bm_mask {bittermelon} | R Documentation |
Modify bitmaps via masking with a 'mask' bitmap
Description
bm_mask()
modifies bitmaps by using a binary bitmap “mask”
to set certain elements to a background value.
Usage
bm_mask(
x,
mask = NULL,
base = NULL,
mode = c("luminance", "alpha"),
hjust = "center-left",
vjust = "center-top"
)
## S3 method for class 'bm_bitmap'
bm_mask(
x,
mask = NULL,
base = NULL,
mode = c("luminance", "alpha"),
hjust = "center-left",
vjust = "center-top"
)
## S3 method for class 'bm_pixmap'
bm_mask(
x,
mask = NULL,
base = NULL,
mode = c("luminance", "alpha"),
hjust = "center-left",
vjust = "center-top"
)
## S3 method for class ''magick-image''
bm_mask(
x,
mask = NULL,
base = NULL,
mode = c("luminance", "alpha"),
hjust = "center-left",
vjust = "center-top"
)
## S3 method for class 'nativeRaster'
bm_mask(
x,
mask = NULL,
base = NULL,
mode = c("luminance", "alpha"),
hjust = "center-left",
vjust = "center-top"
)
## S3 method for class 'raster'
bm_mask(
x,
mask = NULL,
base = NULL,
mode = c("luminance", "alpha"),
hjust = "center-left",
vjust = "center-top"
)
## S3 method for class 'bm_list'
bm_mask(
x,
mask = NULL,
base = NULL,
mode = c("luminance", "alpha"),
hjust = "center-left",
vjust = "center-top"
)
Arguments
x |
Either a |
mask |
An object to use as a binary bitmap “mask”.
Only one of |
base |
A bitmap/pixmap object which will be “masked” by |
mode |
Either "luminance" (default) or "alpha". |
hjust |
One of "left", "center-left", "center-right", "right". "center-left" and "center-right" will attempt to place in "center" if possible but if not possible will bias it one pixel left or right respectively. "centre", "center", and "centre-left" are aliases for "center-left". "centre-right" is an alias for "center-right". |
vjust |
One of "bottom", "center-bottom", "center-top", "top". "center-bottom" and "center-top" will attempt to place in "center" if possible but if not possible will bias it one pixel down or up respectively. "centre", "center", and "centre-top" are aliases for "center-top". "centre-bottom" is an alias for "center-bottom". |
Details
If necessary bitmaps will be extended by bm_extend()
such that
they are the same size.
If necessary the mask
will be coerced into a “binary” mask
by bm_clamp(as_bm_bitmap(mask))
.
If mode
is "luminance" then where the mask
is 1L
the corresponding pixel in base
will be coerced to the background value.
If mode
is "alpha" then where the mask
is 0L
the corresponding pixel in base
will be coerced to the background value.
Value
A bitmap/pixmap object that is the same type as x
(if base
is NULL
) or base
.
Examples
if (require("grid", quietly = TRUE) && capabilities("png")) {
font_file <- system.file("fonts/spleen/spleen-8x16.hex.gz", package = "bittermelon")
font <- read_hex(font_file)
one <- font[[str2ucp("1")]]
circle_large <- as_bm_bitmap(circleGrob(r = 0.50), width = 16L, height = 16L)
circle_small <- as_bm_bitmap(circleGrob(r = 0.40), width = 16L, height = 16L)
circle_outline <- bm_mask(circle_large, circle_small)
print(circle_outline)
}
if (capabilities("png")) {
# U+2776 "Dingbat Negative Circled Digit One"
circle_minus_one <- bm_mask(circle_large, one)
print(circle_minus_one)
}
# Can also do "alpha" mask
square_full <- bm_bitmap(matrix(1L, nrow = 16L, ncol = 16L))
square_minus_lower_left <- square_full
square_minus_lower_left[1:8, 1:8] <- 0L
print(square_minus_lower_left)
if (capabilities("png")) {
circle_minus_lower_left <- bm_mask(circle_large, square_minus_lower_left, mode = "alpha")
print(circle_minus_lower_left)
}
if (capabilities("png")) {
m <- matrix(grDevices::rainbow(8L), byrow = TRUE, ncol = 8L, nrow = 8L)
rainbow <- bm_expand(as_bm_pixmap(m), 2L)
circle_rainbow <- bm_mask(rainbow, circle_large, mode = "alpha")
}
if (cli::is_utf8_output() &&
cli::num_ansi_colors() >= 256L &&
capabilities("png")) {
print(circle_rainbow, compress = "v")
}