test.php

<?php

$width = 400;
$height = 300;

$canvas = imagecreatetruecolor($width, $height);

imagecolorallocatealpha($canvas, 0, 0, 0, 0));
imagefilledrectangle($canvas, 0, 0, $width, $height, $color);

imagefilledarc($canvas, 200, 150, $width / 2, $height / 2, 45, 135, imagecolorallocatealpha($canvas, 255, 255, 255, 0)), IMG_ARC_CHORD));

imagejpeg($canvas, '/path/to/chord.jpg');

$newCanvas = imagecopymerge(imagecreatetruecolor($width, $height), $canvas, 0, 0, 0, 0, $width, $height, 100);

imagedestroy($canvas);

imagefilledarc($newCanvas, 200, 150, $width / 2, $height / 2, 45, 135, imagecolorallocatealpha($canvas, 255, 255, 255, 0)), IMG_ARC_PIE));

imagejpeg($newCanvas, '/path/to/pie.jpg');

imagedestroy($newCanvas);