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// Copyright (c) 2012 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_X_VALUATORS_H_
#define UI_BASE_X_VALUATORS_H_
#include <map>
#include "base/memory/singleton.h"
typedef union _XEvent XEvent;
namespace ui {
// A valuator is not reported in an XEvent if it hasn't changed from the
// previous event from the same device. As a result, it is necessary to track
// the last reported valuator values for a specific device.
// Right now, this is only used to keep track of valuators for events coming in
// from touch-devices, but it can be used for other devices as well.
class ValuatorTracker {
private:
ValuatorTracker();
~ValuatorTracker();
public:
// Define the valuators following the Multi-touch Protocol.
enum Valuator {
VAL_TOUCH_MAJOR = 0, // Length of the touch area.
VAL_TOUCH_MINOR, // Width of the touch area.
VAL_ORIENTATION, // Angle between the X-axis and the major axis of the
// touch area.
VAL_PRESSURE, // Pressure of the touch contact.
// NOTE: A touch event can have multiple touch points. So when we receive a
// touch event, we need to determine which point triggered the event.
// A touch point can have both a 'Slot ID' and a 'Tracking ID', and they can
// be (in fact, usually are) different. The 'Slot ID' ranges between 0 and
// (X - 1), where X is the maximum touch points supported by the device. The
// 'Tracking ID' can be any 16-bit value. With XInput 2.0, an XI_Motion
// event that comes from a currently-unused 'Slot ID' indicates the creation
// of a new touch point, and any event that comes with a 0 value for
// 'Tracking ID' marks the removal of a touch point. During the lifetime of
// a touchpoint, we use the 'Slot ID' as its identifier. The XI_ButtonPress
// and XI_ButtonRelease events are ignored.
#if !defined(USE_XI2_MT)
VAL_SLOT_ID, // ID of the finger that triggered a touch event
// (useful when tracking multiple simultaneous
// touches)
#endif
// NOTE for XInput MT: 'Tracking ID' is provided in every touch event to
// track individual touch. 'Tracking ID' is an unsigned 32-bit value and
// is increased for each new touch. It will wrap back to 0 when reaching
// the numerical limit.
VAL_TRACKING_ID, // ID of the touch point.
VAL_LAST_ENTRY
};
// Returns the ValuatorTracker singleton.
static ValuatorTracker* GetInstance();
// Extract the Valuator from the XEvent. Return true and the value is set
// if the Valuator is found, false and value unchanged if the Valuator
// is not found.
bool ExtractValuator(const XEvent& xev, Valuator val, float* value);
// Normalize the Valuator with value on deviceid to fall into [0, 1].
// *value = (*value - min_value_of_tp) / (max_value_of_tp - min_value_of_tp)
// Returns true and sets the normalized value in|value| if normalization is
// successful. Returns false and |value| is unchanged otherwise.
bool NormalizeValuator(unsigned int deviceid, Valuator val, float* value);
// Extract the range of the Valuator. Return true if the range is available
// and written into min & max, false if the range is not available.
bool GetValuatorRange(unsigned int deviceid,
Valuator val,
float* min,
float* max);
// Sets up the internal bookkeeping of the valuator information. It currently
// does this for touch devices only.
void SetupValuator();
private:
// Requirement for Singleton.
friend struct DefaultSingletonTraits<ValuatorTracker>;
static const int kMaxDeviceNum = 128;
// Index table to find the valuator for the Valuator on the specific device
// by valuator_lookup_[device_id][valuator]. Use 2-D array to get fast
// index at the expense of space. If the kMaxDeviceNum grows larger so that
// the space waste becomes a concern, the 2D lookup table can be replaced by a
// hash map.
signed char valuator_lookup_[kMaxDeviceNum][VAL_LAST_ENTRY];
// Index table to find the min & max value of the Valuator on a specific
// device.
int valuator_min_[kMaxDeviceNum][VAL_LAST_ENTRY];
int valuator_max_[kMaxDeviceNum][VAL_LAST_ENTRY];
// Table to keep track of the last seen value for the specified valuator for
// a device. Defaults to 0 if the valuator was not specified in an earlier
// event.
float last_seen_valuator_[kMaxDeviceNum][VAL_LAST_ENTRY];
DISALLOW_COPY_AND_ASSIGN(ValuatorTracker);
};
} // namespace ui
#endif // UI_BASE_X_VALUATORS_H_
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