#include "image_frame_interface.h"

Inheritance diagram for pagespeed::image_compression::MultipleFrameReader:

Public Member Functions
	MultipleFrameReader (MessageHandler *handler)

virtual ScanlineStatus	Reset ()=0
	Resets the MultipleFrameReader to its initial state.

virtual ScanlineStatus	Initialize ()=0

ScanlineStatus	Initialize (const void *image_buffer, size_t buffer_length)

virtual bool	HasMoreFrames () const =0

virtual bool	HasMoreScanlines () const =0

virtual ScanlineStatus	PrepareNextFrame ()=0

virtual ScanlineStatus	ReadNextScanline (const void **out_scanline_bytes)=0

virtual ScanlineStatus	GetFrameSpec (FrameSpec *frame_spec) const =0

virtual ScanlineStatus	GetImageSpec (ImageSpec *image_spec) const =0

MessageHandler *	message_handler () const

virtual ScanlineStatus	set_quirks_mode (QuirksMode quirks_mode)

virtual QuirksMode	quirks_mode () const

bool	Reset (ScanlineStatus *status)

bool	Initialize (const void image_buffer, size_t buffer_length, ScanlineStatus status)

bool	Initialize (ScanlineStatus *status)

bool	PrepareNextFrame (ScanlineStatus *status)

bool	ReadNextScanline (const void *out_scanline_bytes, ScanlineStatus status)

bool	GetFrameSpec (FrameSpec frame_spec, ScanlineStatus status)

bool	GetImageSpec (ImageSpec image_spec, ScanlineStatus status)

bool	set_quirks_mode (QuirksMode quirks_mode, ScanlineStatus *status)

Protected Attributes
const void *	image_buffer_

size_t	buffer_length_

Detailed Description

Interface for reading both animated and static images.

Typical usage of this API is as follows:

Initialize() GetImageSpec() // optional while (HasMoreFrames()) { PrepareNextFrame() GetFrameSpec() // optional while (HasMoreScanlines()) { ReadNextScanline() } }

The "optional" lines above are not necessary for just reading an image. You might want to call them, though, if the metadata they contain is of interest, or if you're passing the read image to a MultipleFrameWriter, which needs the metadata in ImageSpec and FrameSpec (see below).

Member Function Documentation

virtual ScanlineStatus pagespeed::image_compression::MultipleFrameReader::GetFrameSpec ( FrameSpec * frame_spec ) const

pure virtual

Assigns to '*frame_spec' the FrameSpec describing the current frame.

Todo:: TODO(vchudnov): Consider simplifying this method to return frame_spec rather than the ScanlineStatus.

Implemented in pagespeed::image_compression::ScanlineToFrameReaderAdapter, pagespeed::image_compression::GifFrameReader, and pagespeed::image_compression::MultipleFramePaddingReader.

virtual ScanlineStatus pagespeed::image_compression::MultipleFrameReader::GetImageSpec ( ImageSpec * image_spec ) const

pure virtual

Copies into '*image_spec' the ImageSpec describing the image.

Implemented in pagespeed::image_compression::GifFrameReader, pagespeed::image_compression::ScanlineToFrameReaderAdapter, and pagespeed::image_compression::MultipleFramePaddingReader.

virtual bool pagespeed::image_compression::MultipleFrameReader::HasMoreFrames ( ) const

pure virtual

Returns true iff the image being read has additional frames beyond the current frame being read. For any well-formed image with at least one frame (or for a well-formed static image), this will return true before the first call to PrepareNextFrame().

Implemented in pagespeed::image_compression::ScanlineToFrameReaderAdapter, pagespeed::image_compression::GifFrameReader, and pagespeed::image_compression::MultipleFramePaddingReader.

virtual bool pagespeed::image_compression::MultipleFrameReader::HasMoreScanlines ( ) const

pure virtual

Returns true iff the current frame has more scanlines that have not yet been read.

Implemented in pagespeed::image_compression::ScanlineToFrameReaderAdapter, pagespeed::image_compression::GifFrameReader, and pagespeed::image_compression::MultipleFramePaddingReader.

virtual ScanlineStatus pagespeed::image_compression::MultipleFrameReader::Initialize ( )

pure virtual

Initializes MultipleFrameReader to read image data of length 'buffer_length_' from 'image_buffer_'. This function should take care of calling Reset() if necessary, so that the sequence "Reset(); Initialize();" is never needed.

Implemented in pagespeed::image_compression::ScanlineToFrameReaderAdapter, pagespeed::image_compression::GifFrameReader, and pagespeed::image_compression::MultipleFramePaddingReader.

ScanlineStatus pagespeed::image_compression::MultipleFrameReader::Initialize	(	const void *	image_buffer,
		size_t	buffer_length
	)

inline

Sets 'buffer_length_' and 'image_buffer_' and calls Initialize(). Do not override this function; override the no-arg overload instead.

MessageHandler* pagespeed::image_compression::MultipleFrameReader::message_handler ( ) const

inline

The message handler used by this class. Neither the caller nor this class have ownership.

virtual ScanlineStatus pagespeed::image_compression::MultipleFrameReader::PrepareNextFrame ( )

pure virtual

Prepares to read scanlines from the frame after the current one. Must be called before reading from the first frame.

Implemented in pagespeed::image_compression::ScanlineToFrameReaderAdapter, pagespeed::image_compression::GifFrameReader, and pagespeed::image_compression::MultipleFramePaddingReader.

virtual ScanlineStatus pagespeed::image_compression::MultipleFrameReader::ReadNextScanline ( const void ** out_scanline_bytes )

pure virtual

Reads the next available scanline in the current frame and copies a pointer to it into '*out_scanline_bytes'. This class retains ownership of the read scanline. The scanline encodes as many pixels as the width of the current frame, which is not necessarily the width of the whole image.

Implemented in pagespeed::image_compression::ScanlineToFrameReaderAdapter, pagespeed::image_compression::GifFrameReader, and pagespeed::image_compression::MultipleFramePaddingReader.

bool pagespeed::image_compression::MultipleFrameReader::Reset ( ScanlineStatus * status )

inline

Convenience forms of the methods above. If 'status' indicates an error on entry, each of these methods does nothing and returns false. Otherwise, it calls the corresponding method above, updates 'status', and returns true iff the call succeeded.

The documentation for this class was generated from the following file:

pagespeed/kernel/image/image_frame_interface.h

Public Member Functions

Protected Attributes

Detailed Description

Member Function Documentation