Programming Web Graphics with Perl and GNU Softwar

Name

transparent( ) — make a color transparent

Synopsis

GD::Image::transparent(colorindex)

The transparent( ) method makes any pixels of color colorindex in an image transparent. Only one color may be transparent at a time; a second call to transparent( ) will override the first call, and will return pixels that were previously transparent to their original color. To turn off transparency in an image, give colorindex a value of -1. To find the index of the transparent color in an image, call transparent( ) without a parameter. To make the color that is closest to white in an image transparent, try:

$mostestwhitest = $image->colorClosest(255,255,255);
$image->transparent($whitest);

This function can be used with setBrush( ) to create irregularly shaped brushes. See the setBrush( ) method for an example of this.