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#' A 'ggplot2' geom to add text labels to point genetic features
#'
#' `geom_feature_label()` adds text labels to features drawn with
#' `geom_feature`().
#'
#' Standard 'ggplot2' aesthetics for text are supported (see Aesthetics).
#'
#' @section Aesthetics:
#'
#' - x (required; position of the feature)
#' - y (required; molecule)
#' - label (required; the label text)
#' - forward (optional; will draw text in the appropriate location for features
#' with angled arrowheads)
#' - colour
#' - size
#' - alpha
#' - family
#' - fontface
#' - angle
#'
#' @param mapping,data,stat,position,na.rm,show.legend,inherit.aes,... As
#' standard for ggplot2. inherit.aes is set to FALSE by default, as features
#' are not likely to share any plot aesthetics other than y.
#' @param feature_height `grid::unit()` object giving the height of the feature
#' being labelled, and hence the distance of the label above or below the
#' molecule line. Can be set as a negative value for features drawn below the
#' line. Defaults to 4 mm, to align labels with the default height of
#' `geom_feature()`.
#' @param label_height `grid::unit()` object giving the height of the label
#' text. Defaults to 3 mm.
#'
#' @examples
#'
#' ggplot2::ggplot(example_genes, ggplot2::aes(xmin = start, xmax = end,
#' y = molecule, fill = gene)) +
#' geom_gene_arrow() +
#' geom_feature(data = example_features, ggplot2::aes(x = position, y = molecule,
#' forward = forward)) +
#' geom_feature_label(data = example_features,
#' ggplot2::aes(x = position, y = molecule, label = name,
#' forward = forward)) +
#' ggplot2::facet_wrap(~ molecule, scales = "free")
#'
#' @seealso [geom_feature()]
#'
#' @export
geom_feature_label <- function(
mapping = NULL,
data = NULL,
stat = "identity",
position = "identity",
na.rm = FALSE,
show.legend = FALSE,
inherit.aes = FALSE,
feature_height = unit(4, "mm"),
label_height = unit(3, "mm"),
...
) {
ggplot2::layer(
data = data,
mapping = mapping,
stat = stat,
geom = GeomFeatureLabel,
position = position,
show.legend = show.legend,
inherit.aes = inherit.aes,
params = list(
na.rm = na.rm,
feature_height = feature_height,
label_height = label_height,
...
)
)
}
#' GeomFeatureLabel
#' @noRd
#' @import grid
#' @import ggfittext
GeomFeatureLabel <- ggplot2::ggproto(
"GeomFeatureLabel",
ggplot2::Geom,
required_aes = c("x", "y", "label"),
default_aes = ggplot2::aes(
colour = "black",
size = 8,
alpha = 1,
family = "",
fontface = 1,
angle = 0,
fill = "white",
lineheight = 0.9,
forward = NA
),
draw_key = ggplot2::draw_key_text,
setup_data = function(data, params) {
# The 'forward' aesthetic, if provided, should be logical or coerced to
# logical
if (!is.null(data$forward)) {
data$forward <- as.logical(data$forward)
}
data
},
draw_panel = function(data, panel_scales, coord, feature_height, label_height) {
# Detect flipped coordinates
coord_flip <- inherits(coord, "CoordFlip")
# Transform data to panel scales
data <- coord$transform(data, panel_scales)
gt <- grid::gTree(
data = data,
cl = ifelse(coord_flip, "flipfeaturelabeltree", "featurelabeltree"),
feature_height = feature_height,
label_height = label_height
)
gt$name <- grid::grobName(gt, "geom_feature_label")
gt
}
)
#' @importFrom grid makeContent
#' @export
makeContent.featurelabeltree <- function(x) {
data <- x$data
feature_height <- x$feature_height
label_height <- x$label_height
# Prepare grob for each label
grobs <- lapply(seq_len(nrow(data)), function(i) {
label <- data[i, ]
# Determine if the feature to be labelled is oriented, and set
# appropriate bounding box and place
# For non-oriented features:
if (is.na(label$forward) | ! is.logical(label$forward)) {
label$xmin <- label$x - 0.5
label$xmax <- label$x + 0.5
y_sign <- ifelse(
grid::convertHeight(feature_height, "native", TRUE) >= 0,
1,
-1
)
inside <- label$y + grid::convertHeight(feature_height, "native", TRUE)
outside <- inside +
(y_sign * grid::convertHeight(label_height, "native", TRUE))
label$ymin <- max(min(c(inside, outside)), 0)
label$ymax <- min(max(c(inside, outside)), 1)
align <- "centre"
# For oriented features
} else {
x_sign <- ifelse(label$forward, 1, -1)
if (x_sign == 1) {
label$xmin <- label$x
label$xmax <- 1
align <- "left"
} else {
label$xmin <- 0
label$xmax <- label$x
align <- "right"
}
y_sign <- ifelse(
grid::convertHeight(feature_height, "native", TRUE) >= 0,
1,
-1
)
inside <- label$y + grid::convertHeight(feature_height, "native", TRUE)
outside <- inside +
(y_sign * grid::convertHeight(label_height, "native", TRUE))
label$ymin <- max(min(c(inside, outside)), 0)
label$ymax <- min(max(c(inside, outside)), 1)
}
# Use ggfittext's fittexttree to draw text
gt <- grid::gTree(
data = label,
padding.x = grid::unit(0, "mm"),
padding.y = grid::unit(0, "mm"),
place = align,
min.size = 0,
grow = FALSE,
reflow = FALSE,
cl = "fittexttree",
fullheight = TRUE
)
gt$name <- grid::grobName(gt, "geom_feature_label")
gt
} )
class(grobs) <- "gList"
grid::setChildren(x, grobs)
}
#' @importFrom grid makeContent
#' @export
makeContent.flipfeaturelabeltree <- function(x) {
data <- x$data
feature_height <- x$feature_height
label_height <- x$label_height
# Prepare grob for each label
grobs <- lapply(seq_len(nrow(data)), function(i) {
label <- data[i, ]
label$ymin <- label$y - 0.5
label$ymax <- label$y + 0.5
x_sign <- ifelse(
grid::convertWidth(feature_height, "native", TRUE) >= 0,
1,
-1
)
inside <- label$x + grid::convertWidth(feature_height, "native", TRUE)
outside <- inside +
(x_sign * grid::convertWidth(label_height, "native", TRUE))
label$xmin <- max(min(c(inside, outside)), 0)
label$xmax <- min(max(c(inside, outside)), 1)
align <- "centre"
# Use ggfittext's fittexttree to draw text
gt <- grid::gTree(
data = label,
padding.x = grid::unit(0, "mm"),
padding.y = grid::unit(0, "mm"),
place = align,
min.size = 0,
grow = FALSE,
reflow = FALSE,
cl = "fittexttree",
fullheight = TRUE
)
gt$name <- grid::grobName(gt, "geom_feature_label")
gt
} )
class(grobs) <- "gList"
grid::setChildren(x, grobs)
}
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