Ubuntu Manpage: Prima::Menu - pull-down and pop-up menu objects

Provided by: libprima-perl_1.28-1.4_amd64

NAME

       Prima::Menu - pull-down and pop-up menu objects

SYNOPSIS

          use Prima;
          use Prima::Application;

          my $window = Prima::Window-> new(
               menuItems => [
                  [ '~File' => [
                     [ '~Open', 'Ctrl+O', '^O', \&open_file ],
                     [ '-save_file', '~Save', km::Ctrl | ord('S'), sub { save_file() } ],
                     [],
                     [ '~Exit', 'Alt+X', '@X', sub { exit } ],
                  ]],
                  [ '~Options' => [
                     [ '*option1' => 'Checkable option' => sub { $_[0]-> menu-> toggle( $_[1]) }],
                  ]],
                  [],
                  [ '~Help' => [
                     [ 'Show help' => sub { $::application-> open_help($0); }],
                  ]],
               ],
           );

           sub open_file
           {
               # enable 'save' menu item
               $window-> menu-> save_file-> enable;
           }

           $window-> popupItems( $window-> menuItems);

DESCRIPTION

       The document describes interfaces of Prima::AbstractMenu class, and its three descendants - Prima::Menu,
       Prima::Popup, and Prima::AccelTable, all aimed at different targets.  Prima::AbstractMenu is a descendant
       of Prima::Component class, and its specialization is handling of menu items, held in a tree-like
       structure. Descendants of Prima::AbstractMenu are designed to be attached to widgets and windows, to
       serve as hints for the system-dependent pop-up and pull-down menus.

USAGE

Menu items
The central point of functionality in Prima::AbstractMenu-derived classes and their object instances (
further referred as 'menu classes' and 'menu objects'), is handling of a complex structure, contained in
"::items" property. This property is special in that its structure is a tree-like array of scalars, each
of whose is either a description of a menu item or a reference to an array.

Parameters of an array must follow a special syntax, so the property input can be parsed and assigned
correctly. In general, the syntax is

$menu-> items( [
[ menu item description ],
[ menu item description ],
...
]);

where 'menu item description' is an array of scalars, that can hold from 0 up to 6 elements. Each menu
item has six fields, that qualify a full description of a menu item; the shorter arrays are shortcuts,
that imply default or special cases. These base six fields are:

Menu item name
A string identifier. Menu items can be accessed individually by their names, and the following
fields can be managed by calling elemental properties, that require an item name. If not given, or
empty, item name is assigned a string in a form '#ID' where ID is the unique integer value within the
menu object.

IDs are set for each menu item, disregarding whether they have names or not. Any menu item can be
uniquely identifed by its ID value, by supplying the '#ID' string, in the same fashion as named menu
items. When creating or copying menu items, names in format '#ID' are not accepted, and treated as
if an empty string is passed. When copying menu items to another menu object, all menu items to be
copied change their IDs, but explicitly set names are preserved. Since the anonymous menu items do
not have name, their auto-generated names change also.

If the name is prepended by '-' or '*' characters, or both, these are not treated as part of the name
but as indicator that the item is disabled ( '-' character ) or checked ( '*' character ). This
syntax is valid only for "::items" and "insert()" functions, not for "set_variable()" method.

Menu text / menu image
A non-separator menu item can be visualized either as a text string or an image. These options are
exclusive to each other, and therefore occupy same field. Menu text is an arbitrary string, with with
~ ( tilde ) quoting for a shortcut character, that the system uses as a hot key during menu
navigation. Menu image is a Prima::Image object of no particular color space and dimensions.

Menu text in menu item is accessible via the "::text" property, and menu image via the "::image"
property. These can not accept or return sensible arguments simultaneously.

Accelerator text
An alternate text string, appearing together with a menu item or a menu image, usually serving as a
description to the hot key, associated with a menu item. For example, if a hot key to a menu item is
combination of 'enter' and 'control' keys, then usually accelerator text is 'Ctrl+Enter' string.

Accelerator text in menu item is accessible via "::accel" property.

NB: There is "Prima::KeySelector::describe" function, that converts a key value to a string in human-
readable format.

Hot key
An integer value, combined from either "kb::XXX" constant or a character index with modificator key
values ( "km::XXX" constant ). This representation format is not that informative as three-integer
key event format (CODE,KEY,MOD), described in Prima::Widget. However, these formats are easily
converted to each other: CODE,KEY,MOD is translated to INTEGER format by "translate_key()" method.
The reverse operation is not needed for "Prima::AbstractMenu" functionality and is performed by
"Prima::KeySelector::translate_codes" method.

The integer value can be given in a some more readable format when submitting to "::items". Character
and F-keys (from F1 to F16) can be used literally, without "kb::" prepending, and the modificator
keys can be hinted as prefix characters: km::Shift as '#', km::Ctrl as '^' and km::Alt as '@'. This
way, combination of 'control' and 'G' keys can be expressed as '^G' literal, and
'control'+'shift'+'F10' - as '^#F10'.

Hot key in menu item is accessible via "::key" property. The property does accept literal key format,
described above.

A literal key string can be converted to an integer value by "translate_shortcut" method.

When the user presses the key combination, that matches to hot key entry in a menu item, its action
is triggered.

Action
Every non-separator and non-submenu item is destined to perform an action. The action can be set
either as an anonymous sub, or as string with name of a method on the owner of a menu object. Both
have their niche of usage, and both are supplied with three parameters, when called - the owner of a
menu object, the menu object itself and the name of a menu item, that triggered the action.

Action scalar in menu item is accessible via "::action" property.

User data
At last, a non-separator and non-submenu menu item can hold an arbitrary scalar value, the 'user
data' field. The toolkit does not use this field, leaving that to the programmer.

User data scalar in menu item is accessible via "::data" property.

Syntax of "::items" does not provide 'disabled' and 'checked' states for a menu item as separate fields.
These states can be set by using '-' and '*' prefix characters, as described above, in "Menu item name".
They also can be assigned on per-item basis via "::enabled" and "::checked" properties.

All these fields qualify a most common menu item, that has text, shortcut key and an action - a 'text
item'. However, there are also two other types of menu items - a sub-menu and separator. The type of a
menu items can not be changed except by full menu item tree change functions ( "::items", "remove()",
"insert()".

Sub-menu item can hold same references as text menu item does, except the action field. Instead, the
action field is used for a sub-menu reference scalar, pointing to another set of menu item description
arrays. From that point of view, syntax of "::items" can be more elaborated and shown as

$menu-> items( [
[ text menu item description ],
[ sub-menu item description [

[ text menu item description ],
[ sub-menu item description [
[ text menu item description ],
...
]
[ text menu item description ],
...
] ],
...
]);

Separator items do not hold any fields, except name. Their purpose is to hint a logical division of menu
items by the system, which visualizes them usually as non-selectable horizontal lines.

In menu bars, the first separator item met by parser is treated differently. It serves as a hint, that
the following items must be shown in the right corner of a menu bar, contrary to the left-adjacent
default layout. Subsequent separator items in a menu bar declaration can be either shown as a vertical
division bars, or ignored.

With these menu items types and fields, it is possible to construct the described above menu description
arrays. An item description array can hold from 0 to 6 scalars, and each combination is treated
differently.

six - [ NAME, TEXT/IMAGE, ACCEL, KEY, ACTION/SUBMENU, DATA ]
Six-scalar array is a fully qualified text-item description. All fields correspond to the described
above scalars.

five [ NAME, TEXT/IMAGE, ACCEL, KEY, ACTION/SUBMENU ]
Same as six-scalar syntax, but without DATA field. If DATA is skipped it is "undef" by default.

four [ TEXT/IMAGE, ACCEL, KEY, ACTION/SUBMENU ]
Same as five-scalar syntax, but without NAME field. When NAME is skipped it is assigned to an unique
string within menu object.

three [ NAME, TEXT/IMAGE, ACTION/SUBMENU ]
Same as five-scalar syntax, but without ACCEL and KEY fields. KEY is "kb::NoKey" by default, so no
keyboard combination is bound to the item. Default ACCEL value is an empty string.

two [ TEXT/IMAGE, ACTION/SUBMENU ]
Same as three-scalar syntax, but without NAME field.

one and zero [ ]
Both empty and 1-scalar arrays indicate a separator menu item. In case of 1-scalar syntax, the scalar
value is ignored.

As an example of all above said, a real-life piece of code is exemplified:

$img = Prima::Image-> create( ... );
...
$menu-> items( [
[ "~File" => [
[ "Anonymous" => "Ctrl+D" => '^d' => sub { print "sub\n";}], # anonymous sub
[ $img => sub {
my $img = $_[0]-> menu-> image( $_[1]);
my @r = @{$img-> palette};
$img-> palette( [reverse @r]);
$_[0]->menu->image( $_[1], $img);
}], # image
[], # division line
[ "E~xit" => "Exit" ] # calling named function of menu owner
]],
[ ef => "~Edit" => [ # example of system commands usage
...
[ "Pa~ste" => sub { $_[0]->foc_action('paste')} ],
...
["~Duplicate menu"=>sub{ TestWindow->create( menu=>$_[0]->menu)}],
]],
...
[], # divisor in main menu opens
[ "~Clusters" => [ # right-adjacent part
[ "*".checker => "Checking Item" => "Check" ],
[],
[ "-".slave => "Disabled state" => "PrintText"],
...
]]
] );

The code is stripped from 'menu.pl' from 'examples' directory in the toolkit installation. The reader is
advised to run the example and learn the menu mechanics.

Prima::MenuItem
As described above, text and sub-menu items can be managed by elemental properties - "::accel", "::text",
"::image", "::checked", "::enabled", "::action", "::data". All these, plus some other methods can be
called in an alternative way, resembling name-based component calls of Prima::Object. A code

$menu-> checked('CheckerMenuItem', 1);

can be re-written as

$menu-> CheckerMenuItem-> checked(1);

Name-based call substitutes Prima::MenuItem object, created on the fly. Prima::MenuItem class shares same
functions of Prima::AbstractMenu, that handle individual menu items.

Prima::Menu
Objects, derived from Prima::Menu class are used to tandem Prima::Window objects, and their items to be
shown as menu bar on top of the window.

Prima::Menu is special in that its top-level items visualized horizontally, and in behavior of the top-
level separator items ( see above, "Menu items" ).

If "::selected" is set to 1, then a menu object is visualized in a window, otherwise it is not. This
behavior allows window to host multiple menu objects without clashing. When a Prima::Menu object gets
'selected', it displaces the previous 'selected' menu Prima::Menu object, and its items are installed
into the visible menu bar. Prima::Window property "::menu" then points to the menu object, and
"::menuItems" is an alias for "::items" menu class property. Prima::Window's properties "::menuFont" and
"::menuColorIndex" are used as visualization hints.

Prima::Menu provide no new methods or properties.

Prima::Popup
Objects, derived from Prima::Popup class are used together with Prima::Widget objects. Menu items are
visualized when the user pressed the pop-up key or mouse buttons combination, in response to
Prima::Widget's "Popup" notification.

If "::selected" is set to 1, then a menu object is visualized in the system pop-up menu, otherwise it is
not. This behavior allows widget to host multiple menu objects without clashing. When a Prima::Popup
object gets 'selected', it displaces the previous 'selected' menu Prima::Popup object. Prima::Widget
property "::popup" then points to the menu object, and "::popupItems" is an alias for "::items" menu
class property. Prima::Widget's properties "::popupFont" and "::popupColorIndex" are used as
visualization hints.

A Prima::Popup object can be visualized explicitly, by means of "popup" method. The implicit
visualization by the user is happened only if the "::autoPopup" property is set to 1.

Prima::Popup provides new "popup" method and new "::autoPopup" property.

Prima::AccelTable
This class is destined for a more limited functionality than Prima::Menu and Prima::Popup, primarily for
mapping key strokes to predefined actions. Prima::AccelTable objects are never visualized, and consume
no system resources, although full menu item management syntax is supported.

If "::selected" is set to 1, then it displaces the previous 'selected' menu Prima::AccelTable object.
Prima::Widget property "::accelTable" then points to the menu object, and "::accelItems" is an alias for
"::items" menu class property.

Prima::AccelTable provide no new methods or properties.

API

Properties
accel NAME, STRING / Prima::MenuItem::accel STRING
Manages accelerator text for a menu item. NAME is name of the menu item.

action NAME, SCALAR / Prima::MenuItem::action SCALAR.
Manages action for a menu item. NAME is name of the menu item. SCALAR can be either an anonymous
sub or a method name, defined in the menu object owner's name space. Both called with three
parameters - the owner of a menu object, the menu object itself and the name of the menu item.

autoPopup BOOLEAN
Only in Prima::Popup

If set to 1 in selected state, calls "popup()" action in response to "Popup" notification, when the
user presses the default key or mouse button combination.

If 0, the pop-up menu can not be executed implicitly.

Default value: 1

checked NAME, BOOLEAN / Prima::MenuItem::checked BOOLEAN
Manages 'checked' state of a menu item. If 'checked', a menu item visualized with a distinct check-
mark near the menu item text or image. Its usage with sub-menu items is possible, although
discouraged.

NAME is name of the menu item.

data NAME, SCALAR / Prima::MenuItem::data SCALAR
Manages the user data scalar.

NAME is name of the menu item. SCALAR can be any scalar value, the toolkit does not use this
property internally.

enabled NAME, BOOLEAN / Prima::MenuItem::enabled BOOLEAN
Manages 'enabled' state of a menu item. If 'enabled' is 0, a menu item visualized with grayed or
otherwise dimmed color palette. If a sub-menu item is disabled, whole sub-menu is inaccessible.

NAME is name of the menu item.

image NAME, OBJECT / Prima::MenuItem::image OBJECT
Manages the image, bound with a menu item. OBJECT is a non-null Prima::Image object reference, with
no particular color space or dimensions ( because of dimensions, its usage in top-level Prima::Menu
items is discouraged ).

"::image" and "::text" are mutually exclusive menu item properties, and can not be set together, but
a menu item can change between image and text representation at run time by calling these properties.

NAME is name of the menu item.

items SCALAR
Manages the whole menu items tree. SCALAR is a multi-level anonymous array structure, with syntax
described in "Menu items".

"::items" is an ultimate tool for reading and writing the menu items tree, but often it is too
powerful, so there are elemental properties "::accel", "::text", "::image", "::checked", "::enabled",
"::action", "::data" declared, that handle menu items individually.

key NAME, KEY / Prima::MenuItem::key KEY
Manages the hot key combination, bound with a menu item. Internally KEY is kept as an integer value,
and get-mode call returns integers only, but set-mode accepts the literal key format - like, '^C',
'F5' strings.

NAME is name of the menu item, KEY is an integer value.

selected BOOLEAN
If set to 1, menu object is granted extra functionality from a window or widget owner object.
Different Prima::AbstractMenu descendant provided with different extra functionalities. In Usage
section, see Prima::Menu, Prima::Popup and Prima::AccelTable.

Within each menu class, only one menu object can be selected for its owner.

If set to 0, the only actions performed are implicit hot-key lookup when on "KeyDown" event.

Default value: 1

text NAME, STRING / Prima::MenuItem::text STRING
Manages the text, bound with a menu item. STRING is an arbitrary string, with '~' ( tilde ) quotation
of a hot key character. The hot key character is only used when keyboard navigation of a pop-up or a
pull-down menu is performed; it has no influence outside menu sessions.

"::text" and "::image" are mutually exclusive menu item properties, and can not be set together, but
a menu item can change between image and text representation at run time by calling these properties.

Methods
check NAME / Prima::MenuItem::check
Alias for checked(1). Sets menu item in checked state.

disable NAME / Prima::MenuItem::disable
Alias for enabled(0). Sets menu item in disabled state.

enabled NAME / Prima::MenuItem::enabled
Alias for enabled(1). Sets menu item in enabled state.

get_handle
Returns a system-dependent menu handle.

NB: Prima::AccelTable use no system resources, and this method returns its object handle instead.

has_item NAME
Returns boolean value, whether the menu object has a menu item with name NAME.

insert ITEMS, ROOT_NAME, INDEX
Inserts menu item inside existing item tree. ITEMS has same syntax as "::items". ROOT_NAME is the
name of a menu item, where the insertion must take place; if ROOT_NAME is an empty string, the
insertion is performed to the top level items. INDEX is an offset, which the newly inserted items
would possess after the insertion. INDEX 0 indicates the beginning, thus.

Returns no value.

popup X_OFFSET, Y_OFFSET, [ LEFT = 0, BOTTOM = 0, RIGHT = 0, TOP = 0 ]
Only in Prima::Popup

Executes the system-driven pop-up menu, in location near (X_OFFSET,Y_OFFSET) pixel on the screen,
with items from "::items" tree. The pop-up menu is hinted to be positioned so that the rectangle,
defined by (LEFT,BOTTOM) - (RIGHT,TOP) coordinates is not covered by the first-level menu. This is
useful when a pop-up menu is triggered by a button widget, for example.

If during the execution the user selects a menu item, then its associated action is executed ( see
"action" ).

The method returns immediately and returns no value.

remove NAME / Prima::MenuItem::remove
Deletes a menu item from the items tree, and its sub-menus if the item is a sub-menu item.

select
Alias for selected(1). Sets menu object in selected state.

set_command KEY, ENABLED
Disables or enables menu items, associated with key combinations KEY.

set_variable NAME, NEW_NAME
Changes the name of a menu item with NAME to NEW_NAME. NEW_NAME must not be an empty string and must
not be in a '#integer' form.

toggle NAME / Prima::MenuItem::toggle
Toggles the checked state of a menu item and returns the new state.

translate_accel TEXT
Locates a '~' ( tilde ) - escaped character in a TEXT string and returns its index ( as ord(lc())),
or 0 if no escaped characters were found.

The method can be called with no object.

translate_key CODE, KEY, MOD
Translates three-integer key representation into the one-integer format and returns the integer
value. The three-integer format is used in "KeyDown" and "KeyUp" notifications for Prima::Widget.

See Prima::Widget

The method can be called with no object.

translate_shortcut KEY
Converts literal-represented KEY string into the integer format and returns the integer value.

The method can be called with no object.

uncheck NAME / Prima::MenuItem::uncheck
Alias for checked(0). Sets menu item in unchecked state.

AUTHOR

       Dmitry Karasik, <dmitry@karasik.eu.org>.

NAME

SYNOPSIS

DESCRIPTION

USAGE

API

AUTHOR

SEE ALSO