GPixmap Class Reference

RGB Color images. More...

#include <GPixmap.h>

Inheritance diagram for GPixmap:

[legend]

List of all members.

Public Member Functions
void	destroy (void)
int	get_grays (void) const
void	set_grays (int)
virtual	~GPixmap ()
Blitting and applying stencils.
These function is essential for rendering DjVu images. The elementary functions are {attenuate} and {blit}. The combined functions {blend} and {stencil} should be viewed as optimizations.
void	attenuate (const GBitmap *bm, int x, int y)
void	blend (const GBitmap *bm, int x, int y, const GPixmap *color)
void	blit (const GBitmap *bm, int x, int y, const GPixmap *color)
void	blit (const GBitmap *bm, int x, int y, const GPixel *color)
void	stencil (const GBitmap *bm, const GPixmap *pm, int pms, const GRect *pmr, double corr=1.0)
Stealing or borrowing the memory buffer (advanced).
void	borrow_data (GPixel &data, int w, int h)
void	donate_data (GPixel *data, int w, int h)
GP< GPixmap >	rotate (int count=0)
GPixel *	take_data (size_t &offset)
Accessing pixels.
unsigned int	columns () const
GPixel *	operator[] (int row)
const GPixel *	operator[] (int row) const
unsigned int	rows () const
unsigned int	rowsize () const
Resampling images.
void	downsample (const GPixmap *src, int factor, const GRect *rect=0)
void	downsample43 (const GPixmap *src, const GRect *rect=0)
void	upsample (const GPixmap *src, int factor, const GRect *rect=0)
void	upsample23 (const GPixmap *src, const GRect *rect=0)
Miscellaneous.
unsigned int	get_memory_usage () const
void	save_ppm (ByteStream &bs, int raw=1) const
Initialization.
void	init (ByteStream &ref)
void	init (const GBitmap &ref, const GRect &rect, const GPixel *ramp=0)
void	init (const GBitmap &ref, const GPixel *ramp=0)
void	init (const GPixmap &ref, const GRect &rect)
void	init (const GPixmap &ref)
void	init (int nrows, int ncolumns, const GPixel *filler=0)
GPixmap &	operator= (const GPixmap &ref)
GPixmap &	operator= (const GBitmap &ref)
Static Public Member Functions
Construction.
static GP< GPixmap >	create (ByteStream &ref)
static GP< GPixmap >	create (const GPixmap &ref, const GRect &rect)
static GP< GPixmap >	create (const GPixmap &ref)
static GP< GPixmap >	create (const GBitmap &ref, const GRect &rect)
static GP< GPixmap >	create (const GBitmap &ref)
static GP< GPixmap >	create (const int nrows, const int ncolumns, const GPixel *filler=0)
static GP< GPixmap >	create (void)
Protected Member Functions
	GPixmap (ByteStream &ref)
	GPixmap (const GPixmap &ref, const GRect &rect)
	GPixmap (const GPixmap &ref)
	GPixmap (const GBitmap &ref, const GRect &rect)
	GPixmap (const GBitmap &ref)
	GPixmap (int nrows, int ncolumns, const GPixel *filler=0)
	GPixmap (void)
Protected Attributes
unsigned short	ncolumns
unsigned short	nrows
unsigned short	nrowsize
GPixel *	pixels
GPixel *	pixels_data
Manipulating colors.
void	color_correct (double corr)
void	ordered_32k_dither (int xmin=0, int ymin=0)
void	ordered_666_dither (int xmin=0, int ymin=0)
static void	color_correct (double corr, GPixel *pixels, int npixels)

---

Detailed Description

RGB Color images.

Instances of class GPixmap# represent color images as a two dimensional array of pixels {GPixel}. The bracket operator returns a pointer to the pixels composing one line of the image. This pointer can be used as an array to read or write the pixels of this particular line. Following the general convention of the DjVu Reference Library, line zero is always the bottom line of the image.

Definition at line 148 of file GPixmap.h.

---

Constructor & Destructor Documentation

GPixmap::GPixmap

(

void

)

[protected]

Definition at line 181 of file GPixmap.cpp.

GPixmap::GPixmap	(	int	nrows,
		int	ncolumns,
		const GPixel *	filler = 0
	)			[protected]

Definition at line 186 of file GPixmap.cpp.

GPixmap::GPixmap

(

const GBitmap &

ref

)

[protected]

Definition at line 216 of file GPixmap.cpp.

GPixmap::GPixmap	(	const GBitmap &	ref,
		const GRect &	rect
	)			[protected]

Definition at line 231 of file GPixmap.cpp.

GPixmap::GPixmap

(

const GPixmap &

ref

)

[protected]

Definition at line 246 of file GPixmap.cpp.

GPixmap::GPixmap	(	const GPixmap &	ref,
		const GRect &	rect
	)			[protected]

Definition at line 261 of file GPixmap.cpp.

GPixmap::GPixmap

(

ByteStream &

ref

)

[protected]

Definition at line 201 of file GPixmap.cpp.

GPixmap::~GPixmap

(

)

[virtual]

Virtual destructor.

Definition at line 169 of file GPixmap.cpp.

---

Member Function Documentation

void GPixmap::attenuate	(	const GBitmap *	bm,
		int	x,
		int	y
	)

Attenuates the color image in preparation for a blit.

Bitmap bm# is positionned at location x#,y# over this color image. The matching color image pixels are then multiplied by #1.0-Alpha# where Alpha# denotes the gray value, in range #[0,1]#, represented by the corresponding pixel of bitmap bm#.

Definition at line 1295 of file GPixmap.cpp.

void GPixmap::blend	(	const GBitmap *	bm,
		int	x,
		int	y,
		const GPixmap *	color
	)

Performs alpha blending.

This function is similar to first calling {attenuate} with alpha map bm# and then calling {blit} with alpha map bm# and color map color#. Both operations are performed together for efficiency reasons.

Definition at line 1459 of file GPixmap.cpp.

void GPixmap::blit	(	const GBitmap *	bm,
		int	x,
		int	y,
		const GPixmap *	color
	)

Blits pixmap color# through transparency mask bm#.

Bitmap bm# is positionned at location x#,y# over this color image. The matching color image pixels are then modified by adding the corresponding pixel color in pixmap color#, multiplied by Alpha#, where Alpha# denotes the gray value, in range #[0,1]#, represented by the corresponding pixel of bitmap bm#.

Definition at line 1401 of file GPixmap.cpp.

void GPixmap::blit	(	const GBitmap *	bm,
		int	x,
		int	y,
		const GPixel *	color
	)

Blits solid color color# through transparency mask bm#.

Bitmap bm# is positionned at location x#,y# over this color image. The matching color image pixels are then modified by adding color color# multiplied by Alpha#, where Alpha# denotes the gray value, in range #[0,1]#, represented by the corresponding pixel of bitmap bm#.

Definition at line 1345 of file GPixmap.cpp.

void GPixmap::borrow_data	(	GPixel &	data,
		int	w,
		int	h
	)			[inline]

Initializes this GPixmap by borrowing a memory segment.

The GPixmap then directly addresses the memory buffer data# provided by the user. This buffer must be large enough to hold w*h# GPixels. The GPixmap object does not ``own'' the buffer: you must explicitly de-allocate the buffer using operator delete []#. This de-allocation should take place after the destruction or the re-initialization of the GPixmap object.

Definition at line 504 of file GPixmap.h.

void GPixmap::color_correct	(	double	corr,
		GPixel *	pixels,
		int	npixels
	)			[static]

Applies a luminance gamma correction to an array of pixels.

This function is {static} and does not modify this pixmap.

Definition at line 673 of file GPixmap.cpp.

void GPixmap::color_correct

(

double

corr

)

Applies a luminance gamma correction factor of corr#.

Values greater than #1.0# make the image brighter. Values smaller than #1.0# make the image darker. The documentation of program {ppmcoco} explains how to properly use this function.

Definition at line 650 of file GPixmap.cpp.

unsigned int GPixmap::columns

(

)

const [inline]

Returns the number of columns (the image width).

Definition at line 464 of file GPixmap.h.

static GP<GPixmap> GPixmap::create

(

ByteStream &

ref

)

[inline, static]

Creates a GPixmap by reading PPM data from ByteStream ref#.

See {PNM and RLE file formats} for more information.

Definition at line 205 of file GPixmap.h.

static GP<GPixmap> GPixmap::create	(	const GPixmap &	ref,
		const GRect &	rect
	)			[inline, static]

Creates a GPixmap by copying the rectangle rect# of the color image ref#.

The constructed GPixmap has the same size as rectangle rect#. The pixels are initialized with colors copied from ref#.

Definition at line 200 of file GPixmap.h.

static GP<GPixmap> GPixmap::create

(

const GPixmap &

ref

)

[inline, static]

Copy constructors.

Creates a GPixmap by replicating the size and the contents of GPixmap ref#.

Definition at line 194 of file GPixmap.h.

static GP<GPixmap> GPixmap::create	(	const GBitmap &	ref,
		const GRect &	rect
	)			[inline, static]

Creates a GPixmap by copying the rectangle rect# of the gray level image ref#.

The constructed GPixmap has the same size as rectangle rect#. The pixels are initialized with shades of grays converted from the ink levels represented in ref#. This conversion depends on the number of gray levels in ref#.

Definition at line 189 of file GPixmap.h.

static GP<GPixmap> GPixmap::create

(

const GBitmap &

ref

)

[inline, static]

Creates a GPixmap by copying the gray level image ref#.

The constructed GPixmap has the same size as ref#. The pixels are initialized with shades of grays copied from ref#.

Definition at line 181 of file GPixmap.h.

static GP<GPixmap> GPixmap::create	(	const int	nrows,
		const int	ncolumns,
		const GPixel *	filler = 0
	)			[inline, static]

Creates a GPixmap with nrows# rows and ncolumns# columns.

When the optional argument filler# is specified, all pixels are initialized with the corresponding color.

Definition at line 174 of file GPixmap.h.

static GP<GPixmap> GPixmap::create

(

void

)

[inline, static]

Creates an empty GBitmap object.

The returned GPixmap has zero rows and zero columns. Use function {init} to change the size of the image.

Definition at line 169 of file GPixmap.h.

void GPixmap::destroy

(

void

)

Reimplemented from GPEnabled.

Definition at line 175 of file GPixmap.cpp.

void GPixmap::donate_data	(	GPixel *	data,
		int	w,
		int	h
	)

Identical to the above, but GPixmap will do the delete [].

Definition at line 410 of file GPixmap.cpp.

void GPixmap::downsample	(	const GPixmap *	src,
		int	factor,
		const GRect *	rect = 0
	)

Resets this GPixmap with a subsampled segment of color image src#.

This function conceptually rescales image src# by a factor #1:factor#, and copies rectangle rect# of the subsampled image into the current GPixmap. The full subsampled image is copied if rect# is a null pointer. Both operations are however performed together for efficiency reasons. Subsampling works by averaging the colors of the source pixels located in small squares of size factor# times factor#.

Definition at line 812 of file GPixmap.cpp.

void GPixmap::downsample43	(	const GPixmap *	src,
		const GRect *	rect = 0
	)

Resets this GPixmap with a rescaled segment of src# (zoom 75%).

This function conceptually rescales image src# by a factor #3:4#, and copies rectangle rect# of the rescaled image into the current GPixmap. The full rescaled image is copied if rect# is a null pointer. Both operations are however performed together for efficiency reasons. This function has been superseded by class {GPixmapScaler}.

Definition at line 1098 of file GPixmap.cpp.

int GPixmap::get_grays

(

void

)

const [inline]

Definition at line 420 of file GPixmap.h.

unsigned int GPixmap::get_memory_usage

(

void

)

const [inline]

Returns the number of bytes allocated for this image.

Definition at line 516 of file GPixmap.h.

void GPixmap::init

(

ByteStream &

ref

)

Resets the GPixmap by reading PPM data from ByteStream ref#.

See {PNM and RLE file formats} for more information.

Definition at line 463 of file GPixmap.cpp.

void GPixmap::init	(	const GBitmap &	ref,
		const GRect &	rect,
		const GPixel *	ramp = 0
	)

Resets the GPixmap by copying the rectangle rect# of the gray level image ref#.

The optional argument ramp# is an array of 256 pixel values used for mapping the gray levels to color values. Setting ramp# to zero selects a linear ramp computed according to the maximal number of gray levels in ref#.

Definition at line 335 of file GPixmap.cpp.

void GPixmap::init	(	const GBitmap &	ref,
		const GPixel *	ramp = 0
	)

Resets the GPixmap by copying the size and the contents of the gray level image ref#.

The optional argument ramp# is an array of 256 pixel values used for mapping the gray levels to color values. Setting ramp# to zero selects a linear ramp of shades of gray.

Definition at line 304 of file GPixmap.cpp.

void GPixmap::init	(	const GPixmap &	ref,
		const GRect &	rect
	)

Resets the GPixmap by copying the rectangle rect# of the color image ref#.

The previous content of the GPixmap is discarded.

Definition at line 388 of file GPixmap.cpp.

void GPixmap::init

(

const GPixmap &

ref

)

Resets the GPixmap by copying the size and the contents of the color image ref#.

The previous content of the GPixmap is discarded.

Definition at line 371 of file GPixmap.cpp.

void GPixmap::init	(	int	nrows,
		int	ncolumns,
		const GPixel *	filler = 0
	)

Resets the GPixmap to nrows# rows and ncolumns# columns.

When the optional argument filler# is specified, all pixels are initialized with the corresponding color. The previous content of the GPixmap is discarded.

Definition at line 284 of file GPixmap.cpp.

GPixmap & GPixmap::operator=

(

const GPixmap &

ref

)

[inline]

Copy operator.

Resets the GPixmap by copying the size and the contents of the color image ref#. The previous content of the GPixmap is discarded.

Definition at line 497 of file GPixmap.h.

GPixmap & GPixmap::operator=

(

const GBitmap &

ref

)

[inline]

Resets the GPixmap by copying the gray level image ref#.

The pixels are initialized with shades of grays copied from ref#.

Definition at line 490 of file GPixmap.h.

GPixel * GPixmap::operator[]

(

int

row

)

[inline]

Returns a pointer to the first GPixel in row row#.

This pointer can be used as an array to read or write the row elements.

Definition at line 476 of file GPixmap.h.

const GPixel * GPixmap::operator[]

(

int

row

)

const [inline]

Returns a constant pointer to the first GPixel in row row#.

This pointer can be used as an array to read the row elements.

Definition at line 483 of file GPixmap.h.

void GPixmap::ordered_32k_dither	(	int	xmin = 0,
		int	ymin = 0
	)

Dithers the image to 32768 colors.

This function applies an ordered dithering algorithm to reduce the image to 32768 predefined colors. These predefined colors are located on a color cube of 32x32x32 colors: the color RGB coordinates can only take values in which the three least significant bits are set to #1#. This is useful for displaying images with less than 24 bits per pixel. Arguments xmin# and ymin# control the position of the dithering grids. This is useful for dithering tiled images. Arguments xmin# and ymin# must be the position of the bottom left corner of the tile contained in this GPixmap. Properly setting these arguments eliminates dithering artifacts on the tile boundaries.

Definition at line 753 of file GPixmap.cpp.

void GPixmap::ordered_666_dither	(	int	xmin = 0,
		int	ymin = 0
	)

Dithers the image to 216 colors.

This function applies an ordered dithering algorithm to reduce the image to 216 predefined colors. These predefined colors are located on a color cube of 6x6x6 colors: the color RGB coordinates can only take the following values: #0#, #51#, #102#, #163#, #214# or #255#. This is useful for displaying images on a device supporting a maximum of 256 colors. Arguments xmin# and ymin# control the position of the dithering grids. This is useful for dithering tiled images. Arguments xmin# and ymin# must be the position of the bottom left corner of the tile contained in this GPixmap. Properly setting these arguments eliminates dithering artifacts on the tile boundaries.

Definition at line 699 of file GPixmap.cpp.

GP< GPixmap > GPixmap::rotate

(

int

count = 0

)

Rotates pixmap by 90, 180 or 270 degrees anticlockwise and returns a new pixmap, input pixmap is not changed.

count can be 1, 2, or 3 for 90, 180, 270 degree rotation. It returns the same pixmap if not rotated.

Definition at line 1604 of file GPixmap.cpp.

unsigned int GPixmap::rows

(

)

const [inline]

Returns the number of rows (the image height).

Definition at line 458 of file GPixmap.h.

unsigned int GPixmap::rowsize

(

)

const [inline]

Returns the length (in pixels) of a row in memory.

This number is equal to the difference between pointers to pixels located in the same column in consecutive rows. This difference may be larger than the number of columns in the image.

Definition at line 470 of file GPixmap.h.

void GPixmap::save_ppm	(	ByteStream &	bs,
		int	raw = 1
	)			const

Saves the image into ByteStream bs# using the PPM format.

Argument raw# selects the ``Raw PPM'' (1) or the ``Ascii PPM'' (0) format. See {PNM and RLE file formats} for more information.

Definition at line 547 of file GPixmap.cpp.

void GPixmap::set_grays

(

int

)

[inline]

Definition at line 421 of file GPixmap.h.

void GPixmap::stencil	(	const GBitmap *	bm,
		const GPixmap *	pm,
		int	pms,
		const GRect *	pmr,
		double	corr = 1.0
	)

Resample color pixmap and performs color corrected alpha blending.

This function conceptually computes an intermediate color image by first upsampling the GPixmap pm# by a factor pms:1# (see {upsample}), extracting the sub-image designated by rectangle pmr# and applying color correction corr# (see {color_correct}). This intermediate color image is then blended into this pixel map according to the alpha map bm# (see {blend}).

Definition at line 1518 of file GPixmap.cpp.

GPixel * GPixmap::take_data

(

size_t &

offset

)

Steals the memory buffer of a GPixmap.

This function returns the address of the memory buffer allocated by this GPixmap object. The offset of the first pixel in the bottom line is written into variable offset#. Other lines can be accessed using pointer arithmetic (see {rowsize}). The GPixmap object no longer ``owns'' the buffer: you must explicitly de-allocate the buffer using operator delete []#. This de-allocation should take place after the destruction or the re-initialization of the GPixmap object. This function will return a null pointer if the GPixmap object does not ``own'' the buffer in the first place.

Definition at line 421 of file GPixmap.cpp.

void GPixmap::upsample	(	const GPixmap *	src,
		int	factor,
		const GRect *	rect = 0
	)

Resets this GPixmap with a oversampled segment of color image src#.

This function conceptually rescales image src# by a factor factor:1#, and copies rectangle rect# of the oversampled image into the current GPixmap. The full oversampled image is copied if rect# is a null pointer. Both operations are however performed together for efficiency reasons. Oversampling works by replicating the color of the source pixels into squares of size factor# times factor#.

Definition at line 898 of file GPixmap.cpp.

void GPixmap::upsample23	(	const GPixmap *	src,
		const GRect *	rect = 0
	)

Resets this GPixmap with a rescaled segment of src# (zoom 150%).

This function conceptually rescales image src# by a factor #3:2# and copies rectangle rect# of the rescaled image into the current GPixmap. The full rescaled image is copied if rect# is a null pointer. Both operations are however performed together for efficiency reasons. This function has been superseded by class {GPixmapScaler}.

Definition at line 1188 of file GPixmap.cpp.

---

Member Data Documentation

unsigned short GPixmap::ncolumns [protected]

Definition at line 426 of file GPixmap.h.

unsigned short GPixmap::nrows [protected]

Definition at line 421 of file GPixmap.h.

unsigned short GPixmap::nrowsize [protected]

Definition at line 427 of file GPixmap.h.

GPixel* GPixmap::pixels [protected]

Definition at line 428 of file GPixmap.h.

GPixel* GPixmap::pixels_data [protected]

Definition at line 429 of file GPixmap.h.

---

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

• GPixmap.h
• GPixmap.cpp