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</R>Purpose<!R>
The menu widget allows the programmer to create a pull-down menu widget.
Complete with sub-menu items.
</R>Construction Options<!R>
A menu widget is defined using the following syntax. The variable
</B>$menuObject<!B> contains a reference to the menu object.
<C></B>$menuObject = new Cdk::Menu ( options );
The options are defined in the following table.
</U>Option Default Value Type Purpose<!U>
Menulist Required Array Ref This is the menu title list.
Menuloc Required Array Ref This is the menu title location list.
Tattrib Reverse Scalar This is the attribute of the currently highlighted menu title.
SubTattrib Reverse Scalar This is the attribute of the currently highlighted menu item.
</R>Available Methods<!R>
</B>activate<!B>
Activation of an object means to make the object available for use. The
following example demonstrates how to activate a menu widget.
<C></B>$returnValue = $menuObject->activate ();
The variable </B>$returnValue<!B> is an integer value which represents the
selected item. The calculation of this value is determined as follows:
(100 * Current Title ) + Current Subtitle
To extract the correct menu item from this value use the following formula:
$menuList = int ( $returnValue / 100 );
$menuItem = ($returnValue % 100 );
You can then dereference the string value from the array using the above two
calculations.
</B>inject<!B>
This function injects a single character into the widget. The following
examples demonstrates how to call the inject method.
<C></B>$menuObject->inject ( options );
The options are defined in the following table.
</U>Option Default Value Type Purpose<!U>
Shadow Required Scalar The character to inject into the widget.
If you are injecting a special character into the widget, then you can
use a pre-defined value to represent the key.
<C><#UL><#HL(12)><#TT><#HL(15)><#UR>
<C><#VL></U>Key <#VL>Key Value <!U><#VL>
<C><#VL>Left Arrow <#VL>KEY_LEFT <#VL>
<C><#VL>Right Arrow <#VL>KEY_RIGHT <#VL>
<C><#VL>Up Arrow <#VL>KEY_UP <#VL>
<C><#VL>Down Arrow <#VL>KEY_DOWN <#VL>
<C><#VL>Delete <#VL>KEY_DELETE <#VL>
<C><#VL>Backspace <#VL>KEY_BACKSPACE <#VL>
<C><#VL>Page Up <#VL>KEY_PPAGE <#VL>
<C><#VL>Page Down <#VL>KEY_NPAGE <#VL>
<C><#VL>Home <#VL>KEY_HOME <#VL>
<C><#VL>End <#VL>KEY_END <#VL>
<C><#VL>Escape <#VL>KEY_ESC <#VL>
<C><#LL><#HL(12)><#BT><#HL(15)><#LR>
</B>bind<!B>
The bind method binds keys to events. The binding is specific to the individual
objects. The following example demonstrates how to call the bind method.
<C></B>$menuObject->bind ( options );
The options are defined in the following table.
</U>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.
</B>preProcess<!B>
The </B>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></B>$menuObject->preProcess ( options );
The options are defined in the following table.
</U>Option Default Value Type Purpose<!U>
Function Required Scalar This is the name of the
callback function.
To create a pre-process callback the following code segment demonstrates
how to do it properly.
<C></B>$menuObject->preProcess ('Function' => sub { callback (@_); });
Notice that the array </B>@_<!B> is passed into the function called
</B>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>@_<!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></U>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 </B>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></B>$menuObject->postProcess ( options );
The options are defined in the following table.
</U>Option Default Value Type Purpose<!U>
Function Required Scalar This is the name of the
callback function.
To create a post-process callback the following code segment demonstrates
how to do it properly.
<C></B>$menuObject->postProcess ('Function' => sub { callback (@_); });
Notice that the array </B>@_<!B> is passed into the function called
</B>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>@_<!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></U>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>
</B>draw<!B>
This method draws the object on the screen. The following example demonstrates
how to call the draw method.
<C></B>$menuObject->draw ();
</B>erase<!B>
This method removes the object from the screen. This does </B/U>NOT<!B!U>
destroy the object. The following example demonstrates how to call the erase
method.
<C></B>$menuObject->erase ();
</R>Default Key Bindings<!R>
</U>Key Action<!U>
Left Arrow Moves to the menu list on the left.
Right Arrow Moves to the menu list on the right.
Up Arrow Moves the cursor up one menu item.
Down Arrow Moves the cursor up one menu item.
Space Moves the cursor up down menu item.
Return Selects the current menu item.
Tab Moves to the menu list on the right.
Escape Exits the widget and returns undef.
CTRL-R Refreshes the screen.
</R>Tips & Tricks<!R>
None.
</R>Physical Restrictions<!R>
</U>Restriction Value<!U>
Max number of menu items. 30
Max number of sub-menu items. 98
</R>Example Use Of The Widget<!R>
<F=../examples/menu>
<C><#HL(70)>
<C>Document Created: June, 1995
<C>Document Revised: November, 1995
<C>Document Revised: March, 1996
<C>Document Revised: June, 1996
<C>Document Revised: March, 2012
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