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

ui/base/touch/touch_factory.h

 // 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.
 
 #ifndef UI_BASE_TOUCH_TOUCH_FACTORY_H_
 #define UI_BASE_TOUCH_TOUCH_FACTORY_H_
 #pragma once
 
 #include <bitset>
 #include <vector>
 
 #include "base/memory/singleton.h"
+#include "base/hash_tables.h"
 #include "base/timer.h"
 #include "ui/base/ui_export.h"
 
 typedef unsigned long Cursor;
 typedef unsigned long Window;
 typedef struct _XDisplay Display;
 typedef union _XEvent XEvent;
 
 namespace ui {
 
@@ skipping 47 matching lines @@
   void SetupXI2ForXWindow(::Window xid);
 
   // Keeps a list of touch devices so that it is possible to determine if a
   // pointer event is a touch-event or a mouse-event. The list is reset each
   // time this is called.
   void SetTouchDeviceList(const std::vector<unsigned int>& devices);
 
   // Is the device a touch-device?
   bool IsTouchDevice(unsigned int deviceid) const;
 
-#if !defined(USE_XI2_MT)
+#if defined(USE_XI2_MT)
+  // Tries to find an existing slot ID mapping to tracking ID. If there
+  // isn't one already, allocates a new slot ID and sets up the mapping.
+  int GetSlotForTrackingID(uint32 tracking_id);
+
+  // Releases the slot ID mapping to tracking ID.
+  void ReleaseSlotForTrackingID(uint32 tracking_id);
+#endif
+
   // Is the slot ID currently used?
   bool IsSlotUsed(int slot) const;
 
   // Marks a slot as being used/unused.
   void SetSlotUsed(int slot, bool used);
-#endif
 
   // Grabs the touch devices for the specified window on the specified display.
   // Returns if grab was successful for all touch devices.
   bool GrabTouchDevices(Display* display, ::Window window);
 
   // Ungrabs the touch devices. Returns if ungrab was successful for all touch
   // devices.
   bool UngrabTouchDevices(Display* display);
 
   // Updates the root window to show (or hide) the cursor. Also indicate whether
@@ skipping 86 matching lines @@
   // index at the expense of space. If the kMaxDeviceNum grows larger that the
   // space waste becomes a concern, the 2D lookup table can be replaced by a
   // hash map.
   signed char valuator_lookup_[kMaxDeviceNum][TP_LAST_ENTRY];
 
   // Index table to find the min & max value of the TouchParam on a specific
   // device.
   int touch_param_min_[kMaxDeviceNum][TP_LAST_ENTRY];
   int touch_param_max_[kMaxDeviceNum][TP_LAST_ENTRY];
 
-#if !defined(USE_XI2_MT)
   // Maximum simultaneous touch points.
   static const int kMaxTouchPoints = 32;
 
+#if defined(USE_XI2_MT)
+  // Stores the minimum available slot ID which helps get slot ID from
+  // tracking ID. When it equals to kMaxTouchPoints, there is no available
+  // slot.
+  int min_available_slot_;
+#endif
+
   // A lookup table for slots in use for a touch event.
   std::bitset<kMaxTouchPoints> slots_used_;
+
+#if defined(USE_XI2_MT)
+  // A hash table to map tracking ID to slot.
+  typedef base::hash_map<uint32, int> TrackingIdMap;
+  TrackingIdMap tracking_id_map_;
 #endif
-
   DISALLOW_COPY_AND_ASSIGN(TouchFactory);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_TOUCH_TOUCH_FACTORY_H_