This tutorial will help you write text on a background and output as an image using the power of PHP. This is useful during those scenarios when you want to display text using a particular font (which isn`t web friendly i.e the text won`t be displayed with the same font in other’s computer). I have used this technique to display the number of RSS subscribers (top-right). So its pretty simple and very basic.

Click Here for a Demo.

STEP 1 : Create PHP file and Define Headers

First we create a PHP file. Lets call it myimage.php. Now we don`t want the browser to understand myimage.php as an image since we`ll be generating the image using this file. So we need to define the headers in this file which will tell the browser that it is an image.

<?php
//HEADERS
header("Content-type: image/png"); //Picture Format
header("Expires: Mon, 01 Jul 2003 00:00:00 GMT"); // Past date
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); // Consitnuously modified
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Pragma: no-cache"); // NO CACHE

//image generation code

?>

STEP 2 : The entire code !

The entire code is here, the comments should help tell what each function is doing.

<?php

header("Content-type: image/png"); //Picture Format
header("Expires: Mon, 01 Jul 2003 00:00:00 GMT"); // Past date
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); // Consitnuously modified
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Pragma: no-cache"); // NO CACHE

/*image generation code*/
//create Image of size 350px x 75px
$bg = imagecreatetruecolor(350, 75);

//This will make it transparent
imagesavealpha($bg, true);

$trans_colour = imagecolorallocatealpha($bg, 0, 0, 0, 127);
imagefill($bg, 0, 0, $trans_colour);

//Text to be written
$helloworld = isset($_GET['text']) ? $_GET['text'] : "hello World";

// White text
$white = imagecolorallocate($bg, 255, 255, 255);
// Grey Text
$grey = imagecolorallocate($bg, 128, 128, 128);
// Black Text
$black = imagecolorallocate($bg, 0,0,0);

$font = 'arial.ttf'; //path to font you want to use
$fontsize = 20; //size of font

//Writes text to the image using fonts using FreeType 2
imagettftext($bg, $fontsize, 0, 20, 20, $grey, $font, $helloworld);

//Create image
imagepng($bg);

//destroy image
ImageDestroy($bg);
?>

Well thats the source code if you want to generate alpha png images using PHP. Its pretty simple. This isn`t that tough, but there might be some people new to PHP who might want to know.