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Displaying, hiding, and redrawing views 3, Dynamically adding views 3 – Apple Newton Programmer’s Newton 2.0 (for Newton 2.0) User Manual

Page 117

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C H A P T E R 3

Views

Using Views

3-33

Displaying, Hiding, and Redrawing Views

3

To display a view (and its visible child views), send it one of the following
view messages:

Open

—to open the view

Toggle

—to open or close the view

Show

—to show the view if it had previously been opened, then hidden

To hide a view (and its child views), send it one of the following view messages:

Close

—to hide and possibly delete it from memory

Toggle

—to close or open the view

Hide

—to hide it temporarily

You can cause a view (and its child views) to be redrawn by using one of the
following view messages or global functions:

Dirty

—flags the view as “dirty” so it is redrawn during the next system

idle loop

RefreshViews

—redraws all dirty views immediately

SetValue

—sets the value of a slot and possibly dirties the view

SyncView

—redraws the view if its bounds have changed

Dynamically Adding Views

3

Creating a view dynamically (that is, at run time) is a complex issue that has
multiple solutions. Depending on what you really need to do, you can use one of
the following solutions:

Don’t create the view dynamically because it’s easier to accomplish what you
want by creating an invisible view and opening it later.

Create the view by adding a new template to its parent view’s

stepChildren

array in the

ViewSetupChildrenScript

method.

Create the template and the view at run time by using the

AddStepView

function.

Create the template and the view at run time by using the

BuildContext

function.

If you want a pop-up list view, called a picker, use the

PopupMenu

function to

create and manage the view.

These techniques are discussed in the following sections. The first four techniques
are listed in order from easiest to most complex (and error prone). You should use
the easiest solution that accomplishes what you want. The last technique, for
creating a picker view, should be used if you want that kind of view.