Window scaling (aka owner sizes)

[Giuseppe Bilotta]

On Mon, Aug 27, 2018 at 7:38 PM Keith Packard <keithp at keithp.com> wrote:
> Giuseppe Bilotta <giuseppe.bilotta at gmail.com> writes:
> > I guess the only way in which this can fail is if a client tries to
> > draw its own decorations (or something) “outside” of their own window,
> > assuming that origin+width or origin+height actually brings them there
> > in the root context (I mean as opposed to using XTranslateCoords,
> > which can be handled from within the server).
>
> They won't be able to draw 'outside' of their window -- all drawing to
> the window is redirected to the composite pixmap and clipped to the
> owner size. For applications with a border, the border also gets drawn
> to the composite pixmap and then scaled to the current size, although
> the border width is the same, so a tiled border may not look right.

By drawing “outside” of their window I don't mean using the window's
own GC context —that would actually work correctly, since it's the one
that gets scaled— but rather using a (grand)parent window such as the
root or vroot window(s). More in general, there could be issues with
clients that interact with the geometry of other windows (the only
examples I can think of are toys like AMOR or xsnow though, not sure
if there's any “serious” program that could be affected by this).


-- 
Giuseppe "Oblomov" Bilotta