feat(draw): add draw_ctx->buffer_copy

realted to: #3087

src/draw/lv_draw.c

@@ -39,12 +39,7 @@
 
 void lv_draw_init(void)
 {
-    //    backend_head = NULL;
-    //    lv_draw_sw_init();
-    //
-    //#if LV_USE_GPU_STM32_DMA2D == 0
-    //    lv_gpu_stm32_dma2d_init();
-    //#endif
+    /*Nothing to init now*/
 }
 
 /**********************

src/draw/lv_draw.h

@@ -88,8 +88,25 @@ typedef struct _lv_draw_ctx_t  {
     /**
      * Wait until all background operations are finished. (E.g. GPU operations)
      */
-    void (*wait_for_finish)(struct _lv_draw_ctx_t * draw);
+    void (*wait_for_finish)(struct _lv_draw_ctx_t * draw_ctx);
 
+    /**
+     * Copy an area from buffer to an other
+     * @param draw_ctx      pointer to a draw context
+     * @param dest_buf      copy the buffer into this buffer
+     * @param dest_stride   the width of the dest_buf in pixels
+     * @param dest_area     the destination area
+     * @param src_buf       copy from this buffer
+     * @param src_stride    the width of src_buf in pixels
+     * @param src_area      the source area.
+     *
+     * @note dest_area and src_area must have the same width and height
+     *       but can have different x and y position.
+     * @note dest_area and src_area must be clipped to the real dimensions of the buffers
+     */
+    void (*buffer_copy)(struct _lv_draw_ctx_t * draw_ctx, void * dest_buf, lv_coord_t dest_stride,
+                        const lv_area_t * dest_area,
+                        void * src_buf, lv_coord_t src_stride, const lv_area_t * src_area);
 #if LV_USE_USER_DATA
     void * user_data;
 #endif

src/draw/sw/lv_draw_sw.c

@@ -52,6 +52,7 @@ void lv_draw_sw_init_ctx(lv_disp_drv_t * drv, lv_draw_ctx_t * draw_ctx)
     draw_sw_ctx->base_draw.draw_line = lv_draw_sw_line;
     draw_sw_ctx->base_draw.draw_polygon = lv_draw_sw_polygon;
     draw_sw_ctx->base_draw.wait_for_finish = lv_draw_sw_wait_for_finish;
+    draw_sw_ctx->base_draw.buffer_copy = lv_draw_sw_buffer_copy;
     draw_sw_ctx->blend = lv_draw_sw_blend_basic;
 }
 
@@ -69,6 +70,32 @@ void lv_draw_sw_wait_for_finish(lv_draw_ctx_t * draw_ctx)
     /*Nothing to wait for*/
 }
 
+void lv_draw_sw_buffer_copy(lv_draw_ctx_t * draw_ctx,
+                            void * dest_buf, lv_coord_t dest_stride, const lv_area_t * dest_area,
+                            void * src_buf, lv_coord_t src_stride, const lv_area_t * src_area)
+{
+    LV_UNUSED(draw_ctx);
+
+    lv_color_t * dest_bufc =  dest_buf;
+    lv_color_t * src_bufc =  src_buf;
+
+    /*Got the first pixel of each buffer*/
+    dest_bufc += dest_stride * dest_area->y1;
+    dest_bufc += dest_area->x1;
+
+    src_bufc += src_stride * src_area->y1;
+    src_bufc += src_area->x1;
+
+    uint32_t line_length = lv_area_get_width(dest_area) * sizeof(lv_color_t);
+    lv_coord_t y;
+    for(y = dest_area->y1; y <= dest_area->y2; y++) {
+        lv_memcpy(dest_bufc, src_bufc, line_length);
+        dest_bufc += dest_stride;
+        src_bufc += src_stride;
+    }
+
+}
+
 /**********************
  *   STATIC FUNCTIONS
  **********************/

src/draw/sw/lv_draw_sw.h

@@ -63,6 +63,9 @@ LV_ATTRIBUTE_FAST_MEM void lv_draw_sw_line(struct _lv_draw_ctx_t * draw_ctx, con
 void lv_draw_sw_polygon(struct _lv_draw_ctx_t * draw_ctx, const lv_draw_rect_dsc_t * draw_dsc,
                         const lv_point_t * points, uint16_t point_cnt);
 
+void lv_draw_sw_buffer_copy(lv_draw_ctx_t * draw_ctx,
+                            void * dest_buf, lv_coord_t dest_stride, const lv_area_t * dest_area,
+                            void * src_buf, lv_coord_t src_stride, const lv_area_t * src_area);
 /***********************
  * GLOBAL VARIABLES
  ***********************/