[core] fix patch alpha on alpna image

diff --git a/src/switch_core_video.c b/src/switch_core_video.c
index e5b1688db78f2feab7d2ffa55871e309d877d9e2..540edf0ae9972f0c9d4c44e14fceb197b6afc657 100644 (file)
--- a/src/switch_core_video.c
+++ b/src/switch_core_video.c
@@ -325,7 +325,7 @@ static void switch_img_patch_rgb_noalpha(switch_image_t *IMG, switch_image_t *im
                int max_w = MIN(img->d_w, IMG->d_w - abs(x));
                int max_h = MIN(img->d_h, IMG->d_h - abs(y));
                int j;
-               uint8_t alpha, alphadiff;
+               uint8_t alpha;
                switch_rgb_color_t *rgb, *RGB; 
 
                for (i = 0; i < max_h; i++) {           
@@ -334,19 +334,27 @@ static void switch_img_patch_rgb_noalpha(switch_image_t *IMG, switch_image_t *im
                                RGB = (switch_rgb_color_t *)(IMG->planes[SWITCH_PLANE_PACKED] + (y + i) * IMG->stride[SWITCH_PLANE_PACKED] + (x + j) * 4);
                                
                                alpha = rgb->a;
-                               
-                               if (RGB->a != 0) {
+
+                               if (RGB->a == 0) {
+                                       *RGB = *rgb;
                                        continue;
                                }
 
                                if (alpha == 255) {
                                        *RGB = *rgb;
-                               } else if (alpha != 0) {
-                                       alphadiff = 255 - alpha;
-                                       RGB->a = 255;
-                                       RGB->r = ((RGB->r * alphadiff) + (rgb->r * alpha)) >> 8;
-                                       RGB->g = ((RGB->g * alphadiff) + (rgb->g * alpha)) >> 8;
-                                       RGB->b = ((RGB->b * alphadiff) + (rgb->b * alpha)) >> 8;
+                                       continue;
+                               }
+
+                               if (alpha > 0) {
+                                       uint8_t delta1, delta2, delta;
+
+                                       delta1 = 255 - RGB->a;
+                                       delta2 = 255 - rgb->a;
+                                       delta = (delta1 * delta2) >> 8;
+                                       RGB->r = ((RGB->r * RGB->a) + (rgb->r * rgb->a)) / (RGB->a + rgb->a);
+                                       RGB->g = ((RGB->g * RGB->a) + (rgb->g * rgb->a)) / (RGB->a + rgb->a);
+                                       RGB->b = ((RGB->b * RGB->a) + (rgb->b * rgb->a)) / (RGB->a + rgb->a);
+                                       RGB->a = 255 - delta;
                                }
                        }
                }
@@ -394,7 +402,7 @@ SWITCH_DECLARE(void) switch_img_patch_rgb(switch_image_t *IMG, switch_image_t *i
                int height = MIN(img->d_h, IMG->d_h - abs(y));
                void (*ARGBBlendRow)(const uint8_t* src_argb, const uint8_t* src_argb1, uint8_t* dst_argb, int width) = GetARGBBlend();
 
-               switch_img_attenuate(img);
+               // switch_img_attenuate(img);
 
                // Coalesce rows. we have same size images, treat as a single row
                if (src_stride_argb0 == width * 4 &&