PNG Class Reference

Represents an entire png formatted image. More...

#include "png.h"

Collaboration diagram for PNG:

Public Member Functions
	PNG ()
	Creates a default PNG image (that is, a 1x1 opaque white image). More...
	PNG (size_t width, size_t height)
	Creates a default PNG image of the desired dimensions (that is, a width x height opaque white image). More...
	PNG (string const &file_name)
	Creates a PNG image by reading a file in from disk. More...
	PNG (PNG const &other)
	Copy constructor: creates a new PNG image that is a copy of another. More...
	~PNG ()
	Destructor: frees all memory associated with a given PNG object. More...
PNG const &	operator= (PNG const &other)
	Assignment operator for setting two PNGs equal to one another. More...
bool	operator== (PNG const &other) const
	Equality operator: checks if two images are the same. More...
bool	operator!= (PNG const &other) const
	Inequality operator: checks if two images are different. More...
RGBAPixel *	operator() (size_t x, size_t y)
	Non-const pixel access operator. More...
RGBAPixel const *	operator() (size_t x, size_t y) const
	Const pixel access operator. More...
bool	readFromFile (string const &file_name)
	Reads in a PNG image from a file. More...
bool	writeToFile (string const &file_name)
	Writes a PNG image to a file. More...
size_t	width () const
	Gets the width of this image. More...
size_t	height () const
	Gets the height of this image. More...
void	resize (size_t width, size_t height)
	Resizes the image to the given coordinates. More...

Detailed Description

Represents an entire png formatted image.

Constructor & Destructor Documentation

PNG::PNG

(

)

Creates a default PNG image (that is, a 1x1 opaque white image).

PNG::PNG	(	size_t	width,
		size_t	height
	)

Creates a default PNG image of the desired dimensions (that is, a width x height opaque white image).

Parameters

width	Width of the new image.
height	Height of the new image.

PNG::PNG

(

string const &

file_name

)

Creates a PNG image by reading a file in from disk.

Parameters

file_name

Name of the file to be read in to the image.

PNG::PNG

(

PNG const &

other

)

Copy constructor: creates a new PNG image that is a copy of another.

Parameters

other

PNG to be copied.

PNG::~PNG

(

)

Destructor: frees all memory associated with a given PNG object.

Invoked by the system.

Member Function Documentation

PNG const & PNG::operator=

(

PNG const &

other

)

Assignment operator for setting two PNGs equal to one another.

Parameters

other

Image to copy into the current image.

Returns

The current image for assignment chaining.

bool PNG::operator==

(

PNG const &

other

)

const

Equality operator: checks if two images are the same.

Parameters

other

Image to be checked.

Returns

Whether the current image is equal to the other image.

bool PNG::operator!=

(

PNG const &

other

)

const

Inequality operator: checks if two images are different.

Parameters

other

Image to be checked.

Returns

Whether the current image differs from the other image.

RGBAPixel * PNG::operator()	(	size_t	x,
		size_t	y
	)

Non-const pixel access operator.

Gets a pointer to the pixel at the given coordinates in the image. (0,0) is the upper left corner. This pointer allows the image to be changed.

Parameters

x	X-coordinate for the pixel pointer to be grabbed from.
y	Y-coordinate for the pixel pointer to be grabbed from.

Returns

A pointer to the pixel at the given coordinates.

RGBAPixel const * PNG::operator()	(	size_t	x,
		size_t	y
	)		const

Const pixel access operator.

Const version of the previous operator(). Does not allow the image to be changed via the pointer.

Parameters

x	X-coordinate for the pixel pointer to be grabbed from.
y	Y-cooridnate for the pixel pointer to be grabbed from.

Returns

A pointer to the pixel at the given coordinates (can't change the pixel through this pointer).

bool PNG::readFromFile

(

string const &

file_name

)

Reads in a PNG image from a file.

Overwrites any current image content in the PNG. In the event of failure, the image's contents are undefined.

Parameters

file_name

Name of the file to be read from.

Returns

Whether the image was successfully read in or not.

bool PNG::writeToFile

(

string const &

file_name

)

Writes a PNG image to a file.

Parameters

file_name

Name of the file to write to.

Returns

Whether the file was written successfully or not.

size_t PNG::width

(

)

const

Gets the width of this image.

Returns

Width of the image.

size_t PNG::height

(

)

const

Gets the height of this image.

Returns

Height of the image.

void PNG::resize	(	size_t	width,
		size_t	height
	)

Resizes the image to the given coordinates.

Attempts to preserve existing pixel data in the image when doing so, but will crop if necessary. No pixel interpolation is done.

Parameters

width	New width of the image.
height	New height of the image.

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

• png.h
• png.cpp