feat(draw_buf): add draw_buf init API (#5132)

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

src/draw/lv_draw_buf.c

@@ -135,6 +135,27 @@ void lv_draw_buf_copy(void * dest_buf, uint32_t dest_w, uint32_t dest_h, const l
     }
 }
 
+lv_result_t lv_draw_buf_init(lv_draw_buf_t * draw_buf, uint32_t w, uint32_t h, lv_color_format_t cf, uint32_t stride,
+                             void * data, uint32_t data_size)
+{
+    LV_ASSERT_NULL(draw_buf);
+    if(draw_buf == NULL) return LV_RESULT_INVALID;
+
+    lv_memzero(draw_buf, sizeof(lv_draw_buf_t));
+    if(stride == 0) stride = lv_draw_buf_width_to_stride(w, cf);
+    if(stride * h > data_size) {
+        LV_LOG_WARN("Data size too small, required: %" LV_PRId32 ", provided: %" LV_PRId32, stride * h,
+                    data_size);
+        return LV_RESULT_INVALID;
+    }
+
+    lv_image_header_init(&draw_buf->header, w, h, cf, stride, 0);
+    draw_buf->data = lv_draw_buf_align(data, cf);
+    draw_buf->unaligned_data = data;
+    draw_buf->data_size = data_size;
+    return LV_RESULT_OK;
+}
+
 lv_draw_buf_t * lv_draw_buf_create(uint32_t w, uint32_t h, lv_color_format_t cf, uint32_t stride)
 {
     lv_draw_buf_t * draw_buf = lv_malloc_zeroed(sizeof(lv_draw_buf_t));

src/draw/lv_draw_buf.h

@@ -174,13 +174,27 @@ void lv_draw_buf_copy(void * dest_buf, uint32_t dest_w, uint32_t dest_h, const l
  * that meets specified requirements.
  *
  * @param w         the buffer width in pixels
- * @param h
+ * @param h         the buffer height in pixels
  * @param cf        the color format for image
  * @param stride    the stride in bytes for image. Use 0 for automatic calculation based on
  *                  w, cf, and global stride alignment configuration.
  */
 lv_draw_buf_t * lv_draw_buf_create(uint32_t w, uint32_t h, lv_color_format_t cf, uint32_t stride);
 
+/**
+ * Initialize a draw buf with the given buffer and parameters.
+ * @param draw_buf  the draw buf to initialize
+ * @param w         the buffer width in pixels
+ * @param h         the buffer height in pixels
+ * @param cf        the color format
+ * @param stride    the stride in bytes. Use 0 for automatic calculation
+ * @param data      the buffer used for drawing. Unaligned `data` will be aligned internally
+ * @param data_size the size of the buffer in bytes
+ * @return          return LV_RESULT_OK on success, LV_RESULT_INVALID otherwise
+ */
+lv_result_t lv_draw_buf_init(lv_draw_buf_t * draw_buf, uint32_t w, uint32_t h, lv_color_format_t cf, uint32_t stride,
+                             void * data, uint32_t data_size);
+
 /**
  * Duplicate a draw buf with same image size, stride and color format. Copy the image data too.
  * @param draw_buf  the draw buf to duplicate

src/draw/vg_lite/lv_vg_lite_decoder.c

@@ -219,10 +219,8 @@ static lv_result_t decoder_open_variable(lv_image_decoder_t * decoder, lv_image_
 
         lv_draw_buf_t * draw_buf = lv_malloc_zeroed(sizeof(lv_draw_buf_t));
         LV_ASSERT_MALLOC(draw_buf);
-        lv_image_header_init(&draw_buf->header, width, height, cf, stride, LV_VG_LITE_IMAGE_NO_CACHE);
+        lv_draw_buf_init(draw_buf, width, height, cf, stride, (void *)image_data, LV_VG_LITE_IMAGE_NO_CACHE);
         dsc->decoded = draw_buf;
-        draw_buf->data = (void *)image_data;
-        draw_buf->unaligned_data = (void *)image_data;
         return LV_RESULT_OK;
     }
 

src/widgets/canvas/lv_canvas.c

@@ -70,11 +70,7 @@ void lv_canvas_set_buffer(lv_obj_t * obj, void * buf, int32_t w, int32_t h, lv_c
 
     lv_canvas_t * canvas = (lv_canvas_t *)obj;
     uint32_t stride = lv_draw_buf_width_to_stride(w, cf);
-    lv_memzero(&canvas->static_buf, sizeof(canvas->static_buf));
+    lv_draw_buf_init(&canvas->static_buf, w, h, cf, stride, buf, stride * h);
-    lv_image_header_init(&canvas->static_buf.header, w, h, cf, stride, 0);
-    canvas->static_buf.data_size = stride * h;
-    canvas->static_buf.data = lv_draw_buf_align(buf, cf);
-    canvas->static_buf.unaligned_data = buf;
     canvas->draw_buf = &canvas->static_buf;
 
     const void * src = lv_image_get_src(obj);