SVGAnnotation: Tools for post-processing SVG plots created in R

Description Usage Arguments Value Author(s) References Examples

This function and its methods allow the caller to easily and programmatically add JavaScript/ECMAScript code to an SVG document or an HTML document. The functions take care of the details, allowing the code to be inserted directly or a reference to the file via an href link. The code can also be given as verbatim (AsIs) text rather than being in a file which allows the content to be dynamically generated within R functions.

The benefit of inserting the contents of a JavaScript file into the document is that the resulting document does not have external dependencies on this file. We can move the XML document and not have to remember to also move the JavaScript file or update the link.

The downside is that it is often convenient to create the SVG and then modify the JavaScript code. This is very common when developing the JavaScript code. If we keep the JavaScript file separate from the SVG, we can update it and then merely reload the SVG file in our viewer/browser to work with the updated JavaScript code.

An additional drawback to inserting the code is that if we use it many different SVG files, we have many copies of the code and if it is large, we are wasting space and bandwidth.

I tend to include the code after I have finished working out the bugs and features, i.e. when I am generating the SVG file knowing it is woring as desired.

In addition to adding JavaScript code, one can also add JavaScript variables which are created by serializing R objects. This allows us to use data computed in R within our JavaScript code with little effort. The serialization is done primarily via the rjson package, with some generalizations provided by this package.

addECMAScripts(doc, scripts,
               insertJS = inherits(scripts, "AsIs") || 
                             getOption("InsertScriptContents", FALSE),
               at = NA, ..., .jsvars = list(...),
               escapeFun = newXMLCDataNode)

`doc`	the XML document to which the JavaScript code is to be added. This is expected to have been parsed previously rather than be the name of a file.
`scripts`	a character vector giving the names of the JavaScript code files or the code itself. Use `I("text for code")` to ensure the value is treated as verbatim code.
`insertJS`	a logical value which controls whether the JavaScript code is actually inserted into the XML document so that it is a stand-alone document with no references to this JavaScript code, or if `href` references are inserted into the XML document. One can control whether the contents or the reference to the file is inserted via the global option `InsertScriptContents`. Set this to `TRUE` to cause the contents to be inserted.
`at`	an integer that specifies where to add the new XML nodes within the children of the SVG root. By default, the new nodes are added at the end. The order is typically not important.
`...`	`name = value` pairs of JavaScript variable names and R objects which are to be serialized and assigned to those JavaScript variables.
`.jsvars`	an alternative to `...` in order to specify JavaScript variables to be defined and initialized. This is convenient when we have the variables already in a list.
`escapeFun`	either `NULL` or a function that is used to create the node to hold the text of the code. This is typically a CDATA node, but for HTML documents, it is a comment node

The updated XML document, invisibly.

Duncan Temple Lang

http://www.w3.org/TR/SVG11/script.html

   # See linkPlots() for how to do this.
 data(mtcars)
 doc = svgPlot({
                 par(mfrow = c(1, 2))
                 plot(mpg ~ wt, mtcars)
                 plot(mpg ~ vs, mtcars)
               })

 f = system.file("JavaScript", "link.js", package = "SVGAnnotation")
 addECMAScripts(doc, f)
 addECMAScripts(doc, f, insert = TRUE)


 x = rnorm(20)
 y = rnorm(20)

 doc = svgPlot(plot(x, y))
 d = as.matrix(dist(cbind(x, y)))
 D = apply(d, 1, order)
 addECMAScripts(doc,
                "http://www.omegahat.org/SVGAnnotation/tests/knn.js",
                neighbors = D)