How to Create Image Thumbnails

 

How to Create Image Thumbnails

Image thumbnails are basically a smaller size copy of a larger image. They can be created using PHP GD Library functions alongside a file system function that we already learned about.

The getimagesize() file function will return the dimensions of the image specified. It can be used together with the list() function to minimize code and effort.

The imagecopyresampled() function can be used to stick a smaller version of an existing image into a new (smaller) image, thus creating a thumbnail.

The syntax is: imagecopyresampled(resource $dst_image, resource $src_image, int $dst_x, int $dst_y, int $src_x, int $src_y, int $dst_w, int $dst_h, int $src_w, int $src_h)

 dst_image = Destination Image
 src_image = Source Image
 dst_x = X Coordinate of Destination Image
 dst_y = Y Coordinate of Destination Image
 src_x = X Coordinate of Source Image
 src_y = Y Coordinate of Source Image
 dst_w = Destination Width
 dst_h = Destination Height
 src_w = Source Width
 src_h = Source Height

Putting it together, the script will look like this:

<?php
  header('Content-type: image/jpeg');
  $file = 'sky.jpg';

  $new_width = 150;
  $new_height = 150;
  list($old_width, $old_height) = getimagesize($file);

  $new_image = imagecreatetruecolor($new_width, $new_height);
  $old_image = imagecreatefromjpeg($file);

  imagecopyresampled($new_image, $old_image, 0, 0, 0, 0, $new_width, $new_height, $old_width, $old_height);

  imagejpeg($new_image);
  imagedestroy($old_image);
  imagedestroy($new_image);
?>