maxpixelzoom and fullscreen

Erik Krause · July 21, 2026 at 7:15 PM New

Hello,

on the WorldWidePanorama project we have several quite old and small panoramas, some of which get pretty overzoomed if viewed fullscreen. I would assume maxpixelzoom to limit zooming even in fullscreen mode, which for some panoramas would mean they would have to be displayed with black bars all around. Is that feasible in any way?

I know I can adjust the size of the HTML5 canvas element using CSS, but that's quite tedious and a bit hacky because it also changes the aspect ratio of the image, causing it to become stretched or squashed. It would be nice if krpano could handle that on its own.

Disabling full-screen mode for these panoramas isn't ideal either, because depending on the monitor, it would be nice to be able to display the image larger than the viewer window.

klaus.krpano · July 22, 2026 at 3:09 PM New Official Post

Hi,

the maxpixelzoom setting gets dynamically converted to the field-of-view setting based on the window-size. The target resolution is based on the view-center (because on wide angle views the resolution would be even across the view).

To avoid that low-res panos gets zoom-out too far (e.g. having a fov of 150 or even 170), the fov is capped at 90 in this case.

'Black bars' should never appear (it's a 3D view).

Best regards,
Klaus

Erik Krause · July 24, 2026 at 7:51 PM New

Thank you, Klaus!

We have a cylindrical panorama with 3587 x 508 pixels. If this is viewed fullscreen on a full HD monitor it's pretty overzoomed. if maxpixelzoom=1 should prevent this, the only way I see is to limit the viewport.

Tuur · July 24, 2026 at 9:42 PM New

Or perhapse, in those cases, display them in a centered krpano type layer and set the max size as the pano requires?

Tuur

Erik Krause · July 25, 2026 at 6:29 PM New

Quote from Tuur

Or perhapse, in those cases, display them in a centered krpano type layer and set the max size as the pano requires?

Yes, that would be a workaround. I was wondering if there's a built-in option that would save me the trouble. I guess I would need to use display.customFullscreenElement? I played around a bit, and I found that I can point it to a <div> enclosing the #krpanoSWFObject, where I can set padding with :fullscreen pseudo class to reduce the viewer size. Will this work across major browsers?

It just dawned on me, that maxpixelzoom might not work properly, if I have fixed cubeface sizes, as we have on the WWP. Some panoramas get enlarged when converted to cubefaces. Am I right, that I would need to reduce maxpixelzoom by a factor calculated from the ideal cubeface size and the actual one?

klaus.krpano · July 27, 2026 at 6:18 PM New Official Post

Hi,

the purpose of maxpixelzoom is to limit the field of view (FOV) based on the image resolution and window size:

krpano.com - Documentation - XML Reference

It is primarily intended for high-resolution images, to prevent zooming beyond, e.g. 1x or 2x magnification.

Due to the rectangular/perspective projection, there is no way to display extremely low-resolution images without zooming or extreme visual distortions.

Changing the window size is certainly possible, either directly in the web design or via the <area> settings.

Even a dynamic solution using the view.pixelzoom variable might be possible (use area.align=center and something like `area.width = max(100 / view.pixelzoom, 100) + '%'`, same for height), although if that would actually look and work good is another question...

Best regards,
Klaus

Erik Krause · July 29, 2026 at 11:20 PM New

Thanks tuur and Klaus, <area> is nice!

I would like to use <area> exclusively in fullscreen mode. Is there an easier way than changing the settings in an <action> element and then calling it on “onenterfullscreen” and “onexitfullscreen”?

klaus.krpano · July 30, 2026 at 8:35 AM New Official Post

Both is possible:

Code

<area align="center"
	width="link:event.onenterfullscreen,event.onexitfullscreen:fullscreen ? 640 : 100%"
	height="link:event.onenterfullscreen,event.onexitfullscreen:fullscreen ? 480 : 100%"
	/>

or:

Code

<events name="fs" keep="true"
	onenterfullscreen="area.width=640; area.height=480; area.align='center';"
	onexitfullscreen="area.width=100%; area.height=100%;"
	/>

But actually I might rather use the onresize event and decide on the actual size.

Tuur · July 30, 2026 at 11:57 AM New

Code

<area align="center"
width="link:event.onfullscreen,event.onexitfullscreen:fullscreen ? 640 : 100%"
height="link:event.onfullscreen,event.onexitfullscreen:fullscreen ? 480 : 100%"
/>

It seems onfullscreen is not documented. Is that a typo?

Tuur

klaus.krpano · July 30, 2026 at 3:45 PM New Official Post

Right, that’s a typo , I was posting from mobile.

Erik Krause · July 30, 2026 at 7:31 PM New

So many thanks!

In the end I had to write

Code

<events 
	onenterfullscreen="set(area.width,'640'); set(area.height,'480');"
	onexitfullscreen="set(area.width,'100%'); set(area.height,'100%');"
	/>

The solution with only <area> and link: would have been nice, but the WWP is still on 1.20.4 (which is sufficient in every other respect). Now I have to figure out maximum viewer sizes for our legacy panoramas. Thanks again!

maxpixelzoom and fullscreen

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