Apple Newton Utilities Guide de l'utilisateur télécharger pdf (Page 117)

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CHAPTER 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.

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Apple Newton Utilities Guide de l'utilisateur Page 117

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