1 files changed, 96 insertions, 0 deletions
diff --git a/src/graphics/FilterUnmultiplyAlpha.cpp b/src/graphics/FilterUnmultiplyAlpha.cpp
new file mode 100644
index 0000000..09bf2ff
--- /dev/null
+++ b/src/graphics/FilterUnmultiplyAlpha.cpp
@@ -0,0 +1,96 @@
+//
+//  libavg - Media Playback Engine. 
+//  Copyright (C) 2003-2014 Ulrich von Zadow
+//
+//  This library is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU Lesser General Public
+//  License as published by the Free Software Foundation; either
+//  version 2 of the License, or (at your option) any later version.
+//
+//  This library is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+//  Lesser General Public License for more details.
+//
+//  You should have received a copy of the GNU Lesser General Public
+//  License along with this library; if not, write to the Free Software
+//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//
+//  Current versions can be found at www.libavg.de
+//
+
+#include "FilterUnmultiplyAlpha.h"
+#include "Pixeldefs.h"
+
+#include "../base/Exception.h"
+#include "../base/ScopeTimer.h"
+
+namespace avg {
+    
+FilterUnmultiplyAlpha::FilterUnmultiplyAlpha()
+  : Filter()
+{
+}
+
+FilterUnmultiplyAlpha::~FilterUnmultiplyAlpha()
+{
+
+}
+
+static ProfilingZoneID ProfilingZone("FilterUnmultiplyAlpha");
+
+void FilterUnmultiplyAlpha::applyInPlace(BitmapPtr pBmp) 
+{
+    ScopeTimer Timer(ProfilingZone);
+    AVG_ASSERT(pBmp->getBytesPerPixel() == 4);
+    IntPoint size = pBmp->getSize();
+    for (int y = 0; y < size.y; y++) {
+        unsigned char * pPixel = pBmp->getPixels() + y*pBmp->getStride();
+        for (int x = 0; x < size.x; x++) { 
+            int alpha = *(pPixel+ALPHAPOS);
+            if (alpha != 0) {
+                *(pPixel+REDPOS) = (int(*(pPixel+REDPOS))*255)/alpha;
+                *(pPixel+GREENPOS) = (int(*(pPixel+GREENPOS))*255)/alpha;
+                *(pPixel+BLUEPOS) = (int(*(pPixel+BLUEPOS))*255)/alpha;
+            }
+            pPixel += 4;
+        }
+    }
+    // The color values of transparent pixels are used in bilinear texture
+    // filtering in certain conditions. To avoid artifacts, we transfer the
+    // color from a neighboring non-transparent pixel.
+    for (int y = 1; y < size.y-1; y++) {
+        int stride = pBmp->getStride();
+        unsigned char * pPixel = pBmp->getPixels() + y*stride;
+        for (int x = 1; x < size.x-1; x++) { 
+            int alpha = *(pPixel+ALPHAPOS);
+            if (alpha == 0) {
+                unsigned char * pSrcPixel = pPixel;
+                if (*(pPixel+4+ALPHAPOS) != 0) {
+                    pSrcPixel = pPixel+4;
+                } else if (*(pPixel+stride+4+ALPHAPOS) != 0) {
+                    pSrcPixel = pPixel+stride+4;
+                } else if (*(pPixel+stride+ALPHAPOS) != 0) {
+                    pSrcPixel = pPixel+stride;
+                } else if (*(pPixel+stride-4+ALPHAPOS) != 0) {
+                    pSrcPixel = pPixel+stride-4;
+                } else if (*(pPixel-4+ALPHAPOS) != 0) {
+                    pSrcPixel = pPixel-4;
+                } else if (*(pPixel-stride-4+ALPHAPOS) != 0) {
+                    pSrcPixel = pPixel-stride-4;
+                } else if (*(pPixel-stride+ALPHAPOS) != 0) {
+                    pSrcPixel = pPixel-stride;
+                } else if (*(pPixel-stride+4+ALPHAPOS) != 0) {
+                    pSrcPixel = pPixel-stride+4;
+                }
+
+                *(pPixel+REDPOS) = *(pSrcPixel+REDPOS);
+                *(pPixel+GREENPOS) = *(pSrcPixel+GREENPOS);
+                *(pPixel+BLUEPOS) = *(pSrcPixel+BLUEPOS);
+            }
+            pPixel += 4;
+        }
+    }
+}
+
+}