[WIP] add full size preview if previews are disabled

[sualko]

fix #488

To test this you have to add 'enable_previews' => false to your oc config. Afterwards you should be able to view all your images in the file app as usual.

Any advice how to clean this up?

@oparoz @XANi

[oparoz]

I think that's risky, because this could happen because of some issue and might lead to misleading bug reports.

You should be able to get the value of enable_previews via OC javascript methods.

[sualko]

I only know OC.AppConfig. What issues could occur?

[oparoz]

I did a quick search and couldn't find anything. Maybe worth asking on IRC if there is a way to get these values in JS.
The alternative would be to add a variable to the response we send to indicate that the preview system has been disabled.
Not getting any media types can be a symptom of a bad config (php, oC, etc.) or a bug in Gallery, so if users see the thumbnails and gets the large previews, they might think that everything is working as expected.
I think it's best to detect the exact condition we want to work with.

[sualko]

I think it is sufficient to detect it this way, because no thumbnails are generated. My pr only affects the file viewer, on the gallery page it still says "No pictures found".

[oparoz]

Let me give you an example.
Afaik, the slideshow doesn't work on public shares using the new shorter URLs on 9.0 because the scripts are not loaded any more, so the user sees thumbnails, but clicking on them does nothing downloads them.
Let's say scripts are still loaded, but there is a defect which prevents the proper list of supported media types to be sent.
With your patch, the user would have no idea that something is broken, because he would see the thumbnails and get some kind of preview, but only for a subset of the supported media types.
So it just makes debugging a bit harder and I think this could be avoided by properly letting the frontend know that previews have been disabled.
Doing it in the config controller also has the advantage of sending the same message to the Gallery side, making it easy to print a different message or a notification to the user.

[oparoz]

Let's get some feedback by more people.
@setnes @deMattin @arkascha @elpraga @sualko @Bugsbane @mmattel @jospoortvliet @jancborchardt

[sualko]

• decide if we should use enablePreviews, enable_previews or previewsDisabled as config variable. I vote for previewsDisabled.
• add default value for config var and documentation
• define list of media types which should be open as full size preview. Are there any disadvantages for image/svg+xml, image/x-xbitmap or image/bmp?

[oparoz]

decide if we should use enablePreviews, enable_previews or previewsDisabled as config variable. I vote for previewsDisabled.

I vote for previewsDisabled as well since the default behaviour is to have them enabled.

[oparoz]

Are there any disadvantages for image/svg+xml, image/x-xbitmap or image/bmp?

Since you're using Gallery's endpoints, SVG won't work and the file will be downloaded instead of shown in the browser.
https://github.com/sualko/gallery/blob/d9c5b6a4d40ea19835e821ad842d88111ebcf543/controller/filescontroller.php#L130-L132

[PVince81]

closing due to lack of feedback