Add a new Linux capture based on PipeWire [1] and the Desktop portal [2].
This new capture starts by asking the Desktop portal for a screencapture session.
There are quite a few D-Bus calls involved in this, but the key points are:
1. A connection to org.freedesktop.portal.ScreenCast is estabilished, and the
available cursor modes are updated.
2. CreateSession() is called. This is the first step of the negotiation.
3. SelectSources() is called. This is when a system dialog pops up asking the
user to either select a monitor (desktop capture) or a window (window capture).
4. Start() is called. This signals the compositor that it can setup a PipeWire
stream, and start sending buffers.
The reply to this fourth call gives OBS Studio the PipeWire fd, and the id of the
PipeWire node where the buffers are being sent to. This allows creating a consumer
PipeWire stream, and receive the buffers.
Metadata cursor is always preferred, but on the lack of it, we ask the stream for
an embedded cursor (i.e. the cursor is drawn at the buffer, and OBS Studio has no
control over it.)
Window capturing is implemented as a crop operation on the buffer. Compositors
can send big buffers, and a crop rectangle, and this is used to paint a subregion
of the buffer in the scene.
The new capture is only loaded when running on EGL, since it depends on EGL to
call gs_texture_create_from_dmabuf().
[1] https://pipewire.org/
[2] https://github.com/flatpak/xdg-desktop-portal/
This is to work around a Mesa issue that prevents copying
between RGB and RGBA textures. Other drivers seem to allow
this, even though it's technically not allowed by the GL
spec.
Closesjp9000/obs-studio#514
This adds a property to the source properties which lets the user
specify the X server to capture from. Since this is probably something
thats only useful under certain circumstances it is implemented as
an advanced setting which is only shown when the corresponding option
for advanced settings is checked.
XComposite, which is currently our only capture method for windows,
doesn't handle X border width. This works in a lot of cases but anytime
there's a border, a bug occurs where the lower right is clipped. This
patch has two goals:
1) To position and size the capture texture correctly in accordance to
the border.
2) Adds a configuration option to allow people to toggle it (which in
most cases will simply do nothing) with a default of not including it.
