asCairoDevice {cairoDevice} | R Documentation |
Allows one to convert an arbitrary realized GTK+ widget (usually a
GtkDrawingArea
) or a GdkDrawable
(like a GdkPixmap
) to a Cairo graphics
device, so that R plot commands draw to the widget/drawable.
asCairoDevice(widget, pointsize = 10)
widget |
The realized widget or drawable to which the R graphics are drawn |
pointsize |
The default font size in the R plot |
The main purpose of this function is to allow the user to embed an R plot in a GTK user interface constructed with RGtk2. Please see the examples in the RGtk2 package.
Drawing to an offscreen GdkPixmap
is useful for
buffering and transforming R graphics.
For example, one could copy the pixmap to a GdkPixbuf
and add a watermark before saving as a gif, png, jpg, etc.
In previous versions of the package (pre 2.0), it was possible to call
asCairoDevice
on a widget before it was realized. This should not have been
allowed, because it is impossible to draw to an unrealized widget. Many
published examples called asCairoDevice
before
realizing the widget, but they will now fail with an error. When calling
asCairoDevice
on a widget, first realize the widget, for example
by adding the widget to a container where the top-level ancestor is visible.
Michael Lawrence
http://www.ggobi.org/rgtk2 http://www.gtk.org/ http://www.cairographics.org/