root/main/trunk/greenstone2/perllib/plugins/PDFPlugin.pm @ 24290

Revision 24290, 15.8 KB (checked in by sjm84, 8 years ago)

Several changes to how Greenstone hashes PDF files and also added several more options to the EmbeddedMetadataPlugin?

  • Property svn:keywords set to Author Date Id Revision
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1###########################################################################
2#
3# PDFPlugin.pm -- reasonably with-it pdf plugin
4# A component of the Greenstone digital library software
5# from the New Zealand Digital Library Project at the
6# University of Waikato, New Zealand.
7#
8# Copyright (C) 1999-2001 New Zealand Digital Library Project
9#
10# This program is free software; you can redistribute it and/or modify
11# it under the terms of the GNU General Public License as published by
12# the Free Software Foundation; either version 2 of the License, or
13# (at your option) any later version.
14#
15# This program is distributed in the hope that it will be useful,
16# but WITHOUT ANY WARRANTY; without even the implied warranty of
17# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18# GNU General Public License for more details.
19#
20# You should have received a copy of the GNU General Public License
21# along with this program; if not, write to the Free Software
22# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23#
24###########################################################################
25package PDFPlugin;
26
27use strict;
28no strict 'refs'; # so we can use a var for filehandles (e.g. STDERR)
29
30use ReadTextFile;
31use unicode;
32
33use AutoLoadConverters;
34use ConvertBinaryFile;
35
36@PDFPlugin::ISA = ('ConvertBinaryFile', 'AutoLoadConverters', 'ReadTextFile');
37
38
39my $convert_to_list =
40    [ { 'name' => "auto",
41    'desc' => "{ConvertBinaryFile.convert_to.auto}" },
42      { 'name' => "html",
43    'desc' => "{ConvertBinaryFile.convert_to.html}" },
44      { 'name' => "text",
45    'desc' => "{ConvertBinaryFile.convert_to.text}" },
46      { 'name' => "pagedimg_jpg",
47    'desc' => "{ConvertBinaryFile.convert_to.pagedimg_jpg}"},
48      { 'name' => "pagedimg_gif",
49    'desc' => "{ConvertBinaryFile.convert_to.pagedimg_gif}"},
50      { 'name' => "pagedimg_png",
51    'desc' => "{ConvertBinaryFile.convert_to.pagedimg_png}"},
52      ];
53
54
55my $arguments =
56    [
57     { 'name' => "convert_to",
58       'desc' => "{ConvertBinaryFile.convert_to}",
59       'type' => "enum",
60       'reqd' => "yes",
61       'list' => $convert_to_list,
62       'deft' => "html" },   
63     { 'name' => "process_exp",
64       'desc' => "{BasePlugin.process_exp}",
65       'type' => "regexp",
66       'deft' => &get_default_process_exp(),
67       'reqd' => "no" },
68     { 'name' => "block_exp",
69       'desc' => "{BasePlugin.block_exp}",
70       'type' => "regexp",
71       'deft' => &get_default_block_exp() },
72     { 'name' => "metadata_fields",
73       'desc' => "{HTMLPlugin.metadata_fields}",
74       'type' => "string",
75       'deft' => "" },
76      { 'name' => "metadata_field_separator",
77    'desc' => "{HTMLPlugin.metadata_field_separator}",
78    'type' => "string",
79    'deft' => "" },
80     { 'name' => "noimages",
81       'desc' => "{PDFPlugin.noimages}",
82       'type' => "flag" },
83     { 'name' => "allowimagesonly",
84       'desc' => "{PDFPlugin.allowimagesonly}",
85       'type' => "flag" },
86     { 'name' => "complex",
87       'desc' => "{PDFPlugin.complex}",
88       'type' => "flag" },
89     { 'name' => "nohidden",
90       'desc' => "{PDFPlugin.nohidden}",
91       'type' => "flag" },
92     { 'name' => "zoom",
93       'desc' => "{PDFPlugin.zoom}",
94       'deft' => "2",
95       'range' => "1,3", # actually the range is 0.5-3
96       'type' => "int" },
97     { 'name' => "use_sections",
98       'desc' => "{PDFPlugin.use_sections}",
99       'type' => "flag" },
100     { 'name' => "description_tags",
101       'desc' => "{HTMLPlugin.description_tags}",
102       'type' => "flag" }
103     ];
104
105my $options = { 'name'     => "PDFPlugin",
106        'desc'     => "{PDFPlugin.desc}",
107        'abstract' => "no",
108        'inherits' => "yes",
109        'srcreplaceable' => "yes", # Source docs in PDF can be replaced with GS-generated html     
110        'args'     => $arguments };
111
112sub new {
113    my ($class) = shift (@_);
114    my ($pluginlist,$inputargs,$hashArgOptLists) = @_;
115    push(@$pluginlist, $class);
116
117    push(@$inputargs,"-title_sub");
118    push(@$inputargs,'^(Page\s+\d+)?(\s*1\s+)?');
119
120    push(@{$hashArgOptLists->{"ArgList"}},@{$arguments});
121    push(@{$hashArgOptLists->{"OptList"}},$options);
122
123    my $auto_converter_self = new AutoLoadConverters($pluginlist,$inputargs,$hashArgOptLists,["PDFBoxConverter"],1);
124    my $cbf_self = new ConvertBinaryFile($pluginlist, $inputargs, $hashArgOptLists);
125    my $self = BasePlugin::merge_inheritance($auto_converter_self, $cbf_self);
126   
127    if ($self->{'info_only'}) {
128    # don't worry about any options etc
129    return bless $self, $class;
130    }
131   
132    $self = bless $self, $class;
133    $self->{'file_type'} = "PDF";
134
135    # these are passed through to gsConvert.pl by ConvertBinaryFile.pm
136    my $zoom = $self->{"zoom"};
137    $self->{'convert_options'} = "-pdf_zoom $zoom";
138    $self->{'convert_options'} .= " -pdf_complex" if $self->{"complex"};
139    $self->{'convert_options'} .= " -pdf_nohidden" if $self->{"nohidden"};
140    $self->{'convert_options'} .= " -pdf_ignore_images" if $self->{"noimages"};
141    $self->{'convert_options'} .= " -pdf_allow_images_only" if $self->{"allowimagesonly"};
142
143    # check convert_to
144    if ($self->{'convert_to'} eq "text" && $ENV{'GSDLOS'} =~ /^windows$/i) {
145    print STDERR "Windows does not support pdf to text. PDFs will be converted to HTML instead\n";
146    $self->{'convert_to'} = "html";
147    }
148    elsif ($self->{'convert_to'} eq "auto") {
149    # choose html ?? is this the best option
150    $self->{'convert_to'} = "html";
151    }
152    # set convert_to_plugin and convert_to_ext
153    $self->set_standard_convert_settings();
154
155    my $secondary_plugin_name = $self->{'convert_to_plugin'};
156    my $secondary_plugin_options = $self->{'secondary_plugin_options'};
157
158    if (!defined $secondary_plugin_options->{$secondary_plugin_name}) {
159    $secondary_plugin_options->{$secondary_plugin_name} = [];
160    }
161    my $specific_options = $secondary_plugin_options->{$secondary_plugin_name};
162
163    # following title_sub removes "Page 1" added by pdftohtml, and a leading
164    # "1", which is often the page number at the top of the page. Bad Luck
165    # if your document title actually starts with "1 " - is there a better way?
166    push(@$specific_options , "-title_sub", '^(Page\s+\d+)?(\s*1\s+)?');
167    my $associate_tail_re = $self->{'associate_tail_re'};
168    if ((defined $associate_tail_re) && ($associate_tail_re ne "")) {
169    push(@$specific_options, "-associate_tail_re", $associate_tail_re);
170    }
171    push(@$specific_options, "-file_rename_method", "none");
172   
173    if ($secondary_plugin_name eq "HTMLPlugin") {
174    # pdftohtml always produces utf8 - What about pdfbox???
175    # push(@$specific_options, "-input_encoding", "utf8");
176    push(@$specific_options, "-extract_language") if $self->{'extract_language'};
177    push(@$specific_options, "-processing_tmp_files");
178    # Instruct HTMLPlug (when eventually accessed through read_into_doc_obj)
179    # to extract these metadata fields from the HEAD META fields
180    if (defined $self->{'metadata_fields'} && $self->{'metadata_fields'} =~ /\S/) {
181        push(@$specific_options,"-metadata_fields",$self->{'metadata_fields'});
182    } else {
183        push(@$specific_options,"-metadata_fields","Title,GENERATOR,date,author<Creator>");
184    }
185    if (defined $self->{'metadata_field_separator'} && $self->{'metadata_field_separator'} =~ /\S/) {
186        push(@$specific_options,"-metadata_field_separator",$self->{'metadata_field_separator'});
187    }
188    if ($self->{'use_sections'} || $self->{'description_tags'}) {
189        $self->{'description_tags'} = 1;
190        push(@$specific_options, "-description_tags");
191    }
192    }
193    elsif ($secondary_plugin_name eq "PagedImagePlugin") {
194    push(@$specific_options, "-screenviewsize", "1000");
195    push(@$specific_options, "-enable_cache");
196    push(@$specific_options, "-processing_tmp_files");
197    }
198
199    $self = bless $self, $class;
200    $self->load_secondary_plugins($class,$secondary_plugin_options,$hashArgOptLists);
201    return $self;
202}
203
204sub get_default_process_exp {
205    my $self = shift (@_);
206
207    return q^(?i)\.pdf$^;
208}
209
210# so we don't inherit HTMLPlug's block exp...
211sub get_default_block_exp {
212    return "";
213}
214
215sub init {
216    my $self = shift (@_);
217
218    # ConvertBinaryFile init
219    $self->SUPER::init(@_);
220    $self->AutoLoadConverters::init(@_);
221
222}
223
224sub begin {
225    my $self = shift (@_);
226
227    $self->AutoLoadConverters::begin(@_);
228    $self->SUPER::begin(@_);
229
230}
231
232sub deinit {
233    my $self = shift (@_);
234   
235    $self->AutoLoadConverters::deinit(@_);
236    $self->SUPER::deinit(@_);
237
238}
239 
240# By setting hashing to be on ga xml this ensures that two
241# PDF files that are identical except for the metadata
242# to hash to different values. Without this, when each PDF
243# file is converted to HTML there is a chance that they
244# will both be *identical* if the conversion utility does
245# not embed the metadata in the generated HTML. This is
246# certainly the case when PDFBOX is being used.
247
248# This change makes this convert to based plugin more
249# consistent with the original vision that the same document
250# with different metadata should
251# be seen as different.
252
253sub get_oid_hash_type {
254    my $self = shift (@_);
255    return "hash_on_ga_xml";
256}
257 
258 
259sub tmp_area_convert_file {
260
261    my $self = shift (@_);
262    return $self->AutoLoadConverters::tmp_area_convert_file(@_);
263
264}
265
266sub convert_post_process
267{
268    my $self = shift (@_);
269    my ($conv_filename) = @_;
270
271    my $outhandle=$self->{'outhandle'};
272
273    #$self->{'input_encoding'} = "utf8"; # The output is always in utf8 (is it?? it is for html, but what about other types?)
274    #my ($language, $encoding) = $self->textcat_get_language_encoding ($conv_filename);
275
276    # read in file ($text will be in utf8)
277    my $text = "";
278    # encoding will be utf8 for html files - what about other types? will we do this step for them anyway?
279    $self->read_file ($conv_filename, "utf8", "", \$text);
280
281    # To support the use_sections option with PDFBox: Greenstone splits PDFs into pages for
282    # sections. The PDFPlugin code wants each new page to be prefixed with <a name=pagenum></a>,
283    # which it then splits on to generate page-based sections. However, that's not what PDFBox
284    # generates in its HTML output. Fortunately, PDFBox does have its own page-separator: it
285    # embeds each page in an extra div. The div opener is:
286    # <div style=\"page-break-before:always; page-break-after:always\">
287    # The PDFPlugin now looks for this and prefix <a name=0></a> to each such div. (The
288    # pagenumber is fixed at 0 since I'm unable to work out how to increment the pagenum during
289    # a regex substitution even with regex extensions on.) Later, when we process each section
290    # to get the pagenum, PDFBox's output for this is pre-processed by having a loopcounter
291    # that increments the pagenum for each subsequent section.
292
293    #$pdfbox_pageheader="\<div style=\"page-break-before:always; page-break-after:always\">";
294    my $loopcounter = 0; # used later on!
295    $text =~ s@\<div style=\"page-break-before:always; page-break-after:always\">@<a name=$loopcounter></a><div style=\"page-break-before:always; page-break-after:always\">@g;
296
297
298    # Calculate number of pages based on <a ...> tags (we have a <a name=1> etc
299    # for each page).  Metadata based on this calculation not set until process()
300    #
301    # Note: this is done even if we are not breaking to document into pages as it might
302    # be useful to give an indication of document length in browser through setting
303    # num_pages as metadata.
304    my @pages = ($text =~ m/(\<[Aa] name=\"?\w+\"?>|\<div style=\"page-break-before:always; page-break-after:always\">)/ig); #<div style=\"?page-break-before:always; page-break-after:always\"?>
305    my $num_pages = scalar(@pages);
306    $self->{'num_pages'} = $num_pages;
307
308    if ($self->{'use_sections'}
309    && $self->{'converted_to'} eq "HTML") {
310
311    print $outhandle "PDFPlugin: Calculating sections...\n";
312
313    # we have "<a name=1></a>" etc for each page
314    # it may be <A name=
315    my @sections = split('<[Aa] name=', $text);
316
317    my $top_section = "";
318
319    if (scalar (@sections) == 1) { #only one section - no split!
320        print $outhandle "PDFPlugin: warning - no sections found\n";
321    } else {
322        $top_section .= shift @sections; # keep HTML header etc as top_section
323    }
324
325    # handle first section specially for title? Or all use first 100...
326   
327    my $title = $sections[0];
328    $title =~ s/^\"?\w+\"?>//; # specific for pdftohtml...
329    $title =~ s/<\/([^>]+)><\1>//g; # (eg) </b><b> - no space
330    $title =~ s/<[^>]*>/ /g;
331    $title =~ s/(?:&nbsp;|\xc2\xa0)/ /g; # utf-8 for nbsp...
332    $title =~ s/^\s+//s;
333    $title =~ s/\s+$//;
334    $title =~ s/\s+/ /gs;
335    $title =~ s/^$self->{'title_sub'}// if ($self->{'title_sub'});
336    $title =~ s/^\s+//s; # in case title_sub introduced any...
337    $title = substr ($title, 0, 100);
338    $title =~ s/\s\S*$/.../;
339
340
341    if (scalar (@sections) == 1) { # no sections found
342        $top_section .= $sections[0];
343        @sections=();
344    } else {
345        $top_section .= "<!--<Section>\n<Metadata name=\"Title\">$title</Metadata>\n-->\n <!--</Section>-->\n";
346    }
347
348    # add metadata per section...
349    foreach my $section (@sections) {
350        # section names are not always just digits, may be like "outline"
351        $section =~ s@^\"?(\w+)\"?></a>@@; # leftover from split expression...
352
353        $title = $1; # Greenstone does magic if sections are titled digits
354
355        # A title of pagenum=0 means use_sections is being applied on output from PDFBox,
356        # which didn't originally have a <a name=incremented pagenumber></a> to split each page.
357        # Our Perl code then prefixed <a name=0></a> to it. Now need to increment the pagenum here:
358        if($loopcounter > 0 || ($title eq 0 && $loopcounter == 0)) { # implies use_sections with PDFBox
359        $title = ++$loopcounter;
360        }
361
362        if (! defined($title) ) {
363        print STDERR "no title: $section\n";
364        $title = " "; # get rid of the undefined warning in next line
365        }
366        my $newsection = "<!-- from PDFPlugin -->\n<!-- <Section>\n";
367        $newsection .= "<Metadata name=\"Title\">" . $title
368        . "</Metadata>\n--><br />\n";
369        $newsection .= $section;
370        $newsection .= "<!--</Section>-->\n";
371        $section = $newsection;
372    }
373
374    $text=join('', ($top_section, @sections));
375    }
376
377    if ($self->{'use_sections'}
378    && $self->{'converted_to'} eq "text") {
379    print STDERR "**** When converting PDF to text, cannot apply use_sections\n";
380    }
381
382
383    # The following should no longer be needed, now that strings
384    # read in are Unicode aware (in the Perl sense) rather than
385    # raw binary strings that just happen to be UTF-8 compliant
386
387    # turn any high bytes that aren't valid utf-8 into utf-8.
388##    unicode::ensure_utf8(\$text);
389
390    # Write it out again!
391    $self->utf8_write_file (\$text, $conv_filename);
392}
393
394
395# do plugin specific processing of doc_obj for HTML type
396sub process {
397    my $self = shift (@_);
398    my ($pluginfo, $base_dir, $file, $metadata, $doc_obj, $gli) = @_;
399
400    my $result = $self->process_type($base_dir,$file,$doc_obj);
401
402    # fix up the extracted date metadata to be in Greenstone date format,
403    # and fix the capitalisation of 'date'
404    my $cursection = $doc_obj->get_top_section();
405    foreach my $datemeta (@{$doc_obj->get_metadata($cursection, "date")}) {
406    $doc_obj->delete_metadata($cursection, "date", $datemeta);
407
408    # We're just interested in the date bit, not the time
409    # some pdf creators (eg "Acrobat 5.0 Scan Plug-in for Windows")
410    # set a /CreationDate, and set /ModDate to 000000000. pdftohtml
411    # extracts the ModDate, so it is 0...
412    $datemeta =~ /(\d+)-(\d+)-(\d+)/;
413    my ($year, $month, $day) = ($1,$2,$3);
414    if (defined($year) && defined($month) && defined($day)) {
415        if ($year == 0) {next}
416        if ($year < 100) {$year += 1900} # just to be safe
417        if ($month =~ /^\d$/) {$month="0$month"} # single digit
418        if ($day =~ /^\d$/) {$day="0$day"} # single digit
419        my $date="$year$month$day";
420        $doc_obj->add_utf8_metadata($cursection, "Date", $date);
421    }
422    }
423
424    $doc_obj->add_utf8_metadata($cursection, "NumPages", $self->{'num_pages'});
425   
426    if ($self->{'use_sections'} && $self->{'converted_to'} eq "HTML") {
427    # we explicitly make it a paged document, cos greenstone won't get it
428    # right if any section has an empty title, or one with letters in it
429    $doc_obj->set_utf8_metadata_element ($cursection, "gsdlthistype", "Paged");
430    }
431
432    return $result;
433}
434
4351;
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