Apply a perspective warp to a magick image

Distorts a magick-image using a four-point perspective transformation, giving the "floating HUD panel" effect.

Usage

warp_hud(img, corners = list(), keep_size = TRUE, ...)

Arguments

img

A magick-image object, typically produced by render_hud().

corners

A named list specifying how far each corner of the image should move from its natural position. Each element is a numeric vector of length 2: c(dx, dy), where positive values move right/down. Names must be "tl" (top-left), "tr" (top-right), "bl" (bottom-left), and "br" (bottom-right). Any corner omitted defaults to c(0, 0) (no movement).

Example: tilt the panel so the left edge rises and the right edge drops:

corners = list(tl = c(0, -20), bl = c(0, -20),
               tr = c(0,  20), br = c(0,  20))

keep_size

If TRUE (default), the output image is cropped/padded back to the original pixel dimensions. If FALSE, ImageMagick may expand the canvas to contain the warped result.

...

Currently unused.

Value

A warped magick-image with an alpha channel preserved.

Examples

if (FALSE) { # \dontrun{
library(ggplot2)
p <- ggplot(mtcars, aes(wt, mpg)) + geom_point()
img <- render_hud(p, width = 500, height = 350)

# Tilt the top edge backward (raise both top corners)
warped <- warp_hud(img, corners = list(tl = c(20, -15), tr = c(-20, -15)))
magick::image_browse(warped)
} # }