Copy certain plugins unless "-no-plugins" is specified

[bjorn]

When I released Tiled 0.18.1, the Linux archive built with linuxdeployqt (version 9a1fbab) contained libQt5Svg.so.5 and the libqsvg.so image format plugin. Now that I'm using linuxdeployqt release 2, neither of these are included anymore.

I would like to use release 2, because it fixes the shipping of all other image format plugins. However I would prefer not to drop the SVG plugin. The problem is that Tiled does not itself rely on QtSvg (I tried linking it to QtSvg, but that was not enough to fool linuxdeployqt, I needed to actually use it).

What would a proper solution look like? I could imagine specifying additional Qt libraries to include, or specifying additional Qt plugins to include, or handling SVG explicitly with an -qtsvg command line option.

[probonopd]

What exactly in your AppImage requires/uses the SVG plugin, and how could appimaged detect that?

[bjorn]

There is no way to detect it because this is about shipping the SVG image plugin. This plugin enables reading of SVG image files, but it is only shipped when the application depends on QtSvg (checked specifically by linuxdeployqt). If the SVG image plugin would always be shipped, this would mean linuxdeployqt would always ship QtSvg as well, which may not be desirable because it increases the size of the package (though I think only about 1 MB).

[probonopd]

Sorry for my ignorance here, but which component uses, i.e., takes advantage of a present, SVG image plugin? (So could we say, if this component is present, we should also deploy the SVG image plugin?)

As a workaround, have you tried running linuxdeployt, then manually copying in the SVG image plugin, then running linuxdeployqt -appimage?

[bjorn]

No component in my application uses this plugin. It is a Qt plugin, and if it isn't there, Qt is not able to read images in SVG format. But that means my application can't read SVG images either, so I'd like this plugin to be included and I'm looking for a way to tell this to linuxdeployqt.

[probonopd]

OK, I begin to understand, you are saying conceptually there is no way for linuxdeployqt to know that your application can benefit from this plugin. Is running linuxdeployt, then manually copying in the SVG image plugin, then running linuxdeployqt -appimage an accaptable solution?

[bjorn]

Is running linuxdeployt, then manually copying in the SVG image plugin, then running linuxdeployqt -appimage an accaptable solution?

Hmm, I guess it would! I did not realize that I could use linuxdeployqt this way. I'll give it a try this evening.

[vadi2]

I don't think Qt needs QtSvg to read SVG format - I learnt that a couple of days ago myself on #qt. You only need QtSvg if you are actually QT+=svg and you so stuff with the QtSvg class. Try it to be sure, but I think this is a case of misunderstanding.

[bjorn]

I don't think Qt needs QtSvg to read SVG format

The SVG image plugin uses QtSvg for rasterizing the SVG into a QImage. So, the plugin will not work if you do not distribute QtSvg with your program.

This of course does not apply when you're not distributing your program, or when the program is distributed as an operating system package with Qt as a dependency. In that case, the SVG image plugin installed on the system will be used, which will pick up the QtSvg library installed on the system and you don't need to worry about it.

[probonopd]

Actually we inherited from macdeployqt the sentence

The accessibility, image formats, and text codec plugins are always copied, unless "-no-plugins" is specified

but didn't implement it so far... so would this solve your concern, do you think this would be a sensible thing to implement?

[vadi2]

I'd be fine with it

…

On Sun, 26 Mar 2017 4:28 pm probonopd, ***@***.***> wrote: Actually we inherited from macdeployqt the sentence The accessibility, image formats, and text codec plugins are always copied, unless "-no-plugins" is specified but didn't implement it so far... so would this solve your concern, do you think this would be a sensible thing to implement? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#82 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAGxjJrJjlygiZIDnkVrjq78Hh8GpopIks5rpnXzgaJpZM4MHLOV> .

[bjorn]

Yeah, that would work fine for me as well.

The only problem I guess would be that packages are a little larger for those not shipping QtSvg, but the SVG image plugin is really small anyway (only about 23K), so I guess the logic meant to exclude it could just be removed.

[probonopd]

OK, the path of action is clear then:

The accessibility, image formats, and text codec plugins are always copied, unless "-no-plugins" is specified

needs to be implemented.

[probonopd]

PR welcome!

[bjorn]

I've currently solved the issue in Tiled by copying over the SVG image plugin before running linuxdeployqt, like you suggested back in February:

cp /opt/qt58/plugins/imageformats/libqsvg.so Tiled/usr/plugins/imageformats/

But maybe I can try a PR for this on Monday.