touchui: Convert XI2 MT tracking id to slot id for gesture recognizer

views/events/event_x.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/events/event.h"
 
 #include <gdk/gdk.h>
 #include <gdk/gdkx.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/Xlib.h>
@@ skipping 104 matching lines @@
   if (tracking == 0l) {
     // The touch point has been released.
     return ui::ET_TOUCH_RELEASED;
   }
 
   return ui::ET_TOUCH_MOVED;
 #endif  // defined(USE_XI2_MT)
 }
 
 int GetTouchIDFromXEvent(XEvent* xev) {
-  float id = 0;
+  float slot = 0;

[Daniel Kurtz, 2011/09/24 01:53:36]

id is a better name, since it is used for both touchID and slotID

[sadrul, 2011/09/24 03:06:31]

I think 'slot' is fine. Right now, 'slot id' is essentially the same as 'touch
id'. For _MT, the we compute the 'slot id' from the 'tracking id'. For non-MT,
we already have the 'slot id' from X. Ideally, we would always compute the
'touch id' from the 'tracking id'. Once the code around this settles (there are
refactoring happening in this space), I will try to consolidate this code to
determine the touch-id (this should allow us to get rid of one of the cros
patches we carry).

 #if defined(USE_XI2_MT)
-  // TODO(ningxin.hu@gmail.com): Make the id always start from 0 for a new
-  // touch-sequence when TRACKING_ID is used to extract the touch id.
-  TouchFactory::TouchParam tp = TouchFactory::TP_TRACKING_ID;
+  float tracking_id;
+  TouchFactory* factory = TouchFactory::GetInstance();

[Daniel Kurtz, 2011/09/24 01:53:36]

Pull "TouchFactory*" and "return slot" out of the #ifdef block, and for
consistency, make the if() logic consistent.

[ningxin.hu, 2011/09/25 16:35:39]

Thanks. I will follow up.

+  if (factory->ExtractTouchParam(
+        *xev, TouchFactory::TP_TRACKING_ID, &tracking_id))
+    slot = factory->GetSlotForTrackingID(tracking_id);
+  else
+    LOG(ERROR) << "Could not get the touch ID for the event. Using 0.";
+  return slot;
 #else
-  TouchFactory::TouchParam tp = TouchFactory::TP_SLOT_ID;
+  if (!TouchFactory::GetInstance()->ExtractTouchParam(
+         *xev, TouchFactory::TP_SLOT_ID, &slot))
+    LOG(ERROR) << "Could not get the touch ID for the event. Using 0.";

[Daniel Kurtz, 2011/09/24 01:53:36]

Could not get the slot ID ...

[sadrul, 2011/09/24 03:06:31]

Ditto.

[ningxin.hu, 2011/09/25 16:35:39]

Thanks. Will correct.

+  return slot;
 #endif
-  if (!TouchFactory::GetInstance()->ExtractTouchParam(
-          *xev, tp, &id))
-    LOG(ERROR) << "Could not get the touch ID for the event. Using 0.";
-  return id;
 }
 
 ui::EventType EventTypeFromNative(NativeEvent2 native_event) {
   switch (native_event->type) {
     case KeyPress:
       return ui::ET_KEY_PRESSED;
     case KeyRelease:
       return ui::ET_KEY_RELEASED;
     case ButtonPress:
       if (native_event->xbutton.button == 4 ||
@@ skipping 270 matching lines @@
       radius_x_(GetTouchParamFromXEvent(native_event_2,
                                         TouchFactory::TP_TOUCH_MAJOR,
                                         2.0) / 2.0),
       radius_y_(GetTouchParamFromXEvent(native_event_2,
                                         TouchFactory::TP_TOUCH_MINOR,
                                         2.0) / 2.0),
       rotation_angle_(GetTouchParamFromXEvent(native_event_2,
                                               TouchFactory::TP_ORIENTATION,
                                               0.0)),
       force_(GetTouchForceFromXEvent(native_event_2)) {
-#if !defined(USE_XI2_MT)
+#if defined(USE_XI2_MT)
+  if (type() == ui::ET_TOUCH_RELEASED) {
+    // NOTE: The slot is allocated by TouchFactory for each XI_TouchBegin
+    //       event, which carries a new tracking ID to identify a new touch
+    //       sequence.
+    TouchFactory* factory = TouchFactory::GetInstance();
+    float tracking_id;
+    if (factory->ExtractTouchParam(*native_event_2,
+                                   TouchFactory::TP_TRACKING_ID,
+                                   &tracking_id)) {
+      factory->ReleaseSlotForTrackingID(tracking_id);
+    }
+  }
+#else
   if (type() == ui::ET_TOUCH_PRESSED || type() == ui::ET_TOUCH_RELEASED) {
     TouchFactory* factory = TouchFactory::GetInstance();
     float slot;
     if (factory->ExtractTouchParam(*native_event_2,
                                    TouchFactory::TP_SLOT_ID, &slot)) {
       factory->SetSlotUsed(slot, type() == ui::ET_TOUCH_PRESSED);
     }
   }
 #endif
 }
 
 }  // namespace views