Image proxy made for Weat in 2010.

php_image_proxy.php

<?php

// Requires "file", "size" and "default" parameters
if (!isset($_REQUEST["file"]) || !isset($_REQUEST["size"]) || !isset($_REQUEST["default"])) {
  die("Expected to find \"file\", \"size\" and \"default\" parameters.");
}

// URL of file
$url = $_REQUEST["file"];

// TODO: If image isn't readable, print a default image in $_REQUEST["default"]

// Split URL to get extension
$extension = array_reverse(explode(".", $url));

// Create a new image from extension
switch ($extension[0]) {
	default:
	case "jpg":
	case "jpeg":
		$image = @imagecreatefromjpeg($url);
		break;
	case "png":
		$image = @imagecreatefrompng($url);
		break;
	case "gif":
		$image = @imagecreatefromgif($url);
		break;
};

// Square size of result image
$size = $_REQUEST["size"];

// Grab the image size
list($width, $height) = getimagesize($url);

// Grab the ratio of image
$ratio = $width / $height;

// Horizontal image
if ($ratio > 1) {
	
	// Same horizontal size
	$sizeX = $size;
	
	// Relative vertical size
	$sizeY = $size / $ratio;
	
	// Default left position
	$x = 0;
	
	// Centered top position
	$y = ($size - $sizeY) / 2;

// Vertical
} else {
	
	// Relative horizontal size
	$sizeX = $size * $ratio;
	
	// Same vertical size
	$sizeY = $size;
	
	// Centered left position
	$x = ($size - $sizeX) / 2;
	
	// Default top position
	$y = 0;
}

// Create an empty image to generate definitive result
$result = @imagecreatetruecolor($size, $size) or die("Cannot Initialize new GD image stream.");

// Create a white background
$background = imagecolorallocate($result, 255, 255, 255);

// Set white background to empty image
imagefill($result, 0, 0, $background);

// Save into empty image the original image with calculations
imagecopyresampled($result, $image, $x, $y, 0, 0, $sizeX, $sizeY, $width, $height);

// Print image header
header("Content-Type: image/png");

// Print image
imagepng($result, null, 0, PNG_NO_FILTER);

// Destroy original image
imagedestroy($image);

// Destroy generated image
imagedestroy($result);

?>