[Xorg] Understand Composite and Damage Extenstions

[Amir Bukhari]

I study the composite extension, because I will use it later and may I will
do some modification in it.

 

When I client redirect a window the extension will call
compalloc.c:compRedirectWindow() this function then should move that window
to an off-screen. Where is this off-screen saved (in which C structure)? I
don't figured it from the code of that function.

To understand all the stuff let me make a simple example:

 

1-    a client create a window at 100,100.

2-       Then it maps that window.

3-       Another client receives a mapRequest, and then it redirects (as
manual) it to off-screen.

4-       The first client paint to the window as normal.

As this window has been moved to off-screen nothing will be displayed unless
the other client do that.

 

How Paint functions will make their work on the off-screen not as normal at
the screen directly?

 

The new graphics card has framebuffer. When a client create a window X
server create for it window structure which save the position of the window
on framebuffer. When painting xserver will paint directly to the framebuffer
via GC operations, which am most hardware dependent.

How those work when a window is redirect? I can't figure that from the code
directly.

 

I will be glad if someone gives me sometime to describe this.

 

Amir

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