compressStyles: Replace repeated inline CSS style settings with a CSS...

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

Description

This function takes an SVG document and extracts all the style attributes within the nodes and converts them to a set of CSS specifications and then replaces the style attribute with a class attribute which associates that node with the CSS declaration/rule. This can lead to a "significant" reduction in the size of the file (~ 30%) by avoiding duplication. It also allows one to easily change the appearance of all nodes with the same settings by modifying the centralized CSS rule. Furthermore, it allows somebody to customize the appearance of a plot without using R commands and regenerating the plot. This can be useful if the person doesn't know R or does not have the original data.

Usage

compressStyles(doc,
               classNames =
                       function(x)
                         paste("style", seq(along = x), sep = ""),
               threshold = NA, add = FALSE)

Arguments

doc	the parsed SVG document from svgPlot or xmlParse.
classNames	names for the newly created styles which will be and which will be used as the values of the class attribute in the nodes
threshold	a number (or NA) that controls whether to bother converting the style nodes into CSS entries. The idea is that we will only bother doing the conversion if there is a sufficient number of repeated style values. If all are different, we will have as many CSS rules as there are style nodes and so it may not be worth separating them. This parameter identifies the cut-off point at which we bother to create the CSS entries. If this is NA, we do the conversion. If this is a number between 0 and 1, we take this as a percentang and if the proportion the number of unique styles divided by the total number of styles is less than this, we do the conversion. Alternatively, if threshold is an integer greater than 1, we do the conversion if the number of unique styles is greater than this value.
add	either a logical value or a character string. This controls whether or how the newly created CSS content is added to the document. If add is a character string, we use this as the name of the CSS file and write the CSS content to that and add a reference to that CSS file in the SVG document. If add is a logical value and TRUE, we insert the newly generated CSS file directly into the SVG document. If it is FALSE, we do not add the CSS content to the SVG document but just return the new styles as a character vector and allow the caller to use them in whatever she wants.

Value

If add is FALSE, a named character vector giving the newly-created CSS styles. Otherwise, the updated XMLInternalDocument object is returned. If add is a character string, a new file is created with that name and contains the CSS definitions.

Author(s)

Duncan Temple Lang

See Also

svgPlot convertCSSStylesToSVG

Examples

 d = data.frame(x = runif(100), y = runif(100),
                type = sample(c("A", "B", "C"), 100, replace = TRUE))

 doc = svgPlot(plot(y ~ x, d, col = c("red", "green", "blue")[type]))
 compressStyles(doc)

duncantl/SVGAnnotation documentation built on May 15, 2019, 5:57 p.m.