Apple Newton Utilities Uživatelská příručka stáhnout pdf (Strana 635)

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CHAPTER 17

Additional System Services

Using Additional System Services 17-19

2. Open the status slip. There are three parts to this process:

■

Instantiate your status view by passing its template to the BuildContext

function.

■

Initialize the status slip by passing the template’s setup frame to the status

slip’s

ViewSet method.

■

Invoke the status slip’s Open method to display the slip.

3. Perform the operation on which you are reporting progress, updating the status

slip periodically by invoking the status view’s

UpdateIndicator or

ViewSet method.

4. Write a

CancelRequest method which is executed when the user cancels

your operation with a “Cancel” or “Stop” button. If your action cannot be

cancelled, do not provide such a button.

Each of these steps is described in detail in the following sections.

Deﬁning Status View and Component View Templates 17

You can create a status slip view from the system-supplied templates vStatus,

vGauge, vBarber, vConfirm, vProgress, or vStatusTitle (shown in

Figure 17-8), or you can create your own template for this view.

Your status view template must have a

_proto slot that holds the value

protoStatusTemplate. It may also include

■ Methods and data that must be available to the status view or its child views.

■ An optional initialSetup slot. If this slot is present, the view system uses its

contents to initialize the status slip automatically when the slip is opened.

■ A frame describing a custom component template. This is needed only if you do

not wish to use one of the built-in templates. This frame must contain the

following slots:

height Height of the status slip, (not the component view) expressed

in pixels. Making this value part of the component view

template allows status slips to resize themselves based on the

height speciﬁed by their component views.

name A symbol representing this template to the ViewSet

method. For example, if the name of your component

template is '

vMyBarber, this slot should hold the

vMyBarber symbol.

kids Array of frames specifying the view templates used to

instantiate the components of this view. These templates

should be based on one of the protos described in “Status

View Components” (page 14-14) in Newton Programmer’s

Reference.

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