Re: [Gnustep-cvs] r34174 - in /libs/gui/trunk: ChangeLog Headers/Additions/GNUstepGUI/GSTheme.h Source/GSTheme.m Source/GSThemeDrawing.m Source/NSMenuItemCell.m

[Fred Kiefer]

On 22.11.2011 20:03, Eric Wasylishen wrote:
> On 2011-11-22, at 8:17 AM, Quentin Mathé wrote:
> > And one final point. You us the method call [path setLineWidth:
> > 0.0]; This isn't as well defined as it may seem. Most people think
> > that this will select the smallest possible line width. At least
> > with our current code this may not be true for the cairo backend.
> > There is a long and ongoing discussion about zero line widths on
> > the cairo mailing list.
> >
> > ok, I wasn't aware of this issue. Which width should I use to get
> > the thinnest possible line or something close? 0.5 or 0.1 for
> > example?
>
> I added a fix to the cairo backend a few months ago which will
> interpret 0 as a thin line (I think previously I broke a game which
> was relying on that behaviour.)

I didn't notice that change at the time, or forgot about it. In your 
Changelog entry you state that Quartz draws nothing for a line width of 
zero. Is this only the low level or do the higher level drawing 
operations also ignore zero line width drawing?

> However, I recommend drawing a filled rectangle instead of using
> lines. In general, anywhere you have lines in a user interface, they
> should probably be filled rectangles. Filled rectangles scale up in a
> predictable way and are easy to pixel-align (just make the origin and
> size integers.)

Yes, filling rectangle is more efficient, but you don't want to compute 
the corresponding rectangles all the time. On the other hand, the user 
interface elements we draw are so simple, we could easily come up with 
the rectangles for them.