[OpenJDK 2D-Dev] [9] RFR JDK-8162796: [macosx] LinearGradientPaint and RadialGradientPaint are not printed on OS X.

[Prasanta Sadhukhan]

Hi All,

Please review a fix for jdk9 where it is seen that LinearGradientPaint 
is not getting printed on osx.
The below webrev is only for LinearGradientPaint
and RadialGradientPaint will be handled separately.

Bug: https://bugs.openjdk.java.net/browse/JDK-8162796
webrev: http://cr.openjdk.java.net/~psadhukhan/8162796/webrev.00/

Issue was LinearGradientPaint is not handled in osx from jdk7 onwards. 
It handles simple GradientPaint.
Code is added as per
https://developer.apple.com/library/content/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_shadings/dq_shadings.html#//apple_ref/doc/uid/TP30001066-CH207-TPXREF101

to use "CGGradientRef" quartz datatype to support LinearGradientPaint.
CGGradientRef is used compared to CGShadingRef because it is mentioned 
in CGGradientRef,  i is "Easy to define more than two locations and 
colors." as we set 2 or more colors and 2 or more fractions in 
LinearGradientPaint.

Regards
Prasanta