From 1b7c882be46ec6e3f114ca925f3b38507527891d Mon Sep 17 00:00:00 2001
From: Hermet Park <hermet@lottiefiles.com>
Date: Fri, 28 Jul 2023 18:25:34 +0900
Subject: [PATCH] sw_engine raster: fixed a wrong composition instruction.

it's a regression bug.

@Issue: https://github.com/thorvg/thorvg/issues/1540
---
 src/lib/sw_engine/tvgSwRaster.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/lib/sw_engine/tvgSwRaster.cpp b/src/lib/sw_engine/tvgSwRaster.cpp
index c5383e7e..bd32bf0b 100644
--- a/src/lib/sw_engine/tvgSwRaster.cpp
+++ b/src/lib/sw_engine/tvgSwRaster.cpp
@@ -561,7 +561,8 @@ static bool _rasterMattedRle(SwSurface* surface, SwRleData* rle, uint8_t r, uint
             if (span->coverage == 255) src = color;
             else src = ALPHA_BLEND(color, span->coverage);
             for (uint32_t x = 0; x < span->len; ++x, ++dst, cmp += csize) {
-                *dst = INTERPOLATE(src, *dst, alpha(cmp));
+                auto tmp = ALPHA_BLEND(src, alpha(cmp));
+                *dst = tmp + ALPHA_BLEND(*dst, IA(tmp));
             }
         }
         return true;