We draw animated gifs with libgd.

The point of this article is to give an idea of ​​using the GD library in conjunction with C.



Download libgd or read more about its use here: http://www.libgd.org/ (eng.)



After installing GD, the list of functions and the types of received / returned data can be viewed in the /usr/local/include/gd.h file (in my case, otherwise sudo updatedb && locate gd.h ) to understand the purpose of functions is quite simple by their name.

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The code of a small program with my description, which draws this:











If anything is unclear, I’ll provide a more detailed explanation below.



So, let's begin:

//

#include <gd.h>

#include <stdio.h>



int main( int argc, char **argv) {



gdImagePtr im,im_clear; //

int black, white, trans; //

FILE *out1; //



im = gdImageCreate(100, 100); // 100100

im_clear = gdImageCreate(100, 100);



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

black = gdImageColorAllocate(im, 0, 0, 0);

trans = gdImageColorAllocate(im, 1, 1, 1);



gdImageCopy (im_clear, im, 0,0,0,0, 100, 100); // im im_clear

if (argc>1) out1 = fopen(argv[1], "wb" ); else out1 = fopen( "anim.gif" , "wb" ); //

gdImageGifAnimBegin(im, out1, 1, 0); // gif-



for ( int i=0;i<25;i++)

{

gdImageCopy (im, im_clear, 0,0,0,0, 100, 100); // im

gdImageRectangle(im, i*2, i*2, 100-i*2-1, 100-i*2-1, black); //

gdImageGifAnimAdd(im, out1, 0, 0, 0, 10, 1, NULL); //

};



putc ( ';' , out1); //

fclose(out1); //



gdImageDestroy(im); //

gdImageDestroy(im_clear);



}



* This source code was highlighted with Source Code Highlighter .

Save the file

compile it, in my case like this: gcc-lgd filename_o-o imname executable_file

and run: ./ executable_file_name [where_save_picture]



upd: Ubuntu 8.10 OS was used in my case, in your case there may be minor differences in the commands.