Realtime Image Typesetting with PHP GD

Today I wanted to go over some of the really cool things that can be done with both jQuery and PHP’s Graphical library. To begin, let’s go ahead and take a look at the demo of what I will be breaking down over this tutorial.

Click to see demo of Business Card Builder

The Markup

<h3>Realtime Business Card Builder</h3>
<div class="preview">
    <img src="scripts/server-side.php" />
</div>

Notice how the preview image’s “src” attribute is not pointing to a graphical file, but rather a server side php script? This is important because although we could use PHP to render new images out on our web server on every change, its best to view a single rendering through a static image element.

The client side code

By simply building up a query string that contains the values of our form fields, we can get a realtime performance. The first thing we want to create is a variable named “base” that will contain our preview image’s “src” orignal attribute value.

var base = $(".preview img").attr("src");

We make the “base” variable so that we may reference to the original URL of the server side file later on.

Next we want to gather our image from server side when the document is done loading for the first time. By utilizing jQuery’s serialize we will gather all our form’s fields and their values and request our image from php like so:

var base = $(".preview img").attr("src");

//GATHER IMAGE FOR FIRST TIME
$(".preview img").attr("src",base+'?'+$("#realtime-form").serialize());

As you can see, we set our image’s source attribute to be that of our base url, plus a serialized string of all our form’s input names and values.

Finally we want to setup our keyup event so as the user types into any of our form inputs, a “change request” for our image to be updated will be sent to php.

var base = $(".preview img").attr("src");

//GATHER IMAGE FOR FIRST TIME
$(".preview img").attr("src",base+'?'+$("#realtime-form").serialize());

//KEYUP EVENT AND NEW IMAGE GATHER
$("input,textarea").keyup(function(){
	$(".preview img").attr("src",base+'?'+$("#realtime-form").serialize());	
});

Notice how within our new keyup event we are basicly repeating our previous step of gather our image the first time? This is how we both gather changes the user has made, and request a new version of our image at the same time.

The server side code

Now lets take a look at our PHP image rendering file. The first thing we want to do in this file is to declare what format of image should it be rendering:

header ("Content-type: image/png");

We pass a content type of “image/png” to our files header so that we can have alpha transparency ability that is natural to png image formats.

Next we need to gather every possible value that is being sent to this file via our URI string. We do this by creating new variables and setting their value to each URI string value, like so:

$companyName = $_GET["companyName"];
$companySlogan = $_GET["companySlogan"];
$fullName = $_GET["fullName"];
$jobTitle = $_GET["jobTitle"];
$businessAddress = $_GET["businessAddress"];
$businessAddress = str_replace("\\n","\n",$businessAddress);
$businessAddress = str_replace("\\","",$businessAddress);
$phoneOne = $_GET["phoneOne"];
$phoneTwo = $_GET["phoneTwo"];
$emailAddress = $_GET["emailAddress"];
$siteUrl = $_GET["siteUrl"];

Notice how on some of the value gatherings I am using a str_replace() function? Again, we are replacing any instance of our hard return character (\\n) into an actual hard return upon rending our image and copy.

Next we are going to gather a temp image we will use to create the actual image we render on dynamically, like so:

$handle = $img = imagecreatefrompng( 'template.png' );

(‘template.png’ is a image file that lives on your server.)

Now we need to setup a few more variables that will come in handy when rendering our results:

$brown = ImageColorAllocate ($handle, 84, 48, 26);
$lightBrown = ImageColorAllocate ($handle, 145, 116, 94);
$white = ImageColorAllocate ($handle, 255, 255, 255);
$peach = ImageColorAllocate ($handle, 238, 222, 200);

We setup different font colors by making use of the “ImageColorAllocate()” PHP GD function and assigning it to our new “template.png” image ($handle). The array of numbers that proceeds “$handle” are RGB color values.

Now that we have everything (variable wise) setup to render our image, we need to place and setup our text in our image. Here is an example of how to do just that.

//company name
ImageTTFText ($handle, 18, 0, 20, 35, $brown, "timesbd.TTF", $companyName);

By using the “ImageTTFText()” PHP GD function, we can setup an array of parameters to place and render our copy in our image.
First, we point to our “template.png” image ($handle) want to place this copy onto. Next is an array of numerical values and they are in order as follows:

• Font Size of Copy
• Rotation of Copy
• X Position to Image’s size
• Y Position to Image’s size

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After the “size, rotation and position” values, we set our desired font color via our pre-defined color variables. Next we can choose to use a custom font file that live along side this php file. Last is the copy value it’s self that we gathered from our URI string and turned into variables.

The very last part to rending our image with PHP GD, is to do some clean up work like so:

imagealphablending( $handle, false );
imagesavealpha( $handle, true );
ImagePng ($handle);
imagedestroy( $handle );

We finish off our file format of “.png” and its transparency, and lastly destroy the image when completed to free up server memory.

(Some may notice that the web address copy is rendered from an align of center on out, I show this example in the demo download.)

That’s it everyone! With a little JavaScript and PHP GD you can do some really cool stuff, and I hope to see some great examples soon.

~ Download a copy of the demo

Devin R. Olsen

Located in Portland Oregon. I like to teach, share and dabble deep into the digital dark arts of web and game development.

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