imageMap-methods {Rgraphviz} | R Documentation |
Write an HTML IMG tag together with a MAP image map.
## S4 method for signature 'Ragraph, connection, list, ## character': imageMap(object, con, tags, imgname, width, height, usr = par("usr"))
object |
The graph layout for which we want to create an image map. |
con |
Connection to which the image map is written. |
tags |
Named list whose elements are named character vectors.
Names must correspond to node names in object . See details. |
imgname |
Character. Name of the image file (for example PNG file) that contains the plot. |
width |
Width of the image. |
height |
Height of the image. |
usr |
Numeric vector of length 4. The user coordinates in the
plot window that object was plotted into. |
The most important tags are TITLE
, HREF
,
and TARGET
. If the list tags
contains an element
with name TITLE
, then this must be a named character vector
containing the tooltips that are to be displayed when the mouse moves
over a node. The names of the nodes are specified in the names
attribute of the character vector and must match those of
object
.
Similarly, HREF
may be used to specify hyperlinks that the
browser can follow when the mouse clicks on a node, and TARGET
to specify the target browser window.
Currently, only rectangular regions are implemented; the actual
shape of the nodes as specified in object
is ignored.
Also, tags for edges of the graph are currently not supported.
This function is typically used with the following sequence of steps:
agopen
jpeg
or png
.
imageMap
function.
The function is called for its side effect, which is writing text into
the connection con
.
Wolfgang Huber http://www.dkfz.de/mga/whuber
fhtml = paste(tempfile(), ".html", sep="") fpng =paste(tempfile(), ".png", sep="") if(capabilities()["png"] && interactive()) { ## Create and layout a random graph set.seed(123) g = randomEGraph(letters[14:22], 0.2) lg = agopen(g, name="My layout") ## Make tooltips and hyperlinks tooltip = paste("This is node", nodes(g)) url = paste("This could be a link for node", nodes(g)) names(url) = names(tooltip) = nodes(g) ## Plot it width = height = 512 png(fpng, width=width, height=height) par(mai=rep(0,4)) plot(g) ## Write an HTML file with the image map con = file(fhtml, open="wt") writeLines("<html><head><title>Click Me</title></head><body>\n", con) imageMap(lg, con, fpng, tags=list(HREF=url, TITLE=tooltip), width=width, height=height) writeLines("</body></html>", con) dev.off() close(con) cat("Now have a look at file", fhtml, "with your browser.\n") }