sw_engine raster: fix a regression bug.

mistaken by 8ef31f6cd031b1369ec52e18cc0c97b6efaca6ab

diff --git a/src/lib/sw_engine/tvgSwRaster.cpp b/src/lib/sw_engine/tvgSwRaster.cpp
index 5de990f..e75f260 100644 (file)
--- a/src/lib/sw_engine/tvgSwRaster.cpp
+++ b/src/lib/sw_engine/tvgSwRaster.cpp
@@ -2244,7 +2244,7 @@ static bool _rasterSolidRadialGradientRle(SwSurface* surface, const SwRleData* r
         } else {
             fillFetchRadial(fill, buf, span->y, span->x, span->len);
             auto ialpha = 255 - span->coverage;
-            for (uint32_t i = 0; i < span->len; ++i) {
+            for (uint32_t i = 0; i < span->len; ++i, ++dst) {
                 *dst = ALPHA_BLEND(buf[i], span->coverage) + ALPHA_BLEND(*dst, ialpha);
             }
         }