Generate snapshot of current view serverside

"Or is there a way we can limit the resolution when they request the snapshot, then put the resolution back after the image is done? We're using canvas's built in toDataURL function currently."

What do you mean exactly?

You can translate all the tiles for a particular level back into a full size panoramic image and export a rectalinear snap shot based on the ath,atv, and fov.
If you figure out the math to place each image precisely.
Definitely doable with panotools or maybe krpanotools itself ( I haven't checked).
Probably easy to just have 6 psbs/jpgs for cube faces to stitch from. Stitching straight tiles won't work since they are cubeface pieces, not images taken from a single perspective.

Yeah older iphones and ipads, tend to return black when they run out of memory.

Personally, I just went the canvas route.. but maybe I'll get time to take a look at restitching tiles again since it will always work.
I've seen some server side solutions already implemented. Whether it was from tiles or a psb, I'm not sure. They didn't have very good input sanitization, I know that. ;)
A full size psb should be straight simple to script out but then you need double disk space for each image.

Well, an suggestion from Klaus.
you could make 'screenshots' (e.g. by
loading an additional viewer with the wanted size into a internally
hidden element and making the screenshot there):

<action name="makescreenshot" type="Javascript"><![CDATA[
  if (krpano.webGL &&
krpano.webGL.context.getContextAttributes().preserveDrawingBuffer)
  {
    try
    {
       var img_src = krpano.webGL.canvas.toDataURL();
       ...
    }
    catch(err)
    {
       krpano.trace(3,err);
    }
  }
  else
  {
    krpano.trace(3,"no webgl or no preserveDrawingBuffer");
  }
]]></action>

Hope it can help, i think the same way as sachagriffin said

regards
Andrey

Nice andrey. I hadn't thought of that. Honestly though, I haven't even noticed a performance decrease to preserve drawing buffer.

ptgui used to be a gui for panorama tools. Now it uses its own internal engine based on it.
for the most part krpanotools can handle the output via the command line just fine. The headache of potentially being dossed via this process led me to push toward the canvas method.

The last SuperBowl 50 virtual tour has my implementation using a fallback image indeed.

Hi guys,

Thanks for this thread. It's really helpful.

Once the image is loaded into img_src do you have any ideas for how to then use it?

Ideally I'd like to be able to copy it to the clipboard or share it via Facebook/Twitter.

Any help would be great please.

Andrey, any working example? I always have black screen.

Hi,

This works great..
but when i want to use the data url inside the krpano project i get this error in Safari :

loading error: data:image/jpeg;base64,/9j/4AAQSkZJR

in chrome it works..
Is there a fix or work around??

Tuur

Quote from phatton

Once the image is loaded into img_src do you have any ideas for how to then use it?

You could use a form to send the data to a server side process with, for instance, PHP. You could then store the file on the server or you could open the image in the browser.

the form would look something like this :

<form name="imageForm" id="imageForm" action="./lib/screenshot.php" method="POST" target="_blank">
	<input type="hidden" name=imageData id="imageData">
</form>

you can fill the input element and submit it from the KRpano action with something like this :

document.getElementById('imageData').value = img_src;
		document.imageForm.submit();

on the receiving side, a method for opening the image would look like this :

<?php
$imageDataPost = $_POST['imageData'];
$imageData =  substr($imageDataPost,strpos($imageDataPost,",")+1);


header('Content-type: image/JPEG');
echo base64_decode($imageData);
?>

If you want to save it server side, then you simply write "base64_decode($imageData)" to a file and perhaps target the form to an iframe instead of _blank.

Quote from Tuur

but when i want to use the data url inside the krpano project i get this error in Safari :

loading error: data:image/jpeg;base64,/9j/4AAQSkZJR

I tried various versions of safari (Snow leopard to El Capitan and IOS 9, and none yield an image. It's either black/white or corrupt. It works in FF and Chrome. The safari data does contain the correct dimensions, but it's not a capture of the buffer.
This seems to be an ongoing issue with webkit and webGL canvas.