Create an SVG drop shadow filter

This filter adds a drop shadow to the element it is applied to.

create_filter_drop_shadow(
  id,
  dx = 10,
  dy = dx,
  std_dev = 3,
  colour = "#bbb",
  ...
)

Arguments

id	id to use for filter.
dx, dy	offset of shadow in x and y directions. default: 10
std_dev	standard deviation of the gaussian for the blur. default: 3
colour	default: #bbb
...	other arguments ignored

Value

minisvg::SVGElement object representing a filter

Details

The drop shadow effect is a combination of 4 primitive SVG filters:

1. Blur the element

2. Offset this blurred image

3. Fill the blurred image with the given colour using a flood and a composite

4. Layer the drop shadow behind the original image

For more information see the MDN SVG docs for feGaussianBlur

Examples

if (FALSE) {
# Create an SVG document
library(minisvg)
doc   <- minisvg::svg_doc()

# Create the filter and add to the SVG definitions
drop_shadow_filter <- create_filter_drop_shadow(id = 'dshadow')
doc$defs(drop_shadow_filter)

# Create a rectangle with the animation
rect  <- stag$rect(
  x      = "10%",
  y      = "10%",
  width  = "80%",
  height = "80%",
  fill   = "lightblue",
  stroke = 'black',
  filter = drop_shadow_filter
)

# Add this rectangle to the document, show the SVG text, then render it
doc$append(rect)
doc
doc$show()
}