touchui: support XInput2 MT

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 58 matching lines @@
 
   for (int i = 0; i < 8 * xievent->buttons.mask_len; i++) {
     if (XIMaskIsSet(xievent->buttons.mask, i)) {
       buttonflags |= GetEventFlagsForButton(i);
     }
   }
 
   return buttonflags;
 }
 
+int GetTouchIDFromXEvent(XEvent* xev) {
+  float id = 0;
+  if (!TouchFactory::GetInstance()->ExtractTouchParam(
+          *xev, TouchFactory::TP_TRACKING_ID, &id))

[sadrul, 2011/09/06 14:35:21]

Are TRACKING_ID's recycled by XInput2.1? As far as I know, the drivers send out
TRACKING_ID's in increasing order, i.e. if a finger is pressed, then released,
and then another finger is pressed, then for the last event, it will send
TRACKING_ID 1 instead of 0. Is that not the case with XI2.1?

[ningxin.hu, 2011/09/07 08:49:58]

With XI2.1, TRACKING_ID is increased for each new touch. It is defined as
uint32. It warps to 0 if reaches the num limit.

for your example:
... (a bunch of touch events)
a finger is pressed: XI_TouchBegin with TRACKING_ID 1890
then released: XI_TouchEnd with TRACKING_ID 1890
then another finger is pressed: XI_TouchBegin with TRACKING_ID 1891
....

+    LOG(ERROR) << "Could not get the touch ID for the event. Using 0.";
+  return id;
+}
+
 ui::EventType GetTouchEventType(XEvent* xev) {
-  XGenericEventCookie* cookie = &xev->xcookie;
-  DCHECK_EQ(cookie->evtype, XI_Motion);
-
+  XIEvent* event = static_cast<XIEvent*>(xev->xcookie.data);
   // Note: We will not generate a _STATIONARY event here. It will be created,
   // when necessary, by a RWHVV.
   // TODO(sad): When should _CANCELLED be generated?
 
-  TouchFactory* factory = TouchFactory::GetInstance();
-  float slot;
-  if (!factory->ExtractTouchParam(*xev, TouchFactory::TP_SLOT_ID, &slot))
-    return ui::ET_UNKNOWN;
-
-  if (!factory->IsSlotUsed(slot)) {
-    // This is a new touch point.
-    return ui::ET_TOUCH_PRESSED;
+  switch(event->evtype) {
+    case XI_TouchBegin:
+      return ui::ET_TOUCH_PRESSED;
+    case XI_TouchUpdate:
+      return ui::ET_TOUCH_MOVED;
+    case XI_TouchEnd:
+      return ui::ET_TOUCH_RELEASED;
   }
 
-  float tracking;
-  if (!factory->ExtractTouchParam(*xev, TouchFactory::TP_TRACKING_ID,
-        &tracking))
-    return ui::ET_UNKNOWN;
-
-  if (tracking == 0l) {
-    // The touch point has been released.
-    return ui::ET_TOUCH_RELEASED;
-  }
-
-  return ui::ET_TOUCH_MOVED;
-}
-
-int GetTouchIDFromXEvent(XEvent* xev) {
-  float slot = 0;
-  if (!TouchFactory::GetInstance()->ExtractTouchParam(
-        *xev, TouchFactory::TP_SLOT_ID, &slot))
-    LOG(ERROR) << "Could not get the slot ID for the event. Using 0.";
-  return slot;
+  return ui::ET_UNKNOWN;
 }
 
 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 (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);
-    }
-  }
 }
 
 }  // namespace views