(PHP 5 >= 5.2.2, PHP 7)
imagegrabscreen — Captures the whole screen
Grabs a screenshot of the whole screen.
Returns an image resource identifier on success, FALSE on failure.
Example #1 imagegrabscreen() example
This example demonstrates how to take a screenshot of the current screen and save it as a png image.
<?php
$im = imagegrabscreen();
imagepng($im, "myscreenshot.png");
imagedestroy($im);
?>
Note:
This function is only available on Windows.
If you have multiple displays set up, this function will only grab the primary display; not all of them like you would with the 'Print Screen' key.
Also, this should be pretty obvious but I'll mention it anyway, if you're running GPU-intensive applications (not CPU), calling this function will cause quite some significant lag to your machine and server response until the request is complete.
For this to work your Apache service must be set to 'Allow service to interact with desktop' otherwise you will just get a blank image. To fix this right-click My Computer, select Manage/Services and Applications/Services - find the apache service (like Apache2) and right-click, select Properties - choose the Log on tab and check the 'Allow service to interact with desktop' checkbox. Restart Apache.