Programming Web Graphics with Perl & GNU Software
by Shawn P. Wallace



This errata page lists errors outstanding in the most recent printing.  


If you have any error reports or technical questions, you can send them to
booktech@oreilly.com.  (Please specify the printing date of your copy.)


This page was updated on September 13, 1999.


Here's a key to the markup:

        [page-number]: serious technical mistake
        {page-number}: minor technical mistake
        <page-number>: important language/formatting problem
        (page-number): language change or minor formatting problem
        ?page-number?: reader question or request for clarification



Confirmed errors:


(xii) Booktech e-mail: missing ".com"


{xiii} Paragraph 4 of the Acknowledgments reads:
	
	Bob Freishanham

It should read: 
	
	Bob Friesenhahn


(14-15) Figures 1-5 and 1-6: the captions should note that the 
        PNGs for which file sizes are given are 24-bit images; they 
        would be comparable to or smaller than the GIFs if saved as 
        8-bit indexed images (e.g., use gif2png to convert and
        optionally pngcrush to optimize) 


{46} binmode(STDIN); should be binmode(INFILE);


{48} Change 
	
	if ((length($text) > 20 | ($text =~ / /) ) {
                        
to
                        
	if ((length($text) > 20 || ($text =~ / /) ) {
                

{53} The line at the top of the page reading: 

	$filesize = $filesize / 1000; 

Should read: 

	$filesize = $filesize / 1024; 


(58) In comment line starting "# The right ear: ...." should be 
     the upper left and lower right (not left) 
                      

(65) In the references section, the URL for the Perl-Apache 
     Integration Project should be http://perl.apache.org
 

(71) libjpeg platforms: should be "Most"; also, "IPG" should be "IJG" 


(74) zlib platforms: should be "Most"


(82) Mentions that 

	If you are working on a platform that makes a distinction 
	between text and binary files (such as Windows 95/NT), be 
	sure that you are writing in binary mode by calling the
	binmode() method first." 

But on page 96 it reads 

	On Unix systems, you can pipe the image data to an image 
	viewer, such as xv or the display utility that comes with 
	ImageMagick.

Yet in the example that soon follows is the binmode statement advised 
for Windows 95/NT systems.  

On a UNIX system it doesn't matter whether the filehandle is in 
binary mode or not.  It won't hurt anything, but it doesn't do anything 
either. Remove from future printings.


(99) "allocateColor" should be "colorAllocate." This error occurs 
     twice, in 2. and 3. of the "setBrush()" section


(99) On line 4. Change:
                       
	($whitest)
                        
to
                        
	($mostestwhitest)


{100} 3rd last line. 'INFILE' should read \*INFILE


{111} $image->rectangle(@boundingbox, red); should be
      $image->rectangle(@boundingbox, $red);


(117) Table 5-1, line 1: "GraphDics": delete D


(117)Table 5-1, last line: "Multiple" should be "Multiple-image" 


{128} Under 'base_rows, base_filename' should be 'base_rows'


{129} Under colormap[i], 'set' should be 'Set'.


(321) Two times it lists \Times-Roman instead of /Times-Roman.


(336) Under the font heading on the last line it says...
                        
	corresponds with the set of default Ghostscript fonts with 
	have AFM files:


Should say
                        

	corresponds with the set of default Ghostscript fonts 
	with AFM files: 


(337) The first line reads
                        
	currently fonts currently supported by PostScript::Metrics
   
Should be
                        
	fonts currently supported by PostScript::Metrics


(353) Under linetint and filltint it reads
                        
	with 1 as black and 0 as white.
                        
It should be
                        
	with 1 as white and 0 as black


(340) Two Bugs in the PostScript::TextBlock module in two areas in 
      the Write() subroutine of the TextBlock module that required 
      a patch. They both have to do with proper word wrapping. One 
      problem was that words would not always line up against the 
      left margin due to white space that remained attached to the 
      font of a word when we'd gone over the limit and the word had 
      to be pushed back for later processing. In this case, we would 
      want to remove the leading white space. Below is the updated 
      version of the code section that covers this.

	# If we've gone over, push the word back on
	# for later processing.
	#
	if ( ($wcount>$w) || ($word =~ s/\n//) ) {
	    if ($word =~ /^ /) { $word =~ s/^[ ]+//; }
		# This line is the patch
		    unshift @words, $word;
		    last LINE;
	}

The other problem had to do with the section of code that determined 
if there were any remaining words that needed to be put back for later
processing. The existing code does the logical check: 

	if ($#words) {
             $element->{text} = join '', @words;
	}

but "$#words" returns the subscript of the last element in @words, NOT
the number of elements. Instead, use the code: 

	my $numWords = @words;
	if ($numWords) {
             $element->{text} = join '', @words;
	}