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NAME

       Prima::Window - top-level window management

SYNOPSIS

          use Prima;
          use Prima::Application;

          # this window, when closed, terminated the application
          my $main = Prima::MainWindow-> new( text => 'Hello world' );

          # this is a modal window
          my $dialog = Prima::Dialog->create( size => [ 100, 100 ]);
          my $result = $dialog-> execute;
          $dialog-> destroy;

          run Prima;

DESCRIPTION

       Prima::Window is a descendant of Prima::Widget class.  It deals with top-level windows,
       the windows that are specially treated by the system. Its major difference from
       Prima::Widget is that instances of Prima::Window can only be inferior by the screen, not
       the other windows, and that the system or window manager add decorations to these -
       usually menus, buttons and title bars. Prima::Window provides methods that communicate
       with the system and hint these decorations.

USAGE

       A typical program communicates with the user with aid of widgets, collected upon one or
       more top-level windows.  Prima::Widget already has all functionality required for these
       child-parent operations, so Prima::Window is not special in respect of widget grouping and
       relationship.  Its usage therefore is straightforward:

          my $w = Prima::Window-> create(
              size => [300,300],
              text => 'Startup window',
          );

       There are more about Prima::Window in areas, that it is specifically designed to - the
       system window management and the dialog execution.

   System window management
       As noted before, top-level windows are special for the system, not only in their 'look',
       but also in 'feel': the system adds specific functions to the windows, aiding the user to
       navigate through the desktop. The system ofter dictates the size and position for windows,
       and some times these rules are hard or even impossible to circumvent. This document will
       be long if it would venture to describe the features of different window management
       systems, and the task would be never accomplished - brand new window managers emerge every
       month, and the old change their behavior in an unpredictable way. The only golden rule is
       to never rely on the behavior of one window manager, and test programs with at least two.

       The Prima toolkit provides simple access to buttons, title bar and borders of a window.
       Buttons and title bar are managed by the "::borderIcons" property, and borders by the
       "::borderStyle" property. These operate with set of predefined constants, "bi::XXX" and
       "bs::XXX", correspondingly. The button constants can be combined with each other, but not
       all combinations may be granted by the system.  The same is valid also for the border
       constant, except that they can not be combined - the value of "::borderStyle" is one of
       the integer constants.

       There are other hints that the toolkit can set for a window manager.  The system can be
       supplied with an icon that a window is bound to; the icon dimensions are much different,
       and although can be requested via "sv::XIcon" and "sv::YIcon" system values, the "::icon"
       property scales the image automatically to the closest system-recognizable dimension. The
       window icon is not shown by the toolkit, it is usually resides in the window decorations
       and sometimes on a task bar, along with the window's name. The system can be hinted to not
       reflect the window on the task bar, by setting the "::taskListed" property to 0.

       Another issue is the window positioning. Usually, if no explicit position was given, the
       window is positioned automatically by the system. The same is valid for the size.  But
       some window managers bend it to the extreme - for example, default CDE setup force the
       user to set newly created windows' positions explicitly.  However, there is at least one
       point of certainty.  Typically, when the initial size and/or position of a top-level
       window are expected to be set by the system, the "::originDontCare" and "::sizeDontCare"
       properties can be set to 1 during window creation.  If these set, the system is asked to
       size/position a window regarding its own windowing policy. The reverse is not always true,
       unfortunately.  Either if these properties set to 0, or explicit size or positions are
       given, the system is hinted to use these values instead, but this does not always happen.
       Actually, this behavior is expected by the user and often does not get even noticed as
       something special. Therefore it is a good practice to test a top-level windowing code with
       several window managers.

       There are different policies about window positioning and sizing; some window managers
       behave best when the position is given to the window with the system-dependent
       decorations. It is hardly can be called a good policy, since it is not possible to
       calculate the derived window coordinates with certainty. This problem results in that it
       is impossible to be sure about window position and size before these are set explicitly.
       The only, not much efficient help the toolkit can provide is the property pair
       "::frameOrigin" and "::frameSize", which along with "::origin" and "::size" reflect the
       position and size of a window, but taking into account the system-dependent decorations.

   Dialog execution
       Method of Prima::Window, "execute()" brings a window in a modal state on top of other
       toolkit windows, and returns after the window is dismissed in one or another way.  This
       method is special as it is an implicit event loop, similar to

         run Prima;

       code. The event flow is not disrupted, but the windows and widgets that do not belong to
       the currently executed, the 'modal' window group can not be activated. There can be many
       modal windows on top of each other, but only one is accessible.  As an example a message
       box can be depicted, a window that prevents the user to work with the application windows
       until dismissed.  There can be other message boxes on top of each other, preventing the
       windows below from operation as well.  This scheme is called the 'exclusive' modality.

       The toolkit also provides the shared modality scheme, where there can be several stacks of
       modal windows, not interfering with each other. Each window stack is distinct and contains
       its own windows.  An example analogy is when several independent applications run with
       modal message boxes being activated. This scheme, however, can not be achieved with single
       execute()-like call without creating interlocking conditions. The shared model call,
       "execute_shared()", inserts the window into the shared modal stack, activates the window
       and returns immediately.

       The both kinds of modal windows can coexist, but the exclusive windows prevents the shared
       from operation; while there are exclusive windows, the shared have same rights as the
       usual windows.

       The stacking order for these two models is slightly different.  A window after execute()
       call is set on top of the last exclusive modal window, or, in other words, is added to the
       exclusive window stack. There can be only one exclusive window stack, but many shared
       window stacks; a window after execute_shared() call is added to a shared window stack, to
       the one the window's owner belongs to. The shared window stacks are rooted in so-called
       modal horizons, windows with boolean property "::modalHorizon" set to "true". The default
       horizon is "::application".

       A window in modal state can return to the normal (non-modal) state by calling
       "end_modal()" method. The window is then hidden and disabled, and the windows below are
       accessible to the user. If the window was in the exclusive modal state, the execute() call
       is finished and returns the exit code, the value of "::modalResult" property. There two
       shortuct methods that end modal state, setting "::modalResult" to the basic 'ok' and 'not
       ok' code, correspondingly "ok()" and "cancel()" methods. Behavior of "cancel()" is
       identical to when the user closes the modal window by clicking the system close button,
       pressing Escape key, or otherwise cancelling the dialog execution. "ok()" sets
       "::modalResult" to "mb::OK", "cancel()" to "mb::Cancel", correspondingly.  There are more
       "mb::XXX" constants, but these have no special meaning, any integer value can be passed.
       For example, "Prima::MsgBox::message" method uses these constants so the message window
       can return up to four different "mb" codes.

   Menu
       A top-level window can be equipped with a menu bar. Its outlook is system-dependent, but
       can be controlled by the toolkit up to a certain level. The "::menuItems" property, that
       manages the menu items of a "::menu" object of Prima::Menu class, arrange the layout of
       the menu. The syntax of the items-derived properties is described in Prima::Menu, but it
       must be reiterated that menu items contain only hints, not requests for their exact
       representation. The same is valid for the color and font properties, "::menuColorIndex"
       and "::menuFont".

       Only one menu at a time can be displayed in a top-level window, although a window can be
       an owner for many menu objects. The key property is "Prima::Menu::selected" - if a menu
       object is selected on a widget or a window object, it refers to the default menu actions,
       which, in case of Prima::Window is being displayed as menu bar.

       NB: A window can be an owner for several menu objects and still do not have a menu bar
       displayed, if no menu objects are marked as selected.

   Prima::Dialog
       Prima::Dialog, a descendant from Prima::Window, introduces no new functionality. It has
       its default values adjusted so the colors use more appropriate system colors, and hints
       the system that the outlook of a window is to be different, to resemble the system dialogs
       on systems where such are provided.

   Prima::MainWindow
       The class is a simple descendant of Prima::Window, which overloads "on_destroy"
       notification and calls "$application->close" inside it.  The purpose of declaration of a
       separate class for such a trifle difference is that many programs are designed under a
       paradigm where these is a main window, which is most 'important' to the user. As such
       consruct is used more often than any other, it is considered an optimization to write

          Prima::MainWindow-> create( ... )

       rather than

          Prima::Window-> create( ..., onDestroy => sub { $::application-> close })

       , although these lines are equivalent.

       Also, the $::main_window is pointed to a newly created main window.

API

   Properties
       borderIcons INTEGER
           Hints the system about window's decorations, by selecting the combination of "bi::XXX"
           constants.  The constants are:

              bi::SystemMenu  - system menu button and/or close button
                                ( usually with icon ) is shown
              bi::Minimize    - minimize button
              bi::Maximize    - maximize ( and eventual restore )
              bi::TitleBar    - window title
              bi::All         - all of the above

           Not all systems respect these hints, and many systems provide more navigating
           decoration controls than these.

       borderStyle STYLE
           Hints the system about window's border style, by selecting one of "bs::XXX" constants.
           The constants are:

              bs::None      - no border
              bs::Single    - thin border
              bs::Dialog    - thick border
              bs::Sizeable  - thick border with interactive resize capabilities

           "bs::Sizeable" is an unique window mode. If selected, the user can resize the window,
           not only by dragging the window borders with the mouse but by other system-dependent
           means. The other border styles disallow interactive resizing.

           Not all systems recognize all these hints, although many recognize interactive
           resizing flag.

       frameHeight HEIGHT
           Maintains the height of a window, including the window decorations.

       frameOrigin X_OFFSET, Y_OFFSET
           Maintains the left X and bottom Y boundaries of a window's decorations relative to the
           screen.

       frameSize WIDTH, HEIGHT
           Maintains the width and height of a window, including the window decorations.

       frameWidth WIDTH
           Maintains the width of a window, including the window decorations.

       icon OBJECT
           Hints the system about an icon, associated with a window.  If OBJECT is "undef", the
           system-default icon is assumed.

           See also: "ownerIcon"

       menu OBJECT
           Manages a Prima::Menu object associated with a window.  Prima::Window can host many
           Prima::Menu objects, but only the one that is set in "::menu" property will be seen as
           a menu bar.

           See also: "Prima::Menu", "menuItems"

       menuColorIndex INDEX, COLOR
           Maintains eight color properties of a menu, associated with a window. INDEX must be
           one of "ci::XXX" constants ( see Prima::Widget, colorIndex section ).

           See also: "menuItems", "menuFont", "menu"

       menuColor COLOR
           Basic foreground menu color.

           See also: "menuItems", "menuColorIndex", "menuFont", "menu"

       menuBackColor COLOR
           Basic background menu color.

           See also: "menuItems", "menuColorIndex", "menuFont", "menu"

       menuDark3DColor COLOR
           Color for drawing dark shadings in menus.

           See also: "menuItems", "menuColorIndex", "menuFont", "menu"

       menuDisabledColor COLOR
           Foreground color for disabled items in menus.

           See also: "menuItems", "menuColorIndex", "menuFont", "menu"

       menuDisabledBackColor COLOR
           Background color for disabled items in menus.

           See also: "menuItems", "menuColorIndex", "menuFont", "menu"

       menuFont %FONT
           Maintains the font of a menu, associated with a window.

           See also: "menuItems", "menuColorIndex", "menu"

       menuHiliteColor COLOR
           Foreground color for selected items in menus.

           See also: "menuItems", "menuColorIndex", "menuFont", "menu"

       menuHiliteBackColor COLOR
           Background color for selected items in menus.

           See also: "menuItems", "menuColorIndex", "menuFont", "menu"

       menuItems [ ITEM_LIST ]
           Manages items of a Prima::Menu object associated with a window.  The ITEM_LIST format
           is same as "Prima::AbstractMenu::items" and is described in Prima::Menu.

           See also: "menu", "menuColorIndex", "menuFont"

       menuLight3DColor COLOR
           Color for drawing light shadings in menus.

           See also: "menuItems", "menuColorIndex", "menuFont", "menu"

       modalHorizon BOOLEAN
           Reflects if a window serves as root to the shared modal window stack.  A window with
           "::modalHorizon" set to 1 in shared modal state groups its children windows in a
           window stack, separate from other shared modal stacks. The "::modalHorizon" is
           therefore useful only when several shared modal window stacks are needed.

           The property also serves as an additional grouping factor for widgets and windows. For
           example, default keyboard navigation by tab and arrow keys is limited to the windows
           and widgets of a single window stack.

       modalResult INTEGER
           Maintains a custom integer value, returned by "execute()".  Historically it is one of
           "mb::XXX" constants, but any integer value can be used. The most useful "mb::"
           constants are:

              mb::OK, mb::Ok
              mb::Cancel
              mb::Yes
              mb::No
              mb::Abort
              mb::Retry
              mb::Ignore
              mb::Help

           NB: These constants are defined so they can be bitwise-or'ed, and Prima::MsgBox
           package uses this feature, where one of its functions parameters is a combination of
           "mb::" constants.

       onTop BOOLEAN
           If set, the window is hinted to stay on top of all other windows.

           Default value: 0

       ownerIcon BOOLEAN
           If 1, the icon is synchronized with the owner's.  Automatically set to 0 if "::icon"
           property is explicitly set.  Default value is 1, so assigning an icon to
           $::application spawns the icon to all windows.

       taskListed BOOLEAN
           If set to 0, hints the system against reflecting existence of a window into a system
           task bar, or a top-level window list, or otherwise lower the window's value before the
           other windows. If 1, does not hint anything.

           Default value: 1

       windowState STATE
           A three-state property, that governs the state of a window.  STATE can be one of three
           "ws::XXX" constants:

              ws::Normal
              ws::Minimized
              ws::Maximized

           There can be more or less, or other window states provided by the system, but these
           three were chosen as a 'least common denominator'.  The property can be changed either
           by explicit set-mode call or by the user. In either case, a "WindowState" notification
           is triggered.

           The property has three convenience wrappers: "maximize()", "minimize()" and
           "restore()".

           See also: "WindowState"

   Methods
       cancel
           A standard method to dismiss a modal window with "mb::Cancel" result. The effect of
           calling this method is equal to when the user selects a 'close window' action with
           system-provided menu, button or other tool.

           See also: "ok", "modalResult", "execute", "execute_shared"

       end_modal
           If a window is in modal state, the "EndModal" notification is activated.  Then the
           window is returned from the modal state, gets hidden and disabled.  If the window was
           on top in the exclusive modal state, the last called "execute()" function finishes.
           If the window was not on top in the exclusive modal state, the corresponding
           "execute()" function finishes after all subsequent execute() calls are finished.

       execute INSERT_BEFORE = undef
           A window is turned to the exclusive modal state and is put on top of non-modal and
           shared-modal windows.  By default, if INSERT_BEFORE object is undef, the window is
           also put on top of other exclusive-modal windows; if INSERT_BEFORE is one of the
           exclusive-modal windows the window is placed in queue before the INSERT_BEFORE window.
           The window is showed and enabled, if necessary, and "Execute" notification is
           triggered.

           The function is returned when a window is dismissed, or if the system-dependent
           'exit'-event is triggered by the user ( the latter case falls through all execute()
           calls and terminates "run Prima;" call, exiting gracefully).

       execute_shared INSERT_BEFORE = undef
           A window is turned to the shared modal state and is put on top of non-modal windows in
           the stack of its "::modalHorizon". A window with "::modalHorizon" set to 1 starts its
           own stack, independent of all other window stacks.

           By default, if INSERT_BEFORE object is undef, the window is also put on top of other
           shared-modal windows in its stack.  If INSERT_BEFORE is one of the shared-modal
           windows in its stack, the window is placed in queue before the INSERT_BEFORE window.

           The window is showed and enabled, if necessary, and "Execute" notification is
           triggered.

           The function is returned immediately.

       get_default_menu_font
           Returns the default font for a Prima::Menu class.

       get_modal
           Returns one of three constants, reflecting the modal state of a window:

              mt::None
              mt::Shared
              mt::Exclusive

           Value of "mt::None" is 0, so result of get_modal() can be also treated as a boolean
           value, if only the fact of modality is needed to check.

       get_modal_window MODALITY_TYPE = mt::Exclusive, NEXT = 1
           Returns a modal window, that is next to the given window in the modality chain.
           MODALITY_TYPE selects the chain, and can be either "mt::Exclusive" or "mt::Shared".
           NEXT is a boolean flag, selecting the lookup direction; if it is 1, the 'upper' window
           is returned, if 0, the 'lower' one ( in a simple case when window A is made modal
           (executed) after modal window B, the A window is the 'upper' one ).

           If a window has no immediate modal relations,  "undef" is returned.

       maximize
           Maximizes window. A shortcut for "windowState(ws::Maximized)".

       minimize
           Minimizes window. A shortcut for "windowState(ws::Minimized)".

       ok  A standard method to dismiss a modal window with "mb::OK" result. Typically the effect
           of calling this method is equal to when the user presses the enter key of a modal
           window, signaling that the default action is to be taken.

           See also: "cancel", "modalResult", "execute", "execute_shared"

       restore
           Restores window to normal state from minimized or maximized state. A shortcut for
           "windowState(ws::Normal)".

   Events
       Activate
           Triggered when a window is activated by the user.  Activation mark is usually resides
           on a window that contains keyboard focus, and is usually reflected by highlighted
           system decorations.

           The toolkit does not provide standalone activation functions; "select()" call is used
           instead.

       Deactivate
           Triggered when a window is deactivated by the user.  Window is usually marked
           inactive, when it contains no keyboard focus.

           The toolkit does not provide standalone de-activation functions; "deselect()" call is
           used instead.

       EndModal
           Called before a window leaves modal state.

       Execute
           Called after a window enters modal state.

       WindowState STATE
           Triggered when window state is changed, either by an explicit "windowState()" call, or
           by the user.  STATE is the new window state, one of three "ws::XXX" constants.

AUTHOR

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

SEE ALSO

       Prima, Prima::Object, Prima::Drawable, Prima::Widget.