Gradient Objects {gridSVG}

Create Linear and Radial Gradients

Description

Create objects which describe linear and radial gradients. These objects can later be used to apply a gradient fill to grobs, and also to define a gradient so that it may be reused multiple times.

Usage

linearGradient(col = c("black", "white"),
               stops = seq(0, 1, length.out = length(col)),
               gradientUnits = c("bbox", "coords"),
               x0 = unit(0, "npc"), x1 = unit(1, "npc"),
               y0 = unit(0, "npc"), y1 = unit(1, "npc"),
               default.units = "npc",
               spreadMethod = c("pad", "reflect", "repeat"))
radialGradient(col = c("black", "white"),
               stops = seq(0, 1, length.out = length(col)),
               gradientUnits = c("bbox", "coords"),
               x = unit(0.5, "npc"), y = unit(0.5, "npc"),
               r = unit(0.5, "npc"),
               fx = unit(0.5, "npc"), fy = unit(0.5, "npc"),
               default.units = "npc",
               spreadMethod = c("pad", "reflect", "repeat"))

Arguments

col

A vector of colours used for gradient stops.

stops

A numeric vector of offsets (typically between 0 and 1) to place the the colours (col) at.

gradientUnits

If "bbox", the gradient is positioned relative to the bounding box of the referring grob. All units attempt to be converted to equivalent "npc" coordinates as a result.

If "coords", uses grid coordinates to determine positioning.

x0

Numeric or unit object indicating the starting x-location of the linear gradient.

x1

Numeric or unit object indicating the stopping x-location of the linear gradient.

y0

Numeric or unit object indicating the starting y-location of the linear gradient.

y1

Numeric or unit object indicating the stopping y-location of the linear gradient.

x

Numeric or unit object indicating the x-location of the radial gradient.

y

Numeric or unit object indicating the y-location of the radial gradient.

r

A numeric vector or unit object specifying the radius of the radial gradient.

fx

A numeric vector or unit object specifying an x-location. Determines the x-location of the focal point of the radial gradient.

fy

A numeric vector or unit object specifying an y-location. Determines the y-location of the focal point of the radial gradient.

default.units

A string indicating the default units to use if x, y, r, fx or fy are only given as numeric vectors.

spreadMethod

A character vector determining when happens when a gradient begins or ends within its bounds. See details.

Details

When defining gradient stops via col and stops, the order is important. Gradient stops which are defined earlier are drawn first, with later stops being drawn over the top.

For spreadMethod the possible values are:

• pad Use the terminal colors of the gradient to fill the remainder of the target region.

• reflect Reflect the gradient pattern start-to-end, end-to-start, start-to-end, etc. continuously until the target region is filled.

• repeat Repeat the gradient pattern start-to-end, start-to-end, start-to-end, etc. continuously until the target region is filled.

Value

A gradient object.

Author(s)

Simon Potter