点到格子里基本都是校准失败，乱点的话，很容易成功
以下是部分用ts_calibrate显示的一些数据
xres = 640, yres = 480
Top left : X = 2762 Y = 3889
Top right : X = 3134 Y = 3740
Bot right : X = 3820 Y = 2803
Bot left : X = 3676 Y = 3195
Center : X = 3291 Y = 3361
701.625000 0.043800 -0.154915
145.812500 0.230583 -0.198380
x,y, delta x, delta y: 220, 11, 170, -170
x,y, delta x, delta y: 259, 126, 331, 76
Calibration failed.
Took 5 samples...
Top left : X = 2932 Y = 3646
Took 4 samples...
Top right : X = 2944 Y = 3660
Took 3 samples...
Bot right : X = 3139 Y = 3521
Took 2 samples...
Bot left : X = 3494 Y = 3125
Took 2 samples...
Center : X = 3435 Y = 3174
-43333.000000 6.333252 6.870483
-29823.500000 4.767822 4.356201
x,y, delta x, delta y: 10850, 38, 10800, -10800
x,y, delta x, delta y: 11023, 156, 10433, 106
Calibration failed.
