Notes

Note:

GIF support was removed from the GD library in Version 1.6, and added back in Version 2.0.28. This function is not available between these versions. For more information, see the » GD Project site.

The following code snippet allows you to write more portable PHP applications by auto-detecting the type of GD support which is available. Replace the sequence header ("Content-Type: image/gif"); imagegif ($im); by the more flexible sequence:

<?php
// Create a new image instance
$im = imagecreatetruecolor(100, 100);

// Do some image operations here

// Handle output
if(function_exists('imagegif'))
{
    // For GIF
    header('Content-Type: image/gif');

    imagegif($im);
}
elseif(function_exists('imagejpeg'))
{
    // For JPEG
    header('Content-Type: image/jpeg');

    imagejpeg($im, NULL, 100);
}
elseif(function_exists('imagepng'))
{
    // For PNG
    header('Content-Type: image/png');

    imagepng($im);
}
elseif(function_exists('imagewbmp'))
{
    // For WBMP
    header('Content-Type: image/vnd.wap.wbmp');

    imagewbmp($im);
}
else
{
    imagedestroy($im);

    die('No image support in this PHP server');
}

// If image support was found for one of these
// formats, then free it from memory
if($im)
{
    imagedestroy($im);
}
?>

Note:

As of PHP 4.0.2 you can use the function imagetypes() in place of function_exists() for checking the presence of the various supported image formats:

<?php
if(imagetypes() & IMG_GIF)
{
    header('Content-Type: image/gif');
    imagegif($im);
}
elseif(imagetypes() & IMG_JPG)
{
    /* ... etc. */
}
?>