testAlpha {PBSmodelling}

Test Various Alpha Transparency Values

Description

Display how the alpha transparency for rgb() varies.

Usage

testAlpha(alpha=seq(0,1,len=25), fg="blue", bg="yellow",
      border="black", grid=FALSE, ...)

Arguments

alpha

numeric – vector of alpha transparency values values from 0 to 1.

fg

character – foreground colour of the top shape that varies in transparency.

bg

character – background colour (remains constant) of the underlying shape.

border

character – border colour (which also changes in transparency) of the foreground polygon.

grid

logical – if TRUE, lay a grey grid on the background colour.

...

dots – additional graphical arguments to send to the the ploting functions.

Value

Invisibly returns the compound RGB matrix for fg, alpha, bg, and border.

Author(s)

Jon T. Schnute, Research Scientist Emeritus
Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo BC

Maintainer: Rowan Haigh, Program Head – Offshore Rockfish
Pacific Biological Station (PBS), Fisheries & Oceans Canada (DFO), Nanaimo BC
locus opus: Offsite, Vancouver BC
Last modified Rd: 2023-10-18

See Also

In package PBSmodelling:
testCol, testLty, testLwd
In package PBStools:
testPch