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LVGL screenshot in BMP format

This commit is contained in:
Stephan Hadinger 2021-12-03 20:12:46 +01:00
parent 488c84e61b
commit d6760962cd
1 changed files with 43 additions and 1 deletions
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44
tasmota/xdrv_52_3_berry_lvgl.ino
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@ -956,11 +956,53 @@ extern "C" {
if (!glue) { be_return_nil(vm); }
char fname[32];
snprintf(fname, sizeof(fname), "/screenshot-%d.raw", Rtc.utc_time);
snprintf(fname, sizeof(fname), "/screenshot-%d.bmp", Rtc.utc_time);
File f = dfsp->open(fname, "w");
if (f) {
glue->setScreenshotFile(&f);
uint32_t bmp_width = lv_disp_get_hor_res(nullptr);
uint32_t bmp_height = lv_disp_get_ver_res(nullptr);
// write BMP header
static const uint8_t bmp_sign[] = { 0x42, 0x4d }; // BM = Windows
f.write(bmp_sign, sizeof(bmp_sign));
size_t bmp_size = bmp_width * bmp_height * LV_COLOR_DEPTH / 8 + 0x44;
f.write((uint8_t*)&bmp_size, sizeof(bmp_size));
uint32_t zero = 0;
f.write((uint8_t*) &zero, sizeof(zero)); // reserved 4-bytes
uint32_t bmp_offset_to_pixels = 0x44; // TODO
f.write((uint8_t*) &bmp_offset_to_pixels, sizeof(bmp_offset_to_pixels));
// DIB Header BITMAPINFOHEADER
size_t bmp_dib_header_size = 52; // BITMAPV2INFOHEADER
f.write((uint8_t*) &bmp_dib_header_size, sizeof(bmp_dib_header_size));
f.write((uint8_t*) &bmp_width, sizeof(bmp_width));
f.write((uint8_t*) &bmp_height, sizeof(bmp_height));
// rest of header
// BITMAPV2INFOHEADER = 52 bytes header, 40 bytes sub-header
static const uint8_t bmp_dib_header[] = {
0x01, 0x00, // planes
16, 0x00, // bits per pixel = 16
0x03, 0x00, 0x00, 0x00, // compression = BI_BITFIELDS uncrompressed
0x00, 0x00, 0x00, 0x00, // Image size, 0 is valid for BI_RGB (uncompressed) TODO
0x00, 0x00, 0x00, 0x00, // X pixels per meter
0x00, 0x00, 0x00, 0x00, // Y pixels per meter
0x00, 0x00, 0x00, 0x00, // Colors in table
0x00, 0x00, 0x00, 0x00, // Important color count
// RGB masks
0x00, 0xF8, 0x00, 0x00, // Red channel mask
0xE0, 0x07, 0x00, 0x00, // Green channel mask
0x1F, 0x00, 0x00, 0x00, // Blue channel mask
0x00, 0x00, // Padding to align on 4 bytes boundary
};
f.write(bmp_dib_header, sizeof(bmp_dib_header));
// now we can write the pixels array
// redraw screen
lv_obj_invalidate(lv_scr_act());
lv_refr_now(lv_disp_get_default());