Scrolling views

I want to create a scrolling view. I have created a ScrollingDecorator as a
child
of my main view. When I run this I get the following exception:

10:18:36, 20 May 2004: 'UndefinedObject does not understand
#preferredLayoutExtentOf:'
UndefinedObject(Object)>>doesNotUnderstand:
ScrollingDecorator>>updateScrollBars
ScrollingDecorator>>placement:
ScrollingDecorator(View)>>restorePlacement:resolution:
ScrollingDecorator(STBViewProxy)>>restoreView
[] in ShellView(STBViewProxy)>>restoreView
OrderedCollection>>do:

How can I properly implement a scrolling view?

Peter Simmonds
Northampton, UK

Peter,

My guess is that you nilled the layout manager of the decorator.  It
might be easiest to delete it and paste another.

The idea is to put a view inside the ScrollingDecorator, and the
scrolling is fairly automatic from that point.  Take a look at Ian's
archives for specifics on caculated extents, etc.  Also, look for
#usePreferredExtent.

Have a good one,

Bill

--
Wilhelm K. Schwab, Ph.D.
[hidden email]

Peter,

> How can I properly implement a scrolling view?

You don't have to do too much to get a scrolling window.  Step by step...

- Start up the ViewComposer.
- File/New Shell View
- Set its #layoutManager aspect to BorderLayout
- In the ViewComposer's toolbox locate "Presenter.Scrolling container" and
drag drop onto the ShellView.
- Set the ScrollingContainer's #arrangement aspect to "Centre" (or "Center"
if you can't spell properly either :=) )
- In the ViewComposer's toolbox locate "Presenter.Default view" and drag
drop onto the ScrollingContainer.
- Set the #extent aspect of the inner container to, for example, 2000@2000.

Now, when you test the Shell (File/Test) you should be able to scroll
around.  Just to prove it....

- In the ViewComposer's toolbox locate "BooleanPresenter.Default view" and
drag drop two onto the innermost container.
- Set the #position aspect of one of them to 100@100
- Set the #position aspect of the other to 1800@1900

When you scroll around now you should find one CheckBox at the top left of
the scrollable area and the other at the bottom right.

--
Ian

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