Processing Graphical Submit Buttons

if (isset($_POST['Submit_x']) && isset($_POST['Submit_y']))

Graphical Submit buttons (<input type="image" />) are not only a nice way to spicen up the layout of the form, but they also offer a nice feature: The browser submits the x and the y coordinates of the mouse pointer when clicking on the button. In PHP, this happens by appending _x and _y to the name attribute of the button and writing this into $_GET or $_POST. The preceding code evaluates this information.

Processing Graphical Submit Buttons (image.php; excerpt)

<?php
  if (isset($_POST['Submit_x']) && isset($_POST
   ['Submit_y'])) {
    printf('<h1>You clicked at the following
      coordinates: x-%s, y-%s</h1>',
      htmlspecialchars($_POST['Submit_x']),
      htmlspecialchars($_POST['Submit_y'])
    );
  } else {
?>
  <form method="post" action="<?php echo
     htmlspecialchars($_SERVER['PHP_SELF']); ?>">
    <input type="image" name="Submit" src="sams.gif"
       />
  </form>
<?php
  }
?>

NOTE

When you submit the form using the keyboard (for example, with the Enter key), both coordinates are 0.

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