<?php
/*
  Tye Shavik (tye at tye . ca)
*/
function create_thumbnail($infile,$outfile,$maxw,$maxh,$stretch = FALSE) {
  clearstatcache();
  if (!is_file($infile)) {
    trigger_error("Cannot open file: $infile",E_USER_WARNING);
    return FALSE;
  }
  if (is_file($outfile)) {
      trigger_error("Output file already exists: $outfile",E_USER_WARNING);
    return FALSE;
  }
 
  $functions = array(
    'image/png' => 'ImageCreateFromPng',
    'image/jpeg' => 'ImageCreateFromJpeg',
  );
 
  // Add GIF support if GD was compiled with it
  if (function_exists('ImageCreateFromGif')) { $functions['image/gif'] = 'ImageCreateFromGif'; }
 
  $size = getimagesize($infile);
 
  // Check if mime type is listed above
  if (!$function = $functions[$size['mime']]) {
      trigger_error("MIME Type unsupported: {$size['mime']}",E_USER_WARNING);
    return FALSE;
  }
 
  // Open source image
  if (!$source_img = $function($infile)) {
      trigger_error("Unable to open source file: $infile",E_USER_WARNING);
    return FALSE;
  }
 
  $save_function = "image" . strtolower(substr(strrchr($size['mime'],'/'),1));
 
  // Scale dimensions
  list($neww,$newh) = scale_dimensions($size[0],$size[1],$maxw,$maxh,$stretch);
 
  if ($size['mime'] == 'image/png') {
    // Check if this PNG image is indexed
    $temp_img = imagecreatefrompng($infile);
    if (imagecolorstotal($temp_img) != 0) {
      // This is an indexed PNG
      $indexed_png = TRUE;
    } else {
      $indexed_png = FALSE;
    }
    imagedestroy($temp_img);
  }
 
  // Create new image resource
  if ($size['mime'] == 'image/gif' || ($size['mime'] == 'image/png' && $indexed_png)) {
    // Create indexed 
    $new_img = imagecreate($neww,$newh);
    // Copy the palette
    imagepalettecopy($new_img,$source_img);
 
    $color_transparent = imagecolortransparent($source_img);
    if ($color_transparent >= 0) {
      // Copy transparency
      imagefill($new_img,0,0,$color_transparent);
      imagecolortransparent($new_img, $color_transparent);
    }
  } else {
    $new_img = imagecreatetruecolor($neww,$newh);
  }
 
  // Copy and resize image
  imagecopyresampled($new_img,$source_img,0,0,0,0,$neww,$newh,$size[0],$size[1]);
 
  // Save output file
  if ($save_function == 'imagejpeg') {
      // Change the JPEG quality here
      if (!$save_function($new_img,$outfile,75)) {
          trigger_error("Unable to save output image",E_USER_WARNING);
          return FALSE;
      }
  } else {
      if (!$save_function($new_img,$outfile)) {
          trigger_error("Unable to save output image",E_USER_WARNING);
          return FALSE;
      }
  }
 
  // Cleanup
  imagedestroy($source_img);
  imagedestroy($new_img);
 
  return TRUE;
}
// Scales dimensions
function scale_dimensions($w,$h,$maxw,$maxh,$stretch = FALSE) {
    if (!$maxw && $maxh) {
      // Width is unlimited, scale by width
      $newh = $maxh;
      if ($h < $maxh && !$stretch) { $newh = $h; }
      else { $newh = $maxh; }
      $neww = ($w * $newh / $h);
    } elseif (!$maxh && $maxw) {
      // Scale by height
      if ($w < $maxw && !$stretch) { $neww = $w; }
      else { $neww = $maxw; }
      $newh = ($h * $neww / $w);
    } elseif (!$maxw && !$maxh) {
      return array($w,$h);
    } else {
      if ($w / $maxw > $h / $maxh) {
        // Scale by height
        if ($w < $maxw && !$stretch) { $neww = $w; }
        else { $neww = $maxw; }
        $newh = ($h * $neww / $w);
      } elseif ($w / $maxw <= $h / $maxh) {
        // Scale by width
        if ($h < $maxh && !$stretch) { $newh = $h; }
        else { $newh = $maxh; }
        $neww = ($w * $newh / $h);
      }
    }
    return array(round($neww),round($newh));
}
?>

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