composite manager thoughts

[Allen Akin]

On Sat, Dec 27, 2003 at 08:08:48PM -0800, Keith Packard wrote:
| 
|                  ... Perhaps we should sit down and sketch out the whole 
| system, from toolkit through window and compositing management to see how 
| this part of the system should work.  ...

Sounds reasonable.

I've got abysmal connectivity for the next five days, so I can't participate in
the discussion as much as I'd like.  However, I did want to pose a question.

Is the intent that the compositing manager never perform geometric
transformations when displaying the contents of application drawing surfaces?

If the compositing manager is intended to perform scaling or more complex
geometric transformations, then you might be forced to to have a fairly wide
interface between compositing manager and applications.  Furthermore, it might
become necessary to re-render in a larger number of situations.  For example,
scaling down a window containing text might make the text unpleasant to read
unless the app re-renders with appropriate hinting.  If the scale factor is
nonuniform (e.g. a perspective transformation or an application of a window to
a curved surface), even the specification of the necessary parameters is
challenging.  (Though not impossible; it's similar to the geometric
level-of-detail problem in 3D rendering, and could be attacked at the
vertex-programming level.)

Allen