NAME

Prima::Application - the root of the widget hierarchy

DESCRIPTION

The Prima::Application class serves as the hierarchy root for the majority of Prima objects. All toolkit widgets are ultimately owned by the application object. There can be only one instance of the Prima::Application class at a time.

SYNOPSIS

use Prima qw(Application);
Prima::MainWindow->new();
run Prima;

USAGE

Prima::Application class and its only instance are treated is a special way in the toolkit's paradigm. Its only object instance is stored in the

$::application

scalar, defined in Prima.pm module. The application instance must be created whenever a widget, window, or event loop functionality is needed. Usually the

use Prima::Application;

use Prima qw(Application);

code is enough, but $::application can also be created and assigned explicitly. The 'use' syntax has an advantage as more resistant to eventual changes in the toolkit design. It can also be used in conjunction with custom parameters hash like the new() syntax:

use Prima::Application name => 'Test application', icon => $icon;

In addition to this functionality, Prima::Application is also a wrapper to a set of system functions, not directly related to the object classes. This functionality is generally explained in "API".

Inherited functionality

Prima::Application is a descendant of Prima::Widget but does not conform strictly ( in the OO sense ) to any of the built-in classes. It has methods from both Prima::Widget and Prima::Window, also, the methods inherited from the Prima::Widget class may work quite differently. For example, the ::origin property from Prima::Widget is also implemented in Prima::Application, but always returns (0,0), an expected but not much usable result. The ::size property, on the contrary, returns the extent of the screen in pixels. There are a few properties inherited from Prima::Widget, which return actual but uninformative results, - ::origin is one of those, but there are several others. The methods and properties, that are like ::size providing different functionality, are described separately in "API".

Global functionality

Prima::Application is a wrapper to a set of unrelated functions that do not belong to other classes. A notable example, the painting functionality that is inherited from the Prima::Drawable class, allows drawing on the screen, possibly overwriting the graphic information created by the other programs. Although it is still a subject to the begin_paint()/end_paint() brackets, this functionality does not belong to a single object and is considered global.

Painting

As stated above, the Prima::Application class provides an interface to the on-screen painting. This mode is triggered by the begin_paint()/end_paint() methods, while the other pair, begin_paint_info()/end_paint_info() triggers the information mode. This three-state paint functionality is more thoroughly described in Prima::Drawable.

The painting on the screen surfaces under certain environments (XQuartz, XWayland) is either silently ignored or results in an error. There, begin_paint may return a false value (begin_paint_info though always true).

Hints

$::application hosts a special Prima::HintWidget class object, accessible via get_hint_widget(), but with its color and font functions aliased ( see ::hintColor, ::hintBackColor, ::hintFont ).

This widget serves as a hint label, floating over other widgets if the mouse pointer hovers longer than ::hintPause milliseconds.

Prima::Application internally manages all of the hint functionality. The hint widget itself, however, can be replaced before the application object is created, using the ::hintClass create-only property.

Printer

The result of the get_printer method points to an automatically created printer object, responsible for the system printing. Depending on the operating system, it is either Prima::Printer, if the system provides GUI printing capabilities, or generic Prima::PS::Printer, the PostScript/PDF document interface.

See Prima::Printer for details.

Clipboard

$::application hosts a set of Prima::Clipboard objects created automatically to reflect the system-provided clipboard IPC functionality. Their number depends on the system, - under the X11 environment, there are three clipboard objects, and one under Win32.

There are no specific methods to access these clipboard objects, except bring() ( or the indirect name call ); the clipboard objects are named after the system clipboard names, which are returned by the Prima::Clipboard::get_standard_clipboards method.

The default clipboard is named Clipboard, and is accessible via the

my $clipboard = $::application-> Clipboard;

call.

See Prima::Clipboard for details.

Help subsystem

The toolkit has a built-in help viewer, that understands perl's native POD ( plain old documentation ) format. Whereas the viewer functionality itself is a part of the toolkit that resides in the Prima::HelpViewer module, any custom help viewing module can be assigned. The create-only Prima::Application properties ::helpClass and ::helpModule can be used to set these options.

Prima::Application provides two methods for communicating with the help viewer window: open_help() opens a selected topic in the help window, and close_help() closes the window.

System-dependent information

A complex program will need eventually more information than the toolkit provides. Knowing the toolkit boundaries in some platforms, the program may change its behavior accordingly. Both these topics are facilitated by extra system information returned by Prima::Application methods. The get_system_value method returns a system-defined value for each of the sv::XXX constants, so the program can read the system-specific information. Another method get_system_info returns the short description of the system that augments perl's $^O variable.

The sys_action method is a wrapper to system-dependent functionality that is called in a non-portable way. This method is rarely used in the toolkit, its usage is discouraged, primarily because its options do not serve the toolkit design, its syntax is subject to changes, and cannot be relied upon.

Exceptions and signals

By default Prima doesn't track exceptions caused by die, warn, and signals. Currently, it is possible to enable a GUI dialog tracking the die exceptions, by either operating the boolean guiException property or using the

use Prima qw(sys::GUIException)

syntax.

If you need to track signals or warnings you may do so by using standard perl practices. It is though not advisable to call Prima interactive methods directly inside signal handlers but use a minimal code instead. F.ex. code that would ask whether the user wants to quit would look like this:

use Prima qw(Utils MsgBox);
$SIG{INT} = sub {
   Prima::Utils::post( sub {
       exit if message_box("Got Ctrl+C", "Do you really want to quit?", mb::YesNo) == mb::Yes;
   });
};

and if you want to treat all warnings as potentially fatal, like this:

   use Prima qw(Utils MsgBox);
   $SIG{__WARN__} = sub {
      my ($warn, $stack) = ($_[0], Carp::longmess);
      Prima::Utils::post( sub {
	  exit if $::application && Prima::MsgBox::signal_dialog("Warning", $warn, $stack) == mb::Abort;
      });
   };

API

Properties

autoClose BOOLEAN

If set to 1, issues close() after the last top-level window is destroyed. Does not influence anything if set to 0.

This feature is designed to help with generic 'one main window' application layouts.

Default value: 0

guiException BOOLEAN

If set to 1, when a die exception is thrown, displays a system message dialog. allowing the user to choose the course of action -- to stop, to continue, etc.

Is 0 by default.

Note that the exception is only handled inside the Prima::run and Prima::Dialog::execute calls; if there is a call to f ex Prima::Window::execute or a manual event loop run with yield, the signal dialog will not be shown. One needs to explicitly call $::application->notify(Die => $@) and check the notification result to decide whether to propagate the exception or not.

The alternative syntax for setting guiException to 1 is the

use Prima::sys::GUIException;

use Prima qw(sys::GUIException);

statement.

If for some reason an exception is thrown during dialog execution, it will not be handled by Prima but by the current $SIG{__DIE__} handler.

icon OBJECT

Holds the icon object associated with the application. If undef, the system-provided default icon is assumed. Prima::Window objects inherit this application icon by default.

insertMode BOOLEAN

The system boolean flag signaling whether text widgets through the system should insert ( 1 ) or overwrite ( 0 ) text on user input. Not all systems provide the global state of the flag.

helpClass STRING

Specifies the class of the object used as the help viewing package. The default value is Prima::HelpViewer. Run-time changes to the property do not affect the help subsystem until a call to close_help is made.

helpModule STRING

Specifies the perl module loaded indirectly when a help viewing call is made via the open_help method. Used when the ::helpClass property is overridden and the new class is contained in a third-party module. Run-time changes to the property do not affect the help subsystem until a call to close_help is made.

hintClass STRING

Create-only property.

Specifies the class of the widget used as the hint label.

Default value: Prima::HintWidget

hintColor COLOR

The alias to the foreground color property of the hint label widget.

hintBackColor COLOR

The alias to the background color property of the hint label widget.

hintFont %FONT

The alias to the font property of the hint label widget.

hintPause TIMEOUT

Sets the timeout in milliseconds before the hint label is shown when the mouse pointer hovers over a widget.

language STRING

By default contains the user interface language deduced either from the $ENV{LANG} environment variable (unix) or a system default setting (win32). When changed, updates the textDirection property.

Events

Clipboard $CLIPBOARD, $ACTION, $TARGET

With (the only implemented) $ACTION copy, is called whenever another application requests clipboard data in the format $TARGET. This notification is handled internally to optimize image pasting through the clipboard. Since the clipboard pasting semantics in Prima is such that data must be supplied to the clipboard in advance, before another application can request it, there is a problem with which format to use. To avoid encoding an image or other complex data in all possible formats but do that on demand and in the format the other application wants, this notification can be used.

Only implemented for X11.

CopyImage $CLIPBOARD, $IMAGE

The notification stores $IMAGE in the clipboard.

CopyText $CLIPBOARD, $TEXT

The notification stores $TEXT in the clipboard.

Die $@, $STACK

Called when an exception occurs inside the event loop Prima::run. By default, consults the guiException property, and if it is set, displays the system message dialog allowing the user to decide what to do next.

Idle

Called when the event loop handled all pending events, and is about to sleep waiting for more.

PasteImage $CLIPBOARD, $$IMAGE_REF

The notification queries $CLIPBOARD for image content and stores in $$IMAGE_REF. The default action is that the 'Image' format is queried. On unix, encoded formats 'image/bmp', 'image/png' etc are queried if the default 'Image' is not found.

The PasteImage mechanism can read images from the clipboard in the GTK environment.

PasteText $CLIPBOARD, $$TEXT_REF

The notification queries $CLIPBOARD for text content and stores it in the $$TEXT_REF scalar. Its default action is that only the 'Text' format is queried if wantUnicodeInput is unset. Otherwise, the 'UTF8' format is queried first.

The PasteText mechanism is devised to ease defining text unicode/ascii conversion between clipboard and standard widgets, in a unified way.

Methods

add_startup_notification @CALLBACK

CALLBACK is an array of anonymous subs, which are all executed when the Prima::Application object is created. If the application object is already created during the call, CALLBACKs are called immediately.

Useful for initialization of add-on packages.

begin_paint

Enters the enabled ( active paint ) state, and returns the success flag. Once the object is in the enabled state, painting and drawing methods can perform drawing operations on the whole screen.

begin_paint_info

Enters the information state, and returns the success flag. The object information state is the same as the enabled state ( see begin_paint()), except that painting and drawing methods are not permitted to change the screen.

close

Issues a system termination call, resulting in calling the close method for all top-level windows. The call can be interrupted by the latter, and effectively canceled. If not canceled stops the application event loop.

close_help

Closes the help viewer window.

end_paint

Quits the enabled state and returns the application object to the normal state.

end_paint_info

Quits the information state and returns the application object to the normal state.

font_encodings

Returns an array of encodings represented by strings, that are recognized by the system and available for at least one font. Each system provides different sets of encoding strings; the font encodings are not portable.

fonts NAME = '', ENCODING = ''

Returns a hash of font hashes ( see "Fonts" in Prima::Drawable ) describing fonts of NAME font family and of ENCODING text encoding. If NAME is '' or undef, returns one font hash for each of the font families that match the ENCODING string. If ENCODING is '' or undef, no encoding match is performed. If ENCODING is not valid ( not present in the font_encodings result), it is treated as if it was '' or undef.

In the special case when both NAME and ENCODING are '' or undef, each font metric hash contains the element encodings, which points to an array of the font encodings, available for the fonts of the NAME font family.

get_active_window

Returns the object reference to the currently active window, if any, that belongs to the program. If no such window exists, undef is returned.

The exact definition of 'active window' is system-dependent, but it is generally believed that an active window is the one that has a keyboard focus on one of its children widgets.

get_caption_font

Returns the title font that the system uses to draw top-level window captions. The method can be called with a class string instead of an object instance.

get_default_cursor_width

Returns the width of the system cursor in pixels. The method can be called with a class string instead of an object instance.

get_default_font

Returns the default system font. The method can be called with a class string instead of an object instance.

get_default_scrollbar_metrics

Returns dimensions of the system scrollbars - width of the standard vertical scrollbar and height of the standard horizon scrollbar. The method can be called with a class string instead of an object instance.

get_dnd_clipboard

Returns the predefined special clipboard used as a proxy for drag-and-drop interactions.

See also: Widget/Drag and drop, Clipboard/is_dnd.

get_default_window_borders BORDER_STYLE = bs::Sizeable

Returns width and height of standard system window border decorations for one of the bs::XXX constants. The method can be called with a class string instead of an object instance.

get_focused_widget

Returns object reference to the currently focused widget, if any, that belongs to the program. If no such widget exists, undef is returned.

get_fullscreen_image

Syntax sugar for grabbing the whole screen as in

$::application->get_image( 0, 0, $::application->size)

(MacOSX/XQuartz note: get_image() does not grab all screen bits, but get_fullscreen_image does if Prima is compiled with the Cocoa library).

get_hint_widget

Returns the hint label widget, attached automatically to the Prima::Application object during startup. The widget is of the ::hintClass class, Prima::HintWidget by default.

get_image X_OFFSET, Y_OFFSET, WIDTH, HEIGHT

Returns Prima::Image object with WIDTH and HEIGHT dimensions filled with graphic content of the screen, copied from X_OFFSET and Y_OFFSET coordinates. If WIDTH and HEIGHT extend beyond the screen dimensions, they are adjusted. If the offsets are outside the screen boundaries, or WIDTH and HEIGHT are zero or negative, undef is returned.

Note: When running on MacOSX under XQuartz, the latter does not give access to the whole screen, so the function will not be able to grab the top-level menu bar. This problem is addressed in the get_fullscreen_image method.

get_indents

Returns 4 integers that correspond to extensions of eventual desktop decorations that the windowing system may present on the left, bottom, right, and top edges of the screen. For example, for win32 this reports the size of the part of the screen that the windows taskbar may occupy, if any.

get_printer

Returns the printer object attached automatically to the Prima::Application object. The object is an instance of the ::printerClass class.

get_message_font

Returns the font the system uses to draw the message text. The method can be called with a class string instead of an object instance.

get_modal_window MODALITY_TYPE = mt::Exclusive, TOPMOST = 1

Returns the modal window that resides on an end of the modality chain. MODALITY_TYPE selects the chain, and can be either mt::Exclusive or mt::Shared. TOPMOST is a boolean flag selecting the lookup direction: if it is 1, the 'topmost' window is returned, if 0, the 'lower-most' one ( in a simple case when window A is made modal (executed) after modal window B, the A window is the 'topmost' one ).

If the chain is empty undef is returned. In case the chain consists of just one window, the TOPMOST value is irrelevant.

get_monitor_rects

Returns set of rectangles in the format of (X,Y,WIDTH,HEIGHT) identifying monitor layouts.

get_scroll_rate

Returns two integer values of two system-specific scrolling timeouts. The first is the initial timeout that is applied when the user drags the mouse from a scrollable widget ( a text field, for example ), and the widget is about to scroll, but the actual scroll is performed after the timeout has expired. The second value is the repetitive timeout, - if the dragging condition did not change, the scrolling performs automatically after this timeout. The timeout values are in milliseconds.

get_system_info

Returns a hash with the following keys containing information about the system:

apc

One of the apc::XXX constants reporting the platform the program is running on. Currently, the list of the supported platforms is one of these two:

apc::Win32
apc::Unix

gui

One of the gui::XXX constants reporting the graphic user interface used in the system:

gui::Default
gui::Windows
gui::XLib
gui::GTK

guiDescription

Description of the graphic user interface returned as an arbitrary string.

guiLanguage

The preferred language of the interface returned as an ISO 639 code.

system

An arbitrary string representing the operating system software.

release

An arbitrary string, contains the OS version information.

vendor

The OS vendor string

architecture

The machine architecture string

The method can be called with a class string instead of an object instance.

get_system_value

Returns the system integer value, associated with one of the sv::XXX constants. The constants are:

sv::YMenu            - height of menu bar in top-level windows
sv::YTitleBar        - height of title bar in top-level windows
sv::XIcon            - width and height of main icon dimensions,
sv::YIcon              acceptable by the system
sv::XSmallIcon       - width and height of alternate icon dimensions,
sv::YSmallIcon         acceptable by the system
sv::XPointer         - width and height of mouse pointer icon
sv::YPointer           acceptable by the system
sv::XScrollbar       - width of the default vertical scrollbar
sv::YScrollbar       - height of the default horizontal scrollbar
							( see get_default_scrollbar_metrics() )
sv::XCursor          - width of the system cursor
							( see get_default_cursor_width() )
sv::AutoScrollFirst  - the initial and the repetitive
sv::AutoScrollNext     scroll timeouts
							( see get_scroll_rate() )
sv::InsertMode       - the system insert mode
							( see insertMode )
sv::XbsNone          - widths and heights of the top-level window
sv::YbsNone            decorations, correspondingly, with borderStyle
sv::XbsSizeable        bs::None, bs::Sizeable, bs::Single, and
sv::YbsSizeable        bs::Dialog.
sv::XbsSingle          ( see get_default_window_borders() )
sv::YbsSingle
sv::XbsDialog
sv::YbsDialog
sv::MousePresent     - 1 if the mouse is present, 0 otherwise
sv::MouseButtons     - number of the mouse buttons
sv::WheelPresent     - 1 if the mouse wheel is present, 0 otherwise
sv::SubmenuDelay     - timeout ( in ms ) before a sub-menu shows on
							an implicit selection
sv::FullDrag         - 1 if the top-level windows are dragged dynamically,
							0 - with marquee mode
sv::DblClickDelay    - mouse double-click timeout in milliseconds
sv::ShapeExtension   - 1 if Prima::Widget::shape functionality is supported,
							0 otherwise
sv::ColorPointer     - 1 if the system accepts color pointer icons.
sv::CanUTF8_Input    - 1 if the system can generate key codes in unicode
sv::CanUTF8_Output   - 1 if the system can output utf8 text
sv::CompositeDisplay - 1 if the system uses double-buffering and alpha composition for the desktop,
                       0 if it doesn't, -1 if unknown
sv::LayeredWidgets   - 1 if the system supports layering
sv::FixedPointerSize - 0 if the system doesn't support arbitrarily sized pointers and will resize custom icons to the system size
sv::MenuCheckSize    - width and height of default menu check icon
sv::FriBidi          - 1 if Prima is compiled with libfribidi and full bidi unicode support is available
sv::Antialias        - 1 if the system supports antialiasing and alpha layer for primitives
sv::LibThai          - 1 if Prima is compiled with libthai

The method can be called with a class string instead of an object instance.

get_widget_from_handle HANDLE

HANDLE is an integer value of a toolkit widget handle as used in the underlying GUI level, for example, it is a HWND value on win32. It is usually passed to the program by other IPC means, so that the method can return the associated widget. If no widget is associated with HANDLE, undef is returned.

get_widget_from_point X_OFFSET, Y_OFFSET

Returns the widget that occupies the screen area under (X_OFFSET,Y_OFFSET) coordinates. If no toolkit widgets are found, undef is returned.

go

The main event loop. Called by the

run Prima;

standard code. Returns when the program is about to terminate, if stop was called, or if the exception was signaled. In the latter two cases, the loop can be safely restarted.

lock

Effectively blocks the graphic output for all widgets. The output can be restored with unlock().

load_font FONTNAME

Registers a font resource in the system-specific format. The resource is freed after the program ends.

Notes for win32: To add a font whose information comes from several resource files, point FONTNAME to a string with the file names separated by a | - for example, abcxxxxx.pfm | abcxxxxx.pfb .

Notes for unix: available only when Prima is compiled with fontconfig and Xft .

Returns the number of the font resources added.

open_help TOPIC

Opens the help viewer window with TOPIC string in the link POD format ( see perlpod ) - the string is treated as "manpage/section", where 'manpage' is the file with POD content and 'section' is the topic inside the manpage.

Alternatively can handle the syntax in the form of file://path|section where path is the file with the pod content and section is an optional pod section within the file.

stop

Stops the event loop. The loop can be started again.

sync

Synchronizes all pending requests where there are any. Is an effective XSync(false) on X11, and is a no-op otherwise.

sys_action CALL

CALL is an arbitrary string of the system service name and the parameters to it. This functionality is non-portable, and its usage should be avoided. The system services provided are not documented and are subject to change. The actual services can be looked at in the toolkit source code under the apc_system_action tag.

unlock

Unlocks the graphic output for all widgets, previously locked with lock().

yield $wait_for_event=0

An event dispatcher, called from within the event loop. If the event loop can be schematized, then in this code

while ( application not closed ) {
	yield
}

yield() is the only function called repeatedly inside the loop. The yield(0) call shouldn't be used to organize event loops, but it can be employed to process stacked system events explicitly, to increase the responsiveness of a program, for example, inside a long calculation cycle.

yield(1) though is adapted exactly for external implementation of event loops; it does the same as yield(0), but if there are no events it sleeps until there comes at least one, processes it, and then returns. The return value is 0 if the application doesn't need more event processing, because of shutting down. The corresponding code will be

while ( yield(1)) {
    ...
}

but in turn, this call cannot be used for increasing UI responsiveness inside tight calculation loops.

The method can be called with a class string instead of an object instance; however, the $::application object must be initialized.

AUTHOR

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

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