R/Layer-package.R

In yixuan/Layer: An R Graphics Device with Layer Support (preview)

##' R Graphics Device with Layer Support
##'
##' This package implements an \R graphics device that allows users to create
##' graphics based on layers.
##' 
##' Most graphics devices in \R allow users to draw shapes on a single canvas.
##' That is to say, after executing plotting commands, the curves and shapes
##' previously drawn are mixed up and could not be seperated with each other.
##' As a result, these patterns could not be moved, scaled or rotated by
##' consequent \R commands.
##' 
##' The Layer device provided by this package has the capacity to create images
##' made up of several layers. A layer can be thought of a transparent canvas
##' with opaque patterns on it. The image we see on screen is the combination
##' of all layers, but each of them is independent of the others. Therefore,
##' we can apply operations(e.g. moving, scaling or rotation) to a specific layer
##' without changing the patterns on other layers.
##' 
##' When a layer is created, it will be assigned an ID number and a name. ID
##' is an integer to uniquely identify a layer, and it is created automatically
##' by the device. The name is just like a note of the content of the layer,
##' so it can be any character string.
##' 
##' In Layer device, plotting commands can only be passed to one layer at a
##' time, which we use the term "Current Layer" to stand for. Users can change
##' Current Layer by the \code{\link{set.current.layer}()} function. To see
##' the information of available layers, use the \code{\link{get.layers}()}
##' and \code{\link{get.current.layer}()} functions.
##' 
##' Note that high-level plotting functions will destroy all previously created
##' layers and open a new one, so if you want to create a multi-layer graph, be
##' sure to use low-level plotting functions like \code{points()} and
##' \code{lines()}.
##' 
##' Layer device also provides an interactive operation with the image on the
##' screen. You can adjust the location of the Current Layer by pressing and
##' moving your mouse. To do this, press your left mouse button and keep it
##' down, and then move Current layer along with your mouse, and finally
##' relocate the layer by releasing your mouse button. The operations are
##' similar if you want to scale or rotate a layer.
##'
##' @name Layer-package
##' @docType package 
##' @author Yixuan Qiu (\email{yixuan.qiu@@cos.name})
##' @keywords device iplot
##'
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