#include "png_optimizer.h"

Inheritance diagram for pagespeed::image_compression::PngReaderInterface:

Public Member Functions
virtual bool	ReadPng (const GoogleString &body, png_structp png_ptr, png_infop info_ptr, int transforms, bool require_opaque) const =0

bool	ReadPng (const GoogleString &body, png_structp png_ptr, png_infop info_ptr, int transforms) const

virtual bool	GetAttributes (const GoogleString &body, int out_width, int out_height, int out_bit_depth, int out_color_type) const =0

Static Public Member Functions
static bool	GetBackgroundColor (png_structp png_ptr, png_infop info_ptr, unsigned char red, unsigned char green, unsigned char blue, MessageHandler handler)

static bool	IsAlphaChannelOpaque (png_structp png_ptr, png_infop info_ptr, MessageHandler *handler)

Detailed Description

Helper class that provides an API to read a PNG image from some source.

Member Function Documentation

virtual bool pagespeed::image_compression::PngReaderInterface::GetAttributes	(	const GoogleString &	body,
		int *	out_width,
		int *	out_height,
		int *	out_bit_depth,
		int *	out_color_type
	)		const

pure virtual

Get just the attributes of the given image. out_bit_depth is the number of bits per channel. out_color_type is one of the PNG_COLOR_TYPE_* declared in png.h.

Todo:: TODO(bmcquade): consider merging this with ImageAttributes.

Implemented in pagespeed::image_compression::PngReader, and pagespeed::image_compression::GifReader.

static bool pagespeed::image_compression::PngReaderInterface::GetBackgroundColor	(	png_structp	png_ptr,
		png_infop	info_ptr,
		unsigned char *	red,
		unsigned char *	green,
		unsigned char *	blue,
		MessageHandler *	handler
	)

static

Get the background color, in the form of 8-bit RGB triplets. Note that if the underlying image uses a bit_depth other than 8, the background color will be scaled to 8-bits per channel.

static bool pagespeed::image_compression::PngReaderInterface::IsAlphaChannelOpaque	(	png_structp	png_ptr,
		png_infop	info_ptr,
		MessageHandler *	handler
	)

static

Returns true if the alpha channel is actually a opaque. Returns false otherwise. It is an error to call this method for an image that does not have an alpha channel.

virtual bool pagespeed::image_compression::PngReaderInterface::ReadPng	(	const GoogleString &	body,
		png_structp	png_ptr,
		png_infop	info_ptr,
		int	transforms,
		bool	require_opaque
	)		const

pure virtual

Parse the contents of body, convert to a PNG, and populate the PNG structures with the PNG representation. If 'require_opaque' is true, returns an image without an alpha channel if the original image has no transparent pixels, and fails otherwise. Returns true on success, false on failure.

Implemented in pagespeed::image_compression::PngReader, and pagespeed::image_compression::GifReader.

bool pagespeed::image_compression::PngReaderInterface::ReadPng	(	const GoogleString &	body,
		png_structp	png_ptr,
		png_infop	info_ptr,
		int	transforms
	)		const

inline

Parse the contents of body, convert to a PNG, and populate the PNG structures with the PNG representation. Returns true on success, false on failure.

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

pagespeed/kernel/image/png_optimizer.h

Public Member Functions

Static Public Member Functions

Detailed Description

Member Function Documentation