touch_coords.tc

touch_coords.tc — live touch coordinates on the LVGL screen.

Source on GitHub

// touch_coords.tc — live touch coordinates on the LVGL screen.
//
// Needs firmware with USE_TINYC_LVGL + the touchGet() syscall (TinyC syscall ABI v3,
// SYS_TOUCH_GET 492). touchGet(sel) mirrors the firmware Touch_Status():
//   touchGet(0) -> 1 if pressed, else 0
//   touchGet(1) -> x   (0..width)
//   touchGet(2) -> y   (0..height)
//   touchGet(-1)/touchGet(-2) -> raw x/y (pre-calibration)
//
// Shows a big x=.. y=.. readout + PRESSED/released state, and moves a red dot to the
// touch point so you can see the coordinates track your finger live. Doubles as the
// GT9271 touch bring-up test on the P4 10.1" panel.

#define ALIGN_TOP_MID   2
#define ALIGN_CENTER    9

int main() {
    lvglInit();
    lvglSetBgColor(0, 0x101820);

    int title = lvglLabel(0);
    lvglSetText(title, "Touch coords - touchGet()");
    lvglSetTextColor(title, 0xFFFFFF);
    lvglAlign(title, ALIGN_TOP_MID, 0, 12);

    int coord = lvglLabel(0);
    lvglSetText(coord, "x=--- y=---");
    lvglSetTextColor(coord, 0x40c0ff);
    lvglAlign(coord, ALIGN_CENTER, 0, -30);

    int state = lvglLabel(0);
    lvglSetText(state, "released");
    lvglSetTextColor(state, 0xffd040);
    lvglAlign(state, ALIGN_CENTER, 0, 20);

    // red dot that follows the finger (a 28px box; top-left positioned, so offset by half)
    int dot = lvglObj(0);
    lvglSetSize(dot, 28, 28);
    lvglSetBgColor(dot, 0xff4040);

    char buf[48];
    int px = 0;
    while (1) {
        int p = touchGet(0);
        int x = touchGet(1);
        int y = touchGet(2);
        sprintf(buf, "x=%d  y=%d", x, y);
        lvglSetText(coord, buf);
        if (p) {
            lvglSetText(state, "PRESSED");
            lvglSetPos(dot, x - 14, y - 14);   // centre the 28px dot on the touch point
        } else if (px) {
            lvglSetText(state, "released");
        }
        px = p;
        delay(50);
    }
    return 0;
}