fix add MP support for LVGL 3rd party libraries (#2666)

* Fixes for MP support for LVGL 3rd party libraries

Add missing lv_qrcode_class

Remove 'struct JDEC' from public API. This struct is needed intenally on tjpgd.c and lv_sjpg.c, but doesn't need to be exposed in the public API. When exposed, it increases Micropython binding program size and some fields are not supported today (uint8_t* huffbits[2][2]). To overcome this, moved it to a new H file which is not included in public API, only in sjpg C files

Related: https://github.com/lvgl/lv_binding_micropython/issues/180

* lv_qrcode: add lv_class_qrcode

Must define a distinct class for every widget, to allow Micropython bindings convert lv_obj_t into the specific class

* gifdec.c: fix uninitialized

ESP32 reports some potentially uninitialized variables. Initialize them to prevent the errors

* src/extra/libs/sjpg: smaller public header

Only keep lv_split_jpeg_init in public header, since JPEG is used with image decoder

* Remove tjdec.h

src/extra/libs/gif/gifdec.c

@@ -378,12 +378,12 @@ static int
 read_image_data(gd_GIF *gif, int interlace)
 {
     uint8_t sub_len, shift, byte;
-    int init_key_size, key_size, table_is_full;
-    int frm_off, frm_size, str_len, i, p, x, y;
+    int init_key_size, key_size, table_is_full=0;
+    int frm_off, frm_size, str_len=0, i, p, x, y;
     uint16_t key, clear, stop;
     int ret;
     Table *table;
-    Entry entry;
+    Entry entry = {0};
     size_t start, end;
 
     f_gif_read(gif, &byte, 1);

src/extra/libs/qrcode/lv_qrcode.c

@@ -28,6 +28,10 @@
  *  STATIC VARIABLES
  **********************/
 
+const lv_obj_class_t lv_qrcode_class = {
+    .base_class = &lv_canvas_class
+};
+
 /**********************
  *      MACROS
  **********************/

src/extra/libs/qrcode/lv_qrcode.h

@@ -20,6 +20,8 @@ extern "C" {
  *      DEFINES
  *********************/
 
+extern const lv_obj_class_t lv_qrcode_class;
+
 /**********************
  *      TYPEDEFS
  **********************/

src/extra/libs/sjpg/lv_sjpg.c

@@ -50,6 +50,7 @@
 
 #include "tjpgd.h"
 #include "lv_sjpg.h"
+#include "../../../misc/lv_fs.h"
 
 
 /*********************
@@ -69,6 +70,39 @@
  *      TYPEDEFS
  **********************/
 
+enum io_source_type {
+    SJPEG_IO_SOURCE_C_ARRAY,
+    SJPEG_IO_SOURCE_DISK,
+};
+
+typedef struct {
+    enum io_source_type type;
+    lv_fs_file_t lv_file;
+    uint8_t* img_cache_buff;
+    int img_cache_x_res;
+    int img_cache_y_res;
+    uint8_t *raw_sjpg_data;               //Used when type==SJPEG_IO_SOURCE_C_ARRAY.
+    uint32_t raw_sjpg_data_size;          //Num bytes pointed to by raw_sjpg_data.
+    uint32_t raw_sjpg_data_next_read_pos; //Used for all types.
+} io_source_t;
+
+
+typedef struct {
+    uint8_t *sjpeg_data;
+    uint32_t sjpeg_data_size;
+    int sjpeg_x_res;
+    int sjpeg_y_res;
+    int sjpeg_total_frames;
+    int sjpeg_single_frame_height;
+    int sjpeg_cache_frame_index;
+    uint8_t **frame_base_array;         //to save base address of each split frames upto sjpeg_total_frames.
+    int *frame_base_offset;             //to save base offset for fseek
+    uint8_t *frame_cache;
+    uint8_t* workb;                     //JPG work buffer for jpeg library
+    JDEC *tjpeg_jd;
+    io_source_t io;
+} SJPEG;
+
 /**********************
  *  STATIC PROTOTYPES
  **********************/

src/extra/libs/sjpg/lv_sjpg.h

@@ -15,52 +15,16 @@ extern "C" {
  *********************/
 
 #include <stdio.h>
-#include "tjpgd.h"
 
-#include "../../../misc/lv_fs.h"
 #if LV_USE_SJPG
 
 /*********************
  *      DEFINES
  *********************/
 
-
 /**********************
  *      TYPEDEFS
  **********************/
-enum io_source_type {
-    SJPEG_IO_SOURCE_C_ARRAY,
-    SJPEG_IO_SOURCE_DISK,
-};
-
-typedef struct {
-    enum io_source_type type;
-    lv_fs_file_t lv_file;
-    uint8_t* img_cache_buff;
-    int img_cache_x_res;
-    int img_cache_y_res;
-    uint8_t *raw_sjpg_data;               //Used when type==SJPEG_IO_SOURCE_C_ARRAY.
-    uint32_t raw_sjpg_data_size;          //Num bytes pointed to by raw_sjpg_data.
-    uint32_t raw_sjpg_data_next_read_pos; //Used for all types.
-} io_source_t;
-
-
-typedef struct {
-    uint8_t *sjpeg_data;
-    uint32_t sjpeg_data_size;
-    int sjpeg_x_res;
-    int sjpeg_y_res;
-    int sjpeg_total_frames;
-    int sjpeg_single_frame_height;
-    int sjpeg_cache_frame_index;
-    uint8_t **frame_base_array;         //to save base address of each split frames upto sjpeg_total_frames.
-    int *frame_base_offset;             //to save base offset for fseek
-    uint8_t *frame_cache;
-    uint8_t* workb;                     //JPG work buffer for jpeg library
-    JDEC *tjpeg_jd;
-    io_source_t io;
-} SJPEG;
-
 
 /**********************
  * GLOBAL PROTOTYPES