Arrow curve grob. — grob_arrow

Creates a graphical object that draws curved arrows.

Usage

grob_arrow_curve(
  x1,
  y1,
  x2,
  y2,
  default.units = "mm",
  curvature = 1,
  angle = 90,
  ncp = 1,
  shape = 0.5,
  square = TRUE,
  squareShape = 1,
  inflect = FALSE,
  open = TRUE,
  name = NULL,
  gp = gpar(),
  vp = NULL,
  ...,
  width_head = unit(1, "mm"),
  width_fins = unit(1, "mm")
)

Arguments

x1

A numeric vector or unit object specifying the x-location of the start point.

y1

A numeric vector or unit object specifying the y-location of the start point.

x2

A numeric vector or unit object specifying the x-location of the end point.

y2

A numeric vector or unit object specifying the y-location of the end point.

default.units

A string indicating the default units to use if x1, y1, x2 or y2 are only given as numeric values.

curvature

A numeric value giving the amount of curvature. Negative values produce left-hand curves, positive values produce right-hand curves, and zero produces a straight line.

angle

A numeric value between 0 and 180, giving an amount to skew the control points of the curve. Values less than 90 skew the curve towards the start point and values greater than 90 skew the curve towards the end point.

ncp

The number of control points used to draw the curve. More control points creates a smoother curve.

shape

A numeric vector of values between -1 and 1, which control the shape of the curve relative to its control points. See grid.xspline for more details.

square

A logical value that controls whether control points for the curve are created city-block fashion or obliquely. When ncp is 1 and angle is 90, this is typically TRUE, otherwise this should probably be set to FALSE (see Examples below).

squareShape

A shape value to control the behaviour of the curve relative to any additional control point that is inserted if square is TRUE.

inflect

A logical value specifying whether the curve should be cut in half and inverted (see Examples below).

open

A logical value indicating whether to close the curve (connect the start and end points).

name

A character identifier.

gp

An object of class "gpar", typically the output from a call to the function gpar. This is basically a list of graphical parameter settings.

vp

A Grid viewport object (or NULL).

...

Arguments passed on to grob_arrow

arrow_head,arrow_fins,arrow_mid

A <matrix[n, 2]>, such as those returned by arrow ornament functions, giving arrow shapes. The matrix can (should) have the notch_angle attribute that will be used to fuse the shaft to the arrow ornaments. If NULL, no ornament will be drawn.

length_head,length_fins,length_mid

A <unit> object controlling the size of the arrow ornaments.

resect,resect_fins,resect_head

A <unit> object that can be used to create an offset between the endings of the coordinates and where the arrow will be displayed visually. resect_fins and resect_head control this offset at the start and end of the arrow respectively and both default to resect.

force_arrow

A logical(1) which, if TRUE an arrow will be drawn even when the length of the arrow is shorter than the arrow heads and fins. If FALSE, will drop such arrows.

justify

A numeric(1) between [0-1] to control where the arrows should be drawn relative to the path's endpoints. A value of 0 sets the arrow's tips at the path's end, whereas a value of 1 sets the arrow's base at the path's end.

mid_place

Sets the location of middle (interior) arrows, when applicable. Can be one of the following:

A numeric vector: with values between [0-1] to set middle arrows at relative positions along the arc-length of a path.
A <unit>: to fill a path with arrows with the provided unit as distance between one arrow to the next.

x

A numeric vector or unit object specifying x-values.

y

A numeric vector or unit object specifying y-values.

id

A numeric vector used to separate locations in x and y into multiple lines. All locations with the same id belong to the same line.

id.lengths

A numeric vector used to separate locations in x and y into multiple lines. Specifies consecutive blocks of locations which make up separate lines.

width_fins, width_head

A <unit> object controlling the width of the arrow's shaft at the (x1, y1) and (x2, y2) location respectively.

Value

A <curve_arrow>

graphical object.

Examples

requireNamespace("grid")

# Creating the curved arrow
grob <- grob_arrow_curve(
  x1 = unit(0.25, "npc"), y1 = unit(0.25, "npc"),
  x2 = unit(0.75, "npc"), y2 = unit(0.75, "npc"),
  angle = 90, curvature = 0.5, ncp = 5,
  arrow_head = arrow_head_line()
)

# Drawing the arrow
grid::grid.newpage(); grid::grid.draw(grob)