Use layout.legend.title over layout.annotations to when converting guides for discrete scales

Author: cpsievert

R/ggplotly.R

@@ -999,26 +999,12 @@ gg2list <- function(p, width = NULL, height = NULL,
     }
     traces <- c(traces, colorbar)
 
-    # legend title annotation - https://github.com/plotly/plotly.js/issues/276
-    if (isTRUE(gglayout$showlegend)) {
-      legendTitles <- compact(lapply(gdefs, function(g) if (inherits(g, "legend")) g$title else NULL))
-      legendTitle <- paste(legendTitles, collapse = br())
-      titleAnnotation <- make_label(
-        legendTitle,
-        x = gglayout$legend$x %||% 1.02,
-        y = gglayout$legend$y %||% 1,
-        theme$legend.title,
-        xanchor = "left",
-        yanchor = "bottom",
-        # just so the R client knows this is a title
-        legendTitle = TRUE
-      )
-      gglayout$annotations <- c(gglayout$annotations, titleAnnotation)
-      # adjust the height of the legend to accomodate for the title
-      # this assumes the legend always appears below colorbars
-      gglayout$legend$y <- (gglayout$legend$y %||% 1) -
-        length(legendTitles) * unitConvert(theme$legend.title$size, "npc", "height")
-    }
+    legendTitles <- compact(lapply(gdefs, function(g) if (inherits(g, "legend")) g$title else NULL))
+    legendTitle <- paste(legendTitles, collapse = br())
+    gglayout$legend$title <- list(
+      text = legendTitle,
+      font = text2font(theme$legend.title)
+    )
   }
 
   # flip x/y in traces for flipped coordinates

R/utils.R

@@ -845,9 +845,6 @@ verify_showlegend <- function(p) {
   # this attribute should be set in hide_legend()
   # it ensures that "legend titles" go away in addition to showlegend = FALSE
   if (isTRUE(p$x$.hideLegend)) {
-    ann <- p$x$layout$annotations
-    is_title <- vapply(ann, function(x) isTRUE(x$legendTitle), logical(1))
-    p$x$layout$annotations <- ann[!is_title]
     p$x$layout$showlegend <- FALSE 
   }
   show <- vapply(p$x$data, function(x) x$showlegend %||% TRUE, logical(1))

tests/testthat/test-ggplot-bar.R

@@ -134,7 +134,7 @@ test_that("guides(fill=FALSE) does not affect colour legend", {
     expect_true(is.character(tr$marker$line$color))
     expect_true(tr$showlegend)
   }
-  expect_match(info$layout$annotations[[1]]$text, "time")
+  expect_match(info$layout$legend$title$text, "time")
   expect_true(info$layout$showlegend)
 })
 

tests/testthat/test-ggplot-density2d.R

@@ -51,7 +51,6 @@ test_that("StatDensity2d with GeomPolygon translates to filled path(s)", {
     length(unique(unlist(lapply(polygons, "[[", "fillcolor")))) > 1
   )
   # ensure the legend/guide are placed correctly
-  expect_true(L$layout$legend$y < 0.5)
   expect_true(L$layout$legend$yanchor == "top")
   expect_true(colorbar$marker$colorbar$y == 1)
   expect_true(colorbar$marker$colorbar$yanchor == "top")

tests/testthat/test-ggplot-legend.R

@@ -28,10 +28,9 @@ test_that("Discrete colour and shape get merged into one legend", {
   expect_identical(
     nms, paste0("(", d$vs, ",", d$cyl, ")")
   )
-  a <- info$layout$annotations
-  expect_match(a[[1]]$text, "^factor\\(vs\\)")
-  expect_match(a[[1]]$text, "factor\\(cyl\\)$")
-  expect_true(a[[1]]$y > info$layout$legend$y)
+  legend_title <- info$layout$legend$title$text
+  expect_match(legend_title, "^factor\\(vs\\)")
+  expect_match(legend_title, "factor\\(cyl\\)$")
 })
 
 
@@ -80,7 +79,7 @@ test_that("legend is created with discrete mapping regardless of unique values",
   info <- expect_traces(p, 1, "one-entry")
   expect_true(info$data[[1]]$showlegend)
   expect_true(info$layout$showlegend)
-  expect_equivalent(length(info$layout$annotations), 1)
+  expect_true(nzchar(info$layout$legend$title$text))
 })
 
 test_that("can hide legend", {