(转)浅析linux中鼠标数据读取

我们就是去读/dev/input/mice设备节点,源码如下：

#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/select.h>
#include <string.h>

/* Mouse button bits*/
#define WHEEL_UP 0x10
#define WHEEL_DOWN 0x08

#define BUTTON_L 0x04
#define BUTTON_M 0x02
#define BUTTON_R 0x01
#define SCALE 3 /* default scaling factor for acceleration */
#define THRESH 5 /* default threshhold for acceleration */

static int xpos; /* current x position of mouse */
static int ypos; /* current y position of mouse */
static int minx; /* minimum allowed x position */
static int maxx; /* maximum allowed x position */
static int miny; /* minimum allowed y position */
static int maxy; /* maximum allowed y position */
static int buttons; /* current state of buttons */
static int scale = SCALE; /* acceleration scale factor */
static int thresh = THRESH;/* acceleration threshhold */

static int mouse_update(int dx, int dy, int dz);
static int IMPS2_Read (int *dx, int *dy, int *dz, int *bp);
static void mouse_setposition (int newx, int newy);
static void mouse_setrange (int newminx, int newminy, int newmaxx, int newmaxy);

int mouse_fd;

int main(void)
{
int dx,dy,dz;
static unsigned char imps2_param [] = {243,200,243,100,243,80};//,242};
// 来自vnc4的xc/programs/Xserver/hw/xfree86/input/mouse/mouse.c==>PROT_IMPS2
const char *mdev="/dev/input/mice";

mouse_fd = open (mdev, O_RDWR); // | O_NONBLOCK);
if (mouse_fd < 0) {
printf("[luther.gliethttp]: RW error [please use root user]: %s/n", mdev);
mouse_fd = open (mdev, O_RDONLY); // | O_NONBLOCK);
if (mouse_fd < 0)
return -1;
} else {
write (mouse_fd, imps2_param, sizeof (imps2_param)); // 初始化序列, 这样可以读取4个字节数据
// 0x80用来表示滚轮向上还是向下滚动.de>

de> // 0xa0表示滚轮向上滚动的同时中键按下
de>

de> printf("[luther.gliethttp]: imps2_param ok!/n");
}

mouse_setrange(0, 0, 1024, 768);

for (;;) {
IMPS2_Read(&dx, &dy, &dz, &buttons);
mouse_update(dx, dy, dz);
mouse_setposition(xpos, ypos);
printf("[%04d,%04d,0x%04x]/n", xpos, ypos, buttons);
}

return 0;
}

static int IMPS2_Read (int *dx, int *dy, int *dz, int *bp)
{
static unsigned char buf[5];
static int buttons[7] = { 0, 1, 3, 0, 2, 0, 0}; // 1左键,2中键,3右键
static int nbytes;
int n;

while ((n = read (mouse_fd, &buf [nbytes], 4 - nbytes))) {
if (n < 0) {
if (errno == EINTR)
continue;
else
return -1;
}

nbytes += n;

if (nbytes == 4) {
int wheel;
// printf("[luther.gliethttp]: %02x %02x %02x %02x/n", buf[0], buf[1], buf[2], buf[3]);
if ((buf[0] & 0xc0) != 0) {
buf[0] = buf[1];
buf[1] = buf[2];
buf[2] = buf[3];
nbytes = 3;

return -1;
}

/* FORM XFree86 4.0.1 */
*bp = buttons[(buf[0] & 0x07)];
*dx = (buf[0] & 0x10) ? buf[1] - 256 : buf[1];
*dy = (buf[0] & 0x20) ? -(buf[2] - 256) : -buf[2];

/* Is a wheel event? */
if ((wheel = buf[3]) != 0) {
if(wheel > 0x7f) {
*bp |= WHEEL_UP;
}
else {
*bp |= WHEEL_DOWN;
}
}

*dz = 0;
nbytes = 0;
return 1;
}
}
return 0;
}

static int mouse_update(int dx, int dy, int dz)
{
int r;
int sign;

sign = 1;
if (dx < 0) {
sign = -1;
dx = -dx;
}
if (dx > thresh)
dx = thresh + (dx - thresh) * scale;
dx *= sign;
xpos += dx;
if( xpos < minx )
xpos = minx;
if( xpos > maxx )
xpos = maxx;

sign = 1;
if (dy < 0) {
sign = -1;
dy = -dy;
}
if (dy > thresh)
dy = thresh + (dy - thresh) * scale;
dy *= sign;
ypos += dy;
if ( ypos < miny )
ypos = miny;
if ( ypos > maxy )
ypos = maxy;

return 1;
}

static void mouse_setposition (int newx, int newy)
{
if (newx < minx)
newx = minx;
if (newx > maxx)
newx = maxx;
if (newy < miny)
newy = miny;
if (newy > maxy)
newy = maxy;
if (newx == xpos && newy == ypos)
return;
xpos = newx;
ypos = newy;
}

static void mouse_setrange (int newminx, int newminy, int newmaxx, int newmaxy)
{
minx = newminx;
miny = newminy;
maxx = newmaxx;
maxy = newmaxy;
mouse_setposition ((newminx + newmaxx) / 2, (newminy + newmaxy) / 2);
}

static int mouse_getbutton (void)
{
return buttons;
}

static void mouse_getxy (int* x, int* y)
{
*x = xpos;
*y = ypos;
}