TalkPHP - The Big GD Guide

I have posted this guide here as it uses images and for some reason the article system seems to be very limited when it comes to a editor like the forum one :-D

Part 2

Here finally is my GD guide part 2 sorry to anyone who has been waiting for it. If you have not yet read the first one i would suggest you do.

Image size

Now you can use GD to create a thumbnail or a smaller version of a image, but of course you don't want to have to guess image sizes or always change things. We can get the image size

PHP Code:


		
			
$imgName = $_GET["src"]; // get image name from URL under variable "src
$size = getimagesize("$imgName"); //get the image dimensions and place them in an array called size

In order to access these measurements we can use the array and place them in variables of there own.

PHP Code:


		
			
// Assign width and height of your image to variables
$imgName_w = $size[0];
$imgName_h = $size[1];

Copy

With the GD library you are able to copy from one image and place onto another image using the imagecopy(); function.

PHP Code:


		
			
imagecopy($newImage, $imgImport, $x, $imgName_h - $y - 1, $x, $y, 1, 1);

Properties

PHP Code:


		
			
$newImage   //Destination image link resource      
imgImport     //Source image link resource      
x        //x-coordinate of destination point      
$imgName_h - $y - 1  //y-coordinate of destination point      
x         //x-coordinate of source point      
y        // y-coordinate of source point      
1       //Source width      
1      //Source height

Now that we have actually copied the image and placed it on the destination image.

Lines & Shapes

We can create lines and other shapes in PHP. This allows us to create many nice looking effects like creating graphs or adding additional graphics to images dynamically.

The Lines

PHP Code:


		
			
imageline     ( resource $image    , int $x1    , int $y1    , int $x2    , int $y2    , int $color    )

PHP Code:


		
			
 image                        //An image resource, returned by one of the image creation functions,  such as imagecreatetruecolor().

x1  // x-coordinate for first point      
y1  //y-coordinate for first point      
x2  // x-coordinate for second point      
y2    //y-coordinate for second point      
color   // The line color. A color identifier created with         imagecolorallocate()

As you can see we have 2 y cords and 2 x cords. Now this can be explained how these work using the diagram below.

Results

The Rectangles

You are able to create nice looking rectangles, but they can also look like squares.

PHP Code:


		
			
imagefilledrectangle     ( resource $image    , int $x1    , int $y1    , int $x2    , int $y2    , int $color    )

PHP Code:


		
			
 image    //An image resource, returned by one of the image creation functions,  such as imagecreatetruecolor().      
x1      //x-coordinate for point 1              
y1      //y-coordinate for point 1            
x2      //x-coordinate for point 2      
 y2     //y-coordinate for point 2      
color  //The fill color. A color identifier created with imagecolorallocate()

Result

They are some of the basic of shapes and the easiest. Next we shall be talking about Circles in the next chapter Part 3