Class GkiInteractiveTkBase

source code

    gki.GkiKernel --+
                    |
wutil.FocusEntity --+
                    |
                   GkiInteractiveTkBase

Base class for interactive graphics kernel implementation

This class implements the supporting functionality for the
interactive graphics kernel: menu bar, status line, page
caching, etc.

The actual graphics pane is implemented in a separate class,
which extends this class and must have the attributes:

makeGWidget()           Create the gwidget Tk object and colorManager object
redraw()                Redraw method (don't call this directly, used by
                        the gwidget class)
gRedraw()               Redraw that defers to gwidget
gcur()                  Wait for key to be typed and return cursor value
gcurTerminate()         Terminate active gcur so window can be destroyed
incrPlot()              Plot the stuff added to buffer since last draw
prepareToRedraw()       Prepare for complete redraw from metacode
getHistory()            Get information that needs to be saved in page history
setHistory()            Restore page using getHistory info
clearPage()             Clear page (for initialization)
startNewPage()          Setup for new page
isPageBlank()           Returns true if current page is blank
gki_*()                 Implement various GKI metacode commands

The gwidget object (created by makeGWidget) should have these
attributes (in addition to the usual Tk methods):

lastX, lastY            Last cursor position, initially None
rgbamode                Flag indicating RGB (if true) or indexed color mode
activate()              Make this the focus of plots

activateSWCursor()      Various methods for handling the crosshair cursor
deactivateSWCursor()    (Should rename and clean these up)
isSWCursorActive()
getSWCursor()

#XXX
Still need to work on the ColorManager class, which has a bunch
of OpenGL specific stuff embedded in it.  Could also probably
integrate the gl_ functions into a class and use introspection
to create the dispatch table, just like for the gki functions.
#XXX