#include <cugl.h>

Public Member Functions
	PixelMap ()

	PixelMap (const char *bmpFileName)

	PixelMap (GLint x, GLint y, GLsizei w, GLsizei h)

	~PixelMap ()

void	read (const char *bmpFileName)

void	read (GLint x, GLint y, GLsizei w, GLsizei h, GLenum mode=GL_FRONT)

void	write (const char *bmpFileName)

bool	badSize ()

void	rescale ()

void	draw ()

void	setTexture (GLuint name)

void	setMipmaps (GLuint name)

void	select (const PixelMap &src, int xp, int yp, int width, int height)

unsigned long	getRows () const

unsigned long	getColumns () const

unsigned long	getSize () const

char *	getName () const

bool	ready () const

Private Member Functions
	PixelMap (const PixelMap &pm)

bool	allocate (unsigned long newSize)

Private Attributes
unsigned long	numRows

unsigned long	numCols

unsigned long	size

char *	fileName

unsigned char *	pixels

Friends
bool	compatible (const PixelMap &m1, const PixelMap &m2)

void	mix (const PixelMap &m1, const PixelMap &m2, PixelMap &res, double prop)

std::ostream &	operator<< (std::ostream &os, const PixelMap &pm)

Detailed Description

An instance is an RGB pixel array. An instance of PixelMap holds an array that OpenGL can use as a texture or to display directly.

This class is implemented so that it does not depend on Windows. In principle, it should even work with Linux and other operating systems, although this has not been tested thoroughly.

If you want to use a BMP image as a texture, the width and height must be powers of two. Thus a 256 x 512 BMP image is acceptable but a 640 x 400 image is not. This restriction does not apply to images that are displayed as bitmaps.

Since an instance of PixelMap contains pointers, there are memory management issues. The destructor deletes pixel and other data associated with a pixel map. The copy constructor is declared privately and not implemented: this prevents instances being passed by value, although they may be passed by reference. Since there is a default constructor, you can construct arrays of PixelMap's or pointers to PixelMap.

Definition at line 1958 of file cugl.h.

Constructor & Destructor Documentation

cugl::PixelMap::PixelMap ( )

Construct an empty pixel map.

cugl::PixelMap::PixelMap ( const char * bmpFileName )

Read a pixel map from a file.

Parameters

bmpFileName is a path to a BMP file.

cugl::PixelMap::PixelMap	(	GLint	x,
		GLint	y,
		GLsizei	w,
		GLsizei	h
	)

Construct a pixel map from a region of the pixel buffer.

Parameters

x	is the X coordinate of the lower left corner of the region.
y	is the Y coordinate of the lower left corner of the region.
w	is the width of the region in pixels.
h	is the height of the region in pixels.

Note: See also PixelMap::read(x, y, w, h).

cugl::PixelMap::~PixelMap ( )

Delete a pixel map.

cugl::PixelMap::PixelMap ( const PixelMap & pm )

private

The copy constructor is private and unimplemented. This prevents pixel maps from being copied by mistake.

Member Function Documentation

bool cugl::PixelMap::allocate ( unsigned long newSize )

private

Allocate memory for a new pixel map if necessary.

bool cugl::PixelMap::badSize ( )

Check the dimensions of the bit map. If the dimensions are not powers of 2, return true. If the dimensions of the bitmap are not powers of 2, OpenGL cannot use it as a texture. You should call PixelMap::rescale() to resize the bit map.

void cugl::PixelMap::draw ( )

Draw the pixel map at the current raster position. Error NO_PIX_MAP if there is no pixel map avaialble.

unsigned long cugl::PixelMap::getColumns ( ) const

inline

Return number of columns in pixel map.

Definition at line 2113 of file cugl.h.

References numCols.

char* cugl::PixelMap::getName ( ) const

inline

Return name of BMP file.

Definition at line 2129 of file cugl.h.

References fileName.

unsigned long cugl::PixelMap::getRows ( ) const

inline

Return number of rows in pixel map.

Definition at line 2105 of file cugl.h.

References numRows.

unsigned long cugl::PixelMap::getSize ( ) const

inline

Return bytes of memory used by pixel map.

Definition at line 2121 of file cugl.h.

References size.

void cugl::PixelMap::read ( const char * bmpFileName )

Read a BMP file and convert it to a pixel map. Previous data associated with this object will be deleted. The BMP file must satisfy several criteria if it is to be converted successfully. Conversion failure is indicated by the following CUGL errors.

OPEN_FAILED: the file could not be opened
NOT_BMP_FILE: the file is not a BMP file
NOT_24_BITS: the format is not 24 bits/pixel
COMPRESSED_BMP_FILE: the file is compressed
NOT_ENOUGH_MEMORY: there is not enough memory to store the data

OpenGL cannot use a bitmap as a texture if its dimensions are not powers of 2. To check whether the bitmap has acceptable dimensions, call PixelMap::badSize(). To convert the bitmap dimensions to acceptable values, call PixelMap::rescale().

Parameters

bmpFileName is the name of the file to be read, with the extension '.bmp'.

void cugl::PixelMap::read	(	GLint	x,
		GLint	y,
		GLsizei	w,
		GLsizei	h,
		GLenum	mode = `GL_FRONT`
	)

Read a pixel map from a region of the framebuffer. This function is similar to the constructor with the same parameters, but allocates new memory only if necessary.

Parameters

x	is the X coordinate of the lower left corner of the region.
y	is the Y coordinate of the lower left corner of the region.
w	is the width of the region in pixels.
h	is the height of the region in pixels.
mode	is passed to glReadBuffer before reading the pixels.

Note: See also the constructor PixelMap(x, y, w, h).

bool cugl::PixelMap::ready ( ) const

inline

Return true if a pixel map has been read successfully.

Definition at line 2137 of file cugl.h.

References pixels.

void cugl::PixelMap::rescale ( )

Rescale a bit map whose dimensions are not powers of 2. The new image will be distorted; the amount of distortion depends on how much the dimensions have to be altered. Use PixelMap::badSize() to determine whether the dimensions are powers of 2.

void cugl::PixelMap::select	(	const PixelMap &	src,
		int	xp,
		int	yp,
		int	width,
		int	height
	)

Select a region from a pixel map.

Parameters

src	is the pixel map from which the data is extracted.
xp	defines the left side of the selected region.
yp	defines the right side of the selected region.
width	is the width of the selected region.
height	is the height of the selected region.

void cugl::PixelMap::setMipmaps ( GLuint name )

Set texture parameters for the pixel mipmaps. Construct a family of mipmaps for texturing.

Parameters

name	is an OpenGL index for the texture parameters provided by the caller.

Note: This function sets GL_TEXTURE_MIN_FILTER to GL_LINEAR_MIPMAP_NEAREST. Call glTexParameter() to change this setting.; When this function returns, OpenGL has copied the pixel map into its own memory space. It is therefore safe to delete the PixelMap instance after calling setMipmaps().; Call this function once only for each texture you need in your program. Use glBindTexture to select textures in the display function.

void cugl::PixelMap::setTexture ( GLuint name )

Set texture parameters for the pixel map.

Parameters

name	is an OpenGL index for the texture parameters provided by the caller.

Note: This function sets GL_TEXTURE_MAG_FILTER and GL_TEXTURE_MIN_FILTER to GL_NEAREST. Call glTexParameter() to change these settings.; When this function returns, OpenGL has copied the pixel map into its own memory space. It is therefore safe to delete the PixelMap instance after calling setTexture().

void cugl::PixelMap::write ( const char * bmpFileName )

Write a pixel map to an output stream as a BMP file.

Parameters

bmpFileName is the name of the file to be written, with the extension '.bmp'.

Friends And Related Function Documentation

bool compatible	(	const PixelMap &	m1,
		const PixelMap &	m2
	)

friend

Check that two pixel maps are compatible for combining.

void mix	(	const PixelMap &	m1,
		const PixelMap &	m2,
		PixelMap &	res,
		double	prop
	)

friend

Combine two pixel maps.

Parameters

m1	is the first map to be combined.
m2	is the second map to be combined.
res	is the resulting pixel map. The caller is responsible for constructing this map; it is not constructed by the function.
prop	is the mixing proportion: 0 gives m1, 0.5 gives half of each, and 1 gives m2.

std::ostream& operator<<	(	std::ostream &	os,
		const PixelMap &	pm
	)

friend

Write a description of the pixel map to the output stream.

Member Data Documentation

char* cugl::PixelMap::fileName

private

Name of the file used to store the pixel map.

Definition at line 2168 of file cugl.h.

Referenced by getName().

unsigned long cugl::PixelMap::numCols

private

Number of columns in the pixel map.

Definition at line 2162 of file cugl.h.

Referenced by getColumns().

unsigned long cugl::PixelMap::numRows

private

Number of rows in the pixel map.

Definition at line 2159 of file cugl.h.

Referenced by getRows().

unsigned char* cugl::PixelMap::pixels

private

Pointer to the pixels of the map.

Definition at line 2171 of file cugl.h.

Referenced by ready().

unsigned long cugl::PixelMap::size

private

Size, in bytes, of the pixel map.

Definition at line 2165 of file cugl.h.

Referenced by getSize().

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

cugl.h

Public Member Functions

Private Member Functions

Private Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation

Member Data Documentation