BitmapEx: always convert 1-bit mask to alpha

which is a step towards dropping masks, and only using
alpha.

Change-Id: I6882c0e5b1c805b0cda5a2eaadcbdd078d8566c6
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/114622
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

6 files changed, 104 insertions, 12 deletions

diff --git a/vcl/Library_vcl.mk b/vcl/Library_vcl.mk
index 998eed0e0766..0c4cb6e65864 100644
--- a/vcl/Library_vcl.mk
+++ b/vcl/Library_vcl.mk
@@ -352,6 +352,7 @@ $(eval $(call gb_Library_add_exception_objects,vcl,\
     vcl/source/bitmap/BitmapShadowFilter \
     vcl/source/bitmap/BitmapAlphaClampFilter \
     vcl/source/bitmap/BitmapBasicMorphologyFilter \
+    vcl/source/bitmap/BitmapMaskToAlphaFilter \
     vcl/source/bitmap/BitmapMonochromeFilter \
     vcl/source/bitmap/BitmapSmoothenFilter \
     vcl/source/bitmap/BitmapLightenFilter \
diff --git a/vcl/inc/bitmap/BitmapMaskToAlphaFilter.hxx b/vcl/inc/bitmap/BitmapMaskToAlphaFilter.hxx
new file mode 100644
index 000000000000..355d066846c1
--- /dev/null
+++ b/vcl/inc/bitmap/BitmapMaskToAlphaFilter.hxx
@@ -0,0 +1,21 @@
+/* -*- 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/.
+ *
+ */
+
+#pragma once
+
+#include <vcl/BitmapFilter.hxx>
+
+class BitmapMaskToAlphaFilter final : public BitmapFilter
+{
+public:
+    virtual BitmapEx execute(BitmapEx const& rBitmapEx) const override;
+};
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/qa/cppunit/GraphicTest.cxx b/vcl/qa/cppunit/GraphicTest.cxx
index 0f670a4fee36..608c5f4de85d 100644
--- a/vcl/qa/cppunit/GraphicTest.cxx
+++ b/vcl/qa/cppunit/GraphicTest.cxx
@@ -1072,7 +1072,7 @@ void GraphicTest::testSwappingAnimationGraphic_GIF_WithGfxLink()
 
     // Get the declared byte size of the graphic
     sal_uLong rByteSize = aGraphic.GetSizeBytes();
-    CPPUNIT_ASSERT_EQUAL(sal_uLong(50373), rByteSize);
+    CPPUNIT_ASSERT_EQUAL(sal_uLong(89552), rByteSize);
 
     // Make sure we don't have a file
     CPPUNIT_ASSERT_EQUAL(true, aGraphic.ImplGetImpGraphic()->getSwapFileURL().isEmpty());
@@ -1148,10 +1148,10 @@ void GraphicTest::testSwappingAnimationGraphic_GIF_WithoutGfxLink()
         CPPUNIT_ASSERT_EQUAL(true, bool(xStream));
 
         // Check size of the stream
-        CPPUNIT_ASSERT_EQUAL(sal_uInt64(15183), xStream->remainingSize());
+        CPPUNIT_ASSERT_EQUAL(sal_uInt64(15139), xStream->remainingSize());
 
         std::vector<unsigned char> aHash = calculateHash(xStream);
-        CPPUNIT_ASSERT_EQUAL(std::string("deb13fdf0ffa0b58ce92fff0a6ca9e98c5d26ed9"),
+        CPPUNIT_ASSERT_EQUAL(std::string("ecae5354edd9cf98553eb3153e44181f56d35338"),
                              toHexString(aHash));
     }
 
diff --git a/vcl/qa/cppunit/TypeSerializerTest.cxx b/vcl/qa/cppunit/TypeSerializerTest.cxx
index 5d7b72b0f560..1c7b93d25a62 100644
--- a/vcl/qa/cppunit/TypeSerializerTest.cxx
+++ b/vcl/qa/cppunit/TypeSerializerTest.cxx
@@ -248,9 +248,9 @@ void TypeSerializerTest::testGraphic_Animation()
         }
         aMemoryStream.Seek(STREAM_SEEK_TO_BEGIN);
 
-        CPPUNIT_ASSERT_EQUAL(sal_uInt64(15167), aMemoryStream.remainingSize());
+        CPPUNIT_ASSERT_EQUAL(sal_uInt64(15123), aMemoryStream.remainingSize());
         std::vector<unsigned char> aHash = calculateHash(aMemoryStream);
-        CPPUNIT_ASSERT_EQUAL(std::string("69d0f80832a0aebcbda7ad43ecadf85e99fc1057"),
+        CPPUNIT_ASSERT_EQUAL(std::string("86e02d37ab5e9c96fbeda717f62bc6e35dec3a70"),
                              toHexString(aHash));
 
         aMemoryStream.Seek(STREAM_SEEK_TO_BEGIN);
diff --git a/vcl/source/bitmap/BitmapEx.cxx b/vcl/source/bitmap/BitmapEx.cxx
index 7ff6af59f776..bcf8480163cc 100644
--- a/vcl/source/bitmap/BitmapEx.cxx
+++ b/vcl/source/bitmap/BitmapEx.cxx
@@ -38,6 +38,7 @@
 #include <salinst.hxx>
 #include <svdata.hxx>
 #include <bitmap/BitmapWriteAccess.hxx>
+#include <bitmap/BitmapMaskToAlphaFilter.hxx>
 
 #include <o3tl/any.hxx>
 
@@ -123,20 +124,31 @@ BitmapEx::BitmapEx( const Bitmap& rBmp, const Bitmap& rMask ) :
         maMask           ( rMask ),
         maBitmapSize     ( maBitmap.GetSizePixel() ),
         meTransparent    ( rMask.IsEmpty() ? TransparentType::NONE : TransparentType::Bitmap ),
-        mbAlpha          ( false )
+        mbAlpha          ( !rMask.IsEmpty() )
 {
-    // Ensure a mask is exactly one bit deep,
-    // alternatively also allow 8bpp masks.
-    if (!maMask.IsEmpty() && maMask.getPixelFormat() != vcl::PixelFormat::N1_BPP
-                && !(maMask.getPixelFormat() == vcl::PixelFormat::N8_BPP && maMask.HasGreyPalette8Bit()))
+    if (rMask.IsEmpty())
+        return;
+
+    if( maMask.getPixelFormat() == vcl::PixelFormat::N8_BPP && maMask.HasGreyPalette8Bit() )
+        maMask = rMask;
+    else if (maMask.getPixelFormat() == vcl::PixelFormat::N1_BPP)
+    {
+        // convert 1-bit mask to alpha bitmap
+        BitmapEx aBmpEx(rMask);
+        BitmapFilter::Filter(aBmpEx, BitmapMaskToAlphaFilter());
+        maMask = aBmpEx.GetBitmap();
+    }
+    else
     {
+        // convert to alpha bitmap
         SAL_WARN( "vcl", "BitmapEx: forced mask to monochrome");
-        BitmapEx aMaskEx(maMask);
+        BitmapEx aMaskEx(rMask);
         BitmapFilter::Filter(aMaskEx, BitmapMonochromeFilter(255));
+        BitmapFilter::Filter(aMaskEx, BitmapMaskToAlphaFilter());
         maMask = aMaskEx.GetBitmap();
     }
 
-    if (!maBitmap.IsEmpty() && !maMask.IsEmpty() && maBitmap.GetSizePixel() != maMask.GetSizePixel())
+    if (!maBitmap.IsEmpty() && maBitmap.GetSizePixel() != maMask.GetSizePixel())
     {
         OSL_ENSURE(false, "Mask size differs from Bitmap size, corrected Mask (!)");
         maMask.Scale(maBitmap.GetSizePixel());
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: */