From bc3e36a4f256ab468a9a482e4288268864bf2d45 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <49372158+teunbrand@users.noreply.github.com>
Date: Fri, 15 Sep 2023 11:51:34 +0200
Subject: [PATCH 1/8] Divorce building and drawing/assembly

---
 R/guides-.R                  | 34 ++++++++++++++++++++++++++++------
 R/plot-build.R               |  5 ++---
 tests/testthat/test-guides.R |  2 +-
 3 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/R/guides-.R b/R/guides-.R
index 163559b99c..d3ba02b252 100644
--- a/R/guides-.R
+++ b/R/guides-.R
@@ -282,7 +282,7 @@ Guides <- ggproto(
                    position, theme, labels) {
 
     position  <- legend_position(position)
-    no_guides <- zeroGrob()
+    no_guides <- guides_list()
     if (position == "none") {
       return(no_guides)
     }
@@ -318,10 +318,7 @@ Guides <- ggproto(
     if (length(guides$guides) == 0) {
       return(no_guides)
     }
-
-    # Draw and assemble
-    grobs <- guides$draw(theme)
-    guides$assemble(grobs, theme)
+    guides
   },
 
   # Setup routine for resolving and validating guides based on paired scales.
@@ -494,7 +491,32 @@ Guides <- ggproto(
   },
 
   # Combining multiple guides in a guide box
-  assemble = function(grobs, theme) {
+  assemble = function(self, theme, position) {
+
+    if (length(self$guides) < 1) {
+      return(zeroGrob())
+    }
+
+    position  <- legend_position(position)
+    theme$legend.key.width  <- theme$legend.key.width  %||% theme$legend.key.size
+    theme$legend.key.height <- theme$legend.key.height %||% theme$legend.key.size
+
+
+    default_direction <- if (position == "inside") "vertical" else position
+    theme$legend.box       <- theme$legend.box       %||% default_direction
+    theme$legend.direction <- theme$legend.direction %||% default_direction
+    theme$legend.box.just  <- theme$legend.box.just  %||% switch(
+      position,
+      inside     = c("center", "center"),
+      vertical   = c("left",   "top"),
+      horizontal = c("center", "top")
+    )
+
+    grobs <- self$draw(theme)
+    if (length(grobs) < 1) {
+      return(zeroGrob())
+    }
+
     # Set spacing
     theme$legend.spacing   <- theme$legend.spacing    %||% unit(0.5, "lines")
     theme$legend.spacing.y <- theme$legend.spacing.y  %||% theme$legend.spacing
diff --git a/R/plot-build.R b/R/plot-build.R
index 2c1695e350..7d5f507c16 100644
--- a/R/plot-build.R
+++ b/R/plot-build.R
@@ -177,9 +177,8 @@ ggplot_gtable.ggplot_built <- function(data) {
     position <- "manual"
   }
 
-  legend_box <- plot$guides$build(
-    plot$scales, plot$layers, plot$mapping, position, theme, plot$labels
-  )
+  guides <- plot$guides$build(plot$scales, plot$layers, plot$mapping, position, theme, plot$labels)
+  legend_box <- guides$assemble(theme, position)
 
   if (is.zero(legend_box)) {
     position <- "none"
diff --git a/tests/testthat/test-guides.R b/tests/testthat/test-guides.R
index ac704fdf79..5ae8b5375d 100644
--- a/tests/testthat/test-guides.R
+++ b/tests/testthat/test-guides.R
@@ -158,7 +158,7 @@ test_that("guide_none() can be used in non-position scales", {
     plot$labels
   )
 
-  expect_identical(guides, zeroGrob())
+  expect_length(guides$guides, 0)
 })
 
 test_that("Using non-position guides for position scales results in an informative error", {

From 245d48b0d67d6a643380dabcd06af4cb123dcebe Mon Sep 17 00:00:00 2001
From: Teun van den Brand <49372158+teunbrand@users.noreply.github.com>
Date: Fri, 15 Sep 2023 13:25:51 +0200
Subject: [PATCH 2/8] Fix test guide orders

---
 tests/testthat/test-draw-key.R     | 12 ++++++++----
 tests/testthat/test-geom-dotplot.R |  3 ++-
 tests/testthat/test-guides.R       |  2 +-
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/tests/testthat/test-draw-key.R b/tests/testthat/test-draw-key.R
index aeba592a6c..340ffb4c6d 100644
--- a/tests/testthat/test-draw-key.R
+++ b/tests/testthat/test-draw-key.R
@@ -7,14 +7,16 @@ test_that("alternative key glyphs work", {
   expect_doppelganger("time series and polygon key glyphs",
     ggplot(df, aes(x, y)) +
       geom_line(aes(color = "line"), key_glyph = "timeseries") +
-      geom_point(aes(fill = z), pch = 21, size = 3, key_glyph = "polygon")
+      geom_point(aes(fill = z), pch = 21, size = 3, key_glyph = "polygon") +
+      guides(fill = guide_legend(order = 1))
    )
 
   # specify key glyph by function
   expect_doppelganger("rectangle and dotplot key glyphs",
     ggplot(df, aes(x, y)) +
       geom_line(aes(color = "line"), key_glyph = draw_key_rect) +
-      geom_point(aes(fill = z), pch = 21, size = 3, stroke = 2, key_glyph = draw_key_dotplot)
+      geom_point(aes(fill = z), pch = 21, size = 3, stroke = 2, key_glyph = draw_key_dotplot) +
+      guides(fill = guide_legend(order = 1))
   )
 })
 
@@ -43,11 +45,13 @@ test_that("horizontal key glyphs work", {
   expect_doppelganger("horizontal boxplot and crossbar",
     p +
       geom_boxplot(aes(y = group1, color = group1), stat = "identity") +
-      geom_crossbar(aes(y = group2, fill = group2))
+      geom_crossbar(aes(y = group2, fill = group2)) +
+      guides(color = guide_legend(order = 1))
   )
   expect_doppelganger("horizontal linerange and pointrange",
     p +
       geom_linerange(aes(y = group1, color = group1)) +
-      geom_pointrange(aes(y = group2, shape = group2))
+      geom_pointrange(aes(y = group2, shape = group2)) +
+      guides(color = guide_legend(order = 1))
   )
 })
diff --git a/tests/testthat/test-geom-dotplot.R b/tests/testthat/test-geom-dotplot.R
index eedd4ba4e3..a095158937 100644
--- a/tests/testthat/test-geom-dotplot.R
+++ b/tests/testthat/test-geom-dotplot.R
@@ -196,7 +196,8 @@ test_that("geom_dotplot draws correctly", {
       )
     ) +
       geom_dotplot(binwidth = .4, fill = "red", col = "blue") +
-      continuous_scale("stroke", palette = function(x) scales::rescale(x, to = c(1, 6)))
+      continuous_scale("stroke", palette = function(x) scales::rescale(x, to = c(1, 6))) +
+      guides(linetype = guide_legend(order = 1))
   )
 
   # Stacking groups
diff --git a/tests/testthat/test-guides.R b/tests/testthat/test-guides.R
index 5ae8b5375d..fed331d6d1 100644
--- a/tests/testthat/test-guides.R
+++ b/tests/testthat/test-guides.R
@@ -559,7 +559,7 @@ test_that("guides are positioned correctly", {
   dat <- data_frame(x = LETTERS[1:3], y = 1)
   p2 <- ggplot(dat, aes(x, y, fill = x, colour = 1:3)) +
     geom_bar(stat = "identity") +
-    guides(color = "colorbar") +
+    guides(color = guide_colourbar(order = 1)) +
     theme_test() +
     theme(legend.background = element_rect(colour = "black"))
 

From c3a178a20b6c7617fefe64d073496398888df78b Mon Sep 17 00:00:00 2001
From: Teun van den Brand <49372158+teunbrand@users.noreply.github.com>
Date: Fri, 15 Sep 2023 13:30:36 +0200
Subject: [PATCH 3/8] Disconnect theme from build step

---
 R/coord-cartesian-.R         |  2 +-
 R/guide-.R                   |  5 ++++-
 R/guide-axis.R               |  2 +-
 R/guide-bins.R               | 32 +++++++++++++++------------
 R/guide-colorbar.R           | 36 +++++++++++++++---------------
 R/guide-legend.R             | 13 ++++++-----
 R/guide-none.R               |  2 +-
 R/guide-old.R                |  2 +-
 R/guides-.R                  | 43 +++++++++++-------------------------
 R/plot-build.R               |  2 +-
 tests/testthat/test-guides.R | 15 +++++--------
 11 files changed, 71 insertions(+), 83 deletions(-)

diff --git a/R/coord-cartesian-.R b/R/coord-cartesian-.R
index 8451873b84..1bf1b292cb 100644
--- a/R/coord-cartesian-.R
+++ b/R/coord-cartesian-.R
@@ -151,5 +151,5 @@ panel_guides_grob <- function(guides, position, theme) {
     return(zeroGrob())
   }
   pair <- guides$get_position(position)
-  pair$guide$draw(theme, pair$params)
+  pair$guide$draw(theme, params = pair$params)
 }
diff --git a/R/guide-.R b/R/guide-.R
index ae774d30c9..28b6804cfa 100644
--- a/R/guide-.R
+++ b/R/guide-.R
@@ -280,11 +280,14 @@ Guide <- ggproto(
 
   # Main drawing function that organises more specialised aspects of guide
   # drawing.
-  draw = function(self, theme, params = self$params) {
+  draw = function(self, theme, position = NULL, direction = NULL,
+                  params = self$params) {
 
     key <- params$key
 
     # Setup parameters and theme
+    params$position  <- params$position  %||% position
+    params$direction <- params$direction %||% direction
     params <- self$setup_params(params)
     elems  <- self$setup_elements(params, self$elements, theme)
     elems  <- self$override_elements(params, elems, theme)
diff --git a/R/guide-axis.R b/R/guide-axis.R
index eac32b2b98..ef6766273a 100644
--- a/R/guide-axis.R
+++ b/R/guide-axis.R
@@ -434,7 +434,7 @@ draw_axis <- function(break_positions, break_labels, axis_position, theme,
     !!aes := c(0, 1),
     !!opp := opp_value
   )
-  guide$draw(theme, params)
+  guide$draw(theme, params = params)
 }
 
 draw_axis_labels <- function(break_positions, break_labels, label_element, is_vertical,
diff --git a/R/guide-bins.R b/R/guide-bins.R
index 63c75bd0bd..f20adee759 100644
--- a/R/guide-bins.R
+++ b/R/guide-bins.R
@@ -298,15 +298,15 @@ GuideBins <- ggproto(
     params$title <- scale$make_title(
       params$title %|W|% scale$name %|W|% title
     )
+    params$key <- key
+    params
+  },
+
+  setup_params = function(params) {
     params$direction <- arg_match0(
-      params$direction %||% direction,
+      params$direction,
       c("horizontal", "vertical"), arg_nm = "direction"
     )
-    if (params$direction == "vertical") {
-      key$.value <- 1 - key$.value
-    }
-
-    params$key <- key
     valid_label_pos <- switch(
       params$direction,
       "horizontal" = c("bottom", "top"),
@@ -320,10 +320,6 @@ GuideBins <- ggproto(
         "not {.val {params$label.position}}."
       ))
     }
-    params
-  },
-
-  setup_params = function(params) {
     params <- GuideLegend$setup_params(params)
     params$byrow <- FALSE
     params$rejust_labels <- FALSE
@@ -345,10 +341,15 @@ GuideBins <- ggproto(
     }
     key$.label[c(1, n_labels)[!params$show.limits]] <- ""
 
-    just <- if (params$direction == "horizontal") {
-      elements$text$vjust
-    } else {
-      elements$text$hjust
+    just <- switch(
+      params$direction,
+      horizontal = elements$text$vjust,
+      vertical   = elements$text$hjust,
+      0.5
+    )
+
+    if (params$direction == "vertical") {
+      key$.value <- 1 - key$.value
     }
 
     list(labels = flip_element_grob(
@@ -363,6 +364,9 @@ GuideBins <- ggproto(
   },
 
   build_ticks = function(key, elements, params, position = params$position) {
+    if (params$direction == "vertical") {
+      key$.value <- 1 - key$.value
+    }
     key$.value[c(1, nrow(key))[!params$show.limits]] <- NA
     Guide$build_ticks(key$.value, elements, params, params$label.position)
   },
diff --git a/R/guide-colorbar.R b/R/guide-colorbar.R
index 4917679ebf..c56e7de3f7 100644
--- a/R/guide-colorbar.R
+++ b/R/guide-colorbar.R
@@ -344,27 +344,10 @@ GuideColourbar <- ggproto(
   },
 
   extract_params = function(scale, params,
-                            title  = waiver(), direction = "vertical", ...) {
+                            title  = waiver(), ...) {
     params$title <- scale$make_title(
       params$title %|W|% scale$name %|W|% title
     )
-    params$direction <- arg_match0(
-      params$direction %||% direction,
-      c("horizontal", "vertical"), arg_nm = "direction"
-    )
-    valid_label_pos <- switch(
-      params$direction,
-      "horizontal" = c("bottom", "top"),
-      "vertical"   = c("right", "left")
-    )
-    params$label.position <- params$label.position %||% valid_label_pos[1]
-    if (!params$label.position %in% valid_label_pos) {
-      cli::cli_abort(paste0(
-        "When {.arg direction} is {.val {params$direction}}, ",
-        "{.arg label.position} must be one of {.or {.val {valid_label_pos}}}, ",
-        "not {.val {params$label.position}}."
-      ))
-    }
 
     limits <- c(params$decor$value[1], params$decor$value[nrow(params$decor)])
     params$key$.value <- rescale(
@@ -402,6 +385,23 @@ GuideColourbar <- ggproto(
   },
 
   setup_params = function(params) {
+    params$direction <- arg_match0(
+      params$direction,
+      c("horizontal", "vertical"), arg_nm = "direction"
+    )
+    valid_label_pos <- switch(
+      params$direction,
+      "horizontal" = c("bottom", "top"),
+      "vertical"   = c("right", "left")
+    )
+    params$label.position <- params$label.position %||% valid_label_pos[1]
+    if (!params$label.position %in% valid_label_pos) {
+      cli::cli_abort(paste0(
+        "When {.arg direction} is {.val {params$direction}}, ",
+        "{.arg label.position} must be one of {.or {.val {valid_label_pos}}}, ",
+        "not {.val {params$label.position}}."
+      ))
+    }
     params$title.position <- arg_match0(
       params$title.position %||%
         switch(params$direction, vertical = "top", horizontal = "left"),
diff --git a/R/guide-legend.R b/R/guide-legend.R
index 4667e50388..917a0a507f 100644
--- a/R/guide-legend.R
+++ b/R/guide-legend.R
@@ -244,7 +244,7 @@ GuideLegend <- ggproto(
 
   available_aes = "any",
 
-  hashables = exprs(title, key$.label, direction, name),
+  hashables = exprs(title, key$.label, name),
 
   elements = list(
     background  = "legend.background",
@@ -260,14 +260,10 @@ GuideLegend <- ggproto(
   ),
 
   extract_params = function(scale, params,
-                            title = waiver(), direction = NULL, ...) {
+                            title = waiver(), ...) {
     params$title <- scale$make_title(
       params$title %|W|% scale$name %|W|% title
     )
-    params$direction <- arg_match0(
-      params$direction %||% direction,
-      c("horizontal", "vertical"), arg_nm = "direction"
-    )
     if (isTRUE(params$reverse %||% FALSE)) {
       params$key <- params$key[nrow(params$key):1, , drop = FALSE]
     }
@@ -346,6 +342,11 @@ GuideLegend <- ggproto(
   },
 
   setup_params = function(params) {
+    params$direction <- arg_match0(
+      params$direction %||% direction,
+      c("horizontal", "vertical"), arg_nm = "direction"
+    )
+
     if ("title.position" %in% names(params)) {
       params$title.position <- arg_match0(
         params$title.position %||%
diff --git a/R/guide-none.R b/R/guide-none.R
index ae26a8a1e9..5c0b2d35e2 100644
--- a/R/guide-none.R
+++ b/R/guide-none.R
@@ -35,7 +35,7 @@ GuideNone <- ggproto(
   },
 
   # Draw nothing
-  draw = function(self, params, theme) {
+  draw = function(self, ...) {
     zeroGrob()
   }
 )
diff --git a/R/guide-old.R b/R/guide-old.R
index 2320b0bbf2..cd2dce49f1 100644
--- a/R/guide-old.R
+++ b/R/guide-old.R
@@ -90,7 +90,7 @@ GuideOld <- ggproto(
   train = function(self, params, scale, aesthetic = NULL,
                    title = waiver(), direction = NULL) {
     params$title <- scale$make_title(params$title %|W|% scale$name %|W|% title)
-    params$direction <- params$direction %||% direction
+    params$direction <- params$direction %||% direction %||% "vertical"
     params <- guide_train(params, scale, aesthetic)
     params
   },
diff --git a/R/guides-.R b/R/guides-.R
index d3ba02b252..5526d2eb42 100644
--- a/R/guides-.R
+++ b/R/guides-.R
@@ -278,28 +278,10 @@ Guides <- ggproto(
   # 5. Guides$assemble()
   #      arrange all guide grobs
 
-  build = function(self, scales, layers, default_mapping,
-                   position, theme, labels) {
+  build = function(self, scales, layers, labels) {
 
-    position  <- legend_position(position)
+    # Empty guides list
     no_guides <- guides_list()
-    if (position == "none") {
-      return(no_guides)
-    }
-
-    theme$legend.key.width  <- theme$legend.key.width  %||% theme$legend.key.size
-    theme$legend.key.height <- theme$legend.key.height %||% theme$legend.key.size
-
-
-    default_direction <- if (position == "inside") "vertical" else position
-    theme$legend.box       <- theme$legend.box       %||% default_direction
-    theme$legend.direction <- theme$legend.direction %||% default_direction
-    theme$legend.box.just  <- theme$legend.box.just  %||% switch(
-      position,
-      inside     = c("center", "center"),
-      vertical   = c("left",   "top"),
-      horizontal = c("center", "top")
-    )
 
     # Setup and train on scales
     scales <- scales$non_position_scales()$scales
@@ -307,7 +289,7 @@ Guides <- ggproto(
       return(no_guides)
     }
     guides <- self$setup(scales)
-    guides$train(scales, theme$legend.direction, labels)
+    guides$train(scales, labels)
     if (length(guides$guides) == 0) {
       return(no_guides)
     }
@@ -411,14 +393,13 @@ Guides <- ggproto(
 
   # Loop over every guide-scale combination to perform training
   # A strong assumption here is that `scales` is parallel to the guides
-  train = function(self, scales, direction, labels) {
+  train = function(self, scales, labels) {
 
     params <- Map(
       function(guide, param, scale, aes) {
         guide$train(
           param, scale, aes,
-          title = labels[[aes]],
-          direction = direction
+          title = labels[[aes]]
         )
       },
       guide = self$guides,
@@ -482,9 +463,9 @@ Guides <- ggproto(
   },
 
   # Loop over every guide, let them draw their grobs
-  draw = function(self, theme) {
+  draw = function(self, theme, position, direction) {
     Map(
-      function(guide, params) guide$draw(theme, params),
+      function(guide, params) guide$draw(theme, position, direction, params),
       guide  = self$guides,
       params = self$params
     )
@@ -498,11 +479,13 @@ Guides <- ggproto(
     }
 
     position  <- legend_position(position)
+    if (position == "none") {
+      return(zeroGrob())
+    }
+    default_direction <- if (position == "inside") "vertical" else position
+
     theme$legend.key.width  <- theme$legend.key.width  %||% theme$legend.key.size
     theme$legend.key.height <- theme$legend.key.height %||% theme$legend.key.size
-
-
-    default_direction <- if (position == "inside") "vertical" else position
     theme$legend.box       <- theme$legend.box       %||% default_direction
     theme$legend.direction <- theme$legend.direction %||% default_direction
     theme$legend.box.just  <- theme$legend.box.just  %||% switch(
@@ -512,7 +495,7 @@ Guides <- ggproto(
       horizontal = c("center", "top")
     )
 
-    grobs <- self$draw(theme)
+    grobs <- self$draw(theme, position, default_direction)
     if (length(grobs) < 1) {
       return(zeroGrob())
     }
diff --git a/R/plot-build.R b/R/plot-build.R
index 7d5f507c16..c7ea877ec7 100644
--- a/R/plot-build.R
+++ b/R/plot-build.R
@@ -177,7 +177,7 @@ ggplot_gtable.ggplot_built <- function(data) {
     position <- "manual"
   }
 
-  guides <- plot$guides$build(plot$scales, plot$layers, plot$mapping, position, theme, plot$labels)
+  guides <- plot$guides$build(plot$scales, plot$layers, plot$labels)
   legend_box <- guides$assemble(theme, position)
 
   if (is.zero(legend_box)) {
diff --git a/tests/testthat/test-guides.R b/tests/testthat/test-guides.R
index fed331d6d1..97a82d26e6 100644
--- a/tests/testthat/test-guides.R
+++ b/tests/testthat/test-guides.R
@@ -152,9 +152,6 @@ test_that("guide_none() can be used in non-position scales", {
   guides <- guides$build(
     plot$scales,
     plot$layers,
-    plot$mapping,
-    "right",
-    theme_gray(),
     plot$labels
   )
 
@@ -181,7 +178,7 @@ test_that("guide merging for guide_legend() works as expected", {
 
     guides <- guides_list(NULL)
     guides <- guides$setup(scales$scales)
-    guides$train(scales$scales, "vertical", labs())
+    guides$train(scales$scales, labs())
     guides$merge()
     guides$params
   }
@@ -282,11 +279,11 @@ test_that("legend reverse argument reverses the key", {
   guides <- guides$setup(list(scale))
 
   guides$params[[1]]$reverse <- FALSE
-  guides$train(list(scale), "horizontal", labels = labs())
+  guides$train(list(scale), labels = labs())
   fwd <- guides$get_params(1)$key
 
   guides$params[[1]]$reverse <- TRUE
-  guides$train(list(scale), "horizontal", labels = labs())
+  guides$train(list(scale), labels = labs())
   rev <- guides$get_params(1)$key
 
   expect_equal(fwd$colour, rev(rev$colour))
@@ -301,10 +298,10 @@ test_that("guide_coloursteps and guide_bins return ordered breaks", {
   key <- g$train(scale = scale, aesthetic = "colour")$key
   expect_true(all(diff(key$.value) > 0))
 
-  # Bins guide is decreasing order
+  # Bins guide is increasing order
   g <- guide_bins()
-  key <- g$train(scale = scale, aesthetics = "colour", direction = "vertical")$key
-  expect_true(all(diff(key$.value) < 0))
+  key <- g$train(scale = scale, aesthetics = "colour")$key
+  expect_true(all(diff(key$.value) > 0))
 })
 
 

From eef083d45d2e4a3ef3994cd95d4983e541588458 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <49372158+teunbrand@users.noreply.github.com>
Date: Fri, 13 Oct 2023 11:38:45 +0200
Subject: [PATCH 4/8] Move guide building to `ggplot_build()`

---
 R/plot-build.R | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/R/plot-build.R b/R/plot-build.R
index c7ea877ec7..bc6a9a8706 100644
--- a/R/plot-build.R
+++ b/R/plot-build.R
@@ -84,11 +84,18 @@ ggplot_build.ggplot <- function(plot) {
   layout$setup_panel_params()
   data <- layout$map_position(data)
 
-  # Train and map non-position scales
+  # Hand off position guides to layout
+  layout$setup_panel_guides(plot$guides, plot$layers)
+
+  # Train and map non-position scales and guides
   npscales <- scales$non_position_scales()
   if (npscales$n() > 0) {
     lapply(data, npscales$train_df)
+    plot$guides <- plot$guides$build(npscales, plot$layers, plot$labels)
     data <- lapply(data, npscales$map_df)
+  } else {
+    # Assign empty guides if there are no non-position scales
+    plot$guides <- guides_list()
   }
 
   # Fill in defaults etc.
@@ -168,7 +175,6 @@ ggplot_gtable.ggplot_built <- function(data) {
 
   geom_grobs <- by_layer(function(l, d) l$draw_geom(d, layout), plot$layers, data, "converting geom to grob")
 
-  layout$setup_panel_guides(plot$guides, plot$layers)
   plot_table <- layout$render(geom_grobs, data, theme, plot$labels)
 
   # Legends
@@ -177,8 +183,7 @@ ggplot_gtable.ggplot_built <- function(data) {
     position <- "manual"
   }
 
-  guides <- plot$guides$build(plot$scales, plot$layers, plot$labels)
-  legend_box <- guides$assemble(theme, position)
+  legend_box <- plot$guides$assemble(theme, position)
 
   if (is.zero(legend_box)) {
     position <- "none"

From 72ef96bf90c3aefd16d796b9a928bb378dccf531 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <49372158+teunbrand@users.noreply.github.com>
Date: Fri, 13 Oct 2023 11:39:07 +0200
Subject: [PATCH 5/8] Some error messages are now thrown earlier

---
 tests/testthat/test-guides.R | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/tests/testthat/test-guides.R b/tests/testthat/test-guides.R
index 30b1d0067a..1aa13db169 100644
--- a/tests/testthat/test-guides.R
+++ b/tests/testthat/test-guides.R
@@ -107,8 +107,7 @@ test_that("a warning is generated when guides are drawn at a location that doesn
   plot <- ggplot(mpg, aes(class, hwy)) +
     geom_point() +
     scale_y_continuous(guide = guide_axis(position = "top"))
-  built <- expect_silent(ggplot_build(plot))
-  expect_warning(ggplot_gtable(built), "Position guide is perpendicular")
+  expect_warning(ggplot_build(plot), "Position guide is perpendicular")
 })
 
 test_that("a warning is not generated when a guide is specified with duplicate breaks", {
@@ -162,9 +161,7 @@ test_that("Using non-position guides for position scales results in an informati
   p <- ggplot(mpg, aes(cty, hwy)) +
     geom_point() +
     scale_x_continuous(guide = guide_legend())
-
-  built <- ggplot_build(p)
-  expect_snapshot_warning(ggplot_gtable(built))
+  expect_snapshot_warning(ggplot_build(p))
 })
 
 test_that("guide merging for guide_legend() works as expected", {
@@ -813,8 +810,7 @@ test_that("a warning is generated when guides(<scale> = FALSE) is specified", {
 
   # warn on scale_*(guide = FALSE)
   p <- ggplot(df, aes(x, y, colour = x)) + scale_colour_continuous(guide = FALSE)
-  built <- expect_silent(ggplot_build(p))
-  expect_snapshot_warning(ggplot_gtable(built))
+  expect_snapshot_warning(ggplot_build(p))
 })
 
 test_that("guides() warns if unnamed guides are provided", {

From 127d5da7f2d7054b25d2c1272a3f78401a852b00 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <49372158+teunbrand@users.noreply.github.com>
Date: Fri, 13 Oct 2023 12:08:53 +0200
Subject: [PATCH 6/8] Adapt `guide_old()`

---
 R/guide-old.R | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/R/guide-old.R b/R/guide-old.R
index cd2dce49f1..88b50f9f37 100644
--- a/R/guide-old.R
+++ b/R/guide-old.R
@@ -107,9 +107,10 @@ GuideOld <- ggproto(
     guide_geom(params, layers, default_mapping = NULL)
   },
 
-  draw = function(self, theme, params) {
+  draw = function(self, theme, position = NULL, direction = NULL, params) {
+    params$direction <- params$direction %||% direction %||% "placeholder"
     params$title.position <- params$title.position %||% switch(
-      params$direction %||% "placeholder",
+      params$direction,
       vertical = "top", horizontal = "left",
       NULL
     )

From cc9b75f4075db176e6071ac6b80d17a82bf9be5d Mon Sep 17 00:00:00 2001
From: Teun van den Brand <49372158+teunbrand@users.noreply.github.com>
Date: Tue, 24 Oct 2023 14:27:01 +0200
Subject: [PATCH 7/8] Expose `data` to `process_layers()`

---
 R/guide-.R         | 15 +++++++++++----
 R/guide-colorbar.R | 20 ++------------------
 R/guide-legend.R   | 25 +++++++++++++++----------
 R/guide-old.R      |  2 +-
 R/guides-.R        |  8 ++++----
 R/plot-build.R     |  2 +-
 6 files changed, 34 insertions(+), 38 deletions(-)

diff --git a/R/guide-.R b/R/guide-.R
index 28b6804cfa..f3ee472cdd 100644
--- a/R/guide-.R
+++ b/R/guide-.R
@@ -117,9 +117,12 @@ new_guide <- function(..., available_aes = "any", super) {
 #'   `params$hash`. This ensures that e.g. `guide_legend()` can display both
 #'   `shape` and `colour` in the same guide.
 #'
-#' - `get_layer_key()` Extract information from layers. This can be used to
-#'   check that the guide's aesthetic is actually in use, or to gather
-#'   information about how legend keys should be displayed.
+#' - `process_layers()` Extract information from layers. This acts mostly
+#'   as a filter for which layers to include and these are then (typically)
+#'   forwarded to `get_layer_key()`.
+#'
+#' - `get_layer_key()` This can be used to gather information about how legend
+#'   keys should be displayed.
 #'
 #' - `setup_params()` Set up parameters at the beginning of drawing stages.
 #'   It can be used to overrule user-supplied parameters or perform checks on
@@ -253,7 +256,11 @@ Guide <- ggproto(
 
   # Function for extracting information from the layers.
   # Mostly applies to `guide_legend()` and `guide_binned()`
-  get_layer_key = function(params, layers) {
+  process_layers = function(self, params, layers, data = NULL) {
+    self$get_layer_key(params, layers, data)
+  },
+
+  get_layer_key = function(params, layers, data = NULL) {
     return(params)
   },
 
diff --git a/R/guide-colorbar.R b/R/guide-colorbar.R
index c56e7de3f7..7e71eaba0c 100644
--- a/R/guide-colorbar.R
+++ b/R/guide-colorbar.R
@@ -364,24 +364,8 @@ GuideColourbar <- ggproto(
     return(list(guide = self, params = params))
   },
 
-  get_layer_key = function(params, layers) {
-
-    guide_layers <- lapply(layers, function(layer) {
-
-      matched_aes <- matched_aes(layer, params)
-
-      # Check if this layer should be included
-      if (include_layer_in_guide(layer, matched_aes)) {
-        layer
-      } else {
-        NULL
-      }
-    })
-
-    if (length(compact(guide_layers)) == 0) {
-      return(NULL)
-    }
-    return(params)
+  get_layer_key = function(params, layers, data = NULL) {
+    params
   },
 
   setup_params = function(params) {
diff --git a/R/guide-legend.R b/R/guide-legend.R
index c20938d7ae..341bee47c8 100644
--- a/R/guide-legend.R
+++ b/R/guide-legend.R
@@ -287,17 +287,26 @@ GuideLegend <- ggproto(
   },
 
   # Arrange common data for vertical and horizontal legends
-  get_layer_key = function(params, layers) {
+  process_layers = function(self, params, layers, data = NULL) {
+
+    include <- vapply(layers, function(layer) {
+      aes <- matched_aes(layer, params)
+      include_layer_in_guide(layer, aes)
+    }, logical(1))
+
+    if (!any(include)) {
+      return(NULL)
+    }
+
+    self$get_layer_key(params, layers[include], data[include])
+  },
+
+  get_layer_key = function(params, layers, data) {
 
     decor <- lapply(layers, function(layer) {
 
       matched_aes <- matched_aes(layer, params)
 
-      # Check if this layer should be included
-      if (!include_layer_in_guide(layer, matched_aes)) {
-        return(NULL)
-      }
-
       if (length(matched_aes) > 0) {
         # Filter out aesthetics that can't be applied to the legend
         n <- lengths(layer$aes_params, use.names = FALSE)
@@ -334,10 +343,6 @@ GuideLegend <- ggproto(
 
     # Remove NULL geoms
     params$decor <- compact(decor)
-
-    if (length(params$decor) == 0) {
-      return(NULL)
-    }
     return(params)
   },
 
diff --git a/R/guide-old.R b/R/guide-old.R
index 88b50f9f37..b2a137fffd 100644
--- a/R/guide-old.R
+++ b/R/guide-old.R
@@ -103,7 +103,7 @@ GuideOld <- ggproto(
     guide_transform(params, coord, panel_params)
   },
 
-  get_layer_key = function(params, layers) {
+  process_layers = function(self, params, layers, data = NULL) {
     guide_geom(params, layers, default_mapping = NULL)
   },
 
diff --git a/R/guides-.R b/R/guides-.R
index e82f35f15c..76bac43de0 100644
--- a/R/guides-.R
+++ b/R/guides-.R
@@ -278,7 +278,7 @@ Guides <- ggproto(
   # 5. Guides$assemble()
   #      arrange all guide grobs
 
-  build = function(self, scales, layers, labels) {
+  build = function(self, scales, layers, labels, layer_data) {
 
     # Empty guides list
     no_guides <- guides_list()
@@ -304,7 +304,7 @@ Guides <- ggproto(
 
     # Merge and process layers
     guides$merge()
-    guides$process_layers(layers)
+    guides$process_layers(layers, layer_data)
     if (length(guides$guides) == 0) {
       return(no_guides)
     }
@@ -447,9 +447,9 @@ Guides <- ggproto(
   },
 
   # Loop over guides to let them extract information from layers
-  process_layers = function(self, layers) {
+  process_layers = function(self, layers, data = NULL) {
     self$params <- Map(
-      function(guide, param) guide$get_layer_key(param, layers),
+      function(guide, param) guide$process_layers(param, layers, data),
       guide = self$guides,
       param = self$params
     )
diff --git a/R/plot-build.R b/R/plot-build.R
index bc6a9a8706..10ffaa9ae5 100644
--- a/R/plot-build.R
+++ b/R/plot-build.R
@@ -91,7 +91,7 @@ ggplot_build.ggplot <- function(plot) {
   npscales <- scales$non_position_scales()
   if (npscales$n() > 0) {
     lapply(data, npscales$train_df)
-    plot$guides <- plot$guides$build(npscales, plot$layers, plot$labels)
+    plot$guides <- plot$guides$build(npscales, plot$layers, plot$labels, data)
     data <- lapply(data, npscales$map_df)
   } else {
     # Assign empty guides if there are no non-position scales

From 9066c649fa0876760ad6a9750801070ea4051a2c Mon Sep 17 00:00:00 2001
From: Teun van den Brand <49372158+teunbrand@users.noreply.github.com>
Date: Mon, 30 Oct 2023 10:03:16 +0100
Subject: [PATCH 8/8] Add news bullet

---
 NEWS.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/NEWS.md b/NEWS.md
index 254c49abd1..658b967414 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,8 @@
 # ggplot2 (development version)
 
+* (internal) guide building is now part of `ggplot_build()` instead of 
+  `ggplot_gtable()` to allow guides to observe unmapped data (#5483).
+
 * Legend titles no longer take up space if they've been removed by setting 
   `legend.title = element_blank()` (@teunbrand, #3587).