Reusable style classes — style • vellum

A style bundles vl_gpar() graphical parameters under an optional name so the same look can be reused across many viewports or grobs. A style is a gpar — it carries every graphical-parameter field and obeys the same inheritance rules — with an added name for identification. It can therefore be passed anywhere a gp is accepted.

Usage

style(
  col = NULL,
  fill = NULL,
  lwd = NULL,
  alpha = NULL,
  lty = NULL,
  lineend = NULL,
  linejoin = NULL,
  linemitre = NULL,
  fontfamily = NULL,
  fontface = NULL,
  fontsize = NULL,
  lineheight = NULL,
  name = NULL
)

Arguments

col: Stroke/text colour.
fill: Fill colour, or a gradient from linear_gradient() / radial_gradient().
lwd: Line width (1 == 1/96 inch).
alpha: Opacity multiplier in [0, 1].
lty: Line type: a name ("solid", "dashed", "dotted", "dotdash", "longdash", "twodash"), an integer code 0:6, a hex dash string (e.g. "44"), or a numeric vector of on/off dash lengths. Dash lengths scale with lwd.
lineend: Line cap: "round" (default), "butt", or "square".
linejoin: Line join: "round" (default), "mitre", or "bevel".
linemitre: Mitre limit (>= 1) for mitre joins; default 10.
fontfamily: Font family (text grobs).
fontface: One of "plain", "bold", "italic", "bold.italic".
fontsize: Font size in points.
lineheight: Line-height multiple.
name: Optional style-class name, for identification only; it is ignored by rendering.

Value

A style object (a subclass of gpar).

Details

Attaching a style to a viewport cascades its defaults to the whole subtree via the ordinary gpar inheritance (more-specific overrides less-specific), so a child grob's own gp still wins. This is the reusable "style class" layer that sits below a grammar's themes: a theme can compile into named styles rather than setting gpar fields ad hoc on every element.

Examples

accent <- style(col = "firebrick", lwd = 2, name = "accent")
# Reuse it on a viewport; children inherit unless they override.
vl_viewport(gp = accent)
#> <vellum::class_viewport>
#>  @ x      : unit [1:1] 0.5npc
#>  @ y      : unit [1:1] 0.5npc
#>  @ width  : unit [1:1] 1npc
#>  @ height : unit [1:1] 1npc
#>  @ xscale : num [1:2] 0 1
#>  @ yscale : num [1:2] 0 1
#>  @ angle  : num 0
#>  @ clip   : logi FALSE
#>  @ gp     : <vellum::vellum_style>
#>  .. @ col       : chr "firebrick"
#>  .. @ fill      : NULL
#>  .. @ lwd       : num 2
#>  .. @ alpha     : NULL
#>  .. @ lty       : NULL
#>  .. @ lineend   : NULL
#>  .. @ linejoin  : NULL
#>  .. @ linemitre : NULL
#>  .. @ fontfamily: NULL
#>  .. @ fontface  : NULL
#>  .. @ fontsize  : NULL
#>  .. @ lineheight: NULL
#>  .. @ name      : chr "accent"
#>  @ layout : NULL
#>  @ row    : NULL
#>  @ col    : NULL
#>  @ rowspan: int 1
#>  @ colspan: int 1
#>  @ mask   : NULL
#>  @ alpha  : NULL
#>  @ blend  : NULL
#>  @ name   : NULL
#>  @ cache  : logi FALSE