Add a test. Adjust projection lines for corners.

R/compute-shape-grob.R

@@ -57,11 +57,10 @@ compute_shape_grob.data.frame <- function (from, shape, corners, data, coord,
 compute_shape_grob.default <- function (from, shape, corners, data, coord,
                                         panel_params, expand) {
   if (shape == "rect") {
-    # grid::rectGrob()
     ggforce::shapeGrob(x = c(0, 0, 1, 1),
                        y = c(0, 1, 1, 0), radius = corners)
   } else if (shape == "ellipse") {
-    # resist the temptation to replace this with cirleGrob. You need to
+    # resist the temptation to replace this with circleGrob. You need to
     # mess with it later.
     gridExtra::ellipseGrob(x = 0.5, y = 0.5, size = 0.5, n = 180,
                              position.units = "npc", size.units = "npc")

R/geom-magnify.R

@@ -359,7 +359,7 @@ GeomMagnify <- ggproto("GeomMagnify", Geom,
     # == create projection lines =====
     proj_df <- if (identical(shape, "rect") && ! inherits(from, "grob") &&
                    ! inherits(from, "data.frame")) {
-      calculate_proj_df_rect(proj, d1, coord, panel_params)
+      calculate_proj_df_rect(proj, d1, corners, coord, panel_params)
     } else {
       calculate_proj_df(proj, proj.combine, target_grob, border_grob)
     }
@@ -382,6 +382,7 @@ GeomMagnify <- ggproto("GeomMagnify", Geom,
   }
 )
 
+
 create_plot_gtable <- function (plot, data, axes, recompute, scale.inset) {
   plot_coord <- ggplot_build(plot)$layout$coord
   plot_limits <- plot_coord$limits

R/projection.R

@@ -151,7 +151,7 @@ in_bbox <- function(pts, p1, p2) {
 }
 
 
-calculate_proj_df_rect <- function(proj, data, coord, panel_params) {
+calculate_proj_df_rect <- function(proj, data, corners, coord, panel_params) {
   # using mean allows Dates and maybe other things
   xmin <- data$xmin
   xmax <- data$xmax
@@ -162,13 +162,31 @@ calculate_proj_df_rect <- function(proj, data, coord, panel_params) {
   to_ymin <- data$to_ymin
   to_ymax <- data$to_ymax
 
+  if (corners > 0 && ! identical(proj, "single")) {
+    # the 1 - 1/sqrt(2) adjustment gets to the midpoint of the
+    # rounded corner (at a 45 degree angle), calculated via Pythagoras.
+    # Not perfect.
+    adj <- 1 - 1/sqrt(2)
+    corn_adj_x <- corners * (xmax - xmin) * adj
+    corn_adj_y <- corners * (ymax - ymin) * adj
+    to_corn_adj_x <- corners * (to_xmax - to_xmin) * adj
+    to_corn_adj_y <- corners * (to_ymax - to_ymin) * adj
+    xmin <- xmin + corn_adj_x
+    xmax <- xmax - corn_adj_x
+    ymin <- ymin + corn_adj_y
+    ymax <- ymax - corn_adj_y
+    to_xmin <- to_xmin + to_corn_adj_x
+    to_xmax <- to_xmax - to_corn_adj_x
+    to_ymin <- to_ymin + to_corn_adj_y
+    to_ymax <- to_ymax - to_corn_adj_y
+  }
 
   x <- mean(c(xmin, xmax))
   y <- mean(c(ymin, ymax))
   to_x <- mean(c(to_xmin, to_xmax))
   to_y <- mean(c(to_ymin, to_ymax))
 
-  if (proj %in% c("auto", "corresponding", "facing")) {
+  if (proj %in% c("corresponding", "facing")) {
     # which of the four lines connecting the four corners can we draw?
     can_top_left  <- sign(xmin - to_xmin) == sign(ymax - to_ymax)
     can_bot_right <- sign(xmax - to_xmax) == sign(ymin - to_ymin)

tests/testthat/test-params.R

@@ -35,6 +35,7 @@ test_param("aspect-fixed", aspect = "fixed")
 test_param("axes", axes = "xy")
 test_param("axes-x", axes = "x")
 test_param("axes-y", axes = "y")
+test_param("corners", corners = 0.1)
 test_param("proj-corresponding", proj = "corresponding")
 test_param("proj-single", proj = "single")
 test_param("linetype", linetype = 2)