Question

I’m currently writing a front end for a PHP script(not written by me) that resizes images(PNG,GIF,JPG) and saves them as JPEGs. Its very simple and works fine when inputting JPEGs, but seems not to work for PNG or GIF images.

Here’s the code for the resizer:

<?php
header ("Content-type: image/jpeg");
$img = $_GET['img'];
header("Content-Disposition: attachment; filename=resized-$img");
$percent = $_GET['percent'];
$constrain = $_GET['constrain'];
$w = $_GET['w'];
$h = $_GET['h'];

// get image size of img
$x = @getimagesize($img);
// image width
$sw = $x[0];
// image height
$sh = $x[1];

if ($percent > 0) {
    // calculate resized height and width if percent is defined
    $percent = $percent * 0.01;
    $w = $sw * $percent;
    $h = $sh * $percent;
} else {
    if (isset ($w) AND !isset ($h)) {
        // autocompute height if only width is set
        $h = (100 / ($sw / $w)) * .01;
        $h = @round ($sh * $h);
    } elseif (isset ($h) AND !isset ($w)) {
        // autocompute width if only height is set
        $w = (100 / ($sh / $h)) * .01;
        $w = @round ($sw * $w);
    } elseif (isset ($h) AND isset ($w) AND isset ($constrain)) {
        // get the smaller resulting image dimension if both height
        // and width are set and $constrain is also set
        $hx = (100 / ($sw / $w)) * .01;
        $hx = @round ($sh * $hx);

        $wx = (100 / ($sh / $h)) * .01;
        $wx = @round ($sw * $wx);

        if ($hx < $h) {
            $h = (100 / ($sw / $w)) * .01;
            $h = @round ($sh * $h);
        } else {
            $w = (100 / ($sh / $h)) * .01;
            $w = @round ($sw * $w);
        }
    }
}

$im = @ImageCreateFromJPEG ($img) or // Read JPEG Image
$im = @ImageCreateFromPNG ($img) or // or PNG Image
$im = @ImageCreateFromGIF ($img) or // or GIF Image
$im = false; // If image is not JPEG, PNG, or GIF

if (!$im) {
    // We get errors from PHP's ImageCreate functions...
    // So let's echo back the contents of the actual image.
    readfile ($img);
} else {
    // Create the resized image destination
    $thumb = @ImageCreateTrueColor ($w, $h);
    // Copy from image source, resize it, and paste to image destination
    @ImageCopyResampled ($thumb, $im, 0, 0, 0, 0, $w, $h, $sw, $sh);
    // Output resized image
    @ImageJPEG ($thumb);

}
?>

Can you see any reason why the png/gif options are not working?
I have GD up-to-date and enabled for all formats and am running php 5.3.3

Thanks in advance.

Answer 1

The third item of your $x array from the getimagesize() contains the mime-type of the image. You should use it instead of using the or statement and trying all types.

switch ( $x[2] ) 
{
  case 1: $im = imagecreatefromgif($img); break;
  case 2: $im = imagecreatefromjpeg($img); break;
  case 3: $im = imagecreatefrompng($img); break;
  default: trigger_error('Unsupported filetype!', E_USER_WARNING);  break;
}