playPointInput: Get point, line or rect input from playwith user

Description

Part of the playwith Application Programming Interface.

Usage

playPointInput(playState = playDevCur(), prompt)
playLineInput(playState = playDevCur(), prompt, scales = "dynamic")
playRectInput(playState = playDevCur(), prompt, scales = "dynamic")

Arguments

playState

a playState object representing the plot, window and device.

prompt

text to display in the prompt.

scales

the default allows the user to hold Shift while dragging, to constrain the selection to x or y scales. Otherwise this should be one or more of "x" and "y", specifying which axes to select along.

Value

space: character, specifies the plot space in which the user clicked or dragged. See the space argument to playDo.
coords: native coordinates of the point or shape in space. A list with numeric vectors x and y. For a rectangle or line, these are length 2 where the first element refers to the start of the drag motion. For a point these are length 1. If space is "page", this is NULL.
dc: device coordinates of the point or shape (pixels).
ndc: normalised device coordinates of the point or shape.
is.click: logical, whether it was a click (so probably should not be treated as a rectangle or line). This is not returned by playPointInput.
modifiers: a flag representing which modifier keys were pressed during the click (or at the end of a drag). E.g. to test for Shift key: if (foo$modifiers & GdkModifierType["shift-mask"]). See enums-and-flags.

Details

playPointInput is similar to locator, but returns native coordinates in whichever plot space was clicked on. Device coordinates and normalised device coordinates are also available.

playRectInput and playLineInput allow the user to interactively draw a rectangle or line.

Examples

Run this code

if (interactive()) {

library(lattice)
playwith(xyplot(Sepal.Width ~ Petal.Width | Species, data = iris))
playPointInput()
playRectInput()

}