Views

Using Views

Showing a Hidden View

3

In many cases, you might think that you need to create a view dynamically. However,
if the template can be defined at compile time, it's easier to do that and flag the
view as not visible. At the appropriate time, send it the

Open

message to show it.

The typical example of this is a slip, which you can usually define at compile time.
Using the Newton Toolkit (NTK), simply do not check the

vVisible

flag in the

viewFlags

slot of the view template. This will keep the view hidden when the

application is opened.

Also, it is important to declare this view in your application base view. For
information on declaring a view, see the section "View Instantiation" (page 3-26).

When you need to display the view, send it the

Open

message using the name

under which you have declared it (for example,

myView:Open()

).

This solution even works in cases where some template slots cannot be set until run
time. You can dynamically set slot values during view instantiation in any of the
following view methods:

ViewSetupFormScript

,

ViewSetupChildrenScript

, and

ViewSetupDoneScript

. You can also set

values in a declared view before sending it the

Open

message.

Adding to the stepChildren Array

3

If it is not possible to define the template for a view at compile time, the next best
solution is to create the template (either at compile time or run time) and add it to
the

stepChildren

array of the parent view using the

ViewSetupChildrenScript

method. This way, the view system takes care of

creating the view at the appropriate time (when the child views are shown).

For example, if you want to dynamically create a child view, you first define the
view template as a frame. Then, in the

ViewSetupChildrenScript

method of

its parent view, you add this frame to the

stepChildren

array of the parent view.

To ensure that the

stepChildren

array is in RAM, use this code:

if not HasSlot(self, 'stepChildren) then

self.stepChildren := Clone(self.stepChildren);

AddArraySlot(self.stepChildren,

);

The

if

statement checks whether the

stepChildren

slot already exists in the

current view (in RAM). If it does not, it is copied out of the template (in ROM)
into RAM. Then the new template is appended to the array.

All of this takes place in the

ViewSetupChildrenScript

method of the parent

view, which is before the

stepChildren

array is read and the child views are

created.