[OpenJDK 2D-Dev] CubicCurve2D.solveCubic and containment/intersection bugs.

[Denis Lila]

Hi Jim.

> so it's behaving correctly (at least in this case)

However, contains(Rectangle2D) was still broken, because it
made the assumption that the line joining the endpoints splits
the cubic curve into two convex curves. This is not true - I've
attached a picture that illustrates why not (the reproducer for
4724552 also contains a curve that breaks contains(Rectangle2D)
in the same way).

I've made a first attempt to fix these two methods in:
http://icedtea.classpath.org/~dlila/webrevs/intersectContains/

I'm still not completely clear on how contains and intersects are
supposed to behave in corner cases, so I made the webrev as simple
as possible by ignoring any optimizations that might have been
possible. We can put these in later.

Am I missing anything?

Thank you,
Denis.

----- Original Message -----
> Hi Jim.
> 
> I'm starting a new thread about this, since "X11 uniform scaled
> wide lines and dashed lines; STROKE_CONTROL in Pisces" has
> absolutely nothing to do with what we were discussing :-)
> 
> > You might want to submit it as a separate push and get credit for
> > fixing
> > 4645692 (solveCubic doesn't return all answers), and maybe even the
> > following failures in the containment methods (which could be closed
> > as
> > dups if this fixes the problems) as well:
> >
> > 4724552
> > 4493128
> > 4074742
> > 4724556
> > (etc. Those were just the bugs I found on the first 2 pages of a bug
> > database search)
> 
> I've been thinking about these bugs, but I'm confused about what
> the correct behaviour is supposed to be in many of these cases:
> contain(double, double, double, double) says "Tests if the interior of
> the Shape entirely contains the specified rectangular area". I have
> two questions on this. Does "interior of the Shape" mean the set of
> points
> that are inside the shape as per the "Definition of insideness" in
> awt.Shape,
> or does it mean everything inside *minus* the boundary? Also, I have
> the
> same question about the rectangle parameter: does "entirely
> contain..."
> include the points on the boundary of the rectangle or not?
> 
> I'm also confused about contains(Point2D). What should be returned if
> the
> Point2D is on the boundary? Would this be decided using the
> "Definition of
> insideness"?
> 
> I have similar questions about the intersect methods, but I'm guessing
> those
> can be extrapolated from any answers I might get about the contains
> methods.
> 
> Also, contains(double, double) is working properly in the given
> reproducer
> for 4724556. I'm guessing this is because "contains" used to use
> solveCubic
> but it's not anymore so it's behaving correctly (at least in this
> case). This
> bug report is a bit ambiguous since it's also referring to solveCubic
> not
> finding a root, so I think it should either be closed as fixed or
> notabug
> or it should be made a duplicate of 4645692.
> 
> Thank you,
> Denis.
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