Re: New version of LisaEm up for downloads

On Wed, Mar 14, 2007 at 02:38:45PM -0500, Ray Arachelian wrote:
>
> > Curious. Wich option did you use to build wxwidegt (2.8...) ?
> >
> >
> Ouch! I'll be debugging tonight. :-)
>
> For wxWidgets 2.8.0, you want to download the whole thing, not just wxMac.
> Extract it, then:
>
> cd wxWidgets-2.8.0
> mkdir build_mac
> cd build_mac
> ../configure --disable-shared --enable-sound --enable-clipboard
> --with-mac --enable-xpm --enable-optimise
> make
> make install
>
> I think on mine I also added --enable-debug which complains if there are
> widget problems.
>
> Then do wx-config --version. It should say 2.8.0.

Hi Ray,

If you remember, we had a problem with wxWidgets 2.8 on MacOS X.

It boils down to being a bug in wxMemoryDC:DrawPoint when using CoreGraphics. For now, the solution is easy: use QuickDraw instead. In your wxMac-2.8.0 dir, edit include/wx/mac/carbon/chkconf.h, change the line with '#define wxMAC_USE_CORE_GRAPHICS 1' to be '#define wxMAC_USE_CORE_GRAPHICS 0', and then rebuild wxMac, and rebuild LisaEm against the new wxWidgets.

The reson the bug occurs is due to a combination of antialiasing and Core Graphics' coordinate system.

In Quickdraw, the coordinates x,y refer to the *centre* of the pixel at x,y, where as in Core Graphics they refer to the corner of the corner of the pixel at x,y (or if you prefer, the invisible grid lines between the pixels).

wxMac's CG implementation for wxDC::DoDrawPoint is simple (and broken):  DoDrawLine( x , y , x + 1 , y + 1 ) ;

So it actually ends up drawing *between* several pixels, given a partial grey value to each. This ends up causing drawing artifacts on the Mac.

Have a look at http://alastairs-place.net/cocoa/faq.txt section 3.2.2.

wxMac should in fact to use NSRectFill(), (or NSRectFillList() for a list of random pixles), for DrawPoint.

I'm not sure if this still applies to wxWiddgets 2.8.2. I'll try to verify it in the next couple of days.

Cheers,
Brian.

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