Download a picture OnClick

Question

How do you actually download a picture when you click on it? Is there some kind of a javascript code to do just that? Here is how i show the image with pure HTML.

Answer 1

Most people right-click on the image and choose "Save image as..."

The alternate is to link to use a server-side script that sets a "Content-type" and "Content-disposition" header. In PHP, that would be something like this example from the docs:

header('Content-Type: image/png'); // or 'image/jpg' or 'image/gif'
header('Content-Disposition: attachment; filename="filename.png"');
readfile('original.png');

UPDATE: Since you say the image is generated by a PHP script in the first place, there are a few options:

• Put the URL (sig.php?...) as the parameter to readfile. This will mean double processing for anyone who clicks to download.
• Cache the output from your image generation script to the filesystem, then pass that file to readfile.
• Edit the image generation script to accept an extra parameter like mode=download and then where you are about to output the image, if the parameter is present, set those two headers above.