That looks good for the case where Imin is zero, but it appears that we could also have overflow as well, with a single
very tiny Imin the accumulation of estimatedSize with an "int" type could easily overflow and become essentially a
random number. Changing the estimatedSize variable to a float should prevent that related issue...
...jim
On 5/9/16 6:16 AM, Arunprasad Rajkumar wrote:
Hello Jim,
Thanks for your suggestions. As of now I taking an easy way to fix the issue,
New changes are available at
http://cr.openjdk.java.net/~arajkumar/8155903/webrev.02
I couldn't write a reliable test case using public javafx APIs, the behavior is
intermittent. However I could
consistently produce the issue using our DRT internal test case which is based
on W3C functional test[1].
[1]
http://w3c-test.org/2dcontext/fill-and-stroke-styles/2d.gradient.interpolate.overlap2.html
Thanks,
Arun
On 5/5/2016 11:51 PM, Jim Graham wrote:
Hi Arun,
The change you made to the calculateSingleArray method looks like it produces a
bad array of color stops for the case
where Imin is 0. You should fall into the calculateMultipleArray method
instead which should not have any trouble
with zero length intervals. At that point you don't have to have any code in
calculateSingleArray that deals with
Imin being zero because that can be part of its calling contract.
That is the quick fix.
The harder fix that would let us maintain speed when there is a zero interval
would be to teach the code what to do in
that special case. Basically a zero interval means that we have a case where
approaching the interval point from the
left is interpolating towards colorA, but leaving that point from the right is
interpolating from colorB, with a
sudden transition between those 2. In that case, a zero interval shouldn't
affect the Imin, since the Imin is trying
to determine the size of each interpolated region and we don't interpolate
across a zero-sized interval. So, the scan
for Imin would simply ignore zero length intervals. Later, the code that
populates the array in the
calculateSingleArray function would know that the zero length interval simply means swap
in a new "from color" without
any actual interpolation.
Getting that harder fix right would require a lot of testing, so it may be
better to do the quick fix now to stop the
exceptions and then deal with the optimization as a tweak filed for later...
...jim
On 05/05/2016 01:57 AM, Arunprasad Rajkumar wrote:
Hello Jim,
Please review the below patch.
JIRA: https://bugs.openjdk.java.net/browse/JDK-8155903
Webrev: http://cr.openjdk.java.net/~arajkumar/8155903/webrev.01
Issue: Divide by zero while adding multiple gradient stops at same offset.
Regards,
Arun
