ts_read_raw_mt - read tslib touch samples

NAME SYNOPSIS DESCRIPTION RETURN VALUE EXAMPLE SEE ALSO

NAME

ts_read, ts_read_raw, ts_read_mt, ts_read_raw_mt − read tslib touch samples

SYNOPSIS

#include <tslib.h>

int ts_read(struct tsdev *dev, struct ts_sample *samp, int nr);

int ts_read_raw(struct tsdev *dev, struct ts_sample *samp, int nr);

int ts_read_mt(struct tsdev *dev, struct ts_sample_mt **samp, int slots, int nr);

int ts_read_raw_mt(struct tsdev *dev, struct ts_sample_mt **samp, int slots, int nr);

DESCRIPTION

ts_read() reads nr input samples with tslib’s filters applied. struct ts_sample is define as follows:
struct ts_sample {
int x;
int y;
unsigned int pressure;
struct timeval tv;
};

ts_read_mt() reads nr * slots input samples with tslib’s filters applied. struct ts_sample_mt is defined as follows:
struct ts_sample_mt {
/* most recent ABS_MT_* event codes.
* see linux/input.h for descriptions */
int x;
int y;
unsigned int pressure;
int slot;
int tracking_id;

int tool_type;
int tool_x;
int tool_y;
unsigned int touch_major;
unsigned int width_major;
unsigned int touch_minor;
unsigned int width_minor;
int orientation;
int distance;
int blob_id;

struct timeval tv;

/* BTN_TOUCH state */
short pen_down;

/* the TSLIB_MT_VALID bit is set in valid if this sample
* contains new data;

* valid is set to 0 otherwise */

short valid;
};

The user has to provide the amount of memory described in nr and slots to hold them.

ts_read_raw() and ts_read_raw_mt() do the same thing without tslib’s filters applied.

RETURN VALUE

The number of actually read samples is returned. Especially when opened in non-blocking mode, see ts_setup() , that can be less than requested in the call. On failure, a negative error number is returned.

EXAMPLE

The following program continuously reads tslib multitouch input samples and prints slot and position values to stdout as the touch screen is touched.

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>

#include <tslib.h>

#define READ_SAMPLES 1
#define MAX_SLOTS 5

int main(int argc, char **argv)
{
struct tsdev *ts;
struct ts_sample_mt **samp_mt = NULL;
int i, j;
int ret;

ts = ts_setup(NULL, 0);
if (!ts)
return −1;

samp_mt = malloc(READ_SAMPLES * sizeof(struct ts_sample_mt **));
if (!samp_mt)
return −1;

for (i = 0; i < READ_SAMPLES; i++) {
samp_mt[i] = calloc(MAX_SLOTS, sizeof(struct ts_sample_mt));
if (!samp_mt[i])
return −1;
}

while(1) {
ret = ts_read_mt(ts, samp_mt, MAX_SLOTS, READ_SAMPLES);
for (i = 0; i < ret; i++) {
printf("sample nr %d0, i);
for (j = 0; i < MAX_SLOTS; j++) {
if (!(samp_mt[i][j].valid & TSLIB_MT_VALID))
continue;

printf("slot %d: X:%d Y: %d0,
samp_mt[i][j].slot,
samp_mt[i][j].x,
samp_mt[i][j].y);
}
}
}
}