From: Vincent Povirk <madewokherd@gmail.com>
Subject: [3/3] gdiplus: Add a more optimized loop for composing onto PARGB.
Message-Id: <CAG_NDKrKxHWxy66Jro-Jcw72pxHGzOyVru-QjZLq5gKdocMyCg@mail.gmail.com>
Date: Fri, 19 Sep 2014 11:28:13 -0500

From a911e1082056586225b1a94bf769b722f2fa4e0f Mon Sep 17 00:00:00 2001
From: Vincent Povirk <vincent@codeweavers.com>
Date: Thu, 18 Sep 2014 14:03:26 -0500
Subject: [PATCH 3/3] gdiplus: Add a more optimized loop for composing onto
 PARGB.

---
 dlls/gdiplus/image.c | 39 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/dlls/gdiplus/image.c b/dlls/gdiplus/image.c
index 8511e3e..683a53d 100644
--- a/dlls/gdiplus/image.c
+++ b/dlls/gdiplus/image.c
@@ -1027,6 +1027,42 @@ GpStatus convert_pixels(INT width, INT height,
     return NotImplemented;
 }
 
+static void compose_32bppARGB_on_32bppPARGB(INT dst_x, INT dst_y, INT width, INT height,
+    INT dst_stride, BYTE *dst_bits, INT src_stride, const BYTE *src_bits)
+{
+    INT x, y;
+    dst_bits = dst_bits + dst_x * 4 + dst_y * dst_stride;
+    for (y=0; y<height; y++)
+    {
+        const DWORD *src = (const DWORD*)(src_bits+y*src_stride);
+        DWORD *dst = (DWORD*)(dst_bits+y*dst_stride);
+        for (x=0; x<width; x++)
+        {
+            BYTE b, g, r, a;
+            BYTE fg_alpha, bg_alpha;
+            ARGB bg = dst[x], fg=src[x];
+
+            if ((fg & 0xff000000) == 0)
+                continue;
+            else if ((fg & 0xff000000) == 0xff)
+            {
+                dst[x] = fg;
+                continue;
+            }
+
+            fg_alpha = (fg>>24) & 0xff;
+            bg_alpha = 0xff-fg_alpha;
+
+            a = ((bg>>24)&0xff) * bg_alpha / 0xff + fg_alpha;
+            b = ((bg&0xff) * bg_alpha + (fg&0xff)*fg_alpha) / 0xff;
+            g = (((bg>>8)&0xff) * bg_alpha + ((fg>>8)&0xff)*fg_alpha) / 0xff;
+            r = (((bg>>16)&0xff) * bg_alpha + ((fg>>16)&0xff)*fg_alpha) / 0xff;
+
+            dst[x] = (a<<24)|(r<<16)|(g<<8)|b;
+        }
+    }
+}
+
 GpStatus compose_pixels(INT dst_x, INT dst_y, INT width, INT height,
     INT dst_stride, BYTE *dst_bits, PixelFormat dst_format, ColorPalette *dst_palette,
     INT src_stride, const BYTE *src_bits)
@@ -1112,7 +1148,8 @@ GpStatus compose_pixels(INT dst_x, INT dst_y, INT width, INT height,
     case PixelFormat32bppARGB:
         compose_rgb(getpixel_32bppARGB, setpixel_32bppARGB);
     case PixelFormat32bppPARGB:
-        compose_rgb(getpixel_32bppPARGB, setpixel_32bppPARGB);
+        compose_32bppARGB_on_32bppPARGB(dst_x, dst_y, width, height, dst_stride, dst_bits, src_stride, src_bits);
+        return Ok;
     case PixelFormat48bppRGB:
         compose_rgb(getpixel_48bppRGB, setpixel_48bppRGB);
     case PixelFormat64bppARGB:
-- 
1.9.1