Do not increase the pointer id when type is eraser

third_party/WebKit/Source/core/events/PointerEventFactory.cpp

 // Copyright 2016 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 "core/events/PointerEventFactory.h"
 
 #include "core/frame/FrameView.h"
 #include "platform/geometry/FloatSize.h"
 
 namespace blink {
 
 namespace {
 
 inline int ToInt(WebPointerProperties::PointerType t) {
   return static_cast<int>(t);
 }
 
 const char* PointerTypeNameForWebPointPointerType(
     WebPointerProperties::PointerType type) {
   switch (type) {
     case WebPointerProperties::PointerType::kUnknown:
       return "";
     case WebPointerProperties::PointerType::kTouch:
       return "touch";
     case WebPointerProperties::PointerType::kPen:
     case WebPointerProperties::PointerType::kEraser:

[Navid Zolghadr, 2017/05/09 20:58:46]

nit: With the way you changed the caller of this function we can now remove this
kEraser case to hit the DCHECK at the end of this function.

[lanwei, 2017/05/10 17:50:42]

Done.

       // TODO(mustaq): Fix when the spec starts supporting hovering erasers.
       return "pen";
     case WebPointerProperties::PointerType::kMouse:
       return "mouse";
   }
   NOTREACHED();
   return "";
 }
 
 const AtomicString& PointerEventNameForMouseEventName(
@@ skipping 144 matching lines @@
 
 const int PointerEventFactory::kInvalidId = 0;
 
 // Mouse id is 1 to behave the same as MS Edge for compatibility reasons.
 const int PointerEventFactory::kMouseId = 1;
 
 void PointerEventFactory::SetIdTypeButtons(
     PointerEventInit& pointer_event_init,
     const WebPointerProperties& pointer_properties,
     unsigned buttons) {
-  const WebPointerProperties::PointerType pointer_type =
+  WebPointerProperties::PointerType pointer_type =
       pointer_properties.pointer_type;
-  const IncomingId incoming_id(pointer_type, pointer_properties.id);
-  int pointer_id = AddIdAndActiveButtons(incoming_id, buttons != 0);
-
   // Tweak the |buttons| to reflect pen eraser mode only if the pen is in
   // active buttons state w/o even considering the eraser button.
   // TODO(mustaq): Fix when the spec starts supporting hovering erasers.
   if (pointer_type == WebPointerProperties::PointerType::kEraser &&
       buttons != 0) {
     buttons |= static_cast<unsigned>(WebPointerProperties::Buttons::kEraser);
     buttons &= ~static_cast<unsigned>(WebPointerProperties::Buttons::kLeft);
   }
   pointer_event_init.setButtons(buttons);
 
+  if (pointer_type == WebPointerProperties::PointerType::kEraser)

[dtapuska, 2017/05/09 20:53:08]

Can this be rolled into the other pointer_type == kEraser check... So they are
together? (we'd need to adjust the buttons != 0 conditional moving it inside.

[lanwei, 2017/05/10 17:50:42]

Done.

+    pointer_type = WebPointerProperties::PointerType::kPen;
+  const IncomingId incoming_id(pointer_type, pointer_properties.id);
+  int pointer_id = AddIdAndActiveButtons(incoming_id, buttons != 0);
   pointer_event_init.setPointerId(pointer_id);
   pointer_event_init.setPointerType(
       PointerTypeNameForWebPointPointerType(pointer_type));
   pointer_event_init.setIsPrimary(IsPrimary(pointer_id));
 }
 
 void PointerEventFactory::SetEventSpecificFields(
     PointerEventInit& pointer_event_init,
     const AtomicString& type) {
   pointer_event_init.setBubbles(type != EventTypeNames::pointerenter &&
@@ skipping 343 matching lines @@
     const WebPointerProperties& properties) const {
   if (properties.pointer_type == WebPointerProperties::PointerType::kMouse)
     return PointerEventFactory::kMouseId;
   IncomingId id(properties.pointer_type, properties.id);
   if (pointer_incoming_id_mapping_.Contains(id))
     return pointer_incoming_id_mapping_.at(id);
   return PointerEventFactory::kInvalidId;
 }
 
 }  // namespace blink