</R>Purpose<!R>
The slider widget is a widget which allows a user to select an integer value. The
slider widget forces the user to choose a value between a predetermined high
and low, which eliminates the need to check if the person has typed in a valid
value. The difference between this widget and the slider widget is this widget
displays a bar which represents the current value.

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

Option      Default Value       Type       Purpose<!U>
Label       Required            Scalar     The label to the slider widget.
Low         Required            Scalar     The low value of the slider widget.
High        Required            Scalar     The high value of the slider widget.
Width       Required            Scalar     The width of the field.
Inc         1                   Scalar     The increment value.
Fastinc     5                   Scalar     The accelerated increment value.
Start       Low Value           Scalar     The starting value.
Filler      Reverse Space       Scalar     The character which will be used for the scale.
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 widget.
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 slider widget.
<C>$returnValue = $sliderObject->activate ();

The variable $returnValue<!B> is the value of the field when the widget
exits.

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

The options are defined in the following table.

Option      Default Value       Type       Purpose<!U>
Low         Required            Scalar      Sets the low value of the widget.
High        Required            Scalar      Sets the high value of the widget.
Value       Required            Scalar      Sets the current value of the widget.
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.
<C>$sliderObject->bind ( options );

The options are defined in the following table.

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>$sliderObject->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>$sliderObject->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>$sliderObject->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>$sliderObject->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>
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.

draw<!B>
This method draws the object on the screen. The following example demonstrates
how to call the draw method.
<C>$sliderObject->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.
<C>$sliderObject->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.
<C>$sliderObject->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.
<C>$sliderObject->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.
<C>$sliderObject->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.
<C>$sliderObject->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.
<C>$sliderObject->getwin();

</R>Default Key Bindings<!R>
Key               Action<!U>
Left Arrow        Decrements the current value by the standard value.
Down Arrow        Decrements the current value by the standard value.
d                 Decrements the current value by the standard value.
-                 Decrements the current value by the standard value.
Right Arrow       Increments the current value by the standard value.
Up Arrow          Increments the current value by the standard value.
u                 Increments the current value by the standard value.
+                 Increments the current value by the standard value.
Prev Page         Decrements the current value by the accelerated value.
U                 Decrements the current value by the accelerated value.
CTRL-B            Decrements the current value by the accelerated value.
Next Page         Increments the current value by the accelerated value.
D                 Increments the current value by the accelerated value.
CTRL-F            Increments the current value by the accelerated value.
Home              Sets the field value to the low value.
g                 Sets the field value to the low value.
0                 Sets the field value to the low value.
End               Sets the field value to the high value.
G                 Sets the field value to the high value.
$                 Sets the field value to the high value.
Return            Exits the widget and returns the field value.
Tab               Exits the widget and returns the field value.
Escape            Exits the widget and returns undef.
CTRL-R            Refreshes the screen.

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

</R>Physical Restrictions<!R>
None.

</R>Example Use Of The Widget<!R>
<F=../examples/slider>
<C><#HL(70)>
<C>Document Created: June,     1996
<C>Document Revised: March,    2012
