Identity the mouse pointer type from low-level events for Windows

ui/events/win/events_win.cc

Index: ui/events/win/events_win.cc
diff --git a/ui/events/win/events_win.cc b/ui/events/win/events_win.cc
index cd8dbc72c99e12385a6f6bfe9df9a79b865bdd8d..4c47df431b4909ec2e91026aecc8cc07ffba5c3a 100644
--- a/ui/events/win/events_win.cc
+++ b/ui/events/win/events_win.cc
@@ -19,9 +19,12 @@ namespace ui {
 namespace {
 
 // From MSDN: "Mouse" events are flagged with 0xFF515700 if they come
-// from a touch or stylus device.  In Vista or later, they are also flagged
-// with 0x80 if they come from touch.
+// from a touch or stylus device.  In Vista or later, the eighth bit,
+// masked by 0x80, is used to differentiate touch input from pen input
+// (0 = pen, 1 = touch).
 #define MOUSEEVENTF_FROMTOUCH (0xFF515700 | 0x80)
+#define MOUSEEVENTF_FROMTOUCHPEN 0xFF515700

[mustaq, 2016/06/02 15:28:24]

Please move FROMTOUCHPEN above FROMTOUCH to avoid having the same constant
twice.

[lanwei, 2016/06/02 16:07:06]

Done.

+#define SIGNATURE_MASK 0xFFFFFF00
 
 // Get the native mouse key state from the native event message type.
 int GetNativeMouseKey(const base::NativeEvent& native_event) {
@@ -292,7 +295,14 @@ int GetChangedMouseButtonFlagsFromNative(
 
 PointerDetails GetMousePointerDetailsFromNative(
     const base::NativeEvent& native_event) {
-  return PointerDetails(EventPointerType::POINTER_TYPE_MOUSE);
+  LPARAM message = ::GetMessageExtraInfo();

[Navid Zolghadr, 2016/06/01 19:15:29]

Do we have any sort of unique id for each pen device? Can we set that as well in
PointerDetails?

[lanwei, 2016/06/01 22:54:31]

"The lower 8 bits returned from GetMessageExtraInfo are variable. Of those bits,
7 (the lower 7, masked by 0x7F) are used to represent the cursor ID, zero for
the mouse or a variable value for the pen ID."from Windows doc. I tested, for
both two pens from Wacom, the ID is the same. The pen ID from Surface is
different from Wacom. Do you think we should use this?

[Navid Zolghadr, 2016/06/02 14:29:37]

Although it is not complete and that does not diffrentiate the two Wacom pens I
think it is still better than setting ids to 0 all the time.

+  if ((message & SIGNATURE_MASK) != MOUSEEVENTF_FROMTOUCHPEN)
+    return PointerDetails(EventPointerType::POINTER_TYPE_MOUSE);
+
+  if ((message & MOUSEEVENTF_FROMTOUCH) == MOUSEEVENTF_FROMTOUCH)
+    return PointerDetails(EventPointerType::POINTER_TYPE_TOUCH);

[Navid Zolghadr, 2016/06/01 19:15:29]

Is this possible for this touch if to run? I mean do we filter these mouse
events caused by touch points anywhere?

[lanwei, 2016/06/01 22:54:31]

I am not sure if there are some cases the events are still dispatched.

[tdresser, 2016/06/02 13:40:40]

https://code.google.com/p/chromium/codesearch#chromium/src/ui/views/win/hwnd_...

[lanwei, 2016/06/02 16:07:06]

The mouseevent from touch will set a flag EF_FROM_TOUCH and it will be filtered
at RenderWidgetHostViewAura::OnMouseEvent. I think it is safe to remove touch
pointer type from mouseevent

https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/re...

+
+  return PointerDetails(EventPointerType::POINTER_TYPE_PEN);
 }
 
 gfx::Vector2d GetMouseWheelOffset(const base::NativeEvent& native_event) {