.\" Copyright (c) 2017, Martin Kepplinger <martink@posteo.de>
.\"
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.TH TS_READ 3  "" "" "tslib"
.SH NAME
ts_read, ts_read_raw, ts_read_mt, ts_read_raw_mt \- read tslib touch samples
.SH SYNOPSIS
.nf
.B #include <tslib.h>
.sp
.BI "int ts_read(struct tsdev *" dev ", struct ts_sample *" samp ", int " nr ");"
.sp
.BI "int ts_read_raw(struct tsdev *" dev ", struct ts_sample *" samp ", int " nr ");"
.sp
.BI "int ts_read_mt(struct tsdev *" dev ", struct ts_sample_mt **" samp ", int " slots ", int " nr ");"
.sp
.BI "int ts_read_raw_mt(struct tsdev *" dev ", struct ts_sample_mt **" samp ", int " slots ", int " nr ");"
.sp
.fi

.SH DESCRIPTION
.BR ts_read ()
reads
.BR nr
input samples with tslib's filters applied.
.BI "struct ts_sample"
is define as follows:
.nf
struct ts_sample {
        int             x;
        int             y;
        unsigned int    pressure;
        struct timeval  tv;
};
.fi
.PP

.BR ts_read_mt()
reads
.BR nr
*
.BR slots
input samples with tslib's filters applied.
.BI "struct ts_sample_mt"
is defined as follows:
.nf
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;
};
.fi
.PP
The user has to provide the amount of memory described in
.BR nr
and
.BR slots
to hold them.

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

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

.SH EXAMPLE
The following program continuously reads tslib multitouch input samples
and prints slot and position values to stdout as the touch screen is
touched.
.sp
.nf
#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 %d\n", i);
                        for (j = 0; i < MAX_SLOTS; j++) {
                                if (!(samp_mt[i][j].valid & TSLIB_MT_VALID))
                                        continue;

                                printf("slot %d: X:%d Y: %d\n",
                                       samp_mt[i][j].slot,
                                       samp_mt[i][j].x,
                                       samp_mt[i][j].y);
                        }
                }
        }
}
.fi
.SH SEE ALSO
.BR ts_setup (3),
.BR ts_config (3),
.BR ts_open (3),
.BR ts_close (3),
.BR ts.conf (5)