Dynamic Google Maps circle markers/icons with PHP

A while back I posted on how to create dynamic Google maps markers which allow for any colour and any text in the classic Google map style.

Recently, I have had a need to do the same with circular markers. It uses the ‘Image Smooth Arc‘ function provided by Ulrich Mierendorff.

Similarly, I provide a little demo of some PHP code that does this that I quickly whipped up. Here are some example markers:
DefaultAZ110PQ69%BEΩ$
(Have a look at the image name)

Now that gets a little boring, how about some color:
DefaultAZ110PQ69%BEΩ$
(Again, have a look at the image name)

Again, you will need to download the modified arial font and host it in the same directory.

Have a look at the PHP source code below:

<?php
	include ("imageSmoothArc_optimized.php");

	$color = $_GET['color'];
	if (!$color) {$color = "ff776b";} //default google map color
	$color = str_replace("#", "", $color);
	$string = $_GET['text'];

	$font = realpath('arial.ttf');

	//unfortunately we still must do some offsetting
	switch (ord(substr($string,0,1))) {
		case 49: //1
			$offset = -2;
			break;
		case 55: //7
			$offset = -1;
			break;
		case 65: //A
			$offset = 1;
			break;
		case 74: //J
			$offset = -1;
			break;
		case 84: //T
			$offset = 1;
			break;
		case 99: //c
			$offset = -1;
			break;
		case 106: //j
			$offset = 1;
			break;
	}
	if (strlen($string) == 1) {
		$fontsize = 10.5;
	} else if (strlen($string) == 2) {
		$fontsize = 9;
	} else {
		$fontsize = 10.5;
		$offset = 0; //reset offset
		$string = chr(149);
	}

	$bbox = imagettfbbox($fontsize, 0, $font, $string);
	$width = $bbox[2] - $bbox[0] + 1;
	$height = $bbox[1] - $bbox[7] + 1;

	$im = imagecreatetruecolor(20, 20);

	//add the alpha
	$trans_colour = imagecolorallocatealpha($im, 0, 0, 0, 127);
	imagefill($im, 0, 0, $trans_colour);

	imageAlphaBlending($im, true);
	imageSaveAlpha($im, true);

	$bord_ellipse = array (0, 0, 0, 0);
	imageSmoothArc($im, 9, 10, 17, 17, $bord_ellipse, 0, 2*M_PI); //x, y, width, hegiht

	$fill_ellipse = array (hexdec(substr($color,0,2)), hexdec(substr($color,2,2)), hexdec(substr($color,4,2)), 0);
	imageSmoothArc($im, 9, 10, 16, 16, $fill_ellipse, 0, 2*M_PI); //x, y, width, hegiht

	$black = imagecolorallocate($im, 0, 0, 0);
	imagettftext($im, $fontsize, 0, 11 - $width/2 + $offset, 9 + $height/2, $black, $font, $string);

	header("Content-type: image/png");
	imagepng($im);
	imagedestroy($im);
?>

EDIT: 8 September 2014
Fixed a “Call-time pass-by-reference has been removed” error with ‘imageSmoothArc_optimized.php’. If you are experiencing the same with imageSmoothArc simple replace all instances of ‘&$’ with ‘$’.