feat(decoder): do not even try cache if 'no_cache' is set (#5688)

Signed-off-by: Xu Xingliang <xuxingliang@xiaomi.com>

src/draw/lv_image_decoder.c

@@ -123,10 +123,13 @@ lv_result_t lv_image_decoder_open(lv_image_decoder_dsc_t * dsc, const void * src
 
 #if LV_CACHE_DEF_SIZE > 0
     dsc->cache = img_cache_p;
-    /*
-     * Check the cache first
-     * If the image is found in the cache, just return it.*/
-    if(try_cache(dsc) == LV_RESULT_OK) return LV_RESULT_OK;
+    /*Try cache first, unless we are told to ignore cache.*/
+    if(!(args && args->no_cache)) {
+        /*
+        * Check the cache first
+        * If the image is found in the cache, just return it.*/
+        if(try_cache(dsc) == LV_RESULT_OK) return LV_RESULT_OK;
+    }
 #endif
 
     /*Find the decoder that can open the image source, and get the header info in the same time.*/

src/draw/lv_image_decoder.h

@@ -61,7 +61,7 @@ typedef struct _lv_image_decoder_dsc_t lv_image_decoder_dsc_t;
 typedef struct _lv_image_decoder_args_t {
     bool stride_align;      /*Whether stride should be aligned*/
     bool premultiply;       /*Whether image should be premultiplied or not after decoding*/
-    bool no_cache;          /*Whether this image should be kept out of cache*/
+    bool no_cache;          /*When set, decoded image won't be put to cache, and decoder open will also ignore cache.*/
     bool use_indexed;       /*Decoded indexed image as is. Convert to ARGB8888 if false.*/
 } lv_image_decoder_args_t;