R/annotate_axis_line.R

In davidhodge931/ggblanket: Simplify 'ggplot2' Visualisation

#' Replace a axis line with an annotated segment
#'
#' @description Replace a axis line with an annotated segment, so that geom features are in front of it.
#'
#' @param axis The axis. Either "x" or "y"
#' @param x_position The position of the "x" axis, if applicable. Either "bottom" or "top".
#' @param y_position The position of the "y" axis, if applicable. Either "left" or "right".
#' @param colour The colour of the annotated segment.
#' @param linewidth The linewidth of the annotated segment.
#' @param ... Extra parameters passed to `ggplot2::annotate("segment", ...)`.
#'
#' @return A list of a annotate layer and theme elements.
#' @export
#'
#' @examples
#' library(dplyr)
#' library(ggplot2)
#' library(ggblanket)
#' library(palmerpenguins)
#'
#' set_blanket()
#'
#' penguins |>
#'   add_row(
#'     flipper_length_mm = 175,
#'     body_mass_g = 2500,
#'     species = "Adelie",
#'   ) |>
#'   gg_blanket(
#'     x = flipper_length_mm,
#'     y = body_mass_g,
#'     col = species,
#'   ) +
#'   annotate_axis_line() +
#'   geom_point(size = 2.5)
#'
annotate_axis_line <- function(
    axis = "x",
    x_position = "bottom",
    y_position = "left",
    colour = NULL,
    linewidth = NULL,
    ...
) {

  if (axis == "x") {
    if (rlang::is_null(colour)) colour <- ggplot2::GeomHline$default_aes$colour
    if (rlang::is_null(linewidth)) linewidth <- ggplot2::GeomHline$default_aes$linewidth

    if (x_position == "bottom") {
      stamp <- rlang::list2(
        ggplot2::annotate(
          "segment",
          x = I(-Inf), xend = I(Inf), y = I(-Inf), yend = I(-Inf),
          colour = colour,
          linewidth = linewidth,
          ...
        ),
        ggplot2::theme(axis.line.x.bottom = ggplot2::element_blank())
      )
    }
    else if (x_position == "top")  {
      stamp <- rlang::list2(
        ggplot2::annotate(
          "segment",
          x = I(-Inf), xend = I(Inf), y = I(Inf), yend = I(Inf),
          colour = colour,
          linewidth = linewidth,
          ...
        ),
        ggplot2::theme(axis.line.x.top = ggplot2::element_blank())
      )
    }
  }
  else if (axis == "y") {
    if (rlang::is_null(colour)) colour <- ggplot2::GeomVline$default_aes$colour
    if (rlang::is_null(linewidth)) linewidth <- ggplot2::GeomVline$default_aes$linewidth

    if (y_position == "left") {
      stamp <- rlang::list2(
        ggplot2::annotate(
          "segment",
          x = I(-Inf), xend = I(-Inf), y = I(-Inf), yend = I(Inf),
          colour = colour,
          linewidth = linewidth,
          ...
        ),
        ggplot2::theme(axis.line.y.left = ggplot2::element_blank())
      )
    }
    else if (y_position == "right") {
      stamp <- rlang::list2(
        ggplot2::annotate(
          "segment",
          x = I(Inf), xend = I(Inf), y = I(-Inf), yend = I(Inf),
          colour = colour,
          linewidth = linewidth,
          ...
        ),
        ggplot2::theme(axis.line.y.right = ggplot2::element_blank())
      )
    }
  }
  return(stamp)
}