return dynamic image zf2 - image

Question

I use zend framework 2 and try to return an created with gd2 library jpeg image . but it doesn't work. could you look my code what's the problem? My code is run with plain php in normally but in zf2 problem?
class PictureController extends AbstractActionController
{
public function colorPaletteAction(){
....
....
//canvas created at above.
imagejpeg($canvas);
imagedestroy($canvas);
$response = $this->getResponse();
return $response->getHeaders()->addHeaderLine('Content-Type', 'image/jpeg');
}
}

Answer 1

imagejpeg outputs the data immediately which you don't want to do. You can either use the output buffer to capture this data or write it to a file first. The output buffer is probably easiest:
public function colorPaletteAction()
{
// [create $canvas]
ob_start();
imagejpeg($canvas);
$imageData = ob_get_contents();
ob_end_clean();
imagedestroy($canvas);
$response = $this->getResponse();
$response->getHeaders()->addHeaderLine('Content-Type', 'image/jpeg');
$response->setContent($imageData);
return $response;
}
If this doesn't work, temporarily comment out the Content-Type header line to see what output you're getting. Make sure there aren't any errors or HTML in the output.

Answer 2

You set the Content-Type header to 'image/png' instead of 'image/jpeg'.
Also try adding the content-transfer-encoding and content-length headers:
$response->getHeaders()->addHeaderLine('Content-Transfer-Encoding', 'binary')
->addHeaderLine('Content-Length', mb_strlen($yourJpegContent));
I also don't see you adding the actual content to the response:
$response->setContent($yourJpegContent);
where $yourJpegContent contains the binary image data.