Provided by: libpostscript-perl_0.06-2_all 
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, $yoffset )
The Write() method will generate the PostScript code that will render the text on a
page when passed to a PostScript interpreter such as Ghostscript. The four parameters
are expressed in points (1/72 inch) and indicate the width and height of the box within
which the text should be printed, and the x and y offset of the upper left corner of
this box.
Important: PostScript defines the orgin (0,0) as the lower left corner of the page!
This *will* mess you up.
Standard page sizes in points are:
Paper Size Width, Height (in points)
......................... .........................
Letter 612, 792
Legal 612, 1008
Ledger 1224, 792
Tabloid 792, 1224
A0 2384, 3370
A1 1684, 2384
A2 1191, 1684
A3 842, 1191
A4 595, 842
A5 420, 595
A6 297, 420
A7 210, 297
A8 148, 210
A9 105, 148
B0 2920, 4127
B1 2064, 2920
B2 1460, 2064
B3 1032, 1460
B4 729, 1032
B5 516, 729
B6 363, 516
B7 258, 363
B8 181, 258
B9 127, 181
B10 91, 127
#10 Envelope 297, 684
C5 Envelope 461, 648
DL Envelope 312, 624
Folio 595, 935
Executive 522, 756
The write() method returns two values: a string consisting of the PostScript code
(suitable for printing to a file), and a TextBlock object containing the elements (and
partial elements) that did not fit within the specified area, if any. If the entire
text block fits with the area, the remainder will be undef. The remainder can be used
to layout multiple pages and columns, etc. in a similar manner to most modern desktop
publishing programs. In general, the write() method should be called as in the
following, which writes the PostScript code to a file called 'psoutput.ps':
open OUT, '>psoutput.ps';
my ($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.