AppImage

[probonopd]

This PR, when merged, will compile this application on Travis CI upon each git push, and upload an AppImage to your GitHub Releases page.

Providing an AppImage would have, among others, these advantages:

• Applications packaged as an AppImage can run on many distributions (including Ubuntu, Fedora, openSUSE, CentOS, elementaryOS, Linux Mint, and others)
• One app = one file = super simple for users: just download one AppImage file, make it executable, and run
• No unpacking or installation necessary
• No root needed
• No system libraries changed
• Works out of the box, no installation of runtimes needed
• Optional desktop integration with appimaged
• Optional binary delta updates, e.g., for continuous builds (only download the binary diff) using AppImageUpdate
• Can optionally GPG2-sign your AppImages (inside the file)
• Works on Live ISOs
• Can use the same AppImages when dual-booting multiple distributions
• Can be listed in the AppImageHub central directory of available AppImages
• Can double as a self-extracting compressed archive with the --appimage-extract parameter
• No repositories needed. Suitable/optimized for air-gapped (offline) machines
• Decentralized

Here is an overview of projects that are already distributing upstream-provided, official AppImages.

PLEASE NOTE: For this to work, you need to set up GITHUB_TOKEN in Travis CI for this to work; please see https://github.com/probonopd/uploadtool.
If you would like to see only one entry for the Pull Request in your project's history, then please enable this GitHub functionality on your repo. It allows you to squash (combine) the commits when merging.

If you have questions, AppImage developers are on #AppImage on irc.freenode.net.

[rodlie]

qtfm should use the native qt libraries to get proper integration with the system, also I can (and did) package qtfm as a single binary without the need for appimage. I dropped the binary since qtfm is now included in several distributions.

I have nothing against appimage (I do use Krita from appimage), but I don't think this is something for qtfm. Appimage should be used on large projects (like Krita).

[probonopd]

Let's say it's useful for testing dev builds :-)

[rodlie]

Ok, but then we should use the Qt build I already have prepared, and add support for ImageMagick and FFmpeg. I will look into this later this weekend. We also need to bundle the Adwaita icon theme (I already do this on mac, so no big deal).