Question about settings for monochrome display of LCD screens.

[nezumimrx]

Hi Daumemo,
So glad to find your post on "How to use LVGL library – Arduino on an ESP-32 and SPI LCD". It's really really helpful to my kind of beginners of LVGL lib.

I am currently working on a project that requires a monochrome display on a 240*320-pixel LCD screen to show color-depth 1 BMP format images. But I can't get my code to show images properly. Could you be so kind as to give some examples, please? I am desperate in need of some help.... Especially on those callback functions. I have no idea how to write void my_disp_flush() properly to display monochrome images.

I have did some changes to lv_conf.h.:
#define USE_LV_THEME_MONO 1 /Mono color theme for monochrome displays/
#define LV_USE_BMP 1
#define LV_COLOR_DEPTH 1
#define LV_COLOR_16_SWAP 0

and I read another post (https://maldus512.medium.com/porting-littlevgl-for-a-monochrome-display-6c7be58851ce). So I added some functions.
void my_set_px_cb(lv_disp_drv_t * disp_drv, uint8_t * buf, lv_coord_t buf_w, lv_coord_t x, lv_coord_t y, lv_color_t color, lv_opa_t opa)
void my_rounder_cb(lv_disp_drv_t * disp_drv, lv_area_t * area)

ln setup function, I wrote:
static lv_disp_drv_t disp_drv;
lv_disp_drv_init( &disp_drv );
disp_drv.hor_res = screenWidth;
disp_drv.ver_res = screenHeight;
disp_drv.flush_cb = my_disp_flush; /Callback/
disp_drv.set_px_cb = my_set_px_cb; /Callback/
disp_drv.rounder_cb = my_rounder_cb; /Callback/
disp_drv.draw_buf = &draw_buf;
lv_disp_t * disp;
disp = lv_disp_drv_register(&disp_drv);

but I think the real problem is the my_disp_flush callback function doesn't match with monochrome settings.
void my_disp_flush( lv_disp_drv_t *disp, const lv_area_t *area, lv_color_t *color_p )
{
uint32_t w = ( area->x2 - area->x1 + 1 );
uint32_t h = ( area->y2 - area->y1 + 1 );
tft.startWrite();
tft.setAddrWindow( area->x1, area->y1, w, h );
tft.pushColors( ( uint16_t * )&color_p->full, w * h, true );
tft.endWrite();
lv_disp_flush_ready( disp );
}

since this function display 16bit color.

What should I do to solve this problem?

[daumemo]

Hi, sorry for a one year late replay from me - somehow I have missed your question.
First of all - I myself am no professional in LVGL - I have learned everything by just try-and-test method. The monochrome display use case makes even more difficult to answer your question, as I personally don't have any experience with such type of displays.
One of ideas, that you have proposed yourself, could be checking my_disp_flush function. It uses tft.* method which might be more or less display specific functions. Especially tft.pushColors is used for displaying colored images and not bitmap images - which might need changing to another function altogether.