imagecolortransparent

Define a color as transparent

&reftitle.description; `int` `imagecolortransparent` `GdImage` `image` ``int``null```color`&null;

Gets or sets the transparent color in the given `image`.

&reftitle.parameters;

&gd.image.description;

`color`

- &gd.identifier.color;

&reftitle.returnvalues;

The identifier of the new (or current, if none is specified) transparent color is returned. If `color` is &null;, and the image has no transparent color, the returned identifier will be `-1`.

&reftitle.changelog;

&Version; | &Description;
&gd.changelog.image-param;
8.0.0 | `color` is now nullable.

&reftitle.examples;

### `imagecolortransparent` example

    <?php
    // Create a 55x30 image
    $im = imagecreatetruecolor(55, 30);
    $red = imagecolorallocate($im, 255, 0, 0);
    $black = imagecolorallocate($im, 0, 0, 0);

    // Make the background transparent
    imagecolortransparent($im, $black);

    // Draw a red rectangle
    imagefilledrectangle($im, 4, 4, 50, 25, $red);

    // Save the image
    imagepng($im, './imagecolortransparent.png');
    imagedestroy($im);
    ?>

&example.outputs.similar; Output of example : imagecolortransparent()
&reftitle.notes;

Transparency is copied only with `imagecopymerge` and true color images, not with `imagecopy` or pallete images.

The transparent color is a property of the image, transparency is not a property of the color. Once you have set a color to be the transparent color, any regions of the image in that color that were drawn previously will be transparent.