View System and Messages
viewCObject
slot. The viewCObject
is a C++ object in the underlying view system. It handles the actual drawing, handwriting recognition, displaying pictures, etc.
When your application is launched, it is sent an Open
message. Its views are then sent these three messages in this order:
Before going into the details of each, let us look at what happens on the Newton when your application's views are opened. As you can see in FIGURE 6.1, the first thing that happens is the view system creates an empty view frame (unless it already exists). Next, the viewSetupFormScript
is executed and it adds or modifies any necessary slots in the view. After this, the viewCObject
is created based on slots read from the view.
The next message that is executed is the viewSetupChildrenScript
, which modifies the stepChildren
array, if necessary. If the view has any children, the view creation is started again from scratch for the first child view in the stepChildren
array (see the second column in FIGURE 6.1). If the child has any children of its own (the grandchildren), they are created after the child's own viewSetupChildrenScript
executes.
Once the last child (one with no children of its own) is created, that child's viewSetupDoneScript
is executed (see the third column in FIGURE 6.1). The view system winds itself back up the ancestor chain, executing the viewSetupDoneScript
of each view until it reaches the application's base view (the first view in the chain). Presto! Your views are now open on the Newton.
FIGURE 6.1 : Opening a view on the Newton.
An online version of Programming for the Newton using Macintosh, 2nd ed. ©1996, 1994, Julie McKeehan and Neil Rhodes.
Last modified: 1 DEC 1996