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PDF::Builder::ViewerPreferences - How the PDF should be displayed or printed

=head1 METHODS

This has been split out from C<preferences()> in L<PDF::Builder>.

=cut

sub _snake_case {
    my $name = shift();
    $name =~ s/^([A-Z]+)/lc($1)/e;
    $name =~ s/([A-Z]+)/'_' . lc($1)/ge;
    $name =~ s/pdfsize/pdf_size/;
    return $name;
}

sub _camel_case {
    my $name = shift();
    $name = ucfirst($name);
    $name =~ s/_([a-z]+)/ucfirst($1)/ge;
    $name =~ s/Ui$/UI/;
    $name =~ s/Pdf/PDF/;
    return $name;
}

=head2 new

    $self = $class->new($pdf)

=over

Creates a new ViewerPreferences object from a PDF::Builder object.

=back

=cut

sub new {
    my ($class, $pdf) = @_;
    my $self = bless { pdf => $pdf }, $class;
    weaken $self->{'pdf'};
    return $self;
}

=head2 get_preferences

    %preferences = $self->get_preferences()

=over

Returns a hash containing all of the viewer preferences that are defined in the
PDF.

=back

=cut

sub get_preferences {
    my $self = shift();
    my $prefs = $self->{'pdf'}->{'catalog'}->{'ViewerPreferences'};
    return unless $prefs;
    $prefs->realise();

    my %values;
    foreach my $pref (@booleans) {
        next unless $prefs->{$pref};
        $values{_snake_case($pref)} = $prefs->{$pref}->val() eq 'true' ? 1 : 0;
    }
    foreach my $pref (@names) {
        next unless $prefs->{$pref};
        if      ($pref eq 'Direction') {
            $values{'direction'} = lc($prefs->{$pref}->val());
        } elsif ($pref eq 'Duplex') {
            my $value = $prefs->{$pref}->val();
            $value =~ s/Flip//;
            $value =~ s/Edge//;
            $values{'duplex'} = _snake_case($value);
        } elsif ($pref eq 'NonFullScreenPageMode') {
            my $value = _snake_case($prefs->{$pref}->val());
            $value =~ s/^use_//;
            $value = 'optional_content' if $value eq 'oc';
            $values{'non_full_screen_page_mode'} = $value;
        } else {
            $values{_snake_case($pref)} = _snake_case($prefs->{$pref}->val());
        }
    }
    if ($prefs->{'PrintPageRange'}) {
        my @ranges = map { $_->val() } @{$prefs->{'PrintPageRange'}};
        $values{'print_page_range'} = \@ranges;
    }
    if ($prefs->{'NumCopies'}) {
        $values{'num_copies'} = $prefs->{'NumCopies'}->val();
    }

    return %values;
}

=head2 get_preference

    $value = $self->get_preference($name)

=over

Returns the value of the specified viewer preference if present, or C<undef> if
not.

=back

=cut

sub get_preference {
    my ($self, $name) = @_;
    my %values = $self->get_preferences();
    return $values{$name};
}

=head2 set_preferences

    $self->set_preferences(%values)

=over

Sets one or more viewer preferences, as described in the preferences section
below.

=back

=cut

sub _init_preferences {
    my $self = shift();
    if ($self->{'pdf'}->{'catalog'}->{'ViewerPreferences'}) {
        $self->{'pdf'}->{'catalog'}->{'ViewerPreferences'}->realise();
    }
    else {
        $self->{'pdf'}->{'catalog'}->{'ViewerPreferences'} = PDFDict();
    }
    $self->{'pdf'}->{'pdf'}->out_obj($self->{'pdf'}->{'catalog'});
    return $self->{'pdf'}->{'catalog'}->{'ViewerPreferences'};
}

sub set_preferences {
    my ($self, %values) = @_;
    my $prefs = $self->_init_preferences();
    local @CARP_NOT = qw(PDF::Builder);
    foreach my $snake (keys %values) {
        my $camel = _camel_case($snake);
        if ($camel eq 'NonFullScreenPageMode') {
            my $value = $values{$snake};
            my $name = ($value eq 'none'             ? 'UseNone'     :
                        $value eq 'outlines'         ? 'UseOutlines' :
                        $value eq 'thumbnails'       ? 'UseThumbs'   :
                        $value eq 'optional_content' ? 'UseOC'       :
                        '');
            croak "Invalid value for $snake: $values{$snake}" unless $name;
            $prefs->{$camel} = PDFName($name);
        }
        elsif ($camel eq 'Direction') {
            my $name = $values{$snake};
            unless ($name =~ /^(?:L2R|R2L)$/i) {
                croak "Invalid value for $snake: $name";
            }
            $prefs->{$camel} = PDFName(uc $name);
        }
        elsif ($camel =~ /^(?:View|Print)(?:Area|Clip)$/) {
            my $name = ($values{$snake} eq 'media_box' ? 'MediaBox' :
                        $values{$snake} eq 'crop_box'  ? 'CropBox'  :
                        $values{$snake} eq 'bleed_box' ? 'BleedBox' :
                        $values{$snake} eq 'trim_box'  ? 'TrimBox'  :
                        $values{$snake} eq 'art_box'   ? 'ArtBox'   : '');
            croak "Invalid value for $snake: $name" unless $name;
            $prefs->{$camel} = PDFName($name);
        }
        elsif ($camel eq 'PrintScaling') {
            my $value = $values{$snake};
            my $name = ($value eq 'none'        ? 'None'       :
                        $value eq 'app_default' ? 'AppDefault' : '');
            croak "Invalid value for $snake: $name" unless $name;
            $prefs->{$camel} = PDFName($name);
        }
        elsif ($camel eq 'Duplex') {
            my $value = $values{$snake};
            my $name = ($value eq 'simplex'      ? 'Simplex'             :
                        $value eq 'duplex_short' ? 'DuplexFlipShortEdge' :
                        $value eq 'duplex_long'  ? 'DuplexFlipLongEdge'  : '');
            croak "Invalid value for $snake: $value" unless $name;
            $prefs->{$camel} = PDFName($name);
        }
        elsif ($camel eq 'PrintPageRange') {
            unless (ref($values{$snake}) eq 'ARRAY') {
                croak "The value for $snake must be a reference to an array";
            }
            my @range = @{$values{$snake}};
            unless (@range % 2 == 0) {
                croak "The value for $snake must contain pairs of page numbers";
            }
            if (join('', @range) =~ /\D/) {
                croak "The value for $snake may only contain page numbers";
            }
            $prefs->{$camel} = PDFArray(map { PDFNum($_) } @range);
        }
        elsif ($camel eq 'NumCopies') {
            unless ($values{$snake} =~ /^\d+$/) {
                croak "$snake: $values{$snake} is not an integer";
            }
            $prefs->{$camel} = PDFNum($values{$snake});
        }
        elsif (grep { $camel eq $_ } @booleans) {
            $prefs->{$camel} = PDFBool($values{$snake} ? 1 : 0);
        }
        else {
            croak "Unrecognized viewer preference '$snake'";
        }
    }
    return $self;
}

=head1 PREFERENCES

Viewer Preferences describe how the document should be presented on screen or in
print.  Not all PDF viewers will respect these preferences.

Boolean preferences default to false and take (or return) 0 or 1 as arguments.

Bounding Box preferences take (or return) one of C<media_box>, C<crop_box>,
C<bleed_box>, C<trim_box>, or C<art_box>.

=over

=item hide_toolbar (boolean)

A flag specifying whether to hide the tool bars when the document is active.

=item hide_menubar (boolean)

A flag specifying whether to hide the menu bar when the document is active.

=item hide_window_ui (boolean)

A flag specifying whether to hide the user interface elements in the document's
window (such as scroll bars and navigation controls), leaving only the
document's contents displayed.

=item fit_window (boolean)

A flag specifying whether to resize the document's window to fit the size of the
first displayed page.

=item center_window (boolean)

A flag specifying whether to position the document's window in the center of the
screen.

=item display_doc_title (boolean)

A flag specifying whether the window's title bar should display the document
title taken from the Title entry of the document information directory.  If
false, the title bar should instead display the name of the PDF file containing
the document.

=item non_full_screen_page_mode (name)

The document's page mode, specifying how to display the document on exiting
full-screen mode.  Options are the same as C<page_mode> in L<PDF::Builder>,
except that the C<attachments> and C<full_screen> options aren't supported.

=item direction ('l2r' or 'r2l')

The predominant reading order for text (left-to-right or right-to-left).