rstudio/shiny — pull request #49 by wch (2012-12-03 21:00:57+00:00)
Title: For png output, try quartz and CairoPNG before plain png

This patch makes shiny look for the quartz and CairoPNG devices before the plain old `png` device. This is because, on Windows and Linux, the antialiased output from CairoPNG looks nicer than the output from `png`.

The order of the checks might look a bit strange, because when quartz is present, `png()` uses the quartz device by default. In other words:

* If quartz is present, use `png()`
* else if Cairo package is installed, use `CairoPNG()`
* else use `png()`