make .lighter() and .darker() methods for Sage Color objects

[jasongrout]

See the end of http://groups.google.com/group/sage-support/browse_thread/thread/44971aa416574675

For reference, here is what MMA does:

http://reference.wolfram.com/mathematica/ref/Darker.html

http://reference.wolfram.com/mathematica/ref/Lighter.html

Related tickets:

• Colors: CSS3/SVG presets, construct from HSL/HSV, blend/lighter/darker methods #5601 - predefine colors in Sage.
• make .lighter() and .darker() methods for Sage Color objects #5602 - make .lighter() and .darker() methods for Sage Color objects.
• make a .mix() method for Sage color objects #5603 - make a .mix() method for Sage color objects.
• average Color objects when adding them together #5604 - average Color objects when adding them together.
• Construct Color objects using hsl and hsv values #5605 - Construct Color objects using hsl and hsv values.

CC: @sagetrac-mvngu

Component: graphics

Issue created by migration from https://trac.sagemath.org/ticket/5602

[qed777]

comment:3

See the patch at #5601.

[jasongrout]

comment:4

This works now:

sage: sage.plot.colors.red.lighter()
RGB color (1.0, 0.33333333333333331, 0.33333333333333331)
sage: sage.plot.colors.red.darker()
RGB color (0.66666666666666674, 0.0, 0.0)

So this ticket should be closed.

[sagetrac-mvngu]

comment:5

Close as fixed:

[mvngu@sage ~]$ sage
----------------------------------------------------------------------
| Sage Version 4.4.1, Release Date: 2010-05-02                       |
| Type notebook() for the GUI, and license() for information.        |
----------------------------------------------------------------------
sage: r = sage.plot.colors.red
sage: r
RGB color (1.0, 0.0, 0.0)
sage: r.darker()
RGB color (0.66666666666666674, 0.0, 0.0)
sage: r.lighter()
RGB color (1.0, 0.33333333333333331, 0.33333333333333331)