Page Speed Optimization Libraries
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Pages
Public Member Functions | List of all members
pagespeed::image_compression::JpegScanlineReader Class Reference

#include "jpeg_reader.h"

Inheritance diagram for pagespeed::image_compression::JpegScanlineReader:

Public Member Functions

 JpegScanlineReader (MessageHandler *handler)
virtual bool Reset ()
virtual ScanlineStatus InitializeWithStatus (const void *image_buffer, size_t buffer_length)
virtual ScanlineStatus ReadNextScanlineWithStatus (void **out_scanline_bytes)
 Return the next row of pixels.
virtual size_t GetBytesPerScanline ()
 Return the number of bytes in a row (without padding).
virtual bool HasMoreScanLines ()
 Returns true if there are more scanlines to read.
virtual PixelFormat GetPixelFormat ()
 Returns the pixel format that need to be used by writer.
virtual size_t GetImageHeight ()
 Returns the height of the image.
virtual size_t GetImageWidth ()
 Returns the width of the image.
virtual bool IsProgressive ()
- Public Member Functions inherited from pagespeed::image_compression::ScanlineReaderInterface
bool Initialize (const void *image_buffer, size_t buffer_length)
bool ReadNextScanline (void **out_scanline_bytes)

Detailed Description

JpegScanlineReader decodes JPEG image. It returns a scanline (a row of pixels) each time it is called. The output format is GRAY_8 if the input image has JCS_GRAYSCALE format, or RGB_888 otherwise.

Member Function Documentation

virtual ScanlineStatus pagespeed::image_compression::JpegScanlineReader::InitializeWithStatus ( const void *  image_buffer,
size_t  buffer_length 

Initialize the reader with the given image stream. Note that image_buffer must remain unchanged until the last call to ReadNextScanline().

Implements pagespeed::image_compression::ScanlineReaderInterface.

virtual bool pagespeed::image_compression::JpegScanlineReader::IsProgressive ( )

Returns true if the original image was encoded progressively by the origin site, so that it could be progressively rendered while the image contents were being transferred

Implements pagespeed::image_compression::ScanlineReaderInterface.

virtual bool pagespeed::image_compression::JpegScanlineReader::Reset ( )

Reset the ScanlineReaderIngterface to its initial state. This will only return false as a result of an unhandled error condition, such as a longjmp due to a libpng error.

Implements pagespeed::image_compression::ScanlineReaderInterface.

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