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/* -*- 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/.
*
* 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
* with this work for additional information regarding copyright
* ownership. The ASF licenses this file to you under the Apache
* 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 .
*/
#pragma once
#include <sal/types.h>
#include <memory>
class BitmapEx;
namespace sd::slidesorter::cache
{
class BitmapReplacement;
/** This interface class provides the minimal method set for classes that
implement the compression and decompression of preview bitmaps.
*/
class BitmapCompressor
{
public:
/** Compress the given bitmap into a replacement format that is specific
to the compressor class.
*/
virtual std::shared_ptr<BitmapReplacement> Compress(const BitmapEx& rBitmap) const = 0;
/** Decompress the given replacement data into a preview bitmap.
Depending on the compression technique the returned bitmap may
differ from the original bitmap given to the Compress() method. It
may even of the wrong size or empty or the NULL pointer. It is the
task of the caller to create a new preview bitmap if the returned
one is not as desired.
*/
virtual BitmapEx Decompress(const BitmapReplacement& rBitmapData) const = 0;
/** Return whether the compression and decompression is lossless. This
value is used by the caller of Decompress() to decide whether to use
the returned bitmap as is or if a new preview has to be created.
*/
virtual bool IsLossless() const = 0;
protected:
~BitmapCompressor() {}
};
/** Interface for preview bitmap replacements. Each bitmap
compressor/decompressor has to provide an implementation that is
suitable to store the compressed bitmaps.
*/
class BitmapReplacement
{
public:
virtual sal_Int32 GetMemorySize() const { return 0; }
protected:
~BitmapReplacement() {}
};
/** This is one trivial bitmap compressor. It stores bitmaps unmodified
instead of compressing them.
This compressor is lossless.
*/
class NoBitmapCompression : public BitmapCompressor
{
class DummyReplacement;
public:
virtual ~NoBitmapCompression() {}
virtual std::shared_ptr<BitmapReplacement> Compress(const BitmapEx& rpBitmap) const override;
virtual BitmapEx Decompress(const BitmapReplacement& rBitmapData) const override;
virtual bool IsLossless() const override;
};
/** This is another trivial bitmap compressor. Instead of compressing a
bitmap, it throws the bitmap away. Its Decompress() method returns a
NULL pointer. The caller has to create a new preview bitmap instead.
This compressor clearly is not lossless.
*/
class CompressionByDeletion : public BitmapCompressor
{
public:
virtual ~CompressionByDeletion() {}
virtual std::shared_ptr<BitmapReplacement> Compress(const BitmapEx& rBitmap) const override;
virtual BitmapEx Decompress(const BitmapReplacement& rBitmapData) const override;
virtual bool IsLossless() const override;
};
/** Compress a preview bitmap by reducing its resolution. While the aspect
ratio is maintained the horizontal resolution is scaled down to 100
pixels.
This compressor is not lossless.
*/
class ResolutionReduction : public BitmapCompressor
{
class ResolutionReducedReplacement;
static const sal_Int32 mnWidth = 100;
public:
virtual ~ResolutionReduction() {}
virtual std::shared_ptr<BitmapReplacement> Compress(const BitmapEx& rpBitmap) const override;
/** Scale the replacement bitmap up to the original size.
*/
virtual BitmapEx Decompress(const BitmapReplacement& rBitmapData) const override;
virtual bool IsLossless() const override;
};
/** Compress preview bitmaps using the PNG format.
This compressor is lossless.
*/
class PngCompression : public BitmapCompressor
{
class PngReplacement;
public:
virtual ~PngCompression() {}
virtual std::shared_ptr<BitmapReplacement> Compress(const BitmapEx& rBitmap) const override;
virtual BitmapEx Decompress(const BitmapReplacement& rBitmapData) const override;
virtual bool IsLossless() const override;
};
} // end of namespace ::sd::slidesorter::cache
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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