Thumbnailer: icons have wrong/mixed size on HiDPI screens

[probonopd]

Icons have wrong/mixed size on HiDPI screens. Example: Ubuntu 18.04 on a HiDPI machine.

[TheAssassin]

Did you check whether there's big icons at all in these AppImages? It seems to me like the PdftoWord AppImage's icon has a higher resolution than all the other ones'.

[probonopd]

May be the case, nevertheless it looks like the thumbnailer needs to upscale the lower-resolution icons...

[TheAssassin]

That would involve linking to some library like imagemagick (and all its dependencies) to support all possible formats. I doubt we'd want that.

Maybe check your DE's settings? I could imagine there's an option to have it upscale the icons.

[azubieta]

Are we already making use of some image manipulation lib ? As there are so many image formats I'm wondering which would be the best for our needs. El dom., 20 de may. de 2018 1:07 PM, probonopd <notifications@github.com> escribió:

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May be the case, nevertheless it looks like the thumbnailer needs to upscale the lower-resolution icons... — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#783 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABFdrpijkq3e-t4RMKWQkmBSMaoFy8uhks5t0bDKgaJpZM4UGINu> .

[azubieta]

This issue doesn't happen with the kde thumbnailer because it does chamges the images size to match the standard. I've investigating a bit and I think that thunar is capable of using gnome thumbnailers. So if we make a gnome thumbailer we will have covered the major DE. I'm just wondering if there is a simple thumbailer code that I could use as template.

[probonopd]

linking to some library like imagemagick

Possibly https://lazka.github.io/pgi-docs/GdkPixbuf-2.0/classes/Pixbuf.html#GdkPixbuf.Pixbuf.scale_simple

[TheAssassin]

I'm using CImg to get the resolution of image files. It's a lightweight header-only library. But for obvious reasons it requires to be linked to libpng, libjpeg etc. I guess GdkPixbuf requires shipping those libraries, too. I'm pretty sure we don't want that in the runtime. The only solution I see is to check whether tools like convert (ImageMagick) are available, and implicitly use them.

[probonopd]

Ideally, the desktop environment would do the resizing, but apparently not all do. So we need to do the resizing in the thumbnailer, don't we? Or we need to enforce that certain resolution icons need to be in the AppImage at the AppImage creation time.

[azubieta]

We could do it at the moment of packing by means of "linuxdeploy" so the two icons get created. There is no problem of including image manipulation libraries.
And yes we should warn developers about missing icons at a given resolution.

[probonopd]

We could do it at the moment of packing by means of "linuxdeploy" so the two icons get created. There is no problem of including image manipulation libraries.

Yes, or even in the lower-level appimagetool that gets used by most AppImage creation methods.

[TheAssassin]

appimagetool shouldn't take care of icon manipulation. It should only package what it gets presented.

[probonopd]

Using the UNIX philosophy, we should have a makeicons command line tool that would put the appropriate icons in the appropriate sizes into the appropriate locations in a user-defined $PREFIX a.k.a. AppDir structure. This could be called by the user or by out other tools (if it is installed/bundled).