jpg_view_lvgl.tc

jpg_view_lvgl.tc — show a JPEG FILE from the filesystem on the LVGL screen, rotatable + scalable.

Source on GitHub

// jpg_view_lvgl.tc — show a JPEG FILE from the filesystem on the LVGL screen, rotatable + scalable.
//
// LVGL has no JPEG decoder, BUT dspLoadImage HW-decodes a JPEG file into a PSRAM RGB565
// image slot, and lvglCanvasSetImgSlot puts that on an LVGL canvas (= an lv_image, so
// lvglImageScale/Angle size + rotate it). (PNG files instead go straight through
// lvglImageSrc, which has an LVGL PNG decoder.)  Needs ABI >= 14 + USE_TINYC_LVGL.
//
// NOTE: dspLoadImage's path is a compile-time constant. For a runtime/dynamic path,
// ask for dspLoadImageF (string-arg variant).

#define JPG_FILE  "/photo.jpg"
#define ZOOM      256            // lvglImageScale: 256 = 100%, 128 = 50%

int canvas;

int main() {
    lvglInit();
    lvglClean(0);
    lvglSetBgColor(0, 0x101418);

    int slot = dspLoadImage(JPG_FILE);       // read file + HW-decode JPEG -> PSRAM RGB565 slot
    if (slot < 0) { addLog("jpg_view: load %s FAILED (missing or not JPEG)", JPG_FILE); return -1; }

    canvas = lvglCanvas(0);                   // an lv_image subclass
    lvglCanvasSetImgSlot(canvas, slot);       // show the decoded JPEG through LVGL
    lvglImagePivot(canvas, 0, 0);
    lvglImageScale(canvas, ZOOM, ZOOM);       // size
    lvglImageAngle(canvas, 0);                // rotation (900 = 90.0°)
    lvglAlign(canvas, 2, 0, 80);              // top-mid

    addCommand("ROT");                         // "ROT 900" -> rotate 90°
    addLog("jpg_view: %s on screen", JPG_FILE);
    return 0;
}

void Command(char cmd[]) {
    int a = atoi(cmd);
    if (a >= 0 && a < 3600) { lvglImageAngle(canvas, a); }
    responseCmnd("ok");
}