;
       break;
     default:
       eventType = WebInputEvent::Undefined;
       NOTREACHED();
   }
   touch_event_.touchesLength = 1;
   touch_event_.modifiers = mouse_event.modifiers;
   WebTouchEventTraits::ResetTypeAndTouchStates(
       eventType, mouse_event.timeStampSeconds, &touch_event_);
 
   WebTouchPoint& point = touch_event_.touches[0];
   point.id = 0;
   point.radiusX = 0.5f * cursor_size_.width();
   point.radiusY = 0.5f * cursor_size_.height();
   point.force = 1.f;
   point.rotationAngle = 0.f;
   point.position.x = mouse_event.x;
   point.screenPosition.x = mouse_event.globalX;
   point.position.y = mouse_event.y;
   point.screenPosition.y = mouse_event.globalY;
 
   return true;
 }
 
 bool TouchEmulator::InPinchGestureMode() const {
   return shift_pressed_ && allow_pinch_;
 }
 
 }  // namespace content