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2 changes: 2 additions & 0 deletions NEWS.md
Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,8 @@
calculated as the density times the sum of weights (@teunbrand, #4176).
* `theme()` gets new `spacing` and `margins` arguments that all other spacings
and (non-text) margins inherit from (@teunbrand, #5622).
* `geom_ribbon()` can have varying `fill` or `alpha` in linear coordinate
systems (@teunbrand, #4690)

# ggplot2 3.5.1

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41 changes: 37 additions & 4 deletions R/geom-ribbon.R
Original file line number Diff line number Diff line change
Expand Up @@ -135,11 +135,44 @@ GeomRibbon <- ggproto("GeomRibbon", Geom,
data <- data[order(data$group), ]

# Check that aesthetics are constant
aes <- unique0(data[names(data) %in% c("colour", "fill", "linewidth", "linetype", "alpha")])
if (nrow(aes) > 1) {
cli::cli_abort("Aesthetics can not vary along a ribbon.")
aes <- lapply(
data[names(data) %in% c("colour", "fill", "linewidth", "linetype", "alpha")],
unique0
)
non_constant <- names(aes)[lengths(aes) > 1]
if (coord$is_linear()) {
if (any(c("fill", "alpha") %in% non_constant)) {
check_device("gradients", action = "abort", maybe = TRUE)
}
# For linear coords, we can make a fill/alpha gradient, so we allow
# these to vary
non_constant <- setdiff(non_constant, c("fill", "alpha"))
}
if (length(non_constant) > 0) {
cli::cli_abort(
"Aesthetics can not vary along a ribbon: {.and {.field {non_constant}}}."
)
}
if ((length(aes$fill) > 1 || length(aes$alpha) > 1)) {
transformed <- coord$transform(flip_data(data, flipped_aes), panel_params)
if (flipped_aes) {
keep <- is.finite(tranformed$y)
args <- list(
colours = alpha(data$fill, data$alpha)[keep],
stops = rescale(transformed$y)[keep],
y1 = 0, y2 = 1, x1 = 0.5, x2 = 0.5
)
} else {
keep <- is.finite(transformed$x)
args <- list(
colours = alpha(data$fill, data$alpha)[keep],
stops = rescale(transformed$x)[keep],
x1 = 0, x2 = 1, y1 = 0.5, y2 = 0.5
)
}
aes$fill <- inject(linearGradient(!!!args))
aes$alpha <- NA
}
aes <- as.list(aes)

# Instead of removing NA values from the data and plotting a single
# polygon, we want to "stop" plotting the polygon whenever we're
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2 changes: 1 addition & 1 deletion tests/testthat/_snaps/geom-ribbon.md
Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@
Problem while converting geom to grob.
i Error occurred in the 1st layer.
Caused by error in `draw_group()`:
! Aesthetics can not vary along a ribbon.
! Aesthetics can not vary along a ribbon: linewidth.

---

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18 changes: 17 additions & 1 deletion tests/testthat/test-geom-ribbon.R
Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ test_that("geom_ribbon() checks the aesthetics", {
geom_ribbon(aes(y = year, xmin = level - 5, xmax = level + 5), orientation = "x")
expect_snapshot_error(ggplotGrob(p))
p <- ggplot(huron) +
geom_ribbon(aes(year, ymin = level - 5, ymax = level + 5, fill = year))
geom_ribbon(aes(year, ymin = level - 5, ymax = level + 5, linewidth = year))
expect_snapshot_error(ggplotGrob(p))

expect_snapshot_error(geom_ribbon(aes(year, ymin = level - 5, ymax = level + 5), outline.type = "test"))
Expand Down Expand Up @@ -74,3 +74,19 @@ test_that("outline.type option works", {
expect_s3_class(g_area_default$children[[1]]$children[[2]], "polyline")
expect_equal(g_area_default$children[[1]]$children[[2]]$id, rep(1L, each = 4))
})

test_that("ribbons can have gradients", {
skip_if_not(
check_device("gradients", action = "test"),
"graphics device does not support gradients."
)

df <- data.frame(x = 1:2, ymin = c(-1:-2), ymax = 1:2)
p <- ggplot(df, aes(x, ymin = ymin, ymax = ymax, fill = x)) +
geom_ribbon(outline.type = "full") +
scale_fill_gradientn(colours = c("red", "blue"))
fill <- layer_grob(p)[[1]]$children[[1]]$gp$fill

expect_s3_class(fill, "GridLinearGradient")
expect_equal(fill$colours, alpha(c("red", "blue"), NA))
})