Releasing ids for hovering touch move events

For smart boards, the devices are receiving some touch move events when
there is no finger touching on the screen, like hovering. For those
touch move events, we do not release their ids. We should check if the
touch pointer are in contact with the screen, if not, release the ids
for these touch move events as well.

Bug: 874948
Change-Id: I61f7cb75f92eb600b0dbbbd8f9fb7184c6c0bda1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1670159
Commit-Queue: Lan Wei <lanwei@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Navid Zolghadr <nzolghadr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672694}

ui/views/win/hwnd_message_handler.cc

@@ -2973,15 +2973,28 @@ LRESULT HWNDMessageHandler::HandlePointerEventTypeTouch(UINT message,
         base::TimeDelta::FromMilliseconds(kTouchDownContextResetTimeout));
   }
 
-  size_t mapped_pointer_id = id_generator_.GetGeneratedID(pointer_id);
   POINTER_INFO pointer_info = pointer_touch_info.pointerInfo;
+  POINTER_FLAGS pointer_flags = pointer_info.pointerFlags;
+
+  // When there are touch move events but no finger is pressing on the screen,
+  // which most likely happens for smart board, we should ignore these events
+  // for now. POINTER_FLAG_INCONTACT indicates this pointer is in contact with
+  // the digitizer surface, which means pressing the screen.
+  // POINTER_FLAG_INRANGE indicates the pointer is in the detection range of
+  // the screen.
+  if ((message == WM_POINTERUPDATE) &&
+      !(pointer_flags & POINTER_FLAG_INCONTACT) &&
+      (pointer_flags & POINTER_FLAG_INRANGE)) {
+    SetMsgHandled(TRUE);
+    return 0;
+  }
+
   POINT client_point = pointer_info.ptPixelLocationRaw;
   ScreenToClient(hwnd(), &client_point);
   gfx::Point touch_point = gfx::Point(client_point.x, client_point.y);
-
-  POINTER_FLAGS pointer_flags = pointer_info.pointerFlags;
   ui::EventType event_type = GetTouchEventType(pointer_flags);
   const base::TimeTicks event_time = ui::EventTimeForNow();
+  size_t mapped_pointer_id = id_generator_.GetGeneratedID(pointer_id);
 
   // The pressure from POINTER_TOUCH_INFO is normalized to a range between 0
   // and 1024, but we define the pressure of the range of [0,1].
@@ -3007,17 +3020,16 @@ LRESULT HWNDMessageHandler::HandlePointerEventTypeTouch(UINT message,
   event.latency()->AddLatencyNumberWithTimestamp(
       ui::INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT, event_time, 1);
 
+  // Release the pointer id for touch release events.
+  if (event_type == ui::ET_TOUCH_RELEASED)
+    id_generator_.ReleaseNumber(pointer_id);
+
   // There are cases where the code handling the message destroys the
   // window, so use the weak ptr to check if destruction occurred or not.
   base::WeakPtr<HWNDMessageHandler> ref(msg_handler_weak_factory_.GetWeakPtr());
   delegate_->HandleTouchEvent(&event);
 
   if (ref) {
-    // Release the pointer id only when |HWNDMessageHandler| and |id_generator_|
-    // are not destroyed.
-    if (event_type == ui::ET_TOUCH_RELEASED)
-      id_generator_.ReleaseNumber(pointer_id);
-
     // Mark touch released events handled. These will usually turn into tap
     // gestures, and doing this avoids propagating the event to other windows.
     if (delegate_->GetFrameMode() == FrameMode::SYSTEM_DRAWN) {