[cairo] standalone glitztest

Jon Smirl jonsmirl at yahoo.com
Mon Jul 12 22:20:49 PDT 2004

Compositing requires that the applications draw into offscreen buffers.
These buffers are then composited to the main window by the server. So,
each application thinks it has a full window in this model. The
application windows are never clipped when they are drawn.

The central server then takes these windows and composes the main
display screen. This is normally done doubled buffered. The back buffer
is used for composing and then a page flip is done to the front buffer.

The problem with this is that we haven't implemented drawing to
offscreen buffers (pbuffers and render-to-texture) in mesa yet. These
are being worked on but they aren't finished.

With what you have you can implement a normal windowing system. In a
normal system each application paints directly into the display buffer.
Sample-server implements parts of this but not all. So for each window
sample server set a clip region that protects other parts of the
screen. Then it tells the app to paint. When the app paints it can only
impact it's own part of the screen.

Glitz doesn't really help you with any of this. Glitz is a 2D drawing
API, not a windowing system. Both the application and window manager
are free to use glitz for drawing, but glitz won't help you with windowing.

Jon Smirl
jonsmirl at yahoo.com

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