SVG export: try to reuse original bitmap data for JPG and PNG bitmaps

This has a number of benefits:

1) For a sample JPG photo, the SVG output is now 4,9MB, not 20MB.

2) Even the first export to SVG is fast, see commit
570be56b37 (svx: cache PNG export of
graphic shapes, 2020-02-25) for exact numbers.

3) Allow using less memory as the SdrGrafObj doesn't have to store a PNG
result till the document is closed.

We still require matching checksums, so in case anything problematic
happens with the bitmap (grayscale filter applied, etc), then the
optimization is meant to not help, but still produces correct output.

Change-Id: Id3bc359a8dcc4c4d12d3b66ffb512cfa71939a26
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/89419
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

filter/source/svg/svgwriter.cxx

@@ -2725,29 +2725,52 @@ void SVGActionWriter::ImplWriteBmp( const BitmapEx& rBmpEx,
 
             bool bCached = false;
             SdrGrafObj* pGrafObj = nullptr;
+            bool bPNG = false;
+            bool bJPG = false;
             if (pShape)
             {
                 pGrafObj = GetSdrGrafObjFromXShape(pShape);
-                if (pGrafObj && pGrafObj->GetPNGPreviewChecksum() == rBmpEx.GetChecksum())
+                if (pGrafObj)
                 {
-                    const std::vector<sal_Int8>& rPreviewData = pGrafObj->GetPNGPreviewData();
-                    aOStm.WriteBytes(rPreviewData.data(), rPreviewData.size());
+                    const Graphic& rGraphic = pGrafObj->GetGraphic();
+                    if (rGraphic.GetType() == GraphicType::Bitmap)
+                    {
+                        const BitmapEx& rGraphicBitmap = rGraphic.GetBitmapExRef();
+                        if (rGraphicBitmap.GetChecksum() == rBmpEx.GetChecksum())
+                        {
+                            GfxLink aGfxLink = rGraphic.GetGfxLink();
+                            if (aGfxLink.GetType() == GfxLinkType::NativePng)
+                            {
+                                bPNG = true;
+                            }
+                            else if (aGfxLink.GetType() == GfxLinkType::NativeJpg)
+                            {
+                                bJPG = true;
+                            }
+                            if (bPNG || bJPG)
+                            {
+                                aOStm.WriteBytes(aGfxLink.GetData(), aGfxLink.GetDataSize());
                                 bCached = true;
                             }
                         }
+                    }
+                }
+            }
 
             if( bCached || GraphicConverter::Export( aOStm, rBmpEx, ConvertDataFormat::PNG ) == ERRCODE_NONE )
             {
-                if (!bCached && pGrafObj)
-                {
-                    pGrafObj->SetPNGPreviewChecksum(rBmpEx.GetChecksum());
-                    pGrafObj->SetPNGPreviewData(aOStm);
-                }
-
                 Point                    aPt;
                 Size                     aSz;
                 Sequence< sal_Int8 >     aSeq( static_cast<sal_Int8 const *>(aOStm.GetData()), aOStm.Tell() );
-                OUStringBuffer aBuffer( "data:image/png;base64," );
+                OUStringBuffer aBuffer;
+                if (bJPG)
+                {
+                    aBuffer.append("data:image/jpeg;base64,");
+                }
+                else
+                {
+                    aBuffer.append("data:image/png;base64,");
+                }
                 ::comphelper::Base64::encode( aBuffer, aSeq );
 
                 ImplMap( rPt, aPt );

include/svx/svdograf.hxx

@@ -29,7 +29,6 @@
 #include <vcl/GraphicObject.hxx>
 #include <svx/svxdllapi.h>
 #include <o3tl/typed_flags_set.hxx>
-#include <tools/stream.hxx>
 #include <memory>
 #include <cstddef>
 
@@ -123,9 +122,6 @@ private:
     void onGraphicChanged();
     GDIMetaFile             GetMetaFile(GraphicType &rGraphicType) const;
 
-    BitmapChecksum mnPNGPreviewChecksum = 0;
-    std::vector<sal_Int8> maPNGPreviewData;
-
 protected:
     // protected destructor
     virtual ~SdrGrafObj() override;
@@ -301,11 +297,6 @@ public:
     {
         return mpQrCode.get();
     };
-
-    void SetPNGPreviewChecksum(BitmapChecksum nPNGPreviewChecksum);
-    BitmapChecksum GetPNGPreviewChecksum() const;
-    void SetPNGPreviewData(SvMemoryStream& rPNGPreviewData);
-    const std::vector<sal_Int8>& GetPNGPreviewData() const;
 };
 
 #endif // INCLUDED_SVX_SVDOGRAF_HXX

svx/source/svdraw/svdograf.cxx

@@ -1276,26 +1276,4 @@ void SdrGrafObj::addCropHandles(SdrHdlList& rTarget) const
     rTarget.AddHdl(std::make_unique<SdrCropHdl>(Point(basegfx::fround(aPos.getX()), basegfx::fround(aPos.getY())), SdrHdlKind::LowerRight, fShearX, fRotate));
 }
 
-void SdrGrafObj::SetPNGPreviewChecksum(BitmapChecksum nPNGPreviewChecksum)
-{
-    mnPNGPreviewChecksum = nPNGPreviewChecksum;
-}
-
-BitmapChecksum SdrGrafObj::GetPNGPreviewChecksum() const
-{
-    return mnPNGPreviewChecksum;
-}
-
-void SdrGrafObj::SetPNGPreviewData(SvMemoryStream& rPNGPreviewData)
-{
-    rPNGPreviewData.Seek(0);
-    maPNGPreviewData.resize(rPNGPreviewData.remainingSize());
-    rPNGPreviewData.ReadBytes(maPNGPreviewData.data(), maPNGPreviewData.size());
-}
-
-const std::vector<sal_Int8>& SdrGrafObj::GetPNGPreviewData() const
-{
-    return maPNGPreviewData;
-}
-
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */