php base64 encode imagecreatetruecolor

Question

I have a php script that generates an image then outputs the image as a png.

$img = imagecreatetruecolor($graphWidth,$graphHeight);
...
*drawing routines*
...
header("Content-type: image/png");
imagepng($img);

What I now need is to get the php script to base64 encode the image data and output that string (so I can eventually pass that encoded data to a java script which decodes and adds this image to a generated pdf).

I have tried many times to get it working myself using other stackoverflow posts/answers etc. but I don't understand enough about this technology to have gotten it to work.

Can someone help me with this please?

Thanks in advance,

Chris

Answer 1

The reason this doesn't work is because the image in $img is a resource, not an actual PNG image. When you call imagepng() , it outputs the image.

What I would do is create an output buffer, and base-64 encode it.

ob_start();
imagepng($img);
$buffer = ob_get_clean();
ob_end_clean();
echo base64_encode($buffer);

Don't forget to change your Content-Type header, as this is no longer image/png .