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

Description Details Author(s)

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 set.current.layer() function. To see the information of available layers, use the get.layers() and 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 points() and 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.

Yixuan Qiu (yixuan.qiu@cos.name)

yixuan/Layer documentation built on May 4, 2019, 5:28 p.m.