title: Can't POST large html5 canvas to server?
body: <p>I have a canvas that you can paint on. I need to save it's contents to the server so it can be resumed later. </p>
  
  <p>To do this, I <code>xMLHttpReq.send(*)</code> the <code>encodeURIComponent(canvasP.toDataURL())*</code> via a <code>xMLHttpReq.open("POST", url, false);</code></p>
  
  <p>In my php script, I take the $_POST and <code>base64_decode(json_decode($_POST[data]))</code> and I save it to a .png file on the server.</p>
  
  <p>NOW, this works fine and dandy if the canvas has a small doodle on it. BUT if the 1600x1200px canvas has a lot of stuff drawn on it, and it's like 600kB in size, my script fails, and I get a 0kB png on my server.</p>
  
  <p>How do I fix this? How can I send a large canvas to the server? </p>
  
  <p>Is the problem a limitation to _POST size? Because, no matter how large the canvas is, I can always download it via a <code>window.open(canvasP.toDataURL(), "blabla");</code>.</p>
  
  <p>This is quite the dilemma for me. Any help will be much appreciated!</p>
  
  <p>[EDIT] The PHP simply receives empty <code>$_POST[data]</code> for anything over ~50-something kB...
  So the problem has to occur between <code>canvasP.toDataURL()</code> and the POST-ing...</p>
  
  <p>[EDIT2] Browser says "Uploading...(xx%)" until it's "done". SO WHERE DOES THE DATA GO? :C</p>
  
  <p>[EDIT3] Here's the app, try it for yourself (use google chrome): <a href="http://students.info.uaic.ro/~tudor.berechet/" rel="nofollow noreferrer">http://students.info.uaic.ro/~tudor.berechet/</a></p>
  
  <p>[EDIT4] Mike's answer seems to be right about suhosin <img src="https://i.stack.imgur.com/epRbv.png" alt="phpinfo screenshot"></p>