| Re: PropertySheet Widget Question [message #36371] |
Mon, 15 September 2003 12:43  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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JD Smith writes:
> Without having taken the time to look into it, I was wondering if you can
> use properties and property sheets essentially for any object widget,
> independent of the iTools functionality. I.e., can you just INHERIT from
> a suitable property parent class, and get all the functionality for free?
With some caveats, this is true. I've been converting
the notion of "control panels" to "property sheets"
in my Catalyst Library, for example. I just made my
basic object, which all other objects in the system
inherit, a subclass of both IDL_Container and
IDLitComponent. The latter is required to register
properties for the PropertySheet widget.
You have to be just a bit careful. Properties are
really a notion associated with object graphic entities.
So properties like Line Style, Symbol, and Color have
specific meanings (type) with respect to object graphics axis
objects or plot objects, etc. So, for example, if your
objects work in the direct graphics system rather than
the object graphics system, there may or may not be
counterparts. There is a one-to-one match between line
styles, for example, so you can get away with a Line Style
property. But there are more object graphics symbols than
there are direct graphics symbols, so the user can choose
a symbol you can't provide (without some extra coding),
and this can cause an error.
Still, it is easy enough to work around these problems.
I have my own color picking tool, for example, so I can
create a property named COLOR, but instead of making it
a "color property", I make it a "user defined property".
Then when the user selects this property, my color selection
widget appears instead of the default one. Everything
else about this property works exactly like you would
expect. Very nice.
I did run into one other annoying feature of
property sheet widgets that RSI has promised to
look into it. String properties (e.g., I have been
working with a Tick Format property) beep every time
you hit a carriage return to enter the string value
on my Windows 2000 machine.
No beeps on Windows XP, so we are not sure what causes
this. Even though the property works correctly, I still
look up for error messages EVERY time (even when I know
it is coming...sigh!).
Cheers,
David
--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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