nsPNGDecoder.h - mozsearch

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-

 * 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/. */

#ifndef mozilla_image_decoders_nsPNGDecoder_h

#define mozilla_image_decoders_nsPNGDecoder_h

#include "Decoder.h"

#include "png.h"

#include "StreamingLexer.h"

#include "SurfacePipe.h"

#include "mozilla/gfx/Swizzle.h"

namespace mozilla {

namespace image {

class RasterImage;

class nsPNGDecoder : public Decoder {

 public:

  virtual ~nsPNGDecoder();

  /// @return true if this PNG is a valid ICO resource.

  bool IsValidICOResource() const override;

  DecoderType GetType() const override { return DecoderType::PNG; }

 protected:

  nsresult InitInternal() override;

  nsresult FinishInternal() override;

  LexerResult DoDecode(SourceBufferIterator& aIterator,

                       IResumable* aOnResume) override;

  Maybe<Telemetry::HistogramID> SpeedHistogram() const override;

 private:

  friend class DecoderFactory;

  // Decoders should only be instantiated via DecoderFactory.

  explicit nsPNGDecoder(RasterImage* aImage);

  /// The information necessary to create a frame.

  struct FrameInfo {

    OrientedIntRect mFrameRect;

    bool mIsInterlaced;

};

  nsresult CreateFrame(const FrameInfo& aFrameInfo);

  void EndImageFrame();

  uint32_t ReadColorProfile(png_structp png_ptr, png_infop info_ptr,

                            int color_type, bool* sRGBTag);

  bool HasAlphaChannel() const { return mChannels == 2 || mChannels == 4; }

  enum class TransparencyType { eNone, eAlpha, eFrameRect };

  TransparencyType GetTransparencyType(const OrientedIntRect& aFrameRect);

  void PostHasTransparencyIfNeeded(TransparencyType aTransparencyType);

  void PostInvalidationIfNeeded();

  void WriteRow(uint8_t* aRow);

  // Convenience methods to make interacting with StreamingLexer from inside

  // a libpng callback easier.

  void DoTerminate(png_structp aPNGStruct, TerminalState aState);

  void DoYield(png_structp aPNGStruct);

  enum class State { PNG_DATA, FINISHED_PNG_DATA };

  LexerTransition<State> ReadPNGData(const char* aData, size_t aLength);

  LexerTransition<State> FinishedPNGData();

  StreamingLexer<State> mLexer;

  // The next lexer state transition. We need to store it here because we can't

  // directly return arbitrary values from libpng callbacks.

  LexerTransition<State> mNextTransition;

  // We yield to the caller every time we finish decoding a frame. When this

  // happens, we need to allocate the next frame after returning from the yield.

  // |mNextFrameInfo| is used to store the information needed to allocate the

  // next frame.

  Maybe<FrameInfo> mNextFrameInfo;

  // The length of the last chunk of data passed to ReadPNGData(). We use this

  // to arrange to arrive back at the correct spot in the data after yielding.

  size_t mLastChunkLength;

 public:

  png_structp mPNG;

  png_infop mInfo;

  OrientedIntRect mFrameRect;

  uint8_t* mCMSLine;

  uint8_t* interlacebuf;

  gfx::SurfaceFormat mFormat;

  uint8_t mChannels;

  uint8_t mPass;

  bool mFrameIsHidden;

  bool mDisablePremultipliedAlpha;

  bool mGotInfoCallback;

  bool mUsePipeTransform;

  bool mErrorIsRecoverable;

  struct AnimFrameInfo {

    AnimFrameInfo();

#ifdef PNG_APNG_SUPPORTED

    AnimFrameInfo(png_structp aPNG, png_infop aInfo);

#endif

    DisposalMethod mDispose;

    BlendMethod mBlend;

    int32_t mTimeout;

};

  AnimFrameInfo mAnimInfo;

  SurfacePipe mPipe;  /// The SurfacePipe used to write to the output surface.

  // The number of frames we've finished.

  uint32_t mNumFrames;

  // libpng callbacks

  // We put these in the class so that they can access protected members.

  static void PNGAPI info_callback(png_structp png_ptr, png_infop info_ptr);

  static void PNGAPI row_callback(png_structp png_ptr, png_bytep new_row,

                                  png_uint_32 row_num, int pass);

#ifdef PNG_APNG_SUPPORTED

  static void PNGAPI frame_info_callback(png_structp png_ptr,

                                         png_uint_32 frame_num);

#endif

  static void PNGAPI end_callback(png_structp png_ptr, png_infop info_ptr);

  static void PNGAPI error_callback(png_structp png_ptr,

                                    png_const_charp error_msg);

  static void PNGAPI warning_callback(png_structp png_ptr,

                                      png_const_charp warning_msg);

  // This is defined in the PNG spec as an invariant. We use it to

  // do manual validation without libpng.

  static const uint8_t pngSignatureBytes[];

};

}  // namespace image

}  // namespace mozilla

#endif  // mozilla_image_decoders_nsPNGDecoder_h