R/bspline_closed.R

In YTLogos/ggforce: Accelerating 'ggplot2'

#' Create closed b-spline shapes
#'
#' This geom creates closed b-spline curves and draws them as shapes. The
#' closed b-spline is achieved by wrapping the control points rather than the
#' knots. The *0 version uses the [grid::xsplineGrob()] function with
#' `open = FALSE` and can thus not be manipulated as a shape geom in the same
#' way as the base version (expand, contract, etc).
#'
#' @section Aesthetics:
#' geom_bspline understand the following aesthetics (required aesthetics are in
#' bold):
#'
#'  - **x**
#'  - **y**
#'  - color
#'  - fill
#'  - size
#'  - linetype
#'  - alpha
#'
#' @section Computed variables:
#'
#' \describe{
#'  \item{x, y}{The coordinates for the path describing the spline}
#'  \item{index}{The progression along the interpolation mapped between 0 and 1}
#' }
#'
#' @inheritParams ggplot2::geom_polygon
#' @inheritParams ggplot2::stat_identity
#'
#' @param n The number of points generated for each spline
#'
#' @author Thomas Lin Pedersen. The C++ code for De Boor's algorithm has been
#' adapted from
#' \href{https://chi3x10.wordpress.com/2009/10/18/de-boor-algorithm-in-c/}{Jason Yu-Tseh Chi implementation}
#'
#' @name geom_bspline_closed
#' @rdname geom_bspline_closed
#'
#' @examples
#' controls <- data.frame(
#'   x = runif(6),
#'   y = runif(6)
#' )
#' ggplot(controls, aes(x, y)) +
#'   geom_polygon(fill = NA, colour = 'grey') +
#'   geom_point(colour = 'red') +
#'   geom_bspline_closed(alpha = 0.5)
#'
NULL

#' @rdname geom_bspline_closed
#' @importFrom ggplot2 layer
#' @export
stat_bspline_closed <- function(mapping = NULL, data = NULL, geom = "shape",
                                position = "identity", na.rm = FALSE, n = 100,
                                show.legend = NA, inherit.aes = TRUE, ...) {
    layer(
        stat = StatBspline, data = data, mapping = mapping, geom = geom,
        position = position, show.legend = show.legend, inherit.aes = inherit.aes,
        params = list(na.rm = na.rm, n=n, ...)
    )
}
#' @rdname geom_bspline_closed
#' @importFrom ggplot2 layer
#' @export
geom_bspline_closed <- function(mapping = NULL, data = NULL, stat = "bspline",
                                position = "identity", n = 100, na.rm = FALSE,
                                show.legend = NA, inherit.aes = TRUE, ...) {
    layer(data = data, mapping = mapping, stat = stat, geom = GeomShape,
          position = position, show.legend = show.legend, inherit.aes = inherit.aes,
          params = list(na.rm = na.rm, n=n, type = 'closed', ...))
}
#' @rdname ggforce-extensions
#' @format NULL
#' @usage NULL
#' @importFrom grid xsplineGrob gpar
#' @importFrom ggplot2 ggproto GeomPolygon alpha
#' @export
GeomBsplineClosed0 <- ggproto('GeomBspline0', GeomPolygon,
    draw_panel = function(data, panel_scales, coord, na.rm = FALSE) {
        coords <- coord$transform(data, panel_scales)
        startPoint <- match(unique(coords$group), coords$group)
        xsplineGrob(coords$x, coords$y, id = coords$group, default.units = "native",
                    shape = 1, open = FALSE,
                    gp = gpar(col = coords$colour[startPoint],
                              fill = alpha(coords$fill[startPoint], coords$alpha[startPoint]),
                              lwd = coords$size[startPoint] * .pt,
                              lty = coords$linetype[startPoint]))
    }
)

#' @rdname geom_bspline_closed
#' @importFrom ggplot2 layer
#' @export
geom_bspline_closed0 <- function(mapping = NULL, data = NULL, stat = "identity",
                                 position = "identity", na.rm = FALSE,
                                 show.legend = NA, inherit.aes = TRUE, ...) {
    layer(data = data, mapping = mapping, stat = stat, geom = GeomBsplineClosed0,
          position = position, show.legend = show.legend, inherit.aes = inherit.aes,
          params = list(na.rm = na.rm, ...))
}