/**
* Creates a thumbnail of a PNG/JPEG/GIF file. PNG-24 alpha channels are supported, GIF transparency however is not.
*
* Use $_GET['image'] to determine the source file
*
* HTTP Content-Type will be the same as the source file or text/plain if an error occurs
*
* @author David Luposchainsky
*/
class Thumbnail {
/**
* Defines the maximum dimension of the resulting thumbnail
*
* @var int
*/
protected $MaxResultDimension;
/**
* If set to TRUE the aspect ratio of the source image will be maintained (by scaling one down to maximum height/width and calculating the other one appropriately), else the image will always be stretched to maximum dimensions
*
* @var bool
*/
protected $MaintainAspectRatio;
/**
* If set to TRUE, images smaller than the maximum width will
* not be resized (i.e. enlarged) at all
*
* @var bool
*/
protected $EnlargeSmallImages;
/**
* Settings for the checker background for transparent areas of
* resized PNG graphics. If set to FALSE, the transparency will
* be maintained, otherwise the array below defines the checker
* pattern appearance.
*
* @var false|array
*/
protected $TransparencyChecker;
/**
* Stores the filename of the source image
*
* @var string Path to the source image
*/
protected $SourceFilename;
/**
* Stores the MIME type of the image generated by self::generate(). Until that function is run, the value is undefined.
*
* @var string The MIME type of the generated thumbnail
*/
protected $Mime;
/**
* Initializes default data
*
* @param string $SourceFilename Path to the source image
* @throws Exception
*/
function __construct($SourceFilename) {
// Check whether GD2 is ready to work
if(!function_exists('getimagesize') || !function_exists('imagecreatetruecolor')) {
throw new Exception('GD2 not installed/configured');
}
$this->SourceFilename = $SourceFilename;
// Initialize default values
$this->MaxResultDimension = array(256, 192);
$this->MaintainAspectRatio = true;
$this->EnlargeSmallImages = false;
$this->TransparencyChecker = array(
'Width' => 8, // Width of a checker cell
'Height' => 8, // Height of a checker cell
'R1' => 0xe8, // Red of cell type #1 (particularly the top-left one)
'G1' => 0xe8, // Green
'B1' => 0xe8, // Blue
'R2' => 0xff, // Red of cell type #2
'G2' => 0xff, // Green
'B2' => 0xff, // Blue
);
// Check whether the source file exists
if(!file_exists($this->SourceFilename)) {
throw new Exception('File not found');
}
}
function setMaxDimension($MaxWidth, $MaxHeight) {
$this->MaxResultDimension = array($MaxWidth, $MaxHeight);
}
function setMaintainAspectRatio($Value) {
$this->MaintainAspectRatio = $Value;
}
function setEnlargeSmallImages($Value) {
$this->EnlargeSmallImages = $Value;
}
function setTransparencyChecker($Settings) {
if(!$Settings) {
$this->TransparencyChecker = false;
} else {
foreach($Settings as $Key => $Value) {
$this->TransparencyChecker[$Key] = $Value;
}
}
}
function getMime() {
if(is_string($this->Mime)) {
return $this->Mime;
} else {
throw new Exception('No valid MIME type available, make sure to run generate(true) first');
}
}
/**
* Generates the thumbnail
*
* @param bool $Return If set to TRUE the image code is returned instead of printed.
* @return string Returns the thumbnail data
* @throws Exception
*/
function generate($Return = false) {
// Determine file dimensions and MIME of the source image
$ImageSize = getimagesize($this->SourceFilename);
if(!$ImageSize) {
throw new Exception('imagesize() error');
}
$this->Mime = $ImageSize['mime'];
$SourceImageWidth = $ImageSize[0];
$SourceImageHeight = $ImageSize[1];
// Create source image ressource
switch($this->Mime) {
case 'image/jpeg':
$SourceImage = imagecreatefromjpeg($this->SourceFilename);
break;
case 'image/png':
$SourceImage = imagecreatefrompng($this->SourceFilename);
break;
case 'image/gif':
$SourceImage = imagecreatefromgif($this->SourceFilename);
break;
default:
throw new Exception('Only the following MIME types are allowed: image/png, image/jpeg, image/gif');
}
// :TODO: compress the block below
// Determine thumbnail image size
if($this->MaintainAspectRatio) {
$NewImageWidth = $this->MaxResultDimension[0];
$NewImageHeight = round($NewImageWidth / $SourceImageWidth * $SourceImageHeight);
if($NewImageHeight > $this->MaxResultDimension[1]) { // If the x-scaled image should exceed the maximum y size scale down the y axis instead of the x
$NewImageHeight = $this->MaxResultDimension[1];
$NewImageWidth = round($NewImageHeight / $SourceImageHeight * $SourceImageWidth);
}
} else {
$NewImageWidth = $MaxResultDimension[0];
$NewImageHeight = $MaxResultDimension[1];
}
if(!$this->EnlargeSmallImages && ($NewImageWidth > $SourceImageWidth || $NewImageHeight > $SourceImageHeight)) {
$NewImageWidth = $SourceImageWidth;
$NewImageHeight = $SourceImageHeight;
}
// Generate thumbnail image
$NewImage = imagecreatetruecolor($NewImageWidth, $NewImageHeight);
switch($this->Mime) { // Handle output differently for each format
case 'image/png': // Handle transparent PNG areas
if($this->TransparencyChecker) {
// Fill background with color #1
$CheckerColor1 = imagecolorallocate($NewImage, $this->TransparencyChecker['R1'], $this->TransparencyChecker['G1'], $this->TransparencyChecker['B1']);
imagefilledrectangle($NewImage, 0, 0, $this->MaxResultDimension[0] - 1, $this->MaxResultDimension[1] - 1, $CheckerColor1);
// Initialize color #2
$CheckerColor2 = imagecolorallocate($NewImage, $this->TransparencyChecker['R2'], $this->TransparencyChecker['G2'], $this->TransparencyChecker['B2']);
// Paint the pattern
$XLineOffset = 0; // Offset to create checker pattern (move every 2nd line to the right)
for($y = 0; $y < $NewImageHeight; $y += $this->TransparencyChecker['Height']) {
for($x = 0; $x < $NewImageWidth; $x += (2 * $this->TransparencyChecker['Width'])) {
$x1 = $x + $XLineOffset;
$y1 = $y;
$x2 = $x1 + $this->TransparencyChecker['Width'] - 1;
$y2 = $y1 + $this->TransparencyChecker['Height'] - 1;
imagefilledrectangle($NewImage, $x1, $y1, $x2, $y2, $CheckerColor2);
}
if($XLineOffset == 0) {
$XLineOffset = $this->TransparencyChecker['Width'];
} else {
$XLineOffset = 0;
}
}
} else {
imagealphablending($NewImage, false); // Don't ask me why these 2 parameters are set to true-false, I just checked all 3 other combinations when true-true didn't work :\
imagesavealpha($NewImage, true);
}
break;
case 'image/jpeg': // Interlace JPEGs
imageinterlace($NewImage, 1);
break;
}
// Scale the image down
imagecopyresampled($NewImage, $SourceImage, 0, 0, 0, 0, $NewImageWidth, $NewImageHeight, $SourceImageWidth, $SourceImageHeight);
// Generate image
if($Return) {
ob_start();
} else {
header('content-type: '.$this->Mime);
}
switch($this->Mime) {
case 'image/jpeg':
imagejpeg($NewImage, null, 100);
break;
case 'image/png':
imagepng($NewImage);
break;
case 'image/gif':
imagegif($NewImage);
break;
// default has already been caught in the switch before
}
imagedestroy($SourceImage);
imagedestroy($NewImage);
if($Return) {
$ImageData = ob_get_contents();
ob_end_clean();
return $ImageData;
}
}
}
Ausserdem kennt der ImageMagick Server so ne Art Cache Funktion. Wenn er merkt, dass er das Bild schon mal umgerechnet hat (welches bei unserer MedienDatenbank ab und zu der Fall sein kann da er Bildern online verändern kann und Texte drüberlegen usw...) rechnet er das Bild nicht neu, sondern gibt dieses aus dem Cache zurück...
Es kommt auf jeden Fall auf die Verwendungszwecke an, welches für einem besser ist. Ich bin halt da mehr der ImageMagick Fan wie es den Anschein macht 
