[platform-swt-dev] Cannot fill and outline a half circle reliably

[Randy Hudson <hudsonr@xxxxxxxxxx>]

I cannot seem to fill and then outline
a half circle using the arc functions on GC (fillArc(), drawArc()).
The drawArc does not consistently sweep
the same region as fillArc(), probably because drawArc requires that the
width and height be one less than with fillArc()

public
static
void
main(String args[]){
        Display
d = new
Display();
        final
Color red = new
Color(d, 255,10,10);
        final
Color yellow = new
Color(d, 255, 255, 10);
        final
Shell shell = new
Shell(d);
        shell.setSize(400,
290);

        shell.addPaintListener(new
PaintListener() {
         
      public
void
paintControl(PaintEvent e) {
         
              e.gc.setBackground(red);
         
              e.gc.fillArc(30,0,91,91,180,180);
         
              e.gc.drawArc(30,0,90,90,180,180);
         
              
         
              e.gc.setBackground(yellow);
         
              e.gc.fillArc(150,20,90,90,0,180);
         
              e.gc.drawArc(150,20,89,89,0,180);
         
      }
        });

        shell.open();
        while
(!shell.isDisposed())
         
      while
(!d.readAndDispatch())
         
              d.sleep();
}


The problem might be that OS.Pie takes
ints, and one of the two dimension (fill or draw) will always be ODD.  So
one of the two will be subject to integer rounding problems.

When GC generates x1, y1 and x2, y2
for the Pie function, could it generate these further away from the ellipse's
center?  The OS might interpret the intersection of these lines with
the ellipse better.
Or, is it possible to call API in the
platform with doubles instead of ints?

I think there is probably an (x1, y1)
and (x2, y2) that would give the desired results, but it might take some
effort to find them.