SlsBitmapCompressor.cxx

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
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 *   License, Version 2.0 (the "License"); you may not use this file
 *   except in compliance with the License. You may obtain a copy of
 *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
 */
 
#include "SlsBitmapCompressor.hxx"
 
#include <tools/stream.hxx>
#include <vcl/bitmapex.hxx>
#include <vcl/filter/PngImageReader.hxx>
#include <vcl/filter/PngImageWriter.hxx>
 
namespace sd::slidesorter::cache {
 
//===== NoBitmapCompression ===================================================
 
class NoBitmapCompression::DummyReplacement
    : public BitmapReplacement
{
public:
    BitmapEx maPreview;
 
    explicit DummyReplacement (const BitmapEx& rPreview) : maPreview(rPreview)  { }
    virtual ~DummyReplacement() {}
    virtual sal_Int32 GetMemorySize() const override { return maPreview.GetSizeBytes(); }
};
 
std::shared_ptr<BitmapReplacement> NoBitmapCompression::Compress (const BitmapEx& rBitmap) const
{
    return std::make_shared<DummyReplacement>(rBitmap);
}
 
BitmapEx NoBitmapCompression::Decompress (const BitmapReplacement& rBitmapData) const
{
    return dynamic_cast<const DummyReplacement&>(rBitmapData).maPreview;
}
 
bool NoBitmapCompression::IsLossless() const
{
    return true;
}
 
//===== CompressionByDeletion =================================================
 
std::shared_ptr<BitmapReplacement> CompressionByDeletion::Compress (const BitmapEx& ) const
{
    return std::shared_ptr<BitmapReplacement>();
}
 
BitmapEx CompressionByDeletion::Decompress (const BitmapReplacement& ) const
{
    // Return a NULL pointer.  This will eventually lead to a request for
    // the creation of a new one.
    return BitmapEx();
}
 
bool CompressionByDeletion::IsLossless() const
{
    return false;
}
 
//===== ResolutionReduction ===================================================
 
class ResolutionReduction::ResolutionReducedReplacement : public BitmapReplacement
{
public:
    BitmapEx maPreview;
    Size maOriginalSize;
 
    virtual ~ResolutionReducedReplacement();
    virtual sal_Int32 GetMemorySize() const override;
};
 
ResolutionReduction::ResolutionReducedReplacement::~ResolutionReducedReplacement()
{
}
 
sal_Int32 ResolutionReduction::ResolutionReducedReplacement::GetMemorySize() const
{
    return maPreview.GetSizeBytes();
}
 
std::shared_ptr<BitmapReplacement> ResolutionReduction::Compress (
    const BitmapEx& rBitmap) const
{
    auto pResult = std::make_shared<ResolutionReducedReplacement>();
    pResult->maPreview = rBitmap;
    Size aSize (rBitmap.GetSizePixel());
    pResult->maOriginalSize = aSize;
    if (aSize.Width()>0 && aSize.Width()<mnWidth)
    {
        int nHeight = aSize.Height() * mnWidth / aSize.Width() ;
        pResult->maPreview.Scale(Size(mnWidth,nHeight));
    }
 
    return pResult;
}
 
BitmapEx ResolutionReduction::Decompress (const BitmapReplacement& rBitmapData) const
{
    BitmapEx aResult;
 
    const ResolutionReducedReplacement* pData (
        dynamic_cast<const ResolutionReducedReplacement*>(&rBitmapData));
 
    if ( pData && ! pData->maPreview.IsEmpty())
    {
        aResult = pData->maPreview;
        if (pData->maOriginalSize.Width() > mnWidth)
            aResult.Scale(pData->maOriginalSize);
    }
 
    return aResult;
}
 
bool ResolutionReduction::IsLossless() const
{
    return false;
}
 
//===== PNGCompression ========================================================
 
class PngCompression::PngReplacement : public BitmapReplacement
{
public:
    void* mpData;
    sal_Int32 mnDataSize;
    PngReplacement()
        : mpData(nullptr),
          mnDataSize(0)
    {}
    virtual ~PngReplacement()
    {
        delete [] static_cast<char*>(mpData);
    }
    virtual sal_Int32 GetMemorySize() const override
    {
        return mnDataSize;
    }
};
 
std::shared_ptr<BitmapReplacement> PngCompression::Compress (const BitmapEx& rBitmap) const
{
    SvMemoryStream aStream (32768, 32768);
    vcl::PngImageWriter aWriter(aStream);
    aWriter.write(rBitmap);
 
    auto pResult = std::make_shared<PngReplacement>();
    pResult->mnDataSize = aStream.Tell();
    pResult->mpData = new char[pResult->mnDataSize];
    memcpy(pResult->mpData, aStream.GetData(), pResult->mnDataSize);
 
    return pResult;
}
 
BitmapEx PngCompression::Decompress (
    const BitmapReplacement& rBitmapData) const
{
    BitmapEx aResult;
    const PngReplacement* pData (dynamic_cast<const PngReplacement*>(&rBitmapData));
    if (pData != nullptr)
    {
        SvMemoryStream aStream (pData->mpData, pData->mnDataSize, StreamMode::READ);
        vcl::PngImageReader aReader (aStream);
        aResult = aReader.read().GetBitmap();
    }
 
    return aResult;
}
 
bool PngCompression::IsLossless() const
{
    return true;
}
 
} // end of namespace ::sd::slidesorter::cache
 
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