Apple Newton Utilities Guide de l'utilisateur télécharger pdf (Page 113)

100

101

CHAPTER 3

Views

About Views 3-29

5. The viewChildren and stepChildren slots are read and the child views

are instantiated using this same process. As part of the process, the following

messages are sent to each child view, in this order:

ViewSetupFormScript,

ViewSetupChildrenScript, and ViewSetupDoneScript.

6. The

ViewSetupDoneScript message is sent to the view.

7. The view is displayed if its

vVisible viewFlags bit is set.

8. The

ViewShowScript message is sent to the view and then the

ViewDrawScript message is sent to the view. (Note that the

ViewShowScript message is not sent to any child views, however.)

9. Each of the child views is drawn, in hierarchical order, and the

ViewDrawScript message is sent to each of these views, immediately

after it is drawn.

As you can see from step 5, when a view is opened, all child views in the hierarchy

under it are also shown (as long as they are ﬂagged as visible). A nonvisible child

view can be subsequently shown by sending it the

Open message—as long as it

has been declared.

Closing a View 3

When you send a view the Close message, the graphic representation of the view

(and of all of its child views) is destroyed, but the view memory object is not

necessarily destroyed. There are two possibilities:

■ If the view was declared, and the view in which it was declared is still open, the

frame is preserved. You can send the view another

Open or Toggle message to

reopen it at a later time.

A view memory object is ﬁnally destroyed when the view in which it was

declared is closed. That is, when a view is closed, all views declared in it are

made available for garbage collection.

■ If the view being closed was not declared, both its graphic representation and its

view memory object are made available for garbage collection when it is closed.

When a view is closed, the following steps occur:

1. If the view is closing because it was directly sent the

Close or Toggle

message, the system sends it the

ViewHideScript message. (If the view

is closing because it is a child of a view being closed directly, the

ViewHideScript message is not sent to it.)

2. The graphic representation of the view is removed from the screen.

3. The view is sent the

ViewQuitScript message.

The view itself may or may not be marked for garbage collection, depending on

whether or not it was declared.

1 2 ... 108 109 110 111 112 113 114 115 116 117 118 ... 941 942

Commentaires sur ces manuels

Pas de commentaire

Apple Newton Utilities Guide de l'utilisateur Page 113

Commentaires sur ces manuels

Produits connexes et manuels pour Logiciel Apple Newton Utilities