Addresses issue #13. Adds cut_path to override vjust.

R/geom_textpath.R

@@ -63,6 +63,10 @@
 #'   line should be plotted along with the text. If FALSE, any parameters or
 #'   aesthetics relating to the drawing of the line in the layer will be
 #'   ignored.
+#' @param cut_path A single logical TRUE or FALSE which if TRUE breaks the path
+#'   into two sections, one on either side of the string and if FALSE leaves the
+#'   path unbroken. The default value is NA, which will break the line if the
+#'   string has a vjust of between 0 and 1.
 #'
 #' @details The \code{spacing} aesthetic allows fine control of spacing of text,
 #'   which is called 'tracking' in typography. The default is 0 and units are
@@ -168,7 +172,7 @@ geom_textpath <- function(
   position = "identity", na.rm = FALSE, show.legend = NA,
   inherit.aes = TRUE,  ...,
   lineend = "butt", linejoin = "round", linemitre = 10,
-  include_line = TRUE
+  include_line = TRUE, cut_path = NA
   )
 {
   layer(geom = GeomTextpath, mapping = mapping, data = data, stat = stat,
@@ -180,6 +184,7 @@ geom_textpath <- function(
           linejoin     = linejoin,
           linemitre    = linemitre,
           include_line = include_line,
+          cut_path     = cut_path,
           ...
         ))
 }
@@ -222,7 +227,7 @@ GeomTextpath <- ggproto("GeomTextpath", Geom,
   # into a tree of grobs for plotting.
   draw_panel = function(
     data, panel_params, coord,
-    lineend = "butt", linejoin = "round", linemitre = 10
+    lineend = "butt", linejoin = "round", linemitre = 10, cut_path = NA
   ) {
 
     #---- type conversion, checks & warnings ---------------------------#
@@ -301,6 +306,7 @@ GeomTextpath <- ggproto("GeomTextpath", Geom,
       id = data$group,
       hjust = data$hjust[first],
       vjust = data$vjust,
+      cut_path = cut_path,
       gp_text = text_gp,
       gp_path = path_gp,
       default.units = "npc"

R/geometry_helpers.R

@@ -225,6 +225,10 @@
 #' @param letters A `data.frame` with at least a numeric `length` column and
 #'   integer `id` column. The `id` column must match that in the `path`
 #'   argument.
+#' @param cut_path A single logical TRUE or FALSE which if TRUE breaks the path
+#'   into two sections, one on either side of the string and if FALSE leaves the
+#'   path unbroken. The default value is NA, which will break the line if the
+#'   string has a vjust of between 0 and 1
 #'
 #' @details We probably want the option to draw the path itself, since this will
 #'   be less work for the end-user. If the `vjust` is between 0 and 1 then the
@@ -247,18 +251,24 @@
 #' xy <- .add_path_data(xy)
 #' glyphs <- .get_path_points(xy)
 #' .get_surrounding_lines(xy, glyphs)
-.get_surrounding_lines <- function(path, letters) {
+.get_surrounding_lines <- function(path, letters, cut_path = NA) {
+
+
+  if(is.na(cut_path))
+  {
+    cut_path <- !(all(path$vjust <= 0) || all(path$vjust >= 1))
+  }
 
   # Simplify if text isn't exactly on path
-  if (all(path$vjust < 0) || all(path$vjust > 1)) {
+  if (!cut_path) {
     path$section <- "all"
   } else {
     # Lengths of group runs (assumed to be sorted)
     # The `rle()` function handles NAs inelegantly,
     # but I'm assuming `group` cannot be NA.
     letter_lens <- rle(letters$id)$lengths
     curve_lens  <- rle(path$id)$lengths
-    trim <- rep_len(!(path$vjust < 0 | path$vjust > 1), length(letter_lens))
+    trim <- rep_len(TRUE, length(letter_lens))
     trim <- rep(trim, curve_lens)
 
     # Get locations where strings start and end

R/grob_textpath.R

@@ -12,6 +12,10 @@
 #' @param gp_text,gp_path An object of class `"gpar"`, typically the output from
 #'   a call from the [`gpar()`][grid::gpar] function. These are basically lists
 #'   of graphical parameters for the text and path respectively.
+#' @param cut_path A single logical TRUE or FALSE which if TRUE breaks the path
+#'   into two sections, one on either side of the string and if FALSE leaves the
+#'   path unbroken. The default value is NA, which will break the line if the
+#'   string has a vjust of between 0 and 1
 #' @inheritParams grid::textGrob
 #'
 #' @return An object of class `gTree`, containing grobs.
@@ -44,6 +48,7 @@ textpathGrob <- function(
   vjust = NULL,
   gp_text = gpar(),
   gp_path = gpar(),
+  cut_path = NA,
   default.units = "npc",
   name = NULL,
   vp = NULL
@@ -85,6 +90,7 @@ textpathGrob <- function(
       x = x, y = y,
       id = rep(seq_along(id_lens), id_lens),
       vjust = vjust, hjust = hjust,
+      cut_path = cut_path,
       gp_text = gp_text,
       gp_path = gp_path
     ),
@@ -123,7 +129,7 @@ makeContent.textpath <- function(x) {
     path <- do.call(rbind.data.frame, c(path, make.row.names = FALSE))
 
     # Get bookends by trimming paths when it intersects text
-    path <- .get_surrounding_lines(path, text)
+    path <- .get_surrounding_lines(path, text, v$cut_path)
 
     # Recycle graphical parameters to match lengths of path
     gp_path <- recycle_gp(v$gp_path, `[`, i = path$id[path$start])
@@ -190,3 +196,5 @@ gp_fill_defaults <- function(gp, ..., defaults = get.gpar()) {
 `%||%` <- function(x, y) {
   if (is.null(x)) y else x
 }
+
+