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<TITLE>gd 1.3</TITLE>
</HEAD>
<BODY>
<H1>gd 1.3</H1>
<H2>A graphics library for fast GIF creation</H2>
<H2>Follow this link to the 
<A HREF="http://www.boutell.com/gd/">latest version
of this document</A>.</H2>
<H3>Table of Contents</H3>
<UL>
<LI><A HREF="#notice">Credits and license terms</A>
<LI><A HREF="#whatsnew1.3">What's new in version 1.3?</A>
<LI><A HREF="#whatis">What is gd?</A>
<LI><A HREF="#gdother">What if I want to use another programming language?</A>
<LI><A HREF="#required">What else do I need to use gd?</A>
<LI><A HREF="#getgd">How do I get gd?</A>
<LI><A HREF="#buildgd">How do I build gd?</A>
<LI><A HREF="#basics">gd basics: using gd in your program</A>
<LI><A HREF="#webgif">webgif: a useful example</A>
<LI><A HREF="#reference">Function and type reference by category</A>
<LI><A HREF="#gdformat">About the additional .gd image file format</A>
<LI><A HREF="#informing"><strong>Please</strong>
 tell us you're using gd!</A>
<LI><A HREF="#problems">If you have problems</A>
<LI><A HREF="#index">Alphabetical quick index</A>
</UL>
<P><A HREF="http://www.boutell.com/">
Up to the <EM>Boutell.Com, Inc. Home Page</EM></A>
<A NAME="notice"><H3>Credits and license terms</A></H3>
<P>
In order to resolve any possible confusion regarding the authorship
of gd, the following copyright statement covers all of the authors
who have required such a statement. <em>Although his LZW compression
code no longer appears in gd, the authors wish to thank David Rowley 
for the original LZW-based GIF compression code, which has been removed
due to patent concerns.</em> <strong>If you are aware of any oversights
in this copyright notice, please contact 
<a href="mailto:boutell@boutell.com">Thomas Boutell</a> who will be 
pleased to correct them.</strong>
<pre>
COPYRIGHT STATEMENT FOLLOWS THIS LINE
</pre>
<blockquote>
Portions copyright 1994, 1995, 1996, 1997, 1998, by Cold Spring
Harbor Laboratory. Funded under Grant P41-RR02188 by the National 
Institutes of Health.
<P>
Portions copyright 1996, 1997, 1998, by Boutell.Com, Inc.
<p>
GIF decompression code copyright 1990, 1991, 1993, by David Koblas 
(koblas@netcom.com). 
<p>
Non-LZW-based GIF compression code copyright 1998, by Hutchison Avenue 
Software Corporation (<a href="http://www.hasc.com">http://www.hasc.com/</a>, 
info@hasc.com). 
<p>
<strong>Permission has been granted to copy and distribute gd in any 
context, including a commercial application, provided that this notice 
is present in user-accessible supporting documentation.</strong>
<p>
This does not affect your ownership of the derived work itself, and the intent
is to assure proper credit for the authors of gd, not to interfere
with your productive use of gd. If you have questions, ask. 
"Derived works" includes all programs that utilize the library. 
Credit must be given in user-accessible documentation.
<p>
Permission to use, copy, modify, and distribute this software and its 
documentation for any purpose and without fee is hereby granted, provided 
that the above copyright notice appear in all copies and that both that 
copyright notice and this permission notice appear in supporting 
documentation.  This software is provided "as is" without express or 
implied warranty.
<p>
</blockquote>
<pre>
END OF COPYRIGHT STATEMENT
</pre>
<A NAME="whatis"><H3>What is gd?</H3></A>
<P>
gd is a graphics library. It allows your code to quickly
draw images complete with lines, arcs, text, multiple
colors, cut and paste from other images, and flood fills, and
write out the result as a .GIF file. This is particularly
useful in World Wide Web applications, where .GIF is the
format used for inline images.
<P>
gd is not a paint program. 
If you are looking for a paint program, you are looking in
the wrong place. If you are not a programmer, you are looking
in the wrong place.
<P>
gd does not provide for every possible desirable graphics
operation. It is not necessary or desirable for gd to become
a kitchen-sink graphics package, but version 1.3 incorporates
most of the commonly requested features for an 8-bit 2D package.
Support for scalable fonts, and truecolor images, JPEG and PNG
is planned for version 2.0. Version 1.3 was released to correct
longstanding bugs and provide an LZW-free GIF compression routine.
<P>
<A NAME="gdother"><H3>What if I want to use another programming
language?</h3></A>
<h4>Perl</h4>
gd can also be used from Perl, courtesy of
Lincoln Stein's
<a href="http://www-genome.wi.mit.edu/ftp/pub/software/WWW/GD.html">
GD.pm</a> library, which uses gd as the basis for a set of
Perl 5.x classes. GD.pm is based on gd 1.1.1 but gd 1.2 should
be compatible.
<h4>Any Language</h4>
There are, at the moment, at least three simple interpreters that
perform gd operations. You can output the desired commands to a simple
text file from whatever scripting language you prefer to use, then
invoke the interpreter.
<p>
These packages are based on gd 1.2 as of this writing but should
be compatible with gd 1.3 with minimal tweaking. 
<ul>
<li><a href="http://s27w007.pswfs.gov/tgd/">tgd</a>, by Bradley K. Sherman
<li><a href="http://www.unimelb.edu.au/fly/fly.html">fly</a>, by Martin Gleeson
</ul>
<P><A NAME="whatsnew1.2"><H3>What's new in version 1.3?</H3></A>
Version 1.3 features the following changes:
<dl>
<dt>Non-LZW-based GIF compression code
<dd>
Version 1.3 contains GIF compression code that uses simple Run Length 
Encoding instead of LZW compression, while still retaining compatibility 
with normal LZW-based GIF decoders (your browser will still like your GIFs).
<strong>LZW compression is patented by Unisys. This is why there have
been no new versions of gd for a long time. THANKS to
Hutchison Avenue Software Corporation for contributing
this code. THE NEW CODE PRODUCES LARGER GIFS AND IS NOT WELL
SUITED TO PHOTOGRAPHIC IMAGES. THIS IS A LEGAL ISSUE.
IT IS NOT A QUESTION OF TECHNICAL SKILL. PLEASE DON'T
COMPLAIN ABOUT THE SIZE OF GIF OUTPUT. THANKS!</strong>
<dt>8-bit fonts, and 8-bit font support
<dd>This improves support for European languages. Thanks are due 
to Honza Pazdziora <adelton@informatics.muni.cz> and also to 
Jan Pazdziora <adelton@fi.muni.cz>. Also see the provided bdftogd
Perl script if you wish to convert fixed-width X11 fonts
to gd fonts.
<dt>16-bit font support (no fonts provided)
<dd>Although no such fonts are provided in the distribution, 
fonts containing more than 256 characters should work if the 
gdImageString16 and gdImageStringUp16 routines are used.
<dt>Improvements to the "webgif" example/utility
<dd>The "webgif" utility is now a slightly more useful application. Thanks to
Brian Dowling for this code.
<dt>Corrections to the color resolution field of GIF output
<dd>Thanks to Bruno Aureli.
<dt>Fixed polygon fills
<dd>A one-line patch for the infamous polygon fill bug, courtesy
of Jim Mason. I believe this fix is sufficient. However, if you
find a situation where polygon fills still fail to behave properly,
please send code that demonstrates the problem, <em>and</em> a fix if
you have one. Verifying the fix is important.
<dt>Row-major, not column-major
<dd>Internally, gd now represents the array of pixels as
an array of rows of pixels, rather than an array of columns
of pixels. This improves the performance of compression and
decompression routines slightly, because horizontally adjacent
pixels are now next to each other in memory. <strong>This should
not affect properly written gd applications, but applications that
directly manipulate the <code>pixels</code> array will require
changes.</strong>
</dl>
<A NAME="required"><H3>What else do I need to use gd?</H3></A>
<P>
To use gd, you will need an ANSI C compiler. <strong>All popular 
Windows 95 and NT C compilers are ANSI C compliant.</strong> Any 
full-ANSI-standard C compiler should be adequate. <strong>The cc 
compiler released with SunOS 4.1.3 is not an ANSI C compiler. 
Most Unix users who do not already have gcc should get it.
gcc is free, ANSI compliant and a de facto industry standard.
Ask your ISP why it is missing.</strong>
<P>
You will also want a GIF viewer, if you do not already have
one for your system, since you will need a good way to check the
results of your work. Any web browser will work, but you might
be happier with a package like Lview Pro for Windows or
xv for X. There are GIF viewers available for every graphics-capable
computer out there, so consult newsgroups relevant to
your particular system.
<P>
<A NAME="getgd"><H3>How do I get gd?</H3></A>
<h4>By HTTP</h4>
<ul>
<li><a href="http://www.boutell.com/gd/http/gd1.3.tar.gz">Gzipped Tar File (Unix)</a>
<li><a href="http://www.boutell.com/gd/http/gd13.zip">.ZIP File (Windows)</a>
</ul>
<h4>By FTP</h4>
<ul>
<li><a href="ftp://ftp.boutell.com/pub/boutell/gd/gd1.3.tar.gz">Gzipped Tar File (Unix)</a>
<li><a href="ftp://ftp.boutell.com/pub/boutell/gd/gd13.zip">.ZIP File (Windows)</a>
</ul>
<P>
<A NAME="buildgd"><H3>How do I build gd?</H3></A>
<P>
In order to build gd, you must first unpack the archive you have
downloaded. If you are not familiar with <code>tar</code> and
<code>gunzip</code> (Unix) or <code>ZIP</code> (Windows), please
consult with an experienced user of your system. Sorry, we cannot
answer questions about basic Internet skills.
<p>
Unpacking the archive will produce a directory called "gd1.3".
<p>
<h4>For Unix</h4>
<code>cd</code> to the gd1.3 directory and examine the Makefile, which 
you will probably need to change slightly depending on your operating
system and your needs.
<h4>For Windows, Mac, Et Cetera</h4>
Create a project using your favorite programming environment.
Copy all of the gd files to the project directory. Add <code>gd.c</code> 
to your project. Add other source files as appropriate. Learning the
basic skills of creating projects with your chosen C environment
is up to you.
<P>
Now, to build the demonstration program, just type "make gddemo"
if you are working in a command-line environment, or build a project
that includes gddemo.c if you are using a graphical environment. If all 
goes well, the program "gddemo" will be compiled and linked without incident.
Depending on your system you may need to edit the Makefile.
Understanding the basic techniques of compiling and linking
programs on your system is up to you.
<P>
You have now built a demonstration program which shows off
the capabilities of gd. To see it in action, type
"gddemo".
<P>
gddemo should execute without incident, creating the file
demoout.gif. (Note there is also a file named demoin.gif,
which is provided in the package as part of the demonstration.)
<P>
Display demoout.gif in your GIF viewer. The image should
be 128x128 pixels and should contain an image of the
space shuttle with quite a lot of graphical elements drawn
on top of it.
<P>
(If you are missing the demoin.gif file, the other items
should appear anyway.)
<P>
Look at demoin.gif to see the original space shuttle
image which was scaled and copied into the output image.
<P>
<A NAME="basics"><H3>gd basics: using gd in your program</H3></A>
gd lets you create GIF images on the fly. To use gd in your
program, include the file gd.h, and link with the libgd.a
library produced by "make libgd.a", under Unix. Under other
operating systems you will add gd.c to your own project.
<P>
If you want to use the provided fonts, include
gdfontt.h, gdfonts.h, gdfontmb.h, gdfontl.h and/or gdfontg.h. If you 
are not using the provided Makefile and/or a library-based approach, be
sure to include the source modules as well in your
project. (They may be too large for 16-bit memory models,
that is, 16-bit DOS and Windows.)
<P>
Here is a short example program. <strong>(For a more advanced example,
see gddemo.c, included in the distribution. gddemo.c is NOT the same program; 
it demonstrates additional features!)</strong>
<P>
<PRE>
/* Bring in gd library functions */
#include "gd.h"

/* Bring in standard I/O so we can output the GIF to a file */
#include &lt;stdio.h&gt;

int main() {
	/* Declare the image */
	<A HREF="#gdImagePtr">gdImagePtr</A> im;
	/* Declare an output file */
	FILE *out;
	/* Declare color indexes */
	int black;
	int white;

	/* Allocate the image: 64 pixels across by 64 pixels tall */
	im = <A HREF="#gdImageCreate">gdImageCreate</A>(64, 64);

	/* Allocate the color black (red, green and blue all minimum).
		Since this is the first color in a new image, it will
		be the background color. */
	black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	

	/* Allocate the color white (red, green and blue all maximum). */
	white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
	
	/* Draw a line from the upper left to the lower right,
		using white color index. */
	<A HREF="#gdImageLine">gdImageLine</A>(im, 0, 0, 63, 63, white);	

	/* Open a file for writing. "wb" means "write binary", important
		under MSDOS, harmless under Unix. */
	out = fopen("test.gif", "wb");

	/* Output the image to the disk file. */
	<A HREF="#gdImageGif">gdImageGif</A>(im, out);	

	/* Close the file. */
	fclose(out);

	/* Destroy the image in memory. */
	<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
}
</PRE>
When executed, this program creates an image, allocates
two colors (the first color allocated becomes the background
color), draws a diagonal line (note that 0, 0 is the upper
left corner), writes the image to a GIF file, and
destroys the image.
<P>
The above example program should
give you an idea of how the package works.
gd provides many additional functions, which are listed
in the following reference chapters, complete with code
snippets demonstrating each. There is also an
<A HREF="#index">alphabetical index</A>. 
<H3><A NAME="webgif">Webgif: a more powerful gd example</A></H3>
Webgif is a simple utility program to manipulate GIFs from the
command line. It is written for Unix and similar command-line
systems, but should be easily adapted for other environments. 
Webgif allows you to set transparency and interlacing and
output interesting information about the GIF in question.
<P>
webgif.c is provided in the distribution. Unix users can
simply type "make webgif" to compile the program. Type
"webgif" with no arguments to see the available options.
<H2><A NAME="reference">Function and type reference</A></H2>
<UL>
<LI><A HREF="#types">Types</A></LI>
<LI><A HREF="#creating">Image creation, destruction, loading and saving</A></LI>
<LI><A HREF="#drawing">Drawing, styling, brushing, tiling and 
filling functions</A></LI>
<LI><A HREF="#query">Query functions (not color-related)</A></LI>
<LI><A HREF="#fonts">Font and text-handling functions</A></LI>
<LI><A HREF="#colors">Color handling functions</A></LI>
<LI><A HREF="#copying">Copying and resizing functions</A></LI>
<LI><A HREF="#misc">Miscellaneous Functions</A></LI>
<LI><A HREF="#constants">Constants</A></LI>
</UL>
<H3><A NAME="types">Types</A></H3>
<DL>
<DT><A NAME="gdImage"><code>gdImage</code><strong>(TYPE)</strong></A>
<DD>
The data structure in which gd stores images. <A HREF="#gdImageCreate">
gdImageCreate</A> returns
a pointer to this type, and the other functions expect to receive
a pointer to this type as their first argument. You may
read the members <code>sx</code> (size on X axis),
<code>sy</code> (size on Y axis), <code>colorsTotal</code>
(total colors), <code>red</code> (red component of colors;
an array of 256 integers between 0 and 255), <code>green</code>
(green component of colors, as above), <code>blue</code>
(blue component of colors, as above), and <code>transparent</code>
(index of transparent color, -1 if none); please do so
using the macros provided. Do NOT set the members directly
from your code; use the functions provided.
<PRE>
typedef struct {
	unsigned char ** pixels;
	int sx;
	int sy;
	int colorsTotal;
	int red[gdMaxColors];
	int green[gdMaxColors];
	int blue[gdMaxColors]; 
	int open[gdMaxColors];
	int transparent;
} gdImage;
</PRE>
<DT><A NAME="gdImagePtr">gdImagePtr</A> <strong>(TYPE)</strong>
<DD>
A pointer to an image structure. <A HREF="#gdImageCreate">gdImageCreate</A>
returns this type, and the other functions expect it as the first
argument.
<DT><A NAME="gdFont">gdFont</A> <strong>(TYPE)</strong>
<DD>
A font structure. Used to declare the characteristics of a font.
Plese see the files gdfontl.c and gdfontl.h for an example of the
proper declaration of this structure. You can provide your
own font data by providing such a structure and the associated
pixel array. You can determine the width and height of a single
character in a font by examining the w and h members of the
structure. If you will not be creating your own fonts, you will
not need to concern yourself with the rest of the components of this 
structure.
<PRE>
typedef struct {
	/* # of characters in font */
	int nchars;
	/* First character is numbered... (usually 32 = space) */
	int offset;
	/* Character width and height */
	int w;
	int h;
	/* Font data; array of characters, one row after another.
		Easily included in code, also easily loaded from
		data files. */
	char *data;
} gdFont;
</PRE>
<DT><A NAME="gdFontPtr">gdFontPtr</A> <strong>(TYPE)</strong>
<DD>
A pointer to a font structure. Text-output functions expect these
as their second argument, following the <A HREF="#gdImagePtr">
gdImagePtr</A> argument. Two such pointers are declared in the
provided include files gdfonts.h and gdfontl.h.
<DT><A NAME="gdPoint">gdPoint</A> <strong>(TYPE)</strong>
<DD>
Represents a point in the coordinate space of the image; used
by <A HREF="#gdImagePolygon">gdImagePolygon</A> and
<A HREF="#gdImageFilledPolygon">gdImageFilledPolygon</A>.
<PRE>
typedef struct {
        int x, y;
} gdPoint, *gdPointPtr;
</PRE>
<DT><A NAME="gdPointPtr">gdPointPtr</A> <strong>(TYPE)</strong>
<DD>
A pointer to a <A HREF="#gdPoint">gdPoint</A> structure; passed
as an argument to <A HREF="#gdImagePolygon">gdImagePolygon</A>
and <A HREF="#gdImageFilledPolygon">gdImageFilledPolygon</A>.
</DL>
<H3><A NAME="creating">Image creation, destruction, loading and saving</A></H3>
<DL>
<DT><A NAME="gdImageCreate">gdImageCreate(sx, sy)</A> 
<strong>(FUNCTION)</strong>
<DD>
gdImageCreate is called to create images. Invoke gdImageCreate
with the x and y dimensions of the desired image. gdImageCreate
returns a <A HREF="#gdImagePtr">gdImagePtr</A> to the new image, or 
NULL if unable to
allocate the image. The image must eventually be destroyed
using <A HREF="#gdImageDestroy">gdImageDestroy()</A>.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
im = gdImageCreate(64, 64);
/* ... Use the image ... */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageCreateFromGif">gdImageCreateFromGif(FILE *in)</A> 
<strong>(FUNCTION)</strong>
<DD>
gdImageCreateFromGif is called to load images from GIF format files. 
Invoke gdImageCreateFromGif with an already opened pointer to a file 
containing the desired image. 
gdImageCreateFromGif
returns a <A HREF="#gdImagePtr">gdImagePtr</A> to the new image, or NULL 
if unable to load the image (most often because the file is corrupt or 
does not contain a GIF image). gdImageCreateFromGif does <em>not</em>
close the file. You can inspect the sx and sy members of the
image to determine its size. The image must eventually be destroyed
using <A HREF="#gdImageDestroy">gdImageDestroy()</A>.
<PRE>
<A HREF="#gdImagePtr">gdImagePtr</A> im;
... inside a function ...
FILE *in;
in = fopen("mygif.gif", "rb");
im = gdImageCreateFromGif(in);
fclose(in);
/* ... Use the image ... */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageCreateFromGd">gdImageCreateFromGd(FILE *in)</A> 
<strong>(FUNCTION)</strong>
<DD>
gdImageCreateFromGd is called to load images from gd format files. 
Invoke gdImageCreateFromGd
with an already opened pointer to a file containing the desired image
in the <A HREF="#gdformat">gd file format</A>, which is specific to 
gd and intended for very fast loading. (It is <em>not</em> intended for 
compression; for compression, use GIF.)
gdImageCreateFromGd
returns a <A HREF="#gdImagePtr">gdImagePtr</A> to the new image, or NULL 
if unable to load the image (most often because the file is corrupt or 
does not contain a gd format image). gdImageCreateFromGd does <em>not</em>
close the file. You can inspect the sx and sy members of the
image to determine its size. The image must eventually be destroyed
using <A HREF="#gdImageDestroy">gdImageDestroy()</A>.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
FILE *in;
in = fopen("mygd.gd", "rb");
im = gdImageCreateFromGd(in);
fclose(in);
/* ... Use the image ... */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageCreateFromXbm">gdImageCreateFromXbm(FILE *in)</A> 
<strong>(FUNCTION)</strong>
<DD>
gdImageCreateFromXbm is called to load images from X bitmap format
files. Invoke gdImageCreateFromXbm
with an already opened pointer to a file containing the desired image. 
gdImageCreateFromXbm
returns a <A HREF="#gdImagePtr">gdImagePtr</A> to the new image, or NULL 
if unable to load the image (most often because the file is corrupt or 
does not contain an X bitmap format image). gdImageCreateFromXbm does 
<em>not</em> close the file. You can inspect the sx and sy members of the
image to determine its size. The image must eventually be destroyed
using <A HREF="#gdImageDestroy">gdImageDestroy()</A>.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
FILE *in;
in = fopen("myxbm.xbm", "rb");
im = gdImageCreateFromXbm(in);
fclose(in);
/* ... Use the image ... */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageDestroy">gdImageDestroy(gdImagePtr im)</A> <STRONG>(FUNCTION)</STRONG>
<DD>gdImageDestroy is used to free the memory associated with
an image. It is important to invoke gdImageDestroy before 
exiting your program or assigning a new image to
a <A HREF="#gdImagePtr">gdImagePtr</A> variable.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(10, 10);
/* ... Use the image ... */
/* Now destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageGif">
void gdImageGif(gdImagePtr im, FILE *out)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageGif outputs the specified image to the specified
file in GIF format. The file must be open for writing. Under MSDOS,
it is important to use "wb" as opposed to simply "w"
as the mode when opening the file, and under Unix there
is no penalty for doing so. gdImageGif does <em>not</em>
close the file; your code must do so.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black, white;
FILE *out;
/* Create the image */
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Allocate background */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);
/* Allocate drawing color */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);
/* Draw rectangle */
<A HREF="#gdImageRectangle">gdImageRectangle</A>(im, 0, 0, 99, 99, black);
/* Open output file in binary mode */
out = fopen("rect.gif", "wb");
/* Write GIF */
gdImageGif(im, out);
/* Close file */
fclose(out);
/* Destroy image */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageGd">
void gdImageGd(gdImagePtr im, FILE *out)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageGd outputs the specified image to the specified
file in the <A HREF="#gdformat">gd image format</A>. The file must 
be open for writing. Under MSDOS, it is important to use "wb" as 
opposed to simply "w" as the mode when opening the file, and under 
Unix there is no penalty for doing so. gdImageGif does <em>not</em>
close the file; your code must do so.
<P>
The gd image format is intended for fast reads and writes of
images your program will need frequently to build other
images. It is <em>not</em> a compressed format, and is not intended
for general use.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black, white;
FILE *out;
/* Create the image */
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Allocate background */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);
/* Allocate drawing color */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);
/* Draw rectangle */
<A HREF="#gdImageRectangle">gdImageRectangle</A>(im, 0, 0, 99, 99, black);
/* Open output file in binary mode */
out = fopen("rect.gd", "wb");
/* Write gd format file */
gdImageGd(im, out);
/* Close file */
fclose(out);
/* Destroy image */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
</DL>
<H3><A NAME="drawing">Drawing Functions</A></H3>
<DL>
<DT><A NAME="gdImageSetPixel">void gdImageSetPixel(gdImagePtr im, int x, int y, int color)</A> <STRONG>(FUNCTION)</STRONG> 
<DD>gdImageSetPixel sets a pixel to a particular color index. Always use
this function or one of the other drawing functions to access pixels;
do not access the pixels of the <A HREF="#gdImage">gdImage</A> structure 
directly.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Set a pixel near the center. */
gdImageSetPixel(im, 50, 50, white);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageLine">void gdImageLine(gdImagePtr im, int x1, int y1, int x2, int y2, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageLine is used to draw a line between two endpoints (x1,y1 and x2, y2).
The line is drawn using the color index specified. Note that the color
index can be an actual color returned by <A HREF="#gdImageColorAllocate">
gdImageColorAllocate</A> or one of <A HREF="#gdStyled">gdStyled</A>,
<A HREF="#gdBrushed">gdBrushed</A> or <A HREF="#gdStyledBrushed">
gdStyledBrushed</A>.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Draw a line from the upper left corner to the lower right corner. */
gdImageLine(im, 0, 0, 99, 99, white);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageDashedLine">void gdImageDashedLine(gdImagePtr im, int x1, int y1, int x2, int y2, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageDashedLine is provided <strong>solely for backwards compatibility
</strong> with gd 1.0. New programs should draw dashed lines using
the normal <A HREF="#gdImageLine">gdImageLine</A> function and the
new <A HREF="#gdImageSetStyle">gdImageSetStyle</A> function.
<P>
gdImageDashedLine is used to draw a dashed line between two endpoints 
(x1,y1 and x2, y2).
The line is drawn using the color index specified. The portions of the line
that are not drawn are left transparent so the background is visible.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Draw a dashed line from the upper left corner to the lower right corner. */
gdImageDashedLine(im, 0, 0, 99, 99);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImagePolygon">void gdImagePolygon(gdImagePtr im, gdPointPtr points, int pointsTotal, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImagePolygon is used to draw a polygon with the verticies
(at least 3) specified, using the color index specified. 
See also <A HREF="#gdImageFilledPolygon">gdImageFilledPolygon</A>.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
/* Points of polygon */
<A HREF="#gdPoint">gdPoint</A> points[3];
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Draw a triangle. */
points[0].x = 50;
points[0].y = 0;
points[1].x = 99;
points[1].y = 99;
points[2].x = 0;
points[2].y = 99;
gdImagePolygon(im, points, 3, white);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageRectangle">void gdImageRectangle(gdImagePtr im, int x1, int y1, int x2, int y2, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageRectangle is used to draw a rectangle with the two corners
(upper left first, then lower right) specified, using the
color index specified. 
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Draw a rectangle occupying the central area. */
gdImageRectangle(im, 25, 25, 74, 74, white);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageFilledPolygon">void gdImageFilledPolygon(gdImagePtr im, gdPointPtr points, int pointsTotal, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageFilledPolygon is used to fill a polygon with the verticies
(at least 3) specified, using the color index specified. 
See also <A HREF="#gdImageFilledPolygon">gdImagePolygon</A>.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
int red;
/* Points of polygon */
<A HREF="#gdPoint">gdPoint</A> points[3];
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Allocate the color red. */
red = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 0, 0);	
/* Draw a triangle. */
points[0].x = 50;
points[0].y = 0;
points[1].x = 99;
points[1].y = 99;
points[2].x = 0;
points[2].y = 99;
/* Paint it in white */
gdImageFilledPolygon(im, points, 3, white);
/* Outline it in red; must be done second */
<A HREF="#gdImagePolygon">gdImagePolygon</A>(im, points, 3, red);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageFilledRectangle">void gdImageFilledRectangle(gdImagePtr im, int x1, int y1, int x2, int y2, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageFilledRectangle is used to draw a solid rectangle with the two corners
(upper left first, then lower right) specified, using the
color index specified. 
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">int gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Draw a filled rectangle occupying the central area. */
gdImageFilledRectangle(im, 25, 25, 74, 74, white);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageArc">void gdImageArc(gdImagePtr im, int cx, int cy, int w, int h, int s, int e, int color)</A>
<STRONG> (FUNCTION)</STRONG> 
<DD>
gdImageArc is used to draw a partial ellipse centered at the given point,
with the specified width and height in pixels. The arc begins at
the position in degrees specified by <code>s</code> and ends at
the position specified by <code>e</code>. The arc is drawn in
the color specified by the last argument. A circle can be drawn
by beginning from 0 degrees and ending at 360 degrees, with
width and height being equal. e must be greater than s. Values greater 
than 360 are interpreted modulo 360.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 50);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Inscribe an ellipse in the image. */
gdImageArc(im, 50, 25, 98, 48, 0, 360, white);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageFillToBorder">void gdImageFillToBorder(gdImagePtr im, int x, int y, int border, int color)
<STRONG> (FUNCTION)</STRONG> 
<DD>
gdImageFillToBorder floods a portion of the image with the specified
<code>color</code>, beginning at the specified point and stopping at 
the specified <code>border</code> color. For a way of flooding an
area defined by the color of the starting point, see
<A HREF="#gdImageFill">gdImageFill</A>.
<P>
The border color <em>cannot</em> be a special color
such as <A HREF="#gdTiled">gdTiled</A>; it must be a proper
solid color. The fill color can be, however.
<P>
Note that gdImageFillToBorder is recursive. It is not the most
naive implementation possible, and the implementation is
expected to improve, but there will always be degenerate
cases in which the stack can become very deep. This can be
a problem in MSDOS and MS Windows environments. (Of course,
in a Unix or NT environment with a proper stack, this is
not a problem at all.)
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
int red;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 50);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Allocate the color red. */
red = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 0, 0);	
/* Inscribe an ellipse in the image. */
gdImageArc(im, 50, 25, 98, 48, 0, 360, white);
/* Flood-fill the ellipse. Fill color is red, border color is 
	white (ellipse). */
gdImageFillToBorder(im, 50, 50, white, red);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageFill">void gdImageFill(gdImagePtr im, int x, int y, int color)
<STRONG> (FUNCTION)</STRONG> 
<DD>
gdImageFill floods a portion of the image with the specified
<code>color</code>, beginning at the specified point and flooding the
surrounding region of the same color as the starting point.
For a way of flooding a region defined by a specific border
color rather than by its interior color, see
<A HREF="#gdImageFillToBorder">gdImageFillToBorder</A>.
<P>
The fill color can be <A HREF="#gdTiled">gdTiled</A>, resulting
in a tile fill using another image as the tile. However,
the tile image cannot be transparent. If the image you wish
to fill with has a transparent color index, call
<A HREF="#gdImageTransparent">gdImageTransparent</A> on the
tile image and set the transparent color index to -1 
to turn off its transparency.
<P>
Note that gdImageFill is recursive. It is not the most
naive implementation possible, and the implementation is
expected to improve, but there will always be degenerate
cases in which the stack can become very deep. This can be
a problem in MSDOS and MS Windows environments. (Of course,
in a Unix or NT environment with a proper stack, this is
not a problem at all.)
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
int red;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 50);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Allocate the color red. */
red = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 0, 0);	
/* Inscribe an ellipse in the image. */
gdImageArc(im, 50, 25, 98, 48, 0, 360, white);
/* Flood-fill the ellipse. Fill color is red, and will replace the
	black interior of the ellipse. */
gdImageFill(im, 50, 50, red);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageSetBrush">void gdImageSetBrush(gdImagePtr im, gdImagePtr brush)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
A "brush" is an image used to draw wide, shaped strokes in another image. Just
as a paintbrush is not a single point, a brush image need not be
a single pixel. <em>Any</em> gd image can be used as a brush, and by
setting the transparent color index of the brush image with
<A HREF="#gdImageColorTransparent">gdImageColorTransparent</A>,
a brush of any shape can be created. All line-drawing functions,
such as <A HREF="#gdImageLine">gdImageLine</A> and
<A HREF="#gdImagePolygon">gdImagePolygon</A>, will use the
current brush if the special "color" <A HREF="#gdBrushed">
gdBrushed</A> or <A HREF="#gdStyledBrushed">gdStyledBrushed</A>
is used when calling them.
<P>
gdImageSetBrush is used to specify the brush to be used in a
particular image. You can set any image to be the brush.
If the brush image does not have the same color map as the
first image, any colors missing from the first image
will be allocated. If not enough colors can be allocated,
the closest colors already available will be used. This
allows arbitrary GIFs to be used as brush images. It also
means, however, that you should not set a brush unless you
will actually use it; if you set a rapid succession of
different brush images, you can quickly fill your color map,
and the results will not be optimal.
<P>
You need not take any special action when you are finished
with a brush. As for any other image, if you will not
be using the brush image for any further purpose,
you should call <A HREF="#gdImageDestroy">gdImageDestroy</A>.
You must not use the color <A HREF="#gdBrushed">gdBrushed</A>
if the current brush has been destroyed; you can of
course set a new brush to replace it.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im, brush;
FILE *in;
int black;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Open the brush GIF. For best results, portions of the
	brush that should be transparent (ie, not part of the
	brush shape) should have the transparent color index. */
in = fopen("star.gif", "rb");
brush = <A HREF="#gdImageCreateFromGif">gdImageCreateFromGif</A>(in);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
gdImageSetBrush(im, brush);
/* Draw a line from the upper left corner to the lower right corner
	using the brush. */
<A HREF="#gdImageLine">gdImageLine</A>(im, 0, 0, 99, 99, <A HREF="#gdBrushed">gdBrushed</A>);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
/* Destroy the brush image */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(brush);
</PRE>
<DT><A NAME="gdImageSetTile">void gdImageSetTile(gdImagePtr im, gdImagePtr tile)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
A "tile" is an image used to fill an area with  a repeated pattern.
<em>Any</em> gd image can be used as a tile, and by
setting the transparent color index of the tile image with
<A HREF="#gdImageColorTransparent">gdImageColorTransparent</A>,
a tile that allows certain parts of the underlying area to shine
through can be created. All region-filling functions,
such as <A HREF="#gdImageFill">gdImageFill</A> and
<A HREF="#gdImageFilledPolygon">gdImageFilledPolygon</A>, will use the
current tile if the special "color" <A HREF="#gdTiled">
gdTiled</A> is used when calling them.
<P>
gdImageSetTile is used to specify the tile to be used in a
particular image. You can set any image to be the tile.
If the tile image does not have the same color map as the
first image, any colors missing from the first image
will be allocated. If not enough colors can be allocated,
the closest colors already available will be used. This
allows arbitrary GIFs to be used as tile images. It also
means, however, that you should not set a tile unless you
will actually use it; if you set a rapid succession of
different tile images, you can quickly fill your color map,
and the results will not be optimal.
<P>
You need not take any special action when you are finished
with a tile. As for any other image, if you will not
be using the tile image for any further purpose,
you should call <A HREF="#gdImageDestroy">gdImageDestroy</A>.
You must not use the color <A HREF="#gdBrushed">gdTiled</A>
if the current tile has been destroyed; you can of
course set a new tile to replace it.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im, tile;
FILE *in;
int black;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Open the tile GIF. For best results, portions of the
	tile that should be transparent (ie, allowing the
	background to shine through) should have the transparent 
	color index. */
in = fopen("star.gif", "rb");
tile = <A HREF="#gdImageCreateFromGif">gdImageCreateFromGif</A>(in);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
gdImageSetTile(im, tile);
/* Fill an area using the tile. */
<A HREF="#gdImageFilledRectangle">gdImageFilledRectangle</A>(im, 25, 25, 75, 75, <A HREF="#gdTiled">gdTiled</A>);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
/* Destroy the tile image */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(tile);
</PRE>
<DT><A NAME="gdImageSetStyle">void gdImageSetStyle(gdImagePtr im, int *style, int styleLength)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
It is often desirable to draw dashed lines, dotted lines, and other
variations on a broken line. gdImageSetStyle can be used to set
any desired series of colors, including a special color that
leaves the background intact, to be repeated during the drawing
of a line. 
<P>
To use gdImageSetStyle, create an array of integers and assign
them the desired series of color values to be repeated. 
You can assign the special color value <A HREF="#gdTransparent">
gdTransparent</A> to indicate that the existing color should
be left unchanged for that particular pixel (allowing a dashed
line to be attractively drawn over an existing image). 
<P>
Then, to draw a line using the style, use the normal
<A HREF="#gdImageLine">gdImageLine</A> function with the
special color value <A HREF="#gdStyled">gdStyled</A>.
<P>
As of <A HREF="#whatsnew1.1.1">version 1.1.1</A>, the style
array is copied when you set the style, so you need not
be concerned with keeping the array around indefinitely.
This should not break existing code that assumes styles
are not copied.
<P>
You can also combine styles and brushes to draw the brush
image at intervals instead of in a continuous stroke. 
When creating a style for use with a brush, the
style values are interpreted differently: zero (0) indicates
pixels at which the brush should not be drawn, while one (1) 
indicates pixels at which the brush should be drawn. 
To draw a styled, brushed line, you must use the
special color value <A HREF="#gdStyledBrushed">
gdStyledBrushed</A>. For an example of this feature
in use, see gddemo.c (provided in the distribution).
<PRE>
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int styleDotted[2], styleDashed[6];
FILE *in;
int black;
int red;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
red = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 0, 0);	
/* Set up dotted style. Leave every other pixel alone. */
styleDotted[0] = red;
styleDotted[1] = gdTransparent;
/* Set up dashed style. Three on, three off. */
styleDashed[0] = red;
styleDashed[1] = red;
styleDashed[2] = red;
styleDashed[3] = gdTransparent;
styleDashed[4] = gdTransparent;
styleDashed[5] = gdTransparent;
/* Set dotted style. Note that we have to specify how many pixels are
	in the style! */
gdImageSetStyle(im, styleDotted, 2);
/* Draw a line from the upper left corner to the lower right corner. */
<A HREF="#gdImageLine">gdImageLine</A>(im, 0, 0, 99, 99, <A HREF="#gdStyled">gdStyled</A>);
/* Now the dashed line. */
gdImageSetStyle(im, styleDashed, 6);
<A HREF="#gdImageLine">gdImageLine</A>(im, 0, 99, 0, 99, <A HREF="#gdStyled">gdStyled</A>);

/* ... Do something with the image, such as saving it to a file ... */

/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
</DL>
<H3><A NAME="query">Query Functions</A></H3>
<DL>
<DT><A NAME="gdImageBlue">
int gdImageBlue(gdImagePtr im, int color)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageBlue is a macro which returns the blue component of
the specified color index. Use this macro rather than accessing the
structure members directly.
<DT><A NAME="gdImageGetPixel">int gdImageGetPixel(gdImagePtr im, int x, int y)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageGetPixel() retrieves the color index of a particular
pixel. Always use this function to query pixels;
do not access the pixels of the <A HREF="#gdImage">gdImage</A> structure 
directly.
<PRE>
... inside a function ...
FILE *in;
gdImagePtr im;
int c;
in = fopen("mygif.gif", "rb");
im = <A HREF="#gdImageCreateFromGif">gdImageCreateFromGif</A>(in);
fclose(in);
c = gdImageGetPixel(im, gdImageSX(im) / 2, gdImageSY(im) / 2);
printf("The value of the center pixel is %d; RGB values are %d,%d,%d\n",
	c, im->red[c], im->green[c], im->blue[c]);
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>	
<DT><A NAME="gdImageBoundsSafe">
int gdImageBoundsSafe(gdImagePtr im, int x, int y)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageBoundsSafe returns true (1) if the specified point is within the bounds
of the image, false (0) if not. This function is intended primarily for 
use by those who wish to add functions to gd. All of the gd drawing 
functions already clip safely to the edges of the image.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
if (gdImageBoundsSafe(im, 50, 50)) {
	printf("50, 50 is within the image bounds\n");
} else {
	printf("50, 50 is outside the image bounds\n");
}
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageGreen">
int gdImageGreen(gdImagePtr im, int color)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageGreen is a macro which returns the green component of
the specified color index. Use this macro rather than accessing the
structure members directly.
<DT><A NAME="gdImageRed">
int gdImageRed(gdImagePtr im, int color)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageRed is a macro which returns the red component of
the specified color index. Use this macro rather than accessing the
structure members directly.
<DT><A NAME="gdImageSX">
int gdImageSX(gdImagePtr im)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageSX is a macro which returns the width of the image
in pixels. Use this macro rather than accessing the
structure members directly.
<DT><A NAME="gdImageSY">
int gdImageSY(gdImagePtr im)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageSY is a macro which returns the height of the image
in pixels. Use this macro rather than accessing the
structure members directly.
</DL>
<H3><A NAME="fonts">Fonts and text-handling functions</A></H3>
<DL>
<DT><A NAME="gdImageChar">
void gdImageChar(gdImagePtr im, gdFontPtr font, int x, int y, 
	int c, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageChar is used to draw single characters on the image.
(To draw multiple characters, use <A HREF="#gdImageString">
gdImageString</A> or <A HREF="#gdImageString16">
gdImageString16</A>.) The second argument is a
pointer to a font definition structure; five fonts are
provided with gd, gdFontTiny, gdFontSmall, gdFontMediumBold,
gdFontLarge, and gdFontGiant. You must
include the files "gdfontt.h", "gdfonts.h", "gdfontmb.h",
"gdfontl.h" and "gdfontg.h" respectively
and (if you are not using a library-based approach) link with the 
corresponding .c files to use the provided fonts.
The character specified by the fifth
argument is drawn from left to right in the specified 
color. (See <A HREF="#gdImageCharUp">gdImageCharUp</A> for a way
of drawing vertical text.) Pixels not
set by a particular character retain their previous color. 
<PRE>
#include "gd.h"
#include "gdfontl.h"
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Draw a character. */
gdImageChar(im, gdFontLarge, 0, 0, 'Q', white);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageCharUp">
void gdImageCharUp(gdImagePtr im, gdFontPtr font, int x, int y, 
int c, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageCharUp is used to draw single characters on the image,
rotated 90 degrees.
(To draw multiple characters, use <A HREF="#gdImageStringUp">
gdImageStringUp</A> or <A HREF="#gdImageStringUp16">
gdImageStringUp16</A>.) The second argument is a
pointer to a font definition structure; five fonts are
provided with gd, gdFontTiny, gdFontSmall, gdFontMediumBold,
gdFontLarge, and gdFontGiant. You must
include the files "gdfontt.h", "gdfonts.h", "gdfontmb.h",
"gdfontl.h" and "gdfontg.h" respectively
and (if you are not using a library-based approach) link with the 
corresponding .c files to use the provided fonts. The character specified by 
the fifth argument is drawn 
from bottom to top, rotated at a 90-degree angle,  in the specified 
color.  (See <A HREF="#gdImageChar">gdImageChar</A> for a way
of drawing horizontal text.)  Pixels not
set by a particular character retain their previous color. 
<PRE>
#include "gd.h"
#include "gdfontl.h"
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Draw a character upwards so it rests against the top of the image. */
gdImageCharUp(im, gdFontLarge, 
	0, gdFontLarge->h, 'Q', white);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageString">
void gdImageString(gdImagePtr im, gdFontPtr font, int x, int y, 
unsigned char *s, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageString is used to draw multiple characters on the image.
(To draw single characters, use <A HREF="#gdImageChar">
gdImageChar</A>.) The second argument is a
pointer to a font definition structure; five fonts are
provided with gd, gdFontTiny, gdFontSmall, gdFontMediumBold,
gdFontLarge, and gdFontGiant. You must
include the files "gdfontt.h", "gdfonts.h", "gdfontmb.h",
"gdfontl.h" and "gdfontg.h" respectively
and (if you are not using a library-based approach) link with the 
corresponding .c files to use the provided fonts.
The null-terminated C string specified
by the fifth argument is drawn from left to right in the specified 
color.  (See <A HREF="#gdImageStringUp">gdImageStringUp</A> for a way
of drawing vertical text.)  Pixels not
set by a particular character retain their previous color. 
<PRE>
#include "gd.h"
#include "gdfontl.h"
#include &lt;string.h&gt;
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
/* String to draw. */
char *s = "Hello.";
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Draw a centered string. */
gdImageString(im, gdFontLarge,
	im->w / 2 - (strlen(s) * gdFontLarge->w / 2),
	im->h / 2 - gdFontLarge->h / 2,
	s, white);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageString16">
void gdImageString16(gdImagePtr im, gdFontPtr font, int x, int y, 
unsigned short *s, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageString is used to draw multiple 16-bit characters on the image.
(To draw single characters, use <A HREF="#gdImageChar">
gdImageChar</A>.) The second argument is a
pointer to a font definition structure; five fonts are
provided with gd, gdFontTiny, gdFontSmall, gdFontMediumBold,
gdFontLarge, and gdFontGiant. You must
include the files "gdfontt.h", "gdfonts.h", "gdfontmb.h",
"gdfontl.h" and "gdfontg.h" respectively
and (if you are not using a library-based approach) link with the 
corresponding .c files to use the provided fonts.
The null-terminated string of characters represented as 16-bit unsigned 
short integers specified by the fifth argument is drawn from left to right 
in the specified 
color.  (See <A HREF="#gdImageStringUp16">gdImageStringUp16</A> for a way
of drawing vertical text.)  Pixels not
set by a particular character retain their previous color. 
<p>
This function was added in gd1.3 to provide a means of rendering
fonts with more than 256 characters for those who have them. A
more frequently used routine is <a href="#gdImageString">gdImageString</a>.
<DT><A NAME="gdImageStringUp">
void gdImageStringUp(gdImagePtr im, gdFontPtr font, int x, int y, 
unsigned char *s, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageStringUp is used to draw multiple characters on the image,
rotated 90 degrees.
(To draw single characters, use <A HREF="#gdImageCharUp">
gdImageCharUp</A>.) The second argument is a
pointer to a font definition structure; five fonts are
provided with gd, gdFontTiny, gdFontSmall, gdFontMediumBold,
gdFontLarge, and gdFontGiant. You must
include the files "gdfontt.h", "gdfonts.h", "gdfontmb.h",
"gdfontl.h" and "gdfontg.h" respectively
and (if you are not using a library-based approach) link with the 
corresponding .c files to use the provided fonts.The null-terminated C string specified
by the fifth argument is drawn from bottom to top (rotated
90 degrees) in the specified color.  (See 
<A HREF="#gdImageString">gdImageString</A> for a way
of drawing horizontal text.)  Pixels not
set by a particular character retain their previous color. 
<PRE>
#include "gd.h"
#include "gdfontl.h"
#include &lt;string.h&gt;
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int white;
/* String to draw. */
char *s = "Hello.";
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color white (red, green and blue all maximum). */
white = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 255, 255);	
/* Draw a centered string going upwards. Axes are reversed,
	and Y axis is decreasing as the string is drawn. */
gdImageStringUp(im, gdFontLarge,
	im->w / 2 - gdFontLarge->h / 2,
	im->h / 2 + (strlen(s) * gdFontLarge->w / 2),
	s, white);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageStringUp16">
void gdImageStringUp16(gdImagePtr im, gdFontPtr font, int x, int y, 
unsigned short *s, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageString is used to draw multiple 16-bit characters vertically on 
the image. (To draw single characters, use <A HREF="#gdImageChar">
gdImageChar</A>.) The second argument is a
pointer to a font definition structure; five fonts are
provided with gd, gdFontTiny, gdFontSmall, gdFontMediumBold,
gdFontLarge, and gdFontGiant. You must
include the files "gdfontt.h", "gdfonts.h", "gdfontmb.h",
"gdfontl.h" and "gdfontg.h" respectively
and (if you are not using a library-based approach) link with the 
corresponding .c files to use the provided fonts.
The null-terminated string of characters represented as 16-bit unsigned 
short integers specified by the fifth argument is drawn from bottom to top
in the specified color.  
(See <A HREF="#gdImageStringUp16">gdImageStringUp16</A> for a way
of drawing horizontal text.)  Pixels not
set by a particular character retain their previous color. 
<p>
This function was added in gd1.3 to provide a means of rendering
fonts with more than 256 characters for those who have them. A
more frequently used routine is <a href="#gdImageStringUp">gdImageStringUp</a>.</DL>
<H3><A NAME="colors">Color-handling functions</A></H3>
<DL>
<DT><A NAME="gdImageColorAllocate">
int gdImageColorAllocate(gdImagePtr im, int r, int g, int b)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageColorAllocate finds the first available color index in
the image specified, sets its RGB values to those requested
(255 is the maximum for each),
and returns the index of the new color table entry. When
creating a new image, the first time you invoke this function,
you are setting the background color for that image.
<P>
In the event that all <A HREF="#gdMaxColors">gdMaxColors</A> colors
(256) have already been allocated, gdImageColorAllocate will
return -1 to indicate failure. (This is not uncommon when
working with existing GIF files that already use 256 colors.)
Note that gdImageColorAllocate
does not check for existing colors that match your request;
see <A HREF="#gdImageColorExact">gdImageColorExact</A>
and <A HREF="#gdImageColorClosest">gdImageColorClosest</A>
for ways to locate existing colors that approximate the
color desired in situations where a new color is not available.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
int red;
im = <A HREF="#gdImageCreate">gdImageCreate</A>(100, 100);
/* Background color (first allocated) */
black = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 0, 0, 0);	
/* Allocate the color red. */
red = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 0, 0);	
/* Draw a dashed line from the upper left corner to the lower right corner. */
gdImageDashedLine(im, 0, 0, 99, 99, red);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageColorClosest">
int gdImageColorClosest(gdImagePtr im, int r, int g, int b)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageColorClosest searches the colors which have been
defined thus far in the image specified and returns the
index of the color with RGB values closest to those of the
request. (Closeness is determined by Euclidian distance,
which is used to determine the distance in three-dimensional color 
space between colors.)
<P>
If no colors have yet been allocated in the image,
gdImageColorClosest returns -1.
<P>
This function is most useful as a backup method for choosing
a drawing color when an image already contains
<A HREF="#gdMaxColors">gdMaxColors</A> (256) colors and
no more can be allocated. (This is not uncommon when
working with existing GIF files that already use many colors.)
See <A HREF="#gdImageColorExact">gdImageColorExact</A>
for a method of locating exact matches only.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
FILE *in;
int red;
/* Let's suppose that photo.gif is a scanned photograph with
	many colors. */
in = fopen("photo.gif", "rb");
im = <A HREF="#gdImageCreateFromGif">gdImageCreateFromGif</A>(in);
fclose(in);
/* Try to allocate red directly */
red = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 0, 0);	
/* If we fail to allocate red... */
if (red == (-1)) {
	/* Find the <em>closest</em> color instead. */
	red = gdImageColorClosest(im, 255, 0, 0);
}
/* Draw a dashed line from the upper left corner to the lower right corner */
gdImageDashedLine(im, 0, 0, 99, 99, red);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageColorExact">
int gdImageColorExact(gdImagePtr im, int r, int g, int b)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageColorExact searches the colors which have been
defined thus far in the image specified and returns the
index of the first color with RGB values which exactly
match those of the request. If no allocated color matches the
request precisely, gdImageColorExact returns -1.
See <A HREF="#gdImageColorClosest">gdImageColorClosest</A>
for a way to find the color closest to the color requested.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int red;
in = fopen("photo.gif", "rb");
im = <A HREF="#gdImageCreateFromGif">gdImageCreateFromGif</A>(in);
fclose(in);
/* The image may already contain red; if it does, we'll save a slot
	in the color table by using that color. */
/* Try to allocate red directly */
red = gdImageColorExact(im, 255, 0, 0);
/* If red isn't already present... */
if (red == (-1)) {
	/* Second best: try to allocate it directly. */
	red = <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>(im, 255, 0, 0);	
	/* Out of colors, so find the <em>closest</em> color instead. */
	red = gdImageColorClosest(im, 255, 0, 0);
}
/* Draw a dashed line from the upper left corner to the lower right corner */
gdImageDashedLine(im, 0, 0, 99, 99, red);
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageColorsTotal">
int gdImageColorsTotal(gdImagePtr im)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageColorsTotal is a macro which returns the number of
colors currently allocated in the image. Use this macro
to obtain this information; do not access the structure
directly.
<DT><A NAME="gdImageColorRed">
int gdImageColorRed(gdImagePtr im, int c)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageColorRed is a macro which returns the red portion
of the specified color in the image. Use this macro
to obtain this information; do not access the structure
directly.
<DT><A NAME="gdImageColorGreen">
int gdImageColorGreen(gdImagePtr im, int c)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageColorGreen is a macro which returns the green portion
of the specified color in the image. Use this macro
to obtain this information; do not access the structure
directly.
<DT><A NAME="gdImageColorBlue">
int gdImageColorBlue(gdImagePtr im, int c)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageColorBlue is a macro which returns the green portion
of the specified color in the image. Use this macro
to obtain this information; do not access the structure
directly.
<DT><A NAME="gdImageGetInterlaced">
int gdImageGetInterlaced(gdImagePtr im)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageGetInterlaced is a macro which returns true (1)
if the image is interlaced, false (0) if not.
Use this macro to obtain this information; do not 
access the structure directly.
See <A NAME="gdImageInterlace">gdImageInterlace</A> for
a means of interlacing images.
<DT><A NAME="gdImageGetTransparent">
int gdImageGetTransparent(gdImagePtr im)</A>
<STRONG>(MACRO)</STRONG> 
<DD>
gdImageGetTransparent is a macro which returns the 
current transparent color index in the image.
If there is no transparent color, gdImageGetTransparent
returns -1. Use this macro to obtain this information; do not 
access the structure directly.
<DT><A NAME="gdImageColorDeallocate">
void gdImageColorDeallocate(gdImagePtr im, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageColorDeallocate marks the specified color as being
available for reuse. It does not attempt to determine whether
the color index is still in use in the image. After a call
to this function, the next call to 
<A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>
for the same image will set new RGB values for that
color index, changing the color of any pixels which 
have that index as a result. If multiple calls to
gdImageColorDeallocate are made consecutively, the lowest-numbered
index among them will be reused by the next 
<A HREF="#gdImageColorAllocate"> gdImageColorAllocate</A> call.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int red, blue;
in = fopen("photo.gif", "rb");
im = <A HREF="#gdImageCreateFromGif">gdImageCreateFromGif</A>(in);
fclose(in);
/* Look for red in the color table. */
red = gdImageColorExact(im, 255, 0, 0);
/* If red is present... */
if (red != (-1)) {
	/* Deallocate it. */
	gdImageColorDeallocate(im, red);
	/* Allocate blue, reusing slot in table.
		Existing red pixels will change color. */
	blue = gdImageColorAllocate(im, 0, 0, 255);
} 
/* ... Do something with the image, such as saving it to a file... */
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
<DT><A NAME="gdImageColorTransparent">
void gdImageColorTransparent(gdImagePtr im, int color)</A>
<STRONG>(FUNCTION)</STRONG> 
<DD>
gdImageColorTransparent sets the transparent color index
for the specified image to the specified index. To indicate
that there should be <em>no</em> transparent color, invoke
gdImageColorTransparent with a color index of -1.
<P>
The color index used should be an index
allocated by <A HREF="#gdImageColorAllocate">gdImageColorAllocate</A>,
whether explicitly invoked by your code or implicitly
invoked by loading an image.
In order to ensure that your image has a reasonable appearance
when viewed by users who do not have transparent background
capabilities, be sure to give reasonable RGB values to the
color you allocate for use as a transparent color,
<em>even though it will be transparent on systems
that support transparency</em>.
<PRE>
... inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im;
int black;
FILE *in, *out;
in = fopen("photo.gif", "rb");
im = <A HREF="#gdImageCreateFromGif">gdImageCreateFromGif</A>(in);
fclose(in);
/* Look for black in the color table and make it transparent. */
black = <A HREF="#gdImageColorExact">gdImageColorExact</A>(im, 0, 0, 0);
/* If black is present... */
if (black != (-1)) {
	/* Make it transparent */
	gdImageColorTransparent(im, black);
} 
/* Save the newly-transparent image back to the file */
out = fopen("photo.gif", "wb");
<A HREF="#gdImageGif">gdImageGif</A>(im, out);
fclose(out);
/* Destroy it */
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
</DL>
<H3><A NAME="copying">Copying and resizing functions</A></H3>
<DL>
<DT><A NAME="gdImageCopy">void gdImageCopy(gdImagePtr dst, gdImagePtr src, int dstX, int dstY, int srcX, int srcY, int w, int h)
<STRONG> (FUNCTION)</STRONG> 
<DD>
gdImageCopy is used to copy a rectangular portion of one image to
another image. (For a way of stretching or shrinking the image
in the process, see <A HREF="#gdImageCopyResized">
gdImageCopyResized</A>.)
<P>
The <code>dst</code> argument is the destination image to which the
region will be copied. The <code>src</code> argument is the source
image from which the region is copied. The <code>dstX</code>
and <code>dstY</code> arguments specify the point in the destination
image to which the region will be copied. The <code>srcX</code>
and <code>srcY</code> arguments specify the upper left corner
of the region in the source image. The <code>w</code>
and <code>h</code> arguments specify the width and height
of the region.
<P>
When you copy a region from one location in an image to another
location in the same image, gdImageCopy will perform as expected
unless the regions overlap, in which case the result is
unpredictable.
<P>
<strong>Important note on copying between images:</strong> since 
different images do 
not necessarily have the same color tables, pixels are not simply set to the
same color index values to copy them. gdImageCopy will attempt
to find an identical RGB value in the destination image for
each pixel in the copied portion of the source image by
invoking <A HREF="#gdImageColorExact">gdImageColorExact</A>. If
such a value is not found, gdImageCopy will attempt to
allocate colors as needed using <A HREF="#gdImageColorAllocate">
gdImageColorAllocate</A>. If both of these methods fail,
gdImageCopy will invoke <A HREF="#gdImageColorClosest">
gdImageColorClosest</A> to find the color in the destination
image which most closely approximates the color of the
pixel being copied.
<PRE>
... Inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im_in;
<A HREF="#gdImagePtr">gdImagePtr</A> im_out;
int x, y;
FILE *in;
FILE *out;
/* Load a small gif to tile the larger one with */
in = fopen("small.gif", "rb");
im_in = <A HREF="#gdImageCreateFromGif">gdImageCreateFromGif</A>(in);
fclose(in);
/* Make the output image four times as large on both axes */
im_out = <A HREF="#gdImageCreate">gdImageCreate</A>(im_in->sx * 4, im_in->sy * 4); 
/* Now tile the larger image using the smaller one */
for (y = 0; (y < 4); y++) {
	for (x = 0; (x < 4); x++) {
		gdImageCopy(im_out, im_in, 
			x * im_in->sx, y * im_in->sy,
			0, 0,
			im_in->sx, im_in->sy);
	}
}
out = fopen("tiled.gif", "wb");
<A HREF="#gdImageGif">gdImageGif</A>(im_out, out);
fclose(out);
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im_in);
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im_out);
</PRE>
<DT><A NAME="gdImageCopyResized">void gdImageCopyResized(gdImagePtr dst, gdImagePtr src, int dstX, int dstY, int srcX, int srcY, int destW, int destH, int srcW, int srcH)
<STRONG> (FUNCTION)</STRONG> 
<DD>
gdImageCopyResized is used to copy a rectangular portion of one image to
another image. The X and Y dimensions of the original region and the
destination region can vary, resulting in stretching or shrinking of
the region as appropriate. (For a simpler version of this function
which does not deal with resizing, see <A HREF="#gdImageCopy">
gdImageCopy</A>.)
<P>
The <code>dst</code> argument is the destination image to which the
region will be copied. The <code>src</code> argument is the source
image from which the region is copied. The <code>dstX</code>
and <code>dstY</code> arguments specify the point in the destination
image to which the region will be copied. The <code>srcX</code>
and <code>srcY</code> arguments specify the upper left corner
of the region in the source image. The <code>dstW</code>
and <code>dstH</code> arguments specify the width and height
of the destination region. The <code>srcW</code>
and <code>srcH</code> arguments specify the width and height
of the source region and can differ from the destination size,
allowing a region to be scaled during the copying process.
<P>
When you copy a region from one location in an image to another
location in the same image, gdImageCopy will perform as expected
unless the regions overlap, in which case the result is
unpredictable. If this presents a problem, create a scratch image
in which to keep intermediate results.
<P>
<strong>Important note on copying between images:</strong> since images 
do not necessarily have the same color tables, pixels are not simply set 
to the same color index values to copy them. gdImageCopy will attempt
to find an identical RGB value in the destination image for
each pixel in the copied portion of the source image by
invoking <A HREF="#gdImageColorExact">gdImageColorExact</A>. If
such a value is not found, gdImageCopy will attempt to
allocate colors as needed using <A HREF="#gdImageColorAllocate">
gdImageColorAllocate</A>. If both of these methods fail,
gdImageCopy will invoke <A HREF="#gdImageColorClosest">
gdImageColorClosest</A> to find the color in the destination
image which most closely approximates the color of the
pixel being copied.
<PRE>
... Inside a function ...
<A HREF="#gdImagePtr">gdImagePtr</A> im_in;
<A HREF="#gdImagePtr">gdImagePtr</A> im_out;
int x, y;
FILE *in;
FILE *out;
/* Load a small gif to expand in the larger one */
in = fopen("small.gif", "rb");
im_in = <A HREF="#gdImageCreateFromGif">gdImageCreateFromGif</A>(in);
fclose(in);
/* Make the output image four times as large on both axes */
im_out = <A HREF="#gdImageCreate">gdImageCreate</A>(im_in->sx * 4, im_in->sy * 4); 
/* Now copy the smaller image, but four times larger */
gdImageCopyResized(im_out, im_in, 0, 0, 0, 0, 
	im_out->sx, im_out->sy,
	im_in->sx, im_in->sy);	 
out = fopen("large.gif", "wb");
<A HREF="#gdImageGif">gdImageGif</A>(im_out, out);
fclose(out);
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im_in);
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im_out);
</PRE>
</DL>
<H3><A NAME="misc">Miscellaneous Functions</A></H3>
<DL>
<DT><A NAME="gdImageInterlace">gdImageInterlace(gdImagePtr im, int interlace)</A> <strong>(FUNCTION)</strong>
<DD>
gdImageInterlace is used to determine whether an image should be stored
in a linear fashion, in which lines will appear on the display from
first to last, or in an interlaced fashion, in which the image
will "fade in" over several passes. By default, images are not
interlaced. 
<P>
A nonzero value for the interlace argument turns on interlace;
a zero value turns it off. Note that interlace has no effect
on other functions, and has no meaning unless you save the
image in GIF format; the gd and xbm formats do not support
interlace. 
<P>
When a GIF is loaded with <A HREF="#gdImageCreateFromGif">gdImageCreateFromGif
</A>, interlace will be set according to the setting in the GIF file.
<P>
Note that many GIF viewers and web browsers do <em>not</em> support
interlace. However, the interlaced GIF should still display; it
will simply appear all at once, just as other images do.
<PRE>
gdImagePtr im;
FILE *out;
/* ... Create or load the image... */

/* Now turn on interlace */
gdImageInterlace(im, 1); 
/* And open an output file */
out = fopen("test.gif", "wb");
/* And save the image */
<A HREF="#gdImageGif">gdImageGif</A>(im, out);
fclose(out);
<A HREF="#gdImageDestroy">gdImageDestroy</A>(im);
</PRE>
</DL>
<H3><A NAME="constants">Constants</A></H3>
<DL>
<DT><A NAME="gdBrushed">gdBrushed</A> <strong>(CONSTANT)</strong>
<DD>
Used in place of a color when invoking a line-drawing
function such as <A HREF="#gdImageLine">gdImageLine</A>
or <A HREF="#gdImageRectangle">gdImageRectangle</A>.
When gdBrushed is used as the color, the brush
image set with <A HREF="#gdImageSetBrush">gdImageSetBrush</A>
is drawn in place of each pixel of the line (the brush is
usually larger than one pixel, creating the effect
of a wide paintbrush). See also
<A HREF="#gdStyledBrushed">gdStyledBrushed</A> for a way
to draw broken lines with a series of distinct copies of an image.
<DT><A NAME="gdMaxColors"><code>gdMaxColors</code><strong>(CONSTANT)</strong>
<DD>
The constant 256. This is the maximum number of colors in a GIF file
according to the GIF standard, and is also the maximum number of
colors in a gd image.
<DT><A NAME="gdStyled">gdStyled</A> <strong>(CONSTANT)</strong>
<DD>
Used in place of a color when invoking a line-drawing
function such as <A HREF="#gdImageLine">gdImageLine</A>
or <A HREF="#gdImageRectangle">gdImageRectangle</A>.
When gdStyled is used as the color, the colors of the pixels are
drawn successively from the style that has been
set with <A HREF="#gdImageSetStyle">gdImageSetStyle</A>.
If the color of a pixel is equal to 
<A HREF="#gdTransparent">gdTransparent</A>, that pixel
is not altered. (This mechanism is completely unrelated
to the "transparent color" of the image itself; see
<A HREF="#gdImageColorTransparent">gdImageColorTransparent</A>
gdImageColorTransparent for that mechanism.) See also 
<A NAME="#gdStyledBrushed"> gdStyledBrushed</A>.
<DT><A NAME="gdStyledBrushed">gdStyledBrushed</A> <strong>(CONSTANT)</strong>
<DD>
Used in place of a color when invoking a line-drawing
function such as <A HREF="#gdImageLine">gdImageLine</A>
or <A HREF="#gdImageRectangle">gdImageRectangle</A>.
When gdStyledBrushed is used as the color, the brush
image set with <A HREF="#gdImageSetBrush">gdImageSetBrush</A>
is drawn at each pixel of the line, providing that the
style set with <A HREF="#gdImageSetStyle">gdImageSetStyle</A>
contains a nonzero value (OR gdTransparent, which
does not equal zero but is supported for consistency) 
for the current pixel. (Pixels are drawn successively from the style as the
line is drawn, returning to the beginning when the
available pixels in the style are exhausted.) Note that
this differs from the behavior of <A HREF="#gdStyled">gdStyled</A>,
in which the values in the style are used as actual
pixel colors, except for gdTransparent.
<DT><A NAME="gdDashSize">gdDashSize</A> <strong>(CONSTANT)</strong>
<DD>
The length of a dash in a dashed line. Defined to be 4 for
backwards compatibility with programs that use
<A NAME="gdImageDashedLine">gdImageDashedLine</A>. New
programs should use <A NAME="gdImageSetStyle">
gdImageSetStyle</A> and call the standard
<A NAME="gdImageLine">gdImageLine</A> function
with the special "color" <A NAME="gdStyled">
gdStyled</A> or <A NAME="gdStyledBrushed">gdStyledBrushed</A>.
<DT><A NAME="gdTiled">gdTiled</A> <strong>(CONSTANT)</strong>
<DD>
Used in place of a normal color in <A HREF="#gdImageFilledRectangle">
gdImageFilledRectangle</A>, <A HREF="#gdImageFilledPolygon">
gdImageFilledPolygon</A>,
<A HREF="#gdImageFill">gdImageFill</A>, and <A HREF="#gdImageFillToBorder">
gdImageFillToBorder</A>. gdTiled selects a pixel from the
tile image set with <A HREF="#gdImageSetTile">gdImageSetTile</A>
in such a way as to ensure that the filled area will be
tiled with copies of the tile image. See the discussions of
<A HREF="#gdImageFill">gdImageFill</A> and
<A HREF="#gdImageFillToBorder">gdImageFillToBorder</A> for special
restrictions regarding those functions.
<DT><A NAME="gdTransparent">gdTransparent</A> <strong>(CONSTANT)</strong>
<DD>
Used in place of a normal color in a style to be set with
<A HREF="#gdImageSetStyle">gdImageSetStyle</A>. 
gdTransparent is <strong>not</strong> the transparent
color index of the image; for that functionality please
see <A HREF="gdImageColorTransparent">gdImageColorTransparent</A>.
</DL>
<A NAME="gdformat"><H3>About the additional .gd image file format</H3></A>
In addition to reading and writing the GIF format and reading the
X Bitmap format, gd has the capability to read and write its
own ".gd" format. This format is <em>not</em> intended for
general purpose use and should never be used to distribute
images. It is not a compressed format. Its purpose is solely to 
allow very fast loading of images your program needs often in
order to build other images for output. If you are experiencing
performance problems when loading large, fixed GIF images your
program needs to produce its output images, you may wish
to examine the functions <A HREF="#gdImageCreateFromGd">
gdImageCreateFromGd</A> and <A HREF="#gdImageGd">gdImageGd</A>,
which read and write .gd format images.
<P>
The program "giftogd.c" is provided as a simple way of converting
.gif files to .gd format. I emphasize again that you will not
need to use this format unless you have a need for high-speed loading
of a few frequently-used images in your program.
<A NAME="informing"><H3>Please tell us you're using gd!</H3>
When you contact us and let us know you are using gd,
you help us justify the time spent in maintaining and improving
it. So please let us know. If the results are publicly
visible on the web, a URL is a wonderful thing to receive, but
if it's not a publicly visible project, a simple note is just 
as welcome.
<A NAME="problems"><H3>If you have problems</H3></A>
If you have any difficulties with gd, feel free to contact
the author, <A HREF="http://www.boutell.com/boutell/">Thomas Boutell</A>. 
Be sure to read this manual carefully first.
<H3><A NAME="index">Alphabetical quick index</A></H3>
<A HREF="#gdBrushed">gdBrushed</A> |
<A HREF="#gdDashSize">gdDashSize</A> | 
<A HREF="#gdFont">gdFont</A> | 
<A HREF="#gdFontPtr">gdFontPtr</A> | 
<A HREF="#gdImage">gdImage</A> | 
<A HREF="#gdImageArc">gdImageArc</A> | 
<A HREF="#gdImageBlue">gdImageBlue</A> |
<A HREF="#gdImageBoundsSafe">gdImageBoundsSafe</A> | 
<A HREF="#gdImageChar">gdImageChar</A> | 
<A HREF="#gdImageCharUp">gdImageCharUp</A> | 
<A HREF="#gdImageColorAllocate">gdImageColorAllocate</A> | 
<A HREF="#gdImageColorClosest">gdImageColorClosest</A> | 
<A HREF="#gdImageColorDeallocate">gdImageColorDeallocate</A> | 
<A HREF="#gdImageColorExact">gdImageColorExact</A> | 
<A HREF="#gdImageColorTransparent">gdImageColorTransparent</A> | 
<A HREF="#gdImageCopy">gdImageCopy</A> | 
<A HREF="#gdImageCopyResized">gdImageCopyResized</A> | 
<A HREF="#gdImageCreate">gdImageCreate</A> | 
<A HREF="#gdImageCreateFromGd">gdImageCreateFromGd</A> | 
<A HREF="#gdImageCreateFromGif">gdImageCreateFromGif</A> | 
<A HREF="#gdImageCreateFromXbm">gdImageCreateFromXbm</A> | 
<A HREF="#gdImageDashedLine">gdImageDashedLine</A> | 
<A HREF="#gdImageDestroy">gdImageDestroy</A> | 
<A HREF="#gdImageFill">gdImageFill</A> | 
<A HREF="#gdImageFillToBorder">gdImageFillToBorder</A> | 
<A HREF="#gdImageFilledRectangle">gdImageFilledRectangle</A> | 
<A HREF="#gdImageGd">gdImageGd</A> | 
<A HREF="#gdImageGetInterlaced">gdImageGetInterlaced</A> |
<A HREF="#gdImageGetPixel">gdImageGetPixel</A> | 
<A HREF="#gdImageGetTransparent">gdImageGetTransparent</A> |
<A HREF="#gdImageGif">gdImageGif</A> | 
<A HREF="#gdImageGreen">gdImageGreen</A> |
<A HREF="#gdImageInterlace">gdImageInterlace</A> |
<A HREF="#gdImageLine">gdImageLine</A> | 
<A HREF="#gdImageFilledPolygon">gdImageFilledPolygon</A> |
<A HREF="#gdImagePolygon">gdImagePolygon</A> |
<A HREF="#gdImagePtr">gdImagePtr</A> | 
<A HREF="#gdImageRectangle">gdImageRectangle</A> | 
<A HREF="#gdImageRed">gdImageRed</A> |
<A HREF="#gdImageSetBrush">gdImageSetBrush</A> |
<A HREF="#gdImageSetPixel">gdImageSetPixel</A> | 
<A HREF="#gdImageSetStyle">gdImageSetStyle</A> |
<A HREF="#gdImageSetTile">gdImageSetTile</A> |
<A HREF="#gdImageString">gdImageString</A> | 
<A HREF="#gdImageString16">gdImageString16</A> | 
<A HREF="#gdImageStringUp">gdImageStringUp</A> | 
<A HREF="#gdImageStringUp">gdImageStringUp16</A> | 
<A HREF="#gdMaxColors">gdMaxColors</A> |
<A HREF="#gdPoint">gdPoint</A> |
<A HREF="#gdStyled">gdStyled</A> |
<A HREF="#gdStyledBrushed">gdStyledBrushed</A> |
<A HREF="#gdTiled">gdTiled</A> |
<A HREF="#gdTransparent">gdTransparent</A>
<P>
<em><A HREF="http://www.boutell.com/">
Boutell.Com, Inc.</A></em>
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