Intermittent Image Display Success

How-to
1

What do you want to achieve?

I would like to reliably display a PNG image from a file. I can successfully display just an image from a file. However, when I add another widget (for example’s sake, a rectangle), the image is not reliably displayed. Sometimes (maybe 1 out of every 10-20 times), the image displays correctly.

I am a beginner and often overlook things that may be obvious to those with more experience. Thanks for reading my post and any help or assistance you can provide. I have been pulling my hair out for several days trying to solve this.

What have you tried so far?

  • Printing lv_image_decoder_get_info() output. Regardless of whether the image is successfully displayed or not I get Decoder result=1, header=10 x 10 (correct dimensions).
  • Printing lv_obj_get_width(img) and lv_obj_get_height(img), after calling lv_obj_update_layout(img). Again, the correct values are listed, even when the image fails to display.
  • When the rectangle widget is removed, the image displays reliably.

Code to reproduce

    fat_init();
    bsp_display_start();
    bsp_display_lock(-1);

    lv_obj_t * scr1 = lv_screen_active();

    lv_obj_t * rect = lv_obj_create(scr1);
    lv_obj_set_pos(rect, 150, 150);
    lv_obj_set_size(rect, 200, 100);
    lv_obj_set_style_bg_color(rect, lv_color_hex(0xF17135), LV_STATE_DEFAULT);
    

    lv_obj_t * img = lv_image_create(scr1);
    lv_image_set_src(img, "A:/copy.png");
    lv_obj_set_pos(img, 220, 220);
    lv_obj_set_size(img, 10, 10);

    lv_obj_move_foreground(img);
    lv_obj_invalidate(img);

    bsp_display_unlock();

Screenshot and/or video

Environment

  • MCU/MPU/Board: Waveshare ESP32-S3-Touch-AMOLED-1.75C
  • LVGL version: 9.6.0
  • Decoder: Lode PNG
2

Hi @ejm ,

Thank you for opening this topic.

Looking your code, it appears that you are forcing an invalidation, however, the lv_image_set_src function already handles this process internally.

I suggest to remove this invalidation, as it is likely affecting the expected performance. Also, there is no need to explicitly move the image to the top of the screen, since LVGL organizes objects based on the order in which they were created.