All of the widgets in the figure on the previous page that display an image (also the colormap display), are based on the extended Tk image type rtdimage . Tk4.0 introduced a new "image" command and a C interface for adding new image types. A Tk image is much like a Tk widget in that it is both an object and a Tcl command. rtdimage is designed for real-time image display. Images can be loaded from shared memory or FITS format files. For real-time usage, a background daemon process rtdServer (1) communicates with the rtdimage software over a socket interface to display and update images rapidly from shared memory. An rtdimage is created with the image create Tk command. After this, you can use the image in a Tk canvas by specifying it with the -image option. For example:
set image [image create rtdimage ...] $canvas create image 0 0 -image $image ...
Please send questions or comments to abrighto@eso.org.
Copyright © 1998 ESO - European Southern Observatory