fix(lodepng): fix LodePNG 8 bit palette image to RGBA data conversion bug (#5108)

src/libs/lodepng/lodepng.c

@@ -5326,7 +5326,7 @@ unsigned lodepng_decode(unsigned char ** out, unsigned * w, unsigned * h,
                         LodePNGState * state,
                         const unsigned char * in, size_t insize)
 {
-    *out = 0;
+    *out = NULL;
     decodeGeneric(out, w, h, state, in, insize);
     if(state->error) return state->error;
     if(!state->decoder.color_convert || lodepng_color_mode_equal(&state->info_raw, &state->info_png.color)) {
@@ -5339,8 +5339,7 @@ unsigned lodepng_decode(unsigned char ** out, unsigned * w, unsigned * h,
         }
     }
     else {   /*color conversion needed*/
-        unsigned char * data = *out;
-        size_t outsize;
+        lv_draw_buf_t * old_buf = (lv_draw_buf_t *)*out;
 
         /*TODO: check if this works according to the statement in the documentation: "The converter can convert
         from grayscale input color type, to 8-bit grayscale or grayscale with alpha"*/
@@ -5349,14 +5348,22 @@ unsigned lodepng_decode(unsigned char ** out, unsigned * w, unsigned * h,
             return 56; /*unsupported color mode conversion*/
         }
 
-        outsize = lodepng_get_raw_size(*w, *h, &state->info_raw);
-        *out = (unsigned char *)lodepng_malloc(outsize);
-        if(!(*out)) {
+        lv_draw_buf_t * new_buf = lv_draw_buf_create(*w, *h, LV_COLOR_FORMAT_ARGB8888, 4 * *w);
+        if(new_buf == NULL) {
             state->error = 83; /*alloc fail*/
         }
-        else state->error = lodepng_convert(*out, data, &state->info_raw,
-                                                &state->info_png.color, *w, *h);
-        lodepng_free(data);
+        else {
+            state->error = lodepng_convert(new_buf->data, old_buf->data, 
+                                            &state->info_raw, &state->info_png.color, *w, *h);
+            
+            if (state->error) {
+                lv_draw_buf_destroy(new_buf);
+                new_buf = NULL;
+            }
+        }
+
+        *out = (unsigned char*)new_buf;
+        lv_draw_buf_destroy(old_buf);
     }
     return state->error;
 }

src/libs/lodepng/lv_lodepng.c

@@ -182,6 +182,14 @@ static lv_result_t decoder_open(lv_image_decoder_t * decoder, lv_image_decoder_d
     }
 
     lv_draw_buf_t * decoded = decode_png_data(png_data, png_data_size);
+    if(!decoded) {
+        LV_LOG_WARN("Error decoding PNG\n");
+        if(png_data != NULL) {
+            lv_free((void *)png_data);
+        }
+        return LV_RESULT_INVALID;
+    }
+
     /*Stride check and adjustment accordingly*/
     if(args && args->stride_align) {
         uint32_t expected = lv_draw_buf_width_to_stride(decoded->header.w, decoded->header.cf);
@@ -248,7 +256,7 @@ static lv_draw_buf_t * decode_png_data(const void * png_data, size_t png_data_si
     /*Decode the image in ARGB8888 */
     unsigned error = lodepng_decode32((unsigned char **)&decoded, &png_width, &png_height, png_data, png_data_size);
     if(error) {
-        if(img_data != NULL)  lv_draw_buf_destroy(decoded);
+        if(img_data != NULL) lv_draw_buf_destroy(decoded);
         return NULL;
     }
 

tests/src/test_cases/libs/test_lodepng.c

@@ -21,6 +21,7 @@ static void create_images(void)
     lv_obj_t * img;
     lv_obj_t * label;
 
+    /* PNG array */
     LV_IMG_DECLARE(test_img_lvgl_logo_png);
     img = lv_image_create(lv_screen_active());
     lv_image_set_src(img, &test_img_lvgl_logo_png);
@@ -30,13 +31,23 @@ static void create_images(void)
     lv_label_set_text(label, "Array");
     lv_obj_align(label, LV_ALIGN_CENTER, -100, 20);
 
+    /* 32 bit PNG file */
     img = lv_image_create(lv_screen_active());
     lv_image_set_src(img, "A:src/test_assets/test_img_lvgl_logo.png");
-    lv_obj_align(img, LV_ALIGN_CENTER, 100, -20);
+    lv_obj_align(img, LV_ALIGN_CENTER, 100, -100);
 
     label = lv_label_create(lv_screen_active());
-    lv_label_set_text(label, "File");
-    lv_obj_align(label, LV_ALIGN_CENTER, 100, 20);
+    lv_label_set_text(label, "File (32 bit)");
+    lv_obj_align(label, LV_ALIGN_CENTER, 100, -60);
+
+    /* 8 bit palette PNG file */
+    img = lv_image_create(lv_screen_active());
+    lv_image_set_src(img, "A:src/test_assets/test_img_lvgl_logo_8bit_palette.png");
+    lv_obj_align(img, LV_ALIGN_CENTER, 100, 60);
+
+    label = lv_label_create(lv_screen_active());
+    lv_label_set_text(label, "File (8 bit palette)");
+    lv_obj_align(label, LV_ALIGN_CENTER, 100, 100);
 }
 
 void test_lodepng_1(void)