ts_read - Man Page

read tslib touch samples


#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);


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.


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))

                                printf("slot %d: X:%d Y: %d0,

See Also

ts_setup(3), ts_config(3), ts_open(3), ts_close(3), ts.conf(5)

Referenced By

ts_close(3), ts_config(3), ts_error_fn(3), ts_fd(3), ts_get_eventpath(3), ts_libversion(3), ts_open(3), ts_print_ascii_logo(3), ts_setup(3), ts_test_mt(1).

The man pages ts_read_mt(3), ts_read_raw(3) and ts_read_raw_mt(3) are aliases of ts_read(3).