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fix(tjpgd): make it work with subsampled images

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This commit is contained in:
Gabor Kiss-Vamosi
2023-09-26 12:39:29 +02:00
parent 9c437d1073
commit 5fc558edb6
1 changed files with 4 additions and 42 deletions
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46
src/libs/tjpgd/lv_tjpgd.c
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@@ -3,44 +3,6 @@
*
*/
/*----------------------------------------------------------------------------------------------------------------------------------
/ Added normal JPG support [7/10/2020]
/ ----------
/ SJPEG is a custom created modified JPEG file format for small embedded platforms.
/ It will contain multiple JPEG fragments all embedded into a single file with a custom header.
/ This makes JPEG decoding easier using any JPEG library. Overall file size will be almost
/ similar to the parent jpeg file. We can generate sjpeg from any jpeg using a python script
/ provided along with this project.
/ (by vinodstanur | 2020 )
/ SJPEG FILE STRUCTURE
/ --------------------------------------------------------------------------------------------------------------------------------
/ Bytes | Value |
/ --------------------------------------------------------------------------------------------------------------------------------
/
/ 0 - 7 | "_SJPG__" followed by '\0'
/
/ 8 - 13 | "V1.00" followed by '\0' [VERSION OF SJPG FILE for future compatibiliby]
/
/ 14 - 15 | X_RESOLUTION (width) [little endian]
/
/ 16 - 17 | Y_RESOLUTION (height) [little endian]
/
/ 18 - 19 | TOTAL_FRAMES inside sjpeg [little endian]
/
/ 20 - 21 | JPEG BLOCK WIDTH (16 normally) [little endian]
/
/ 22 - [(TOTAL_FRAMES*2 )] | SIZE OF EACH JPEG SPLIT FRAGMENTS (FRAME_INFO_ARRAY)
/
/ SJPEG data | Each JPEG frame can be extracted from SJPEG data by parsing the FRAME_INFO_ARRAY one time.
/
/----------------------------------------------------------------------------------------------------------------------------------
/ JPEG DECODER
/ ------------
/ We are using TJpgDec - Tiny JPEG Decompressor library from ELM-CHAN for decoding each split-jpeg fragments.
/ The tjpgd.c and tjpgd.h is not modified and those are used as it is. So if any update comes for the tiny-jpeg,
/ just replace those files with updated files.
/---------------------------------------------------------------------------------------------------------------------------------*/
/*********************
* INCLUDES
*********************/
@@ -250,9 +212,9 @@ static lv_result_t decoder_get_area(lv_image_decoder_t * decoder, lv_image_decod
my = jd->msy * 8; /* Size of the MCU (pixel) */
if(decoded_area->y1 == LV_COORD_MIN) {
decoded_area->y1 = 0;
decoded_area->y2 = 7;
decoded_area->x1 = 0 - mx;
decoded_area->x2 = 7 - mx;
decoded_area->y2 = my - 1;
decoded_area->x1 = -mx;
decoded_area->x2 = -1;
jd->scale = 0;
jd->dcv[2] = jd->dcv[1] = jd->dcv[0] = 0; /* Initialize DC values */
dsc->img_data = jd->workbuf;
@@ -266,7 +228,7 @@ static lv_result_t decoder_get_area(lv_image_decoder_t * decoder, lv_image_decod
if(decoded_area->x1 >= jd->width) {
decoded_area->x1 = 0;
decoded_area->x2 = 7;
decoded_area->x2 = mx - 1;
decoded_area->y1 += my;
decoded_area->y2 += my;
}