fdo#62104 Optimize thumbnail size by using PNG8 and other tricks

Change-Id: I54ece4a1977fe93c0e7bbb11774bd8657912c6bb

include/vcl/gdimtf.hxx

@@ -24,6 +24,7 @@
 #include <tools/gen.hxx>
 #include <tools/link.hxx>
 #include <vcl/mapmod.hxx>
+#include <vcl/bitmap.hxx>
 #include <vector>
 
 class OutputDevice;
@@ -214,7 +215,10 @@ public:
     friend VCL_DLLPUBLIC SvStream& WriteGDIMetaFile( SvStream& rOStm, const GDIMetaFile& rGDIMetaFile );
 
     /// Creates an antialiased thumbnail, with maximum width or height of nMaximumExtent.
-    bool        CreateThumbnail(BitmapEx& rBmpEx, sal_uInt32 nMaximumSize = 256) const;
+    bool        CreateThumbnail(BitmapEx& rBitmapEx,
+                                sal_uInt32 nMaximumExtent = 256,
+                                BmpConversion nColorConversion = BMP_CONVERSION_24BIT,
+                                long nScaleFlag = BMP_SCALE_BESTQUALITY) const;
 
     void            UseCanvas( bool _bUseCanvas );
     bool        GetUseCanvas() const { return bUseCanvas; }

sfx2/source/doc/graphhelp.cxx

@@ -39,6 +39,7 @@
 #include <vcl/outdev.hxx>
 #include <vcl/virdev.hxx>
 #include <vcl/bitmapex.hxx>
+#include <vcl/graphicfilter.hxx>
 
 #include <tools/stream.hxx>
 #include <tools/helpers.hxx>
@@ -52,7 +53,7 @@
 #include "graphhelp.hxx"
 #include "doc.hrc"
 
-using namespace ::com::sun::star;
+using namespace css;
 
 SvMemoryStream* GraphicHelper::getFormatStrFromGDI_Impl( const GDIMetaFile* pGDIMeta, sal_uInt32 nFormat )
 {
@@ -192,30 +193,33 @@ bool GraphicHelper::supportsMetaFileHandle_Impl()
 
 
 // static
-bool GraphicHelper::getThumbnailFormatFromGDI_Impl( GDIMetaFile* pMetaFile,
-                                                        const uno::Reference< io::XStream >& xStream )
+bool GraphicHelper::getThumbnailFormatFromGDI_Impl(GDIMetaFile* pMetaFile, const uno::Reference<io::XStream>& xStream)
 {
     bool bResult = false;
-    SvStream* pStream = NULL;
 
-    if ( xStream.is() )
-        pStream = ::utl::UcbStreamHelper::CreateStream( xStream );
+    if (!pMetaFile || !xStream.is())
+        return false;
 
-    if ( pMetaFile && pStream && !pStream->GetError() )
-    {
-        BitmapEx aResultBitmap;
+    boost::scoped_ptr<SvStream> pStream(utl::UcbStreamHelper::CreateStream(xStream));
 
-        bResult = pMetaFile->CreateThumbnail(aResultBitmap);
+    if (pStream->GetError())
+        return false;
 
-        if ( bResult )
-            bResult = ( !aResultBitmap.IsEmpty()
-                        && GraphicConverter::Export( *pStream, aResultBitmap, CVT_PNG ) == 0
-                        && ( pStream->Flush(), !pStream->GetError() ) );
+    BitmapEx aResultBitmap;
 
-        delete pStream;
-    }
+    bResult = pMetaFile->CreateThumbnail(aResultBitmap, 256, BMP_CONVERSION_8BIT_COLORS, BMP_SCALE_DEFAULT);
 
-    return bResult;
+    if (!bResult || aResultBitmap.IsEmpty())
+        return false;
+
+    GraphicFilter& rFilter = GraphicFilter::GetGraphicFilter();
+
+    if (rFilter.compressAsPNG(aResultBitmap, *pStream.get(), 9) != GRFILTER_OK)
+        return false;
+
+    pStream->Flush();
+
+    return !pStream->GetError();
 }
 
 // static

vcl/source/gdi/gdimtf.cxx

@@ -2879,7 +2879,7 @@ SvStream& GDIMetaFile::Write( SvStream& rOStm )
     return rOStm;
 }
 
-bool GDIMetaFile::CreateThumbnail(BitmapEx& rBmpEx, sal_uInt32 nMaximumExtent) const
+bool GDIMetaFile::CreateThumbnail(BitmapEx& rBitmapEx, sal_uInt32 nMaximumExtent, BmpConversion eColorConversion, long nScaleFlag) const
 {
     // initialization seems to be complicated but is used to avoid rounding errors
     VirtualDevice   aVDev;
@@ -2889,8 +2889,8 @@ bool GDIMetaFile::CreateThumbnail(BitmapEx& rBmpEx, sal_uInt32 nMaximumExtent) c
     Size            aDrawSize( aVDev.LogicToPixel( GetPrefSize(), GetPrefMapMode() ) );
     Size            aSizePix( labs( aBRPix.X() - aTLPix.X() ) + 1, labs( aBRPix.Y() - aTLPix.Y() ) + 1 );
 
-    if ( !rBmpEx.IsEmpty() )
-        rBmpEx.SetEmpty();
+    if (!rBitmapEx.IsEmpty())
+        rBitmapEx.SetEmpty();
 
     // determine size that has the same aspect ratio as image size and
     // fits into the rectangle determined by nMaximumExtent
@@ -2932,19 +2932,18 @@ bool GDIMetaFile::CreateThumbnail(BitmapEx& rBmpEx, sal_uInt32 nMaximumExtent) c
         const_cast<GDIMetaFile *>(this)->Play(&aVDev, aBackPosPix, aAntialias);
 
         // get paint bitmap
-        Bitmap aBmp( aVDev.GetBitmap( aNullPt, aVDev.GetOutputSizePixel() ) );
+        Bitmap aBitmap( aVDev.GetBitmap( aNullPt, aVDev.GetOutputSizePixel() ) );
 
-        // assure that we have a true color image
-        if ( aBmp.GetBitCount() != 24 )
-            aBmp.Convert( BMP_CONVERSION_24BIT );
+        // scale down the image to the desired size - use the input scaler for the scaling operation
+        aBitmap.Scale(aDrawSize, nScaleFlag);
 
-        // downsize, to get the antialiased picture
-        aBmp.Scale(aDrawSize, BMP_SCALE_BESTQUALITY);
+        // convert to desired bitmap color format
+        aBitmap.Convert(eColorConversion);
 
-        rBmpEx = BitmapEx(aBmp);
+        rBitmapEx = BitmapEx(aBitmap);
     }
 
-    return !rBmpEx.IsEmpty();
+    return !rBitmapEx.IsEmpty();
 }
 
 void GDIMetaFile::UseCanvas( bool _bUseCanvas )