Dynamically resample hotlinked images using php

Question

I have an images directory, some with massive resolutions, so I'd like to serve a much lower resolution version if they get hotlinked and I'm also overlaying a repeating image (like a watermark) informing the viewer that the image is stolen and where they can find the genuine original.

I've got the resampling working fine but when I add the function for the no hotlink image overlay, it doesn't work. The thing is, I know the watermarking script works too, on it's own, because I've used it elsewhere in another file on the site. Unfortunately I can't tell what the error is as the hotlink test sites don't output errors, they just show an empty image placeholder, and my host's log files are all like greek to me.

This is the script I have at the moment:

<?php
ini_set('memory_limit','250M');
$path = $_SERVER['DOCUMENT_ROOT'].$_SERVER['REQUEST_URI'];

class SimpleImage {

    var $image;
    var $image_type;

    function load($filename) {
        $image_info = getimagesize($filename);
        $this->image_type = $image_info[2];
        if( $this->image_type == IMAGETYPE_JPEG ) {
            $this->image = imagecreatefromjpeg($filename);
        } elseif( $this->image_type == IMAGETYPE_GIF ) {
            $this->image = imagecreatefromgif($filename);
        } elseif( $this->image_type == IMAGETYPE_PNG ) {
            $this->image = imagecreatefrompng($filename);
        }
    }
    function save($filename, $image_type=IMAGETYPE_JPEG, $compression=60, $permissions=null) {
        if( $image_type == IMAGETYPE_JPEG ) {
            imagejpeg($this->image,$filename,$compression);
        } elseif( $image_type == IMAGETYPE_GIF ) {
            imagegif($this->image,$filename);
        } elseif( $image_type == IMAGETYPE_PNG ) {
            imagepng($this->image,$filename);
        }
        if( $permissions != null) {
            chmod($filename,$permissions);
        }
    }
    function output($image_type=IMAGETYPE_JPEG) {
        if( $image_type == IMAGETYPE_JPEG ) {
            imagejpeg($this->image);
        } elseif( $image_type == IMAGETYPE_GIF ) {
            imagegif($this->image);
        } elseif( $image_type == IMAGETYPE_PNG ) {
            imagepng($this->image);
        }
        imagedestroy($image);
        exit();
    }
    function getWidth() {
        return imagesx($this->image);
    }
    function getHeight() {
        return imagesy($this->image);
    }
    function resizeToHeight($height) {
        $ratio = $height / $this->getHeight();
        $width = $this->getWidth() * $ratio;
        $this->resize($width,$height);
    }
    function resizeToWidth($width) {
        $ratio = $width / $this->getWidth();
        $height = $this->getheight() * $ratio;
        $this->resize($width,$height);
    }
    function scale($scale) {
        $width = $this->getWidth() * $scale/100;
        $height = $this->getheight() * $scale/100;
        $this->resize($width,$height);
    }
    function resize($width,$height) {
        $new_image = imagecreatetruecolor($width, $height);
        imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
        $this->image = $new_image;
    }
    function nothot() {
        $hotlink = imagecreatefrompng('hotlink.png');
        $hw = imagesx($hotlink);
        $hh = imagesy($hotlink);
        $img_paste_x = 0;
        $img_paste_x = 0;
        while($img_paste_x < $this->getWidth()){
            $img_paste_y = 0;
            while($img_paste_y < $this->getHeight()){
                imagecopy($image, $hotlink, $img_paste_x, $img_paste_y, 0, 0, $hw, $hh);
                $img_paste_y += $hh;
            }
            $img_paste_x += $hw;
        }
        imagedestroy($hotlink);
    }

}
header('Content-Type: image/jpeg');
$image = new SimpleImage();
$image->load($path);
$image->resizeToWidth(600);
$image->nothot();
$image->output();
?>

Thanks for your help.

Answer 1

Change:

 imagecopy($image, $hotlink, $img_paste_x, $img_paste_y, 0, 0, $hw, $hh);

to:

 imagecopy($this->image, $hotlink, $img_paste_x, $img_paste_y, 0, 0, $hw, $hh);

Also not sure about the way you get the $path, some checks on whether the image exists wouldn't go a miss.