libsdl-perl 2.540-1 / usr / lib / perl5 / pods / SDLx / Text.pod

=pod

=head1 NAME

SDLx::Text - SDL extension for manipulating text

=head1 CATEGORY

Extension

=head1 SYNOPSIS

    use SDL;
    use SDLx::App; 
    use SDLx::Text;
    
    my $app = SDLx::App->new;

    my $message = SDLx::Text->new;

    $message->write_to( $app, "Hello, World!" );
    $app->update;


=head1 DESCRIPTION

The standard SDL API for handling fonts and rendering text is full of quirks
and and low-level functions scattered all over the place. This is a sugar
layer meant to let you easily handle text in your SDL apps.

=head1 CONSTRUCTION

=head2 new

=head2 new ( %attributes )

Instantiates a new SDLx::Text object. All attributes are optional:

    my $text = SDLx::Text->new(
            font    => '/path/to/my/font.ttf',
            color   => [255, 255, 255], # "white"
            size    => 24,
            x       => 0,
            y       => 0,
            h_align => 'left',
            shadow  => 1,
            bold    => 1,
            text    => 'All your base are belong to us.'
    );

Please check the accessors below for more information on each attribute.
All values shown above are the B<default values>, except for "text",
which defaults to C<undef>; and "font", which if not provided will load
the C<Gentium Basic> free font (see "L</"COPYRIGHT & LICENSE">" for more
information).

=head1 ACCESSORS

All accessors below can be used to get and set their respective attributes.
For example:

   my $font_size = $obj->size;   # gets the font size
   $obj->size( 42 );             # sets a new font size

Unless otherwise noticed, all accessors return their current value, after being set.

=head2 x

Gets/sets the left (x) positioning of the text to be rendered, relative
to whatever surface you are placing it into. Note that if you set the
C<h_align> property to anything other than 'C<left>', the text might
not start exactly where you set C<x> to be, but relative to that value.

Default value is 0, meaning leftmost corner.

=head2 y

Gets/sets the top (y) positioning of the text to be rendered, relative
to whatever surface you are placing it into.

Default value is 0, meaning top.

=head2 h_align

Gets/sets the horizontal alignment of the text to be rendered relative to
whatever surface you are placing it into. Available alignments are 'C<left>',
'C<right>' and 'C<center>'. Default is 'C<left>'.

=head2 color

Gets/sets the text color. The color is an array reference in C<[R, G, B]> or C<[R, G, B, A]> format. See L<SDL::Color> for more information on colors.

=head2 size

Gets/sets the font size.

=head2 font

Pass it a string containing the path to your desired font to use it. Fonts
can be in TTF, OTF or FON formats. Generates an exception if the font
cannot be loaded.

Returns the L<SDL::TTF::Font> object representing the font.

=head2 shadow

Set this to true to create a nice 3D shadow effect on the rendered text.
This is achieved by creating another version of the text below the
original one, at a given offset.

=head2 shadow_color

Set the RGB color array for the shadow. Defaults to black ( C<[0,0,0]> ).

=head2 shadow_offset

Sets the offset in which to display the shadow. Defaults to 1, meaning
1 pixel below and 1 pixel to the right of the original text.

=head2 Setting the Font Style

The following accessors can be used to set a rendering file for the B<loaded> font.
They will only work for the current font, so if you change fonts, make sure to
apply your modifiers again. A single font can have more than one modifier applied to it, eg:

  my $text = SDLx::Text->new;

  $text->bold(1);
  $text->italic(1);

Set them to a true value to enable, false to disable.

=head3 normal

Sets the font style to normal.

=head3 bold

Sets the font style to bold.

=head3 italic

Sets the font style to italic.

=head3 underline

Sets the font style to underline.

B<Note>: Due to libSDL design and depending on the chosen font, sometimes
the underline may be outside of the generated text surface, and thus not
visible when blitted to the screen. In these cases, you should probably turn
off the option and draw your own underlines in the target surface.

=head3 strikethrough

Sets the font style to strikethrough.

B<Note>: Due to libSDL design and depending on the chosen font, sometimes
the strikethrough may be outside of the generated text surface, and thus not
visible when blitted to the screen. In these cases, you should probably turn
off the option and draw your own strikethroughs in the target surface.

=head1 METHODS

=head2 text( $some_text )

Sets the text to be displayed by the SDLx::Text object. If you call it
without any arguments, you'll get the current text string:

   my $string = $obj->text();

Otherwise, C<text()> will return the SDLx::Text object itself, so you can
easily chain this method around.

    my $obj = SDLx::Text->new->text( "Hello, Dave." );

Note that this will happen even if it's an empty string, or undef.
B<You pass an argument, you get an object>.

Text will always be rendered as utf8, so you can pass any string containing
regular ASCII or valid utf8 characters.

=head2 write_to( $target_surface )

=head2 write_to( $target_surface, "text to write" )

Renders the text onto C<$target_surface> (usually the app itself). The
text string may be passed as a parameter, otherwise it will use whatever
is already set (via the C<new()> or C<text()> methods.

=head2 write_xy( $target_surface, $x, $y )

=head2 write_xy( $target_surface, $x, $y, $text )

Same as C<write_to()>, but will render the text using the given top (y) and
left (x) coordinates.


=head1 READ-ONLY ATTRIBUTES

As you set or update your text, font or size, SDLx::Text updates the surface
that represents it. You don't usually need to worry about this at all, and
we strongly recommend you use the L<"/METHODS"> above to render your text.

If however you need to know how tall or wide the rendered text will be
(in pixels), or if you want to retrieve the surface so you can manipulate and
render it yourself, you can use the following getters:

=head2 surface

Returns the underlying surface representing the text itself. You probably don't need this, unless you're doing something really funky.

=head2 w

Shortcut to see the width of the underlying surface representing the text.

=head2 h

Shortcut to see the height of the underlying surface representing the text.

=head2 font_filename

Returns the file name for the loaded font. Use C<font()> to get the font object itself, or to set a new font.

=head1 ERRORS AND DIAGNOSTICS

=over 4

=item * "SDL_ttf support has not been compiled"

In order to render text in SDL you must have enabled SDL_ttf while building L<Alien::SDL>.

=item * "Cannot init TTF: <some error>"

In order to load fonts and render text, we need to initialize L<SDL::TTF>
- that is, in case it hasn't been initialized already. The error above will
appear in the rare event of any problem during initialization.

=item * "Error opening font: <some error>"

The font file you set either via C<< font( 'font.ttf' ) >> or during
construction could not be loaded. The file may not exist in the given path,
have wrong permissions, be corrupted, or of an unsupported format. Please
refer the C<< <some error> >> message in the message itself for further
information.

=item * "TTF rendering error: <some error>"

When you call C<text()>, it renders the provided string onto an internal
L<SDL::Surface> object. If there was any problem rendering the text, this
message will appear.

=back

=head1 BUGS

Please report any bugs or feature requests to the bug tracker. We will be notified, and then you'll automatically be notified of progress on your bug as we make changes.


=head1 SUPPORT

You can find documentation for this module with the perldoc command.

    perldoc SDLx::Text


=head1 AUTHORS

See L<SDL/AUTHORS>.


=head1 COPYRIGHT & LICENSE

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

This module ships with a default font, "I<Gentium Basic>", Copyright 2003-2008 SIL International (http://sil.org), released under the SIL Open Font License 1.1 (OFL). The font is available for use in free and commercial products, with some minor restrictions. Please read the C<OFL.txt> and C<OFL-FAQ.txt> for further information.

=head1 SEE ALSO

L<SDL>, L<SDLx::App>, L<SDL::TTF>