[OpenJDK Rasterizer] Path2D optimizations

[Laurent Bourgès]

Jim,

Here is a new Path2d patch:
http://cr.openjdk.java.net/~lbourges/path2D/Path2D.2/

Changes:
- Fix ArrayIndexOutOfBounds in ptCrossing / rectCrossing when coords array
is zero-sized (0 capacity constructor): bug present in jdk8
- new tests:
Path2dEmpty to test this bug
Path2dCopyConstructor to test my changes on the copy constructor following
your instructions

Maybe we should create a new bug and split this patch in 2 separated ones ?

Laurent

Le 7 mars 2015 02:43, "Jim Graham" <james.graham at oracle.com> a écrit :
>
> First, the test cases that I asked for were to verify that a path that
was cloned was still operational.  I see no tests that verify that the
returned objects will still function, only tests that examine internal data
structures for a metric that may not be appropriate in the future.
>
> On 3/6/15 11:06 AM, Phil Race wrote:
>>
>> So the test should go in the anonymous package and avoid accessing
>> internals.
>> It should be possible to use just public API  to verify the arrays  of a
>> shape
>> being cloned are trimmed .
>
>
> We should not be testing if the cloned arrays are trimmed.  We don't care
from a testing standpoint.  It is an implementation detail of a performance
feature and we should not write any test that says "Object A should do its
work by doing X, Y, and Z".
>
> If we want to test performance then we should write a benchmark that
tests how long it takes to do an operation.  That will likely be a manual
test, though.  It should not be examining internals to take its
measurements, though.  Benchmarks tend to only use public APIs as they
should be benchmarking operations that Java programs encounter.
>
> If we want to test if your fix will break something, then we need to test
that.  Currently your tests do not do that.  We only need public APIs to do
that.
>
> What I would like to see in the test:
>
> - Delete all of the existing tests in there.  None of them are
appropriate to our testing goals.
>
> - Write tests that create paths in various forms and run them through the
following sub-tests:
>      - each of the following should be tested on a fresh clone...
>      - get a PathIterator and iterate it through until it is done
>        (optional - compare to the expected segments that were in the
original)
>      - get a flattened PathIterator using "getPathIterator(flatness,)"
and make sure it works
>        (optional - compare to original path if the original was already
flat)
>        (but, also run it on a path with curves to make sure flattening
engine didn't break)
>      - add various kinds of segments to the cloned path
>      - get the bounds of the cloned path
>      - use the transform() method on the cloned path
>      - call intersects(point), intersects(rect) and contains(rect) on a
cloned path
>      - call getCurrentPoint() on the cloned path
>
> - Perform each of the above tests on a (set of) clone(s) of the following
paths:
>      - each of the following executed on both a Float and a Double
instance...
>      - an empty path
>      - a path with just a moveto
>      - a path with a moveto+some lines
>      - a path with a moveto+some curves
>
> The way I tend to write tests like this is to use cascading methods like:
>
> void testEqual(Path2D pathA, Path2D path2D pathB) {
>     // Grab 2 path iterators and test for equality with float coords[]
> }
>
> void test(Path2D p2d, boolean isEmpty) {
>     testEqual(new Path2D.Float(p2d), p2d);
>     testEqual(new Path2D.Double(p2d), p2d);
>     testEqual(new GeneralPath(p2d), p2d);
>
>     testIterator(new Path2D.Float(p2d));
>     testIterator(new Path2D.Double(p2d));
>     testIterator((Path2D) p2d.clone());
>
>     testFlattening(... 3 clone variants ...);
>
>     testAddMove(... 3 clone variants ...);
>     // These should expect exception if empty
>     testAddLine(... 3 clone variants ..., isEmpty);
>     testAddQuad(... 3 clone variants ..., isEmpty);
> }
>
> interface PathFactory {
>     Path2D makePath();
> }
>
> void test(PathFactory pf) {
>     test(pf.makePath(), true);
>     test(addMove(pf.makePath()), false);
>     test(addLines(pf.makePath()), false);
>     test(addCurves(pf.makePath())), false);
> }
>
> @Test
> void testFloatPaths() {
>     test(() -> new Path2D.Float());
> }
>
> @Test
> void testDoublePaths() {
>     test(() -> new Path2D.Double());
> }
>
> @Test
> void testGeneralPath() {
>     test(() -> new GeneralPath());
> }
>
>                         ...jim
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