1 files changed, 58 insertions, 0 deletions
diff --git a/vcl/source/bitmap/BitmapMaskToAlphaFilter.cxx b/vcl/source/bitmap/BitmapMaskToAlphaFilter.cxx
new file mode 100644
index 000000000000..3ccca0ebd90b
--- /dev/null
+++ b/vcl/source/bitmap/BitmapMaskToAlphaFilter.cxx
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ */
+
+#include <basegfx/color/bcolortools.hxx>
+
+#include <bitmap/BitmapWriteAccess.hxx>
+#include <bitmap/BitmapMaskToAlphaFilter.hxx>
+
+/**
+ * Convert a 1-bit mask to an alpha layer
+ */
+BitmapEx BitmapMaskToAlphaFilter::execute(BitmapEx const& rBitmapEx) const
+{
+    const Size aSize(rBitmapEx.GetSizePixel());
+
+    Bitmap aBitmap(rBitmapEx.GetBitmap());
+    Bitmap aOutBitmap(aSize, vcl::PixelFormat::N8_BPP, &Bitmap::GetGreyPalette(256));
+
+    Bitmap::ScopedReadAccess pRead(aBitmap);
+    BitmapScopedWriteAccess pWrite(aOutBitmap);
+
+    if (pRead && pWrite)
+    {
+        assert(pRead->HasPalette() && "only supposed to be called with 1-bit mask");
+        assert(pRead->GetPaletteEntryCount() == 2);
+        for (tools::Long nY = 0; nY < aSize.Height(); ++nY)
+        {
+            Scanline pScanline = pWrite->GetScanline(nY);
+            Scanline pScanlineRead = pRead->GetScanline(nY);
+            for (tools::Long nX = 0; nX < aSize.Width(); ++nX)
+            {
+                BitmapColor aBmpColor = pRead->GetPixelFromData(pScanlineRead, nX);
+                if (aBmpColor == COL_BLACK)
+                    aBmpColor = COL_BLACK;
+                else if (aBmpColor == COL_WHITE)
+                    aBmpColor = COL_WHITE;
+                else if (aBmpColor == Color(0, 0, 1))
+                    aBmpColor = COL_WHITE;
+                else
+                    assert(false);
+                pWrite->SetPixelOnData(pScanline, nX, aBmpColor);
+            }
+        }
+    }
+    pWrite.reset();
+    pRead.reset();
+
+    return BitmapEx(aOutBitmap);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */