How to make thumbnails in php

Sometimes we need to resize uploaded images and make their thumbnails so that the page may load faster. So in this post I am sharing a very simple and easy script which can be used by anyone to generate thumbnails or resize images.

This script uses a class which should be included on the page where you want to make thumbnail or resize the original image. This class should be saved as thumb_class.php, its complete code is mentioned below:

thumb_class.php

<?php
// Imaging
class imaging
{
    // Variables
    private $img_input;
    private $img_output;
    private $img_src;
    private $format;
    private $quality = 80;
    private $x_input;
    private $y_input;
    private $x_output;
    private $y_output;
    private $resize;

    // Set image
    public function set_img($img)
    {
        // Find format
        $ext = strtoupper(pathinfo($img, PATHINFO_EXTENSION));
        // JPEG image
        if(is_file($img) && ($ext == "JPG" OR $ext == "JPEG"))
        {
            $this->format = $ext;
            $this->img_input = ImageCreateFromJPEG($img);
            $this->img_src = $img;
        }
        // PNG image
        elseif(is_file($img) && $ext == "PNG")
        {
            $this->format = $ext;
            $this->img_input = ImageCreateFromPNG($img);
            $this->img_src = $img;
        }
        // GIF image
        elseif(is_file($img) && $ext == "GIF")
        {
            $this->format = $ext;
            $this->img_input = ImageCreateFromGIF($img);
            $this->img_src = $img;
        }
        // Get dimensions
        $this->x_input = imagesx($this->img_input);
        $this->y_input = imagesy($this->img_input);
    }

    // Set maximum image size (pixels)
    public function set_size($max_x = 100,$max_y = 100)
    {
        // Resize
        if($this->x_input > $max_x || $this->y_input > $max_y)
        {
            $a= $max_x / $max_y;
            $b= $this->x_input / $this->y_input;
            if ($a<$b)
            {
                $this->x_output = $max_x;
                $this->y_output = ($max_x / $this->x_input) * $this->y_input;
            }
            else
            {
                $this->y_output = $max_y;
                $this->x_output = ($max_y / $this->y_input) * $this->x_input;
            }
            // Ready
            $this->resize = TRUE;
        }
        // Don't resize      
        else { $this->resize = FALSE; }
    }
    // Set image quality (JPEG only)
    public function set_quality($quality)
    {
        if(is_int($quality))
        {
            $this->quality = $quality;
        }
    }
    // Save image
    public function save_img($path)
    {
        // Resize
        if($this->resize)
        {
            $this->img_output = ImageCreateTrueColor($this->x_output, $this->y_output);
            ImageCopyResampled($this->img_output, $this->img_input, 0, 0, 0, 0, $this->x_output, $this->y_output, $this->x_input, $this->y_input);
        }
        // Save JPEG
        if($this->format == "JPG" OR $this->format == "JPEG")
        {
            if($this->resize) { imageJPEG($this->img_output, $path, $this->quality); }
            else { copy($this->img_src, $path); }
        }
        // Save PNG
        elseif($this->format == "PNG")
        {
            if($this->resize) { imagePNG($this->img_output, $path); }
            else { copy($this->img_src, $path); }
        }
        // Save GIF
        elseif($this->format == "GIF")
        {
            if($this->resize) { imageGIF($this->img_output, $path); }
            else { copy($this->img_src, $path); }
        }
    }
    // Get width
    public function get_width()
    {
        return $this->x_input;
    }
    // Get height
    public function get_height()
    {
        return $this->y_input;
    }
    // Clear image cache
    public function clear_cache()
    {
        @ImageDestroy($this->img_input);
        @ImageDestroy($this->img_output);
    }
}
class thumbnail extends imaging {
    private $image;
    private $width;
    private $height;
   
    function __construct($image,$width,$height,$dir) {
parent::set_img($image);
parent::set_quality(80);
parent::set_size($width,$height);
$image_temp=explode('/',$image);
$image_temp1=$image_temp[count($image_temp)-1];
$this->thumbnail= $dir.$image_temp1;
parent::save_img($this->thumbnail);
parent::clear_cache();
        }
    function __toString() {
            return $this->thumbnail;
    }
}
?>

Example Usage

After saving this file as thumb_class.php you can use it as follows:

<?php
include("thumb_class.php");
new thumbnail('test.jpg',400,300,'thumb/');
?>

In the above example
"test.php" is the name of image you want to resize,
"400" is the new width of image,
"300" is the new height of image, and
"thumb/" is the destination folder.

For any queries, suggestions or problems that you may have, feel free to comment on this post, I would love to answer you guyz ;).