Gradient fills

Create a linear or radial gradient to use as a fill in vl_gpar(). A gradient interpolates between colour stops. Its geometry (x1/y1/... or cx/cy/r) is given in the coordinate system named by units and is resolved against the viewport at draw time, so the gradient transforms with the grob just like its outline.

Usage

linear_gradient(
  colours,
  stops = NULL,
  x1 = 0,
  y1 = 0,
  x2 = 1,
  y2 = 0,
  units = "npc",
  extend = "pad"
)

radial_gradient(
  colours,
  stops = NULL,
  cx = 0.5,
  cy = 0.5,
  r = 0.5,
  units = "npc",
  extend = "pad"
)

Arguments

colours

A vector of two or more colours (any R colour spec). With stops = NULL they are spread evenly across [0, 1].

stops

Optional offsets in [0, 1], one per colour. Defaults to evenly spaced.

x1, y1, x2, y2

Start and end points of a linear gradient (default a left-to-right sweep in npc).

units

Coordinate system for the geometry: one of "npc", "native", "mm", "in", "pt".

extend

How the gradient behaves outside [0, 1]: "pad" (clamp to the end stops), "repeat", or "reflect".

cx, cy, r

Centre and radius of a radial gradient (default centred, radius 0.5 npc).

Value

A vellum_gradient object, suitable for vl_gpar(fill = ...).

Examples

linear_gradient(c("white", "navy"))
#> $kind
#> [1] "linear"
#> 
#> $colours
#> [1] "white" "navy" 
#> 
#> $stops
#> [1] 0 1
#> 
#> $coords
#> [1] 0 0 1 0
#> 
#> $units
#> [1] "npc"
#> 
#> $extend
#> [1] "pad"
#> 
#> attr(,"class")
#> [1] "vellum_gradient"
radial_gradient(c("yellow", "red"), cx = 0.5, cy = 0.5, r = 0.5)
#> $kind
#> [1] "radial"
#> 
#> $colours
#> [1] "yellow" "red"   
#> 
#> $stops
#> [1] 0 1
#> 
#> $coords
#> [1] 0.5 0.5 0.5
#> 
#> $units
#> [1] "npc"
#> 
#> $extend
#> [1] "pad"
#> 
#> attr(,"class")
#> [1] "vellum_gradient"