| Re: Wrapper for WIDGET_DRAW [message #16079] |
Tue, 29 June 1999 00:00  |
Pavel Romashkin
Messages: 166
Registered: April 1999
|
Senior Member |
|
|
Phil,
I see what you are saying. Maybe the following will work:
a) Make the DERA_Draw return the ID of the draw widget, so that no error
occurs if the user calls "Widget_Control, drawID, /MOTION_EVENTS" - this
will then work fine.
b) Create compound widget, but place some other widget (a table) hiding
under the DRAW widget.
c) Use that other widget's VALUE and/or UVALUE through PRO_SET_VALUE and
FUNC_GET_VALUE to store and retrieve the DRAW widget type. This way, a
structure may be placed into VALUE and anything - into UVALUE.
Another way - use the UVALUE of the top base of compound widget (the true
parent of the drawID) to store DRAW type, again using PRO_SET_VALUE and
FUNC_GET_VALUE. This UVALUE is not going to be accessible otherwise because
the ID of the base is not known to the user: DERA_Draw returns the ID of the
draw widget. Compared to the first way, you lose one location for storing
information (VALUE), but you still have UVALUE which is sufficient. Don't
let PRO_SET_VALUE modify the stored information; let DERA_Draw do it.
Either way, "widget_control, drawID, set_uvalue='arbitrary' " will not cause
loss of DRAW type information, and all keywords to that drawID that are
valid for the draw widget will work ok. The flaw I see is that cleanup must
be well designed, should a pointer be placed into UVALUEs of the base or
table, because these widgets' IDs and even their existence are not obvious.
Good luck,
Pavel
> ;Create a draw widget
> drawID = DERA_Draw(parent, XSIZE=400, YSIZE=400, GRAPHICS_LEVEL = 2)
> ;Get its value which will be a window object of class
> ;DERAgrWindow
> Widget_Control, drawID, GET_VALUE=thingyWindow
> ;Now draw a view into it
> thingyWindow->draw, thisView
>
> That's what I would like, so obviously you could have a compound
> widget, with a FUNC_GET_VALUE, which returned either the window
> number, the IDLgrWindow class or the DERAgrWindow class.
>
> However if its a compound widget and the top of the compund widget is
> a base, then when the user does
>
> Widget_Control, drawID, /MOTION_EVENTS
>
> ......they will be a little surprised to get an error mesage along the
> lines of
>
> Keyword MOTION_EVENTS not allowed in call to Widget_Control for a base
> widget
>
> However if I have just a draw widget then I have no way to store what
> type it is, except by using the UVALUE. However, if the UVALUE was set
> to something different by the user using Widget_Control, then that
> would be game over for my widget.
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
