</R>Purpose<!R>
The Cdk Itemlist widget allows the user to select a value from a list. This
widget is very much like a 1 line scrolling list.

</R>Construction Options<!R>
A itemlist widget is defined using the following syntax. The variable
$itemlistObject<!B> contains the reference to the itemlist object.
$itemlistObject = new Cdk::Itemlist ( options );
 
The options are defined in the following table.

Option      Default Value       Type       Purpose<!U>
Label       Required            Scalar     The label of the itemlist field.
List        Required            Array Ref  The list of items to choose from.
Default     0                   Scalar     The default choice.
Xpos        Center              Scalar     This is the position of the window on the X axis.
Ypos        Center              Scalar     This is the position of the window on the Y axis.
Lpos        Left                Scalar     This is the position of the label in the window.
Box         True                Scalar     This boolean states whether the dialog box will have a box drawn around it.
Shadow      False               Scalar     This boolean states whether the dialog box will have a shadow on the box.

</R>Available Methods<!R>
activate<!B>
Activation of an object means to make the object available for use. The
following example demonstrates how to activate a itemlist widget.
$returnValue = $itemlistObject->activate ();

The variable $returnValue<!B> contains a scalar value which represents the
integer value of the corresponding item from the list.

inject<!B>
This function injects a single character into the widget. The following
examples demonstrates how to call the inject method.
<C>$itemlistObject->inject ( options );

The options are defined in the following table.
Option      Default Value       Type       Purpose<!U>
Shadow      Required             Scalar     The character to inject into the widget.

If you are injecting a special character into the widget, then you can
use a pre-defined value to represent the key.

<C><#UL><#HL(12)><#TT><#HL(15)><#UR>
<C><#VL>Key         <#VL>Key Value      <!U><#VL>
<C><#VL>Left Arrow  <#VL>KEY_LEFT       <#VL>
<C><#VL>Right Arrow <#VL>KEY_RIGHT      <#VL>
<C><#VL>Up Arrow    <#VL>KEY_UP         <#VL>
<C><#VL>Down Arrow  <#VL>KEY_DOWN       <#VL>
<C><#VL>Delete      <#VL>KEY_DELETE     <#VL>
<C><#VL>Backspace   <#VL>KEY_BACKSPACE  <#VL>
<C><#VL>Page Up     <#VL>KEY_PPAGE      <#VL>
<C><#VL>Page Down   <#VL>KEY_NPAGE      <#VL>
<C><#VL>Home        <#VL>KEY_HOME       <#VL>
<C><#VL>End         <#VL>KEY_END        <#VL>
<C><#VL>Escape      <#VL>KEY_ESC        <#VL>
<C><#LL><#HL(12)><#BT><#HL(15)><#LR>

set<!B>
Sets or resets certain attributes or features of the widget. The following
demonstrates how to call the set method from the itemlist field.
$itemlistObject->set ( options );

The options are defined in the following table.

Option      Default Value       Type       Purpose<!U>
List        Required            Arry Ref   The list of items to choose from.
Default     0                   Scalar     The default choice.
Box         True                Scalar     Changes the current value of the box flag.

bind<!B>
The bind method binds keys to events. The binding is specific to the individual
objects. The following example demonstrates how to call the bind method.
$itemlistObject->bind ( options );

The options are defined in the following table.

Option      Default Value       Type       Purpose<!U>
Key         Required            Scalar     This is the character to bind the event to.
Function    Required            Scalar     This is the name of the callback function.

preProcess<!B>
The preProcess<!B> function sets a process to be run before the key entered
is processed. If this function returns a value of 0, then the key injected
into the widget will not be processed; otherwise the character will be
processed as normal.  The following example demonstrates how to call the
preProcess method.
<C>$itemlistObject->preProcess ( options );

The options are defined in the following table.

Option      Default Value       Type       Purpose<!U>
Function    Required            Scalar     This is the name of the
                                           callback function.

To create a pre-process callback the following code segment demonstrates
how to do it properly.

<C>$itemlistObject->preProcess ('Function' => sub { callback (@_); });

Notice that the array @_<!B> is passed into the function called
callback<!B>. This is done because when the callback process is 
called the key which was pressed is passed into the perl subroutine.
Since we nest the call-back function inside an anonymous subroutine,
we need to pass the array @_<!B> to the call-back function. If
the key given to the call-back function is a non alphanumeric key
then a predefined value will be given to the function. The following
table describes the values passed into the function.

<C><#UL><#HL(12)><#TT><#HL(15)><#UR>
<C><#VL>Key         <#VL>Key Value      <!U><#VL>
<C><#VL>Left Arrow  <#VL>KEY_LEFT       <#VL>
<C><#VL>Right Arrow <#VL>KEY_RIGHT      <#VL>
<C><#VL>Up Arrow    <#VL>KEY_UP         <#VL>
<C><#VL>Down Arrow  <#VL>KEY_DOWN       <#VL>
<C><#VL>Delete      <#VL>KEY_DELETE     <#VL>
<C><#VL>Backspace   <#VL>KEY_BACKSPACE  <#VL>
<C><#VL>Page Up     <#VL>KEY_PPAGE      <#VL>
<C><#VL>Page Down   <#VL>KEY_NPAGE      <#VL>
<C><#VL>Home        <#VL>KEY_HOME       <#VL>
<C><#VL>End         <#VL>KEY_END        <#VL>
<C><#VL>Escape      <#VL>KEY_ESC        <#VL>
<C><#LL><#HL(12)><#BT><#HL(15)><#LR>

If the pre-process function returns a value of 0 the key hit will
not be injected into the widget. This allows the programmer to
selectively pick which characters will or will not get injected
into the widget.

The postProcess<!B> function sets a process to be run before the key entered
is processed. If this function returns a value of 0, then the key injected
into the widget will not be processed; otherwise the character will be
processed as normal.  The following example demonstrates how to call the
postProcess method.
<C>$itemlistObject->postProcess ( options );

The options are defined in the following table.

Option      Default Value       Type       Purpose<!U>
Function    Required            Scalar     This is the name of the
                                           callback function.

To create a post-process callback the following code segment demonstrates
how to do it properly.

<C>$itemlistObject->postProcess ('Function' => sub { callback (@_); });

Notice that the array @_<!B> is passed into the function called
callback<!B>. This is done because when the callback process is 
called the key which was pressed is passed into the perl subroutine.
Since we nest the call-back function inside an anonymous subroutine,
we need to pass the array @_<!B> to the call-back function. If
the key given to the call-back function is a non alphanumeric key
then a predefined value will be given to the function. The following
table describes the values passed into the function.

<C><#UL><#HL(12)><#TT><#HL(15)><#UR>
<C><#VL>Key         <#VL>Key Value      <!U><#VL>
<C><#VL>Left Arrow  <#VL>KEY_LEFT       <#VL>
<C><#VL>Right Arrow <#VL>KEY_RIGHT      <#VL>
<C><#VL>Up Arrow    <#VL>KEY_UP         <#VL>
<C><#VL>Down Arrow  <#VL>KEY_DOWN       <#VL>
<C><#VL>Delete      <#VL>KEY_DELETE     <#VL>
<C><#VL>Backspace   <#VL>KEY_BACKSPACE  <#VL>
<C><#VL>Page Up     <#VL>KEY_PPAGE      <#VL>
<C><#VL>Page Down   <#VL>KEY_NPAGE      <#VL>
<C><#VL>Home        <#VL>KEY_HOME       <#VL>
<C><#VL>End         <#VL>KEY_END        <#VL>
<C><#VL>Escape      <#VL>KEY_ESC        <#VL>
<C><#LL><#HL(12)><#BT><#HL(15)><#LR>
draw<!B>
This method draws the object on the screen. The following example demonstrates
how to call the draw method.
$itemlistObject->draw ( options );
 
The options are defined in the following table.

Option      Default Value       Type       Purpose<!U>
Box         True                Scalar     Draws the window with a box around it.

erase<!B>
This method removes the object from the screen. This does </B/U>NOT<!B!U> 
destroy the object. The following example demonstrates how to call the erase 
method.
$itemlistObject->erase ();

raise<!B>
The raise method raises the widget to the top of the screen. This means if there
were any widgets obscuring part of the view, raising the object would bring the
complete object into view. The following example demonstrates how to call the 
raise method.
$itemlistObject->raise();

lower<!B>
The lower method lowers the object so it doesn't obscure the view of any other 
objects. The following example demonstrates how to call the lower method.
$itemlistObject->lower();

register<!B>
The register method registers the object to the default screen. This does </R>NOT<!R>
have to be called since the objects are registered automatically. This method
should be called if the unregister<!B> method was called. The following
example demonstrates how to call the register method.
$itemlistObject->register();

unregister<!B>
The unregister method should be called when a widget, which is part of the
default screen, needs to be taken away temporarily. This does not delete or free
the object, it just unmaps it from any future screen refreshes. The object can
be registered by calling the register<!B> method. The following example
demonstrates how to call the unregister method.
$itemlistObject->unregister();

getwin<!B>
This method returns a pointer to the window of the object. Not much use for this
yet. It will be useful in the future when the drawing methods are added. The
following example demonstrates how to call the getwin method.
$itemlistObject->getwin();

</R>Default Key Bindings<!R>
Key               Action<!U>
Up Arrow          Displays the next item in the list.
Right Arrow       Displays the next item in the list.
Space             Displays the next item in the list.
+                 Displays the next item in the list.
n                 Displays the next item in the list.
Down Arrow        Displays the previous item in the list.
Left Arrow        Displays the previous item in the list.
-                 Displays the previous item in the list.
p                 Displays the previous item in the list.
d                 Sets the list to the default choice.
D                 Sets the list to the default choice.
0                 Sets the list to the first choice in the list.
$                 Sets the list to the last choice in the list.
Return            Returns the current information in the field and exits the widget.
Tab               Returns the current information in the field and exits the widget.
CTRL-N            Returns the current information in the field and exits the widget.
CTRL-R            Refreshes the screen.

</R>Tips & Tricks<!R>
None.

</R>Physical Restrictions<!R>
Restriction                    Value<!U>
Maximum number of items.       500

</R>Example Use Of The Widget<!R>

#!/usr/local/bin/perl

#
# Load in the Cdk Extension.
#
use Cdk;
Cdk::init();

# Create a new itemlist object.
@list = qw (January Feburary March April May June July August September November December);
$month	= new Cdk::Itemlist ( 'Label' => "Pick a month: ", 'List' => \@list);

# Activate the object.
$choice = $month->activate();

# Exit Cdk.
Cdk::end();

# Print out the results.
print "\n\n\n\n";
print "You selected: <$choice>\n";

<C><#HL(70)>
<C>Document Created: June,     1995
<C>Document Revised: November, 1995
<C>Document Revised: March,    2012
