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SVG export: fix lost semi-transparent line shapes

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The line shape itself didn't really have a height, rather it had a
stroke. For some reason, the SVG mask then decides that nothing has to
be painted there, so unless the line is entirely opaque, the line shape
gets lost on export.

Fix the problem by handling transparency similar to the PDF export,
which detects if the whole purpose of the transparency gradient is to
pass around a transparency percentage. We don't need a mask in that
case, we can just use opacity as described at e.g.
<https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/opacity>.

Change-Id: I0355b9b09b6dd48bbacc5b7cc54fb71866304ef1
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/91932
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins
This commit is contained in:
Miklos Vajna 2020-04-08 17:47:24 +02:00
parent 95dbfd5172
commit ea52d24b5a
4 changed files with 66 additions and 30 deletions
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BIN
filter/qa/unit/data/semi-transparent-line.odg Normal file
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34
filter/qa/unit/svg.cxx
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@ -20,9 +20,7 @@
using namespace ::com::sun::star;
#if !defined MACOSX
char const DATA_DIRECTORY[] = "/filter/qa/unit/data/";
#endif
/// SVG filter tests.
class SvgFilterTest : public test::BootstrapFixture, public unotest::MacrosTest, public XmlTestTools
@ -34,10 +32,8 @@ public:
void setUp() override;
void tearDown() override;
void registerNamespaces(xmlXPathContextPtr& pXmlXpathCtx) override;
#if !defined MACOSX
uno::Reference<lang::XComponent>& getComponent() { return mxComponent; }
void load(const OUString& rURL);
#endif
};
void SvgFilterTest::setUp()
@ -55,13 +51,11 @@ void SvgFilterTest::tearDown()
test::BootstrapFixture::tearDown();
}
#if !defined MACOSX
void SvgFilterTest::load(const OUString& rFileName)
{
OUString aURL = m_directories.getURLFromSrc(DATA_DIRECTORY) + rFileName;
mxComponent = loadFromDesktop(aURL);
}
#endif
void SvgFilterTest::registerNamespaces(xmlXPathContextPtr& pXmlXpathCtx)
{
@ -100,6 +94,34 @@ CPPUNIT_TEST_FIXTURE(SvgFilterTest, testPreserveJpg)
#endif
}
CPPUNIT_TEST_FIXTURE(SvgFilterTest, testSemiTransparentLine)
{
// Load a document with a semi-transparent line shape.
load("semi-transparent-line.odg");
// Export it to SVG.
uno::Reference<frame::XStorable> xStorable(getComponent(), uno::UNO_QUERY_THROW);
SvMemoryStream aStream;
uno::Reference<io::XOutputStream> xOut = new utl::OOutputStreamWrapper(aStream);
utl::MediaDescriptor aMediaDescriptor;
aMediaDescriptor["FilterName"] <<= OUString("draw_svg_Export");
aMediaDescriptor["OutputStream"] <<= xOut;
xStorable->storeToURL("private:stream", aMediaDescriptor.getAsConstPropertyValueList());
aStream.Seek(STREAM_SEEK_TO_BEGIN);
// Get the style of the group around the actual <path> element.
xmlDocPtr pXmlDoc = parseXmlStream(&aStream);
OUString aStyle = getXPath(
pXmlDoc, "//svg:g[@class='com.sun.star.drawing.LineShape']/svg:g/svg:g", "style");
OUString aPrefix("opacity: ");
// Without the accompanying fix in place, this test would have failed, as the style was
// "mask:url(#mask1)", not "opacity: <value>".
CPPUNIT_ASSERT(aStyle.startsWith(aPrefix));
int nPercent = std::round(aStyle.copy(aPrefix.getLength()).toDouble() * 100);
// Make sure that the line is still 30% opaque, rather than completely invisible.
CPPUNIT_ASSERT_EQUAL(30, nPercent);
}
CPPUNIT_PLUGIN_IMPLEMENT();
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */

57
filter/source/svg/svgwriter.cxx
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@ -2382,32 +2382,43 @@ void SVGActionWriter::ImplWriteMask( GDIMetaFile& rMtf,
if( nMoveX || nMoveY )
rMtf.Move( nMoveX, nMoveY );
OUString aMaskId = "mask" + OUString::number( mnCurMaskId++ );
OUString aStyle;
if (rGradient.GetStartColor() == rGradient.GetEndColor())
{
SvXMLElementExport aElemDefs( mrExport, XML_NAMESPACE_NONE, aXMLElemDefs, true, true );
mrExport.AddAttribute( XML_NAMESPACE_NONE, aXMLAttrId, aMaskId );
{
SvXMLElementExport aElemMask( mrExport, XML_NAMESPACE_NONE, "mask", true, true );
const tools::PolyPolygon aPolyPolygon( tools::PolyPolygon( tools::Rectangle( rDestPt, rDestSize ) ) );
Gradient aGradient( rGradient );
// swap gradient stops to adopt SVG mask
Color aTmpColor( aGradient.GetStartColor() );
sal_uInt16 nTmpIntensity( aGradient.GetStartIntensity() );
aGradient.SetStartColor( aGradient.GetEndColor() );
aGradient.SetStartIntensity( aGradient.GetEndIntensity() ) ;
aGradient.SetEndColor( aTmpColor );
aGradient.SetEndIntensity( nTmpIntensity );
ImplWriteGradientEx( aPolyPolygon, aGradient, nWriteFlags );
}
// Special case: constant alpha value.
const Color& rColor = rGradient.GetStartColor();
const double fOpacity = 1.0 - static_cast<double>(rColor.GetLuminance()) / 255;
aStyle = "opacity: " + OUString::number(fOpacity);
}
else
{
OUString aMaskId = "mask" + OUString::number(mnCurMaskId++);
OUString aMaskStyle = "mask:url(#" + aMaskId + ")";
mrExport.AddAttribute( XML_NAMESPACE_NONE, aXMLAttrStyle, aMaskStyle );
{
SvXMLElementExport aElemDefs(mrExport, XML_NAMESPACE_NONE, aXMLElemDefs, true, true);
mrExport.AddAttribute(XML_NAMESPACE_NONE, aXMLAttrId, aMaskId);
{
SvXMLElementExport aElemMask(mrExport, XML_NAMESPACE_NONE, "mask", true, true);
const tools::PolyPolygon aPolyPolygon(tools::PolyPolygon(tools::Rectangle(rDestPt, rDestSize)));
Gradient aGradient(rGradient);
// swap gradient stops to adopt SVG mask
Color aTmpColor(aGradient.GetStartColor());
sal_uInt16 nTmpIntensity(aGradient.GetStartIntensity());
aGradient.SetStartColor(aGradient.GetEndColor());
aGradient.SetStartIntensity(aGradient.GetEndIntensity());
aGradient.SetEndColor(aTmpColor);
aGradient.SetEndIntensity(nTmpIntensity);
ImplWriteGradientEx(aPolyPolygon, aGradient, nWriteFlags);
}
}
aStyle = "mask:url(#" + aMaskId + ")";
}
mrExport.AddAttribute(XML_NAMESPACE_NONE, aXMLAttrStyle, aStyle);
{
SvXMLElementExport aElemG( mrExport, XML_NAMESPACE_NONE, aXMLElemG, true, true );

5
test/source/xmltesttools.cxx
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@ -12,6 +12,7 @@
#include <memory>
#include <vcl/mtfxmldump.hxx>
#include <sal/log.hxx>
namespace {
@ -53,7 +54,9 @@ xmlDocPtr XmlTestTools::parseXmlStream(SvStream* pStream)
std::unique_ptr<sal_uInt8[]> pBuffer(new sal_uInt8[nSize + 1]);
pStream->ReadBytes(pBuffer.get(), nSize);
pBuffer[nSize] = 0;
return xmlParseDoc(reinterpret_cast<xmlChar*>(pBuffer.get()));
auto pCharBuffer = reinterpret_cast<xmlChar*>(pBuffer.get());
SAL_INFO("test", "XmlTestTools::parseXmlStream: pBuffer is '" << pCharBuffer << "'");
return xmlParseDoc(pCharBuffer);
}
xmlDocPtr XmlTestTools::dumpAndParse(MetafileXmlDump& rDumper, const GDIMetaFile& rGDIMetaFile)