[OpenJDK 2D-Dev] [9] Review request for 8160124 SunGraphics2D.hitClip() can give wrong result for floating point scale

[Jim Graham]

Since "return true" would be a compliant implementation of Graphics.hitClip(), this is not a bug...

Read the documentation, it is allowed to use fast math that can return true when technically the answer is false...

			...jim

On 6/23/16 5:04 AM, Alexandr Scherbatiy wrote:
>
> Hello,
>
> Could you review the fix:
>   bug: https://bugs.openjdk.java.net/browse/JDK-8160124
>   webrev: http://cr.openjdk.java.net/~alexsch/8160124/webrev.00
>
>   Let's set the clip [x=5, y=5, width=5, height=5] to a graphics and call the hitClip() with the passed rectangle [x=0,
> y=0, width=5, height=5].
>
>   The result is false for the graphics with scale 1 and true if the scale is floating point 1.5.
>
>   This is because the transformed clip which has floating point bounds [7.5, 7.5, 7.5, 7.5] for the scale 1.5 has bounds
> with rounded down upper-left  and rounded up lower-right corners [7, 7, 8, 8] which now intersects with the transformed
> rectangle [0, 0, 7.5, 7.5].
>
>   The proposed fix adds additional check for the user clip and the user rectangle intersection if the intersection with
> the region clip passes.
>
>  Thanks,
>  Alexandr.
>
>