oracular (3) PostScript::TextBlock.3pm.gz
NAME
PostScript::TextBlock - An object that may be used to construct a block of
text in PostScript.
SYNOPSIS
use PostScript::TextBlock;
my $tb = new PostScript::TextBlock;
$tb->addText( text => "Hullaballo in Hoosick Falls.\n",
font => 'CenturySchL-Ital',
size => 24,
leading => 26
);
$tb->addText( text => "by Charba Gaspee.\n",
font => 'URWGothicL-Demi',
size => 12,
leading => 14
);
print 'There are '.$tb->numElements.' elements in this object.';
open OUT, '>psoutput.ps';
my ($code, $remainder) = $tb->Write(572, 752, 20, 772);
print OUT $code;
DESCRIPTION
The PostScript::TextBlock module implements four methods:
new() - Create a New PostScript::TextBlock object
This method instantiates a new object of class PostScript::TextBlock.
addText( text=>$text, [ font=>$font ], [ size=>$size ], [ leading=>$leading ] )
The addText() method will add a new 'text element' to the TextBlock object. A 'text element' can be
thought of as a section of text that has the same characteristics, i.e. all the characters are the
same font, size and leading. this representation allows you to include text rendered in multiple
fonts at multiple sizes within the same text block by including them as separate elements.
This method takes up to four attributes (note that the '[]' brackets above indicate that a parameter
is optional, not an array reference):
text The text attribute is required, though nothing bad will happen if you leave it out. This is
simply the text to be rendered in the text block. Line breaks may be inserted by including a newline
"\n".
font The font attribute is a string indicating the name of the font to be used to render this element.
The PS package uses an internal description of the Font Metrics of various fonts that is contained in
the PostScript::Metrics module. As of this writing, the PostScript::Metrics module supports the
following fonts (basically, the default GhostScript fonts that have AFM files):
NimbusSanL-ReguCond URWGothicL-Book CenturySchL-Bold CharterBT-Italic URWBookmanL-Ligh
CharterBT-BoldItalic NimbusRomNo9L-ReguItal URWBookmanL-DemiBoldItal CharterBT-Roman
NimbusMonL-ReguObli NimbusSanL-ReguCondItal CenturySchL-Ital CenturySchL-BoldItal URWPalladioL-
Roma URWBookmanL-LighItal CharterBT-Bold NimbusSanL-BoldCond NimbusMonL-BoldObli
NimbusSanL-BoldCondItal URWGothicL-DemiObli NimbusSanL-Regu URWPalladioL-Bold NimbusMonL-
Regu NimbusSanL-ReguItal URWGothicL-BookObli URWPalladioL-Ital
You can get a list of the currently supported fonts with the following:
use PostScript::Metrics;
@okfonts = PostScript::Metrics->listFonts();
NOTE: The font must be available to the PostScript interpreter that is used to render the page
described by the program. If the interpreter cannot load the font, it will ususally attempt to
substitute a similar font. If a font is substituted with a font with different metrics, lines of text
may overrun the right margin of the text block. You have been warned.
It is very easy to create stylesheets for a document:
# Define the styles
#
%body = ( font => 'URWGothicL-DemiObli', size => 12, leading => 16 );
%head1 = ( font => 'NimbusSanL-BoldCond', size => 24, leading => 36 );
%head2 = ( font => 'NimbusSanL-BoldCond', size => 18, leading => 30 );
# Use them where appropriate
#
$tb->addText(text => "Chapter 10\n", %head1);
$tb->addText(text => "Spokane Sam and His Spongepants\n", %head2);
$tb->addText(text => "It was a dark and stormy night and Spokane Sam\'s
Spongepants were thirsty...", %body);
numElements()
Returns the number of elements in the text block object. An 'element' is created each time the
addText() method is called.
Write( $width, $height, $xoffset, $yoffset )
The Write() method will generate the PostScript code that will render the text on a page when passed
to a PostScript interpreter such as Ghostscript. The four parameters are expressed in points (1/72
inch) and indicate the width and height of the box within which the text should be printed, and the x
and y offset of the upper left corner of this box.
Important: PostScript defines the origin (0,0) as the lower left corner of the page! This *will* mess
you up.
Standard page sizes in points are:
Paper Size Width, Height (in points)
......................... .........................
Letter 612, 792
Legal 612, 1008
Ledger 1224, 792
Tabloid 792, 1224
A0 2384, 3370
A1 1684, 2384
A2 1191, 1684
A3 842, 1191
A4 595, 842
A5 420, 595
A6 297, 420
A7 210, 297
A8 148, 210
A9 105, 148
B0 2920, 4127
B1 2064, 2920
B2 1460, 2064
B3 1032, 1460
B4 729, 1032
B5 516, 729
B6 363, 516
B7 258, 363
B8 181, 258
B9 127, 181
B10 91, 127
#10 Envelope 297, 684
C5 Envelope 461, 648
DL Envelope 312, 624
Folio 595, 935
Executive 522, 756
The write() method returns two values: a string consisting of the PostScript code (suitable for
printing to a file), and a TextBlock object containing the elements (and partial elements) that did
not fit within the specified area, if any. If the entire text block fits with the area, the remainder
will be undef. The remainder can be used to layout multiple pages and columns, etc. in a similar
manner to most modern desktop publishing programs. In general, the write() method should be called as
in the following, which writes the PostScript code to a file called 'psoutput.ps':
open OUT, '>psoutput.ps';
my ($code, $remainder) = $tb->Write(572, 752, 20, 772);
print OUT $code;
To print an entire text block that spans multiple pages, you could do something like this:
(add enough text to the text block first..)
open OUT, '>psoutput.ps';
my $pages = 1;
# Create the first page
#
my ($code, $remainder) = $tb->Write(572, 752, 20, 772);
print OUT "%%Page:$pages\n"; # this is required by the Adobe
# Document Structuring Conventions
print OUT $code;
print OUT "showpage\n";
# Print the rest of the pages, if any
#
while ($remainder->numElements) {
$pages++;
print OUT "%%Page:$pages\n";
($code, $remainder) = $remainder->Write(572, 752, 20, 772);
print OUT $code;
print OUT "showpage\n";
}
However, if you use the PostScript::Document module to construct generic multi-page PostScript
documents, you don't have to worry about this.
A NOTE ABOUT FONT METRICS
The write() method uses the module PostScript::Metrics to determine the width of each character; widths
vary from font to font and character to character. If you were writing a stright PostScript program, you
would let the PostScript interpreter do this for you, but in the case of this program, we need to know
the width of each character in a font within the Perl script. The PostScript::Metrics module contains the
font metrics (i.e., a list containing the width of each character in the font) for a bunch of fonts that
are listed above under the description of the addText() method. This set started with the metrics for all
of the default fonts with AFM files that came with GhostScript. It is slowly growing as more fonts are
mapped. To add support for a new font, you must create the array with the metrics for that font and add
it to the PostScript::Metrics module. For a font with an AFM file, the AFM file can be parsed with Gisle
Aas' Font::AFM module, available on CPAN.
Please send all PostScript::Metrics patches to the author at shawn@as220.org.
TODO
* better compliance with Adobe's Document Structuring Conventions * more font metrics descriptions * make
font loading code smarter and more efficient for the interpreter * support a larger character set * it
would be nice to add more functions, e.g. Clone() * how about settable defaults?
AUTHOR
Copyright 1998, 1999 Shawn Wallace. All rights reserved.
Contact the author: shawn@as220.org http://www.as220.org/shawn
Portions of code contributed by Dan Smeltz.
This is free software. You may use, modify, and redistribute this package under the same terms as Perl
itself.
PostScript is a trademark of Adobe Systems.