Re: [Tile-dev] The Background Problem

[Pat T. <pa...@zs...>]

Joe English <jen...@fl...> writes:

>
>Then if someone can figure out exactly how DrawThemeParentBackground()
>is supposed to work in XP, maybe we can get notebooks to look
>right too...

I looked into this a bit. DrawThemeParentBackground is handling
matters at a window level. The prototype is
 DrawThemeParentBackground(HWND hwnd, HDC hdc, RECT *prc);
The idea is that if the theme element has any transparent bits, you
ask the parent window to redraw itself before drawing the themed
element. With HWNDs this is fine as 
 HWND GetParent(HWND hwnd);
returns the parent window. We don't have anything available at the
point where we are drawing elements to request a redraw of the parent
element. Even with this, we would have to construct a clipping region
- we only want the parent to redraw the are covered by _this_ element
after all.

Tile currently always draws elements into a pixmap, so clipping isn't
a problem perhaps - we won't erase siblings. The parent would need to
be able to be offset though. And we need to be able to identify all
ancenstor elements that may be covered by transparent regions in the
current element.


-- 
Pat Thoyts
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