Title: About LibGD @VERSION@

What is gd?:

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 PNG or

JPEG file. This is particularly useful in World Wide Web applications,

where PNG and JPEG are two of the formats accepted for inline images

by most browsers.

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, unless you are installing a required

library in order to run an application.

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 2.0 does include most

frequently requested features, including both truecolor and palette

images, resampling (smooth resizing of truecolor images) and so forth.

gd basics: using gd in your program:

gd lets you create PNG or JPEG images on the fly. To use gd in your

program, include the file gd.h, and link with the gd library and the

other required libraries; the syntax for most Unix flavors is:

> -lgd -lpng -lz -ljpeg -lfreetype -lm

Assuming that all of these libraries are available.

If you want to use the provided simple fonts, include gdfontt.h,

gdfonts.h, gdfontmb.h, gdfontl.h and/or gdfontg.h. For more impressive

results, install FreeType 2.x and use the gdImageStringFT function. 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.

Here is a short example program. (For a more advanced example, see

gddemo.c, included in the distribution. gddemo.c is NOT the same

program; it demonstrates additional features!)

>/* Bring in gd library functions */

>#include "gd.h"

>

>/* Bring in standard I/O so we can output the PNG to a file */

>#include <stdio.h>

>

>int main() {

>  /* Declare the image */

>  gdImagePtr im;

>  /* Declare output files */

>  FILE *pngout, *jpegout;

>  /* Declare color indexes */

>  int black;

>  int white;

>

>  /* Allocate the image: 64 pixels across by 64 pixels tall */

>  im = gdImageCreate(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 = gdImageColorAllocate(im, 0, 0, 0);  

>

>  /* Allocate the color white (red, green and blue all maximum). */

>  white = gdImageColorAllocate(im, 255, 255, 255);  

>  

>  /* Draw a line from the upper left to the lower right,

>    using white color index. */

>  gdImageLine(im, 0, 0, 63, 63, white);  

>

>  /* Open a file for writing. "wb" means "write binary", important

>    under MSDOS, harmless under Unix. */

>  pngout = fopen("test.png", "wb");

>

>  /* Do the same for a JPEG-format file. */

>  jpegout = fopen("test.jpg", "wb");

>

>  /* Output the image to the disk file in PNG format. */

>  gdImagePng(im, pngout);

>

>  /* Output the same image in JPEG format, using the default

>    JPEG quality setting. */

>  gdImageJpeg(im, jpegout, -1);

>

>  /* Close the files. */

>  fclose(pngout);

>  fclose(jpegout);

>

>  /* Destroy the image in memory. */

>  gdImageDestroy(im);

>}

>