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/***************************************************************************
pointerlatencyometer.h - measuring pointer latency
-------------------
begin : Wed Jun 30 12:04:44 CET 2002
copyright : (C) 2002-2003 by Tim Jansen
email : [email protected]
***************************************************************************/
/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#include <qdatetime.h>
#include <kdebug.h>
struct PointerState {
int x, y;
QTime timestamp;
};
class PointerLatencyOMeter {
private:
enum { stateCapacity = 30, maximumLatency = 1000 };
PointerState states[stateCapacity];
int firstState, stateNum;
float last3Latency, last20Latency;
public:
PointerLatencyOMeter() :
firstState(0),
stateNum(0),
last3Latency(125),
last20Latency(25) {
}
// registers a client pointer state
void registerPointerState(int x, int y) {
if (stateNum == stateCapacity)
stateNum--;
if (firstState == 0)
firstState = stateCapacity-1;
else
firstState--;
states[firstState].x = x;
states[firstState].y = y;
states[firstState].timestamp.start();
stateNum++;
}
/* Returns true if pointer should be visible */
bool registerLatency(int msecs) {
last3Latency = ((last3Latency * 2.0) + msecs) / 3.0;
last20Latency = ((last20Latency * 19.0) + msecs) / 20.0;
if (msecs >= maximumLatency)
return true;
if (last3Latency > (1000/4))
return true;
return last20Latency > (1000/12);
}
// Called with server-side coordinates.
// Returns true if pointer should be visible
bool handlePointerEvent(int x, int y) {
for (int i = stateNum-1; i >= 0; i--) {
int idx = (i+firstState) % stateCapacity;
if ((states[idx].x != x) ||
(states[idx].y != y))
continue;
stateNum = i;
int l = states[idx].timestamp.elapsed();
return registerLatency((l > maximumLatency) ? maximumLatency : l);
}
return true;
}
};
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