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       Prima::tutorial - introductory tutorial


       Programming graphic interfaces is often considered somewhat boring, and
       not without a cause. It is a small pride in knowing that your buttons
       and scrollbars work exactly as millions of others buttons and
       scrollbars do, so whichever GUI toolkit is chosen, it is usually
       regarded as a tool of small importance, and the less obtrusive, the
       better. Given that, and trying to live up to the famous Perl ’making
       easy things easy and hard things possible’ mantra, this manual page is
       an introductory tutorial meant to show how to write easy things easy.
       The hard things are explained in the other Prima manual pages ( see
       Prima ).

Introduction - a "Hello world" program

       Prima is written and is expected to be used in some traditions of Perl
       coding, such as DWIM ( do what I mean ) or TMTOWTDI ( there are more
       than one way to do it).  Perl itself is language (arguably) most
       effective in small programs, as the programmer doesn’t need to include
       lines and lines of prerequisite code before even getting to the problem
       itself. Prima can’t compete with that, but the introductory fee is low;
       a minimal working ’Hello world’ can be written in three lines of code:

               use Prima qw(Application);
               Prima::MainWindow-> new( text => 'Hello world!');
               run Prima;

       Line 1 here is the invocation of modules Prima and Prima::Application.
       Sure, one can explicitly invoke both "use Prima" and "use
       Prima::Application" etc etc, but as module Prima doesn’t export method
       names, the exemplified syntax is well-suited for such a compression.

       Line 2 creates a window of Prima::MainWindow class, which is visualized
       as a screen window, titled as ’Hello world’. The class terminates the
       application when the window is closed; this is the only difference from
       ’Window’ windows, that do nothing after their closing. From here,
       "Prima::" prefix in class names will be omitted, and will be used only
       when necessary, such as in code examples.

       Line 3 enters the Prima event loop. The loop is terminated when the
       only instance of Application class, created by "use Prima::Application"
       invocation and stored in $::application scalar, is destroyed.

       Strictly speaking, a minimal ’hello world’ program can be written even
       in two lines:

               use Prima;
               Prima::message('Hello world');

       but it is not illustrative and not useful. "Prima::message" is rarely
       used, and is one of few methods contained in "Prima::" namespace. To
       display a message, the MsgBox module is often preferred, with its
       control over message buttons and pre-defined icons. With its use, the
       code above can be rewritten as

               use Prima qw(Application MsgBox);
               message('Hello world');

       but where "Prima::message" accepts the only text scalar parameters,
       "Prima::MsgBox::message" can do lot more. For example

               use Prima qw(Application MsgBox);
               message('Hello world', mb::OkCancel|mb::Information);

       displays two buttons and an icon. A small achievement, but the
       following is a bit more interesting:

               use Prima qw(Application MsgBox);
               message('Hello world', mb::OkCancel|mb::Information,
                       buttons => {
                               mb::Cancel => {
                                       # there are predefined color constants to use
                                       backColor => cl::LightGreen,
                                       # but RGB integers are also o.k.
                                       color     => 0xFFFFFF,
                               mb::Ok => {
                                       text    => 'Indeed',

       The definition of many object properties at once is a major feature of
       Prima, and is seen throughout the toolkit. Returning back to the very
       first example, we can demonstrate the manipulation of the window
       properties in the same fashion:

               use Prima qw(Application);
               my $window = Prima::MainWindow-> new(
                       text => 'Hello world!',
                       backColor => cl::Yellow,
                       size => [ 200, 200],
               run Prima;

       Note that the "size" property is a two-integer array, and color
       constant is registered in "cl::" namespace. In Prima there is a number
       of such two- and three-letter namespaces, containing usually integer
       constants for various purposes. The design reason for choosing such
       syntax over string constants ( as in Perl-Tk, such as "color =>
       'yellow'" ) is that the syntax is checked on the compilation stage,
       thus narrowing the possibility of a bug.

       There are over a hundred properties, such as color, text, or size,
       defined on descendants of Widget class. These can be set in "new" (
       alias "create" ) call, or referred later, either individually

               $window-> size( 300, 150);

       or in a group

               $window-> set(
                       text => 'Hello again',
                       color => cl::Black,

       In addition to these, there are also more than 30 events, called
       whenever a certain action is performed; the events have syntax
       identical to the properties. Changing the code again, we can catch a
       mouse click on the window:

               use Prima qw(Application MsgBox);
               my $window = Prima::MainWindow-> new(
                       text => 'Hello world!',
                       size => [ 200, 200],
                       onMouseDown => sub {
                               my ( $self, $button, $mod, $x, $y) = @_;
                               message("Aww! You've clicked me right in $x:$y!");
               run Prima;

       While an interesting concept, it is not really practical if the only
       thing you want is to catch a click, and this is the part where a
       standard button is probably should be preferred:

               use Prima qw(Application Buttons MsgBox);
               my $window = Prima::MainWindow-> new(
                       text     => 'Hello world!',
                       size     => [ 200, 200],
               $window-> insert( Button =>
                       text     => 'Click me',
                       growMode => gm::Center,
                       onClick  => sub { message("Hello!") }
               run Prima;

       For those who know Perl-Tk and prefer its ways to position a widget,
       Prima provides pack and place interfaces. Here one can replace the line

               growMode => gm::Center,


               pack     => { expand => 1 },

       with exactly the same effect.

Widgets overview

       Prima contains a set of standard ( in GUI terms ) widgets, such as
       buttons, input lines, list boxes, scroll bars, etc etc. These are
       diluted with the other more exotic widgets, such as POD viewer or
       docking windows. Technically, these are collected in "Prima/*.pm"
       modules and each contains its own manual page, but for informational
       reasons here is the table of these, an excerpt of "Prima" manpage:

       Prima::Buttons - buttons and button grouping widgets

       Prima::Calendar - calendar widget

       Prima::ComboBox - combo box widget

       Prima::DetailedList - multi-column list viewer with controlling header

       Prima::DetailedOutline - a multi-column outline viewer with controlling
       header widget

       Prima::DockManager - advanced dockable widgets

       Prima::Docks - dockable widgets

       Prima::Edit - text editor widget

       Prima::ExtLists - listbox with checkboxes

       Prima::FrameSet - frameset widget class

       Prima::Grids - grid widgets

       Prima::Header - a multi-tabbed header widget

       Prima::ImageViewer - bitmap viewer

       Prima::InputLine - input line widget

       Prima::Label - static text widget

       Prima::Lists - user-selectable item list widgets

       Prima::MDI - top-level windows emulation classes

       Prima::Notebooks - multipage widgets

       Prima::Outlines - tree view widgets

       Prima::PodView - POD browser widget

       Prima::ScrollBar - scroll bars

       Prima::Sliders - sliding bars, spin buttons and input lines, dial
       widget etc.

       Prima::TextView - rich text browser widget

Building a menu

       In Prima, a tree-like menu is built by passing a nested set of arrays,
       where each array corresponds to a single menu entry. Such as, to modify
       the hello-world program to contain a simple menu, it is enough to write

               use Prima qw(Application MsgBox);
               my $window = Prima::MainWindow-> new(
                       text => 'Hello world!',
                       menuItems => [
                               [ '~File' => [
                                       ['~Open', 'Ctrl+O', '^O', sub { message('open!') }],
                                       ['~Save as...', sub { message('save as!') }],
                                       ['~Exit', 'Alt+X', km::Alt | ord('X'), sub { shift-> close } ],
               run Prima;

       Each of five arrays here in the example is written using different
       semantics, to represent either a text menu item, a sub-menu entry, or a
       menu separator. Strictly speaking, menus can also display images, but
       that syntax is practically identical to the text item syntax.

       The idea behind all this complexity is to be able to tell what exactly
       the menu item is, just by looking at the number of items in each array.
       So, zero or one items are treated as a menu separator:

               [ 'my_separator' ]

       The one-item syntax is needed when the separator menu item need to be
       later addressed explicitly. This means that each menu item after it is
       created is assigned a (unique) identifier, and that identifier looks
       like '#1', '#2', etc, unless it is given by the programmer. Here, for
       example, it is possible to delete the separator, after the menu is

               $window-> menu-> remove('my_separator');

       It is also possible to assign the identifier to any menu item, not just
       to a separator.  The other types (text,image,sub-menu) are discerned by
       looking at the type of scalars they contain. Thus, a two-item array
       with the last item an array reference (or, as before, three-item for
       the explicit ID set), is clearly a sub-menu. The reference, as in the
       example, may contain more menu items, in the recursive fashion:

                       menuItems => [
                               [ '~File' => [
                                       [ '~Level1' => [
                                               [ '~Level2' => [
                                                       [ '~Level3' => [

       Finally, text items, with the most complex syntax, can be constructed
       with three to six items in the array. There can be set the left-aligned
       text string for the item, the right-aligned text string for the display
       of the hot key, if any, the definition of the hot hey itself, and the
       action to be taken if the user has pressed either the menu item or the
       hot key combination. Also, as in the previous cases, the explicit ID
       can be set, and also an arbitrary data scalar, for generic needs. This
       said, the text item combinations are:

       Three items - [ ID, text, action ]

       Four items - [ text, hot key text, hot key, action ]

       Five items - [ ID, text, hot key text, hot key, action ]

       Six items - [ ID, text, hot key text, hot key, action, data ]

       Image items are fully analogous to the text items, except that instead
       of the text string, an image object is supplied:

               use Prima qw(Application MsgBox);
               use Prima::Utils qw(find_image);

               my $i = Prima::Image-> load( find_image( 'examples/Hand.gif'));
               $i ||= 'No image found or can be loaded';

               my $window = Prima::MainWindow-> new(
                       text => 'Hello world!',
                       menuItems => [
                               [ '~File' => [
                                       [ $i, sub {} ],
               run Prima;

       The action item of them menu description array points to the code
       executed when the menu item is selected.  It is either an anonymous
       subroutine, as it is shown in all the examples above, or a string.  The
       latter case will cause the method of the menu owner ( in this example,
       the window ) to be called. This can be useful when constructing a
       generic class with menu actions that can be overridden:

               use Prima qw(Application);

               package MyWindow;
               use vars qw(@ISA);
               @ISA = qw(Prima::MainWindow);

               sub action
                       my ( $self, $menu_item) = @_;
                       print "hey! $menu_item called me!\n"

               my $window = MyWindow-> new(
                       menuItems => [
                               [ '~File' => [
                                       ['~Action', q(action) ],

               run Prima;

       All actions are called with the menu item identifier passed in as a
       string parameter.

       Another trick is to define a hot key. While its description can be
       arbitrary, and will be displayed as is, the hot key definition can be
       constructed in two ways. It is either a literal such as "^A" for
       Control+A, or @B for Alt+B, or "^@#F10" for Control+Alt+Shift+F10. Or,
       alternatively, it is a combination of "km::" constants either with
       ordinal of the character letter or the key code, where the key code is
       one of "kb::" constants. The latter method produces a less readable
       code, but is more explicit and powerful:

               [ '~Reboot', 'Ctrl+Alt+Delete', km::Alt | km::Ctrl | kb::Delete, sub {
                       print "wow!\n";
               [ '~Or not reboot?', 'Ctrl+Alt+R', km::Alt | km::Ctrl | ord('R'), sub {}],

       This concludes the short tutorial on menus. To read more, see
       Prima::Menu .


       Dmitry Karasik, <>.