Apple Newton Utilities Guide de l'utilisateur télécharger pdf (Page 230)

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CHAPTER 6

Pickers, Pop-up Views, and Overviews

6-30 Overview Protos

See “Column Speciﬁcations” (page 5-3) in Newton Programmer’s Reference for

details of the slots.

Having a Single Selection in a List Picker 6

The key to getting single selection is that single selection is part of the picker

deﬁnition and not an option of

protoListPicker. That means the particular

class of

nameRef you use must include single selection. In general, this requires

creating your own subclass of the particular name reference class.

The basic solution is to create a data deﬁnition that is a subclass of the particular

class your

protoListPicker variant will view. That data deﬁnition will include

the

singleSelect slot. As an example, suppose you want to use a

protoPeoplePopup that just picks individual people. You could use the

following code to bring up a

protoPeoplePopup that allows selecting only one

individual at a time:

// register the modified data definition

RegDataDef('|nameref.people.single:SIG|,

{_proto: GetDataDefs('|nameRef.people|), singleSelect:

true});

// then pop the thing

protoPeoplePopup:New('|nameref.people.single:SIG|,[],self,[

]);

// sometime later

UnRegDataDef('|nameref.people.single:SIG|);

For other types of protoListPickers and classes, create the appropriate

subclass. For example, a transport that uses

protoAddressPicker for e-mail

messages might create a subclass of

'|nameRef.email| and put that subclass

symbol in the class slot of the

protoAddressPicker.

Since many applications are likely to do this, you may cut down on code in your

installScript and removeScript by registering your dataDef only for the

duration of the picker. That would mean registering the class just before you pop

the picker and unregistering after the picker has closed. You can use the

pickActionScript and pickCanceledScript methods to be notified when

to unregister the

dataDef.

Having Preselected Items in a List Picker 6

If you want to have items that are initially selected in a list picker, use the

viewSetupDoneScript to set up the selected array, rather than setting up

the selected array in your

viewSetupFormScript or

viewSetupChildrenScript, then send the Update message to

protoListPicker to tell it to update the display.

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Apple Newton Utilities Guide de l'utilisateur Page 230

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