[vtk-developers] vtkGenericRenderWindowInteractor

[Bill Hoffman]

With the current observer design it is very easy to override default behavior
from C++.   You add an observer for the KeyPressEvent with a high priority, and
once you get the event, if you use the event, you can stop the event from being
passed on.  That is how the 3d widget classes work with the standard Styles.
Right now there is no way to access that from wrapped languages, but it should
not be that hard to add priority to the AddObserver that is wrapped.  Unfortunately,
it is a hand coded part of the wrapping...

-Bill


At 11:59 PM 4/15/2002 +0100, Michael Halle wrote:

>What if the interactor's events were named after what they do, not
>what triggers them?  For instance, vtkBoxWidget has methods called
>OnMiddleButtonDown() and OnLeftButtonUp().  That means that the
>toolkit knows about mouse clicks, the interactor knows about mouse
>clicks, and the widget knows about mouse clicks.  At some layer, it
>seems we should not be talking about which button of which physical
>device when down or up, but rather what we want to be happening in the
>scene (either at a high or low level of abstraction).  
>
>For analogy, xterm in the X window system doesn't hard-code
>right-click to some action; instead, it provides a layer of
>indirection (the X resources) that map device events to "actions" that
>perform them.  This keeps device differences at a high level.  The
>current toolkit/interactor/generic interactor/widget layering, there
>are multiple levels, but no indirection: the event mapping is
>one-to-one at each level.  Seems to me that at the very least by the
>time you get to the widget level, you should be talking about actions
>that could be bound to events names, not event names themselves.
>Perhaps that transition should be happening even higher, at the
>interactor level;  not sure.
>
>The point raised that all the key events were getting sent to the
>widget and therefore didn't flexibly allow for other user key bindings
>is a warning that something's too rigidly tied together....
>
>Does that make slightly more sense?
>
>                                                        --Mike
>Michael Halle
>mhalle at bwh.harvard.edu
>
>
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