Screnshot composited windows with real alpha channel and native shadow

[Tobias Wolf]

Since windows that are composited consist of textures that are tracked by the compositor it should be possible to get those window textures and their extents out of the compositor.

This will enable nice looking screenshots with alpha transparency, rounded corners and native shadows.

In a rectangle selection scenario the windows enclosed by the rectangle should be recomposited to remove the desktop background and map it to zero opacity.

• Compiz has a screenshot plugin. It might be extended to do this.
• KWin compositor has a screenshot plugin that does this already
• Both recent Windows and OSX do this already.

Previously:

• Comments at http://vimeo.com/19351515
• http://forum.compiz.org/viewtopic.php?f=136&t=13908
• https://svn.reviewboard.kde.org/r/4814/
• http://screenshots.debian.net/package/octave3.2

[Mario Kemper (Romario) (mario-kemper)]

I am aware of the problem, but I don't have the time to work on this currently. I have also filed a bug for this some time ago:
https://bugs.launchpad.net/unity/+bug/781280

Any help would be very much appreciated.

[Marco Hunsicker (ubuntu-triemax)]

An unelegant, but simple (temporary) solution could be to place a solid window behind the application (or as the desktop window), take two screenshots with different colored background window and calculate the transparent pixels yourself. I'm currently using AeroShot on Windows which does it this way and it works great for my use case (I'm only interested in one application window at a time). The Abscapture Python script seems to employ the same approach.

It looks like Gnome-Shell already supports taking screenshots.

[Mario Kemper (Romario) (mario-kemper)]

This workaround is already implemented. I just need some time to polish the code and merge it into the master branch.

[Tobias Wolf (towolf)]

Gnome Shell now implement real ARGB screenshots. So, for all I care this bug can be closed.