patterns Define Gradient and Pattern Fills

Description

Functions to define gradient fills and pattern fills.

Usage

linearGradient(colours = c("black", "white"),
               stops = seq(0, 1, length.out = length(colours)),
               x1 = unit(0, "npc"), y1 = unit(0, "npc"),  
               x2 = unit(1, "npc"), y2 = unit(1, "npc"),
               default.units = "npc",
               extend = c("pad", "repeat", "reflect", "none")) 
radialGradient(colours = c("black", "white"),
               stops = seq(0, 1, length.out = length(colours)),
               cx1 = unit(.5, "npc"), cy1 = unit(.5, "npc"),
               r1 = unit(0, "npc"),
               cx2 = unit(.5, "npc"), cy2 = unit(.5, "npc"),
               r2 = unit(.5, "npc"),
               default.units = "npc",
               extend = c("pad", "repeat", "reflect", "none")) 
pattern(grob,
        x = 0.5, y = 0.5, width = 1, height = 1,
        default.units = "npc",
        just="centre", hjust=NULL, vjust=NULL,
        extend = c("pad", "repeat", "reflect", "none"),
        gp = gpar(fill="transparent")) 

Arguments

colours	Two or more colours for the gradient to transition between.
stops	Locations of the gradient colours between the start and end points of the gradient (as a proportion of the distance from the start point to the end point).
x1, y1, x2, y2	The start and end points for a linear gradient.
default.units	The coordinate system to use if any location or dimension is specified as just a numeric value.
extend	What happens outside the start and end of the gradient (see Details).
cx1, cy1, r1, cx2, cy2, r2	The centre and radius of the start and end circles for a radial gradient.
grob	A grob (or a gTree) that will be drawn as the tile in a pattern fill.
x, y, width, height	The size of the tile for a pattern fill.
just, hjust, vjust	The justification of the tile relative to its location.
gp	Default graphical parameter settings for the tile.

Details

Use these functions to define a gradient fill or pattern fill and then use the resulting object as the value for fill in a call to the gpar() function.

The possible values of extend, and their meanings, are:

• [pad:] propagate the value of the gradient at its boundary.

• [none:] produce no fill beyond the limits of the gradient.

• [repeat:] repeat the fill.

• [reflect:] repeat the fill in reverse.

To create a tiling pattern, provide a simple grob (like a circle), specify the location and size of the pattern to include the simple grob, and specify extend="repeat".

Value

A linear gradient or radial gradient or pattern object.

Warning

Gradient fills and pattern fills are not supported on all graphics devices. Where they are not supported, closed shapes will be rendered with a transparent fill. Where they are supported, not all values of extend are supported.

Author(s)

Paul Murrell

See Also

gpar