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Build a new glyph prototype

Source: R/gspace-glyph-constructor.R
glyph_proto.Rd

Create a gs_glyph object from a static shape and its identifying token. These prototypes form the building blocks of RGraphSpace's glyph vocabulary (e.g. GlyphArrow).

Usage

glyph_proto(
  shape,
  token,
  name = NULL,
  draw = c("polyline", "segments", "polygon", "circle"),
  offset = 0
)

# S3 method for class 'gs_glyph'
plot(x, ..., ncol = NULL, margin = 0.05, colour = "black")

Arguments

shape

A two-column numeric matrix of local points in the canonical frame: column 1 is the coordinate along the edge (reference point at the origin, +x outward), column 2 is the lateral coordinate (+y to the left), at unit size. An empty (0-row) matrix draws nothing.

token

The arrowType token that selects this glyph: ">" (vee-like) or "|" (tee-like), followed by a two-digit number (e.g. ">90", "|90").

name

A short human-readable name shown by glyph_list. Defaults to the token when NULL.

draw

How the points are interpreted: "polyline" connects them tip-to-tail into one open line; "segments" pairs consecutive points (rows 1-2, 3-4, ...) into separate segments and requires an even number of rows; "polygon" connects them into a closed, filled outline; "circle" takes a single point as the centre, drawn at the edge's arrow_size diameter.

offset

Where the edge line ends, as an x position in the glyph's frame: 0 (the default) runs the line to the reference point, and a negative value stops it that far back along the edge, in glyph units. Use it for open outlines, so the line stops at the outline instead of crossing it (e.g. -1 for an open triangle whose base is at x = -1).

x

A gs_glyph object, as returned by glyph_proto() or a built-in glyph (e.g. GlyphArrow).

...

Further gs_glyph objects, drawn side by side with x.

ncol

Number of glyphs per row; defaults to a single row.

margin

Space around the glyphs, as a fraction of the page on each

colour

Colour used to draw the glyph preview.

Value

A gs_glyph object.

New glyphs

New glyphs are added as package contributions, not at runtime: add an exported Glyph* object, built with glyph_proto(), to the gspace-glyph-collection.R source file (see that file for the full recipe). Tokens must be unique across all glyphs; conflicts are reported at package load.

See also

GlyphArrow, glyph_list

Examples

# a pair of vee-like shapes: a filled triangle (odd number) and its open
# form, the same outline as a closed polyline (next, even number)
m <- rbind(c(0, 0), c(-1, 0.6), c(-1, -0.6))
filled <- glyph_proto(m, token = ">91", draw = "polygon")
m <- rbind(c(-1, 0), c(-1, 0.6), c(0, 0), c(-1, -0.6), c(-1, 0))
open <- glyph_proto(m, token = ">92", draw = "polyline")
plot(filled, open)


# a pair of tee-like shapes: a filled block across the edge at the reference
# point, and its open form, the same outline as a closed polyline
m <- rbind(c(0, 0.65), c(0, -0.65), c(-0.25, -0.65), c(-0.25, 0.65))
filled <- glyph_proto(m, token = "|91", draw = "polygon")
m <- rbind(c(-0.25, 0), c(-0.25, 0.65), c(0, 0.65), c(0, -0.65),
  c(-0.25, -0.65), c(-0.25, 0))
open <- glyph_proto(m, token = "|92", draw = "polyline")
plot(filled, open)


# a pair of tee-like shapes: a circle (diameter one unit) touching the
# reference point, and its open form, a ring traced as a polyline
filled <- glyph_proto(rbind(c(-0.5, 0)), token = "|93", draw = "circle")
a <- seq(0, 2 * pi, length.out = 49)
m <- cbind(-0.5 - 0.5 * cos(a), 0.5 * sin(a))
open <- glyph_proto(m, token = "|94", draw = "polyline")
plot(filled, open)


# a single open glyph: a bar across the edge at the reference point, as
# one segment
m <- rbind(c(0, 0.65), c(0, -0.65))
glyph <- glyph_proto(m, token = "|95", draw = "segments")
plot(glyph)