sd/source/ui/slidesorter/cache/SlsBitmapCompressor.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #pragma once
  21
  22 #include <sal/types.h>
  23 #include <memory>
  24
  25 class BitmapEx;
  26
  27 namespace sd::slidesorter::cache
  28 {
  29 class BitmapReplacement;
  30
  31 /** This interface class provides the minimal method set for classes that
  32     implement the compression and decompression of preview bitmaps.
  33 */
  34 class BitmapCompressor
  35 {
  36 public:
  37     /** Compress the given bitmap into a replacement format that is specific
  38         to the compressor class.
  39     */
  40     virtual std::shared_ptr<BitmapReplacement> Compress(const BitmapEx& rBitmap) const = 0;
  41
  42     /** Decompress the given replacement data into a preview bitmap.
  43         Depending on the compression technique the returned bitmap may
  44         differ from the original bitmap given to the Compress() method.  It
  45         may even of the wrong size or empty or the NULL pointer.  It is the
  46         task of the caller to create a new preview bitmap if the returned
  47         one is not as desired.
  48     */
  49     virtual BitmapEx Decompress(const BitmapReplacement& rBitmapData) const = 0;
  50
  51     /** Return whether the compression and decompression is lossless.  This
  52         value is used by the caller of Decompress() to decide whether to use
  53         the returned bitmap as is or if a new preview has to be created.
  54     */
  55     virtual bool IsLossless() const = 0;
  56
  57 protected:
  58     ~BitmapCompressor() {}
  59 };
  60
  61 /** Interface for preview bitmap replacements.  Each bitmap
  62     compressor/decompressor has to provide an implementation that is
  63     suitable to store the compressed bitmaps.
  64 */
  65 class BitmapReplacement
  66 {
  67 public:
  68     virtual sal_Int32 GetMemorySize() const { return 0; }
  69
  70 protected:
  71     ~BitmapReplacement() {}
  72 };
  73
  74 /** This is one trivial bitmap compressor.  It stores bitmaps unmodified
  75     instead of compressing them.
  76     This compressor is lossless.
  77 */
  78 class NoBitmapCompression : public BitmapCompressor
  79 {
  80     class DummyReplacement;
  81
  82 public:
  83     virtual ~NoBitmapCompression() {}
  84     virtual std::shared_ptr<BitmapReplacement> Compress(const BitmapEx& rpBitmap) const override;
  85     virtual BitmapEx Decompress(const BitmapReplacement& rBitmapData) const override;
  86     virtual bool IsLossless() const override;
  87 };
  88
  89 /** This is another trivial bitmap compressor.  Instead of compressing a
  90     bitmap, it throws the bitmap away.  Its Decompress() method returns a
  91     NULL pointer.  The caller has to create a new preview bitmap instead.
  92     This compressor clearly is not lossless.
  93 */
  94 class CompressionByDeletion : public BitmapCompressor
  95 {
  96 public:
  97     virtual ~CompressionByDeletion() {}
  98     virtual std::shared_ptr<BitmapReplacement> Compress(const BitmapEx& rBitmap) const override;
  99     virtual BitmapEx Decompress(const BitmapReplacement& rBitmapData) const override;
 100     virtual bool IsLossless() const override;
 101 };
 102
 103 /** Compress a preview bitmap by reducing its resolution.  While the aspect
 104     ratio is maintained the horizontal resolution is scaled down to 100
 105     pixels.
 106     This compressor is not lossless.
 107 */
 108 class ResolutionReduction : public BitmapCompressor
 109 {
 110     class ResolutionReducedReplacement;
 111     static const sal_Int32 mnWidth = 100;
 112
 113 public:
 114     virtual ~ResolutionReduction() {}
 115     virtual std::shared_ptr<BitmapReplacement> Compress(const BitmapEx& rpBitmap) const override;
 116     /** Scale the replacement bitmap up to the original size.
 117     */
 118     virtual BitmapEx Decompress(const BitmapReplacement& rBitmapData) const override;
 119     virtual bool IsLossless() const override;
 120 };
 121
 122 /** Compress preview bitmaps using the PNG format.
 123     This compressor is lossless.
 124 */
 125 class PngCompression : public BitmapCompressor
 126 {
 127     class PngReplacement;
 128
 129 public:
 130     virtual ~PngCompression() {}
 131     virtual std::shared_ptr<BitmapReplacement> Compress(const BitmapEx& rBitmap) const override;
 132     virtual BitmapEx Decompress(const BitmapReplacement& rBitmapData) const override;
 133     virtual bool IsLossless() const override;
 134 };
 135
 136 } // end of namespace ::sd::slidesorter::cache
 137
 138 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */