cranvas (version 0.8.5)

Common.meta: Common meta data structure in cranvas

Description

A meta data is created with reference classes (setRefClass) in the methods and signaling fields in the objectProperties package (properties). It is used to make several plotting routines more modularized (e.g. the axes and background layers).

Usage

Common.meta

Format

List of 26
 $ alpha          : chr "numeric"
 $ main           : chr "character"
 $ xlim           : chr "numeric"
 $ ylim           : chr "numeric"
 $ xat            : chr "numeric"
 $ yat            : chr "numeric"
 $ xlab           : chr "character"
 $ ylab           : chr "character"
 $ xlabels        : chr "character"
 $ ylabels        : chr "character"
 $ limits         : chr "matrix"
 $ color          : chr "character"
 $ border         : chr "character"
 $ size           : chr "numeric"
 $ start          : chr "numeric"
 $ pos            : chr "numeric"
 $ active         : chr "logical"
 $ brush.move     : chr "logical"
 $ brush.size     : chr "numeric"
 $ brush.adj      : chr "numeric"
 $ manual.brush   : chr "function"
 $ minor          : chr "character"
 $ keys           : chr "character"
 $ identified     : chr "integer"
 $ identify.labels: chr "character"
 $ handlers       : chr "list"

Details

This object only provides a template for the common meta data, we have to call properties in order to really create a meta object.

We can use Meta.template$new() to generate an object, which is essentially an environment. This environment object is dynamic in the sense that no matter where we copy it to or how we modify the components in it, all its copies can sync with each other. This free us from considering lexical scopes frequently when we do interactive graphics, which often involves with global or local changes of variables.

Another advantage is that we can attach events on this object. When a component is changed, an event can be triggered (see examples below).

The common meta structure contains the following components:

alpha

the alpha transparency

main

the main title

xlim, ylim

the real x- and y-axis limits calculated from original data

xat, yat

the tickmarks locations on the x and y axis

xlab, ylab

x and y axis titles

xlabels, ylabels

the tickmarks labels

minor

possible values are '', 'x', 'y' and 'xy', indicating which axis to draw minor grid lines

limits

the limits of the main plot layer (it is often the case that some other layers need to sync with the main plot layer in limits, so this component is very important)

color, border, size

the real color, border and size vectors used to draw the graphical elements, which can be different from the corresponding columns in the original data

start, pos

the starting position and the current position of the cursor

brush.move

indicating if the brush is in the move mode (if not, the brush will be resized when mouse moves

brush.size

the size of the brush rectangle (a numeric vector of length 2)

brush.adj

the amount of x and y adjustment for the brush rectangle to capture a graphical element without having to cover its center

manual.brush

a function to manually brush the plot given the mouse position

identified, identify.labels

the identified indices and the text label to draw in the plot for the identified cases

handlers

a list of event handlers (functions of two arguments: layer and event)

active

logical: if the current plot window is active

Examples

library(objectSignals)
My.meta <- setRefClass("My_meta", fields = objectProperties::properties(c(Common.meta, 
    list(horizontal = "logical", xleft = "numeric"))))
meta <- My.meta$new(alpha = 1)
meta$alpha
meta$xat <- 1:5
meta$pos <- c(1, 4)
meta$horizontal <- FALSE

meta2 <- meta
meta2$xat <- 2:6
meta$xat  # meta is changed too

meta$posChanged$connect(function() {
    message("the mouse position is (", paste(meta$pos, collapse = ","), ") now")
})
meta$pos <- c(2, 0)

ls(meta)  # list all the objects in it