Lab 4: Two examples: multimedia and scanned images

4.1. Looking at a multimedia collection

  1. Copy the entire folder

    sample_files → beatles → advbeat_large

    (with all its contents) into your Greenstone collect folder. If you have installed Greenstone in the usual place, this is

    My Computer → Local Disk (C:) → Program Files → Greenstone → collect

    Put advbeat_large in there.

  1. If the Greenstone Digital Library Local Library Server is already running, re-start it by clicking the CD icon on the task bar and then pressing Restart Library. If not, start it up by selecting Greenstone Digital Library from the Start menu.

  1. Explore the Beatles collection. Note how the Browse button divides the material into seven different types. Within each category, the documents have appropriate icons. Some documents have an audio icon: when you click these you hear the music (assuming your computer is set up with appropriate player software). Others have an image thumbnail: when you click these you see the images.

  1. Look at the Titles browser. Each title has a bookshelf that may include several related items. For example, Hey Jude has a MIDI file, lyrics, and a discography item.

  1. Observe the low quality of the metadata. For example, the four items under A Hard Day's Night (under "H" in the Titles browser) have different variants as their titles. The collection would have been easier to organize had the metadata been cleaned up manually first, but that would be a big job. Only a tiny amount of metadata was added by hand—fewer than ten items. The original metadata was left untouched and Greenstone facilities used to clean it up automatically. (You will find in Building a multimedia collection that this is possible but tricky.)

  1. In the Windows file browser, take a look at the files that makes up the collection, in the

    sample_files → beatles → advbeat_large → import

    folder. What a mess! There are over 450 files under seven top-level sub-folders. Organization is minimal, reflecting the different times and ways the files were gathered. For example, html_lyrics and discography are excerpts of web sites, and images contains various images in JPEG format. For each type, drill down through the hierarchy and look at a sample document.

4.2. Building a multimedia collection

We will proceed to reconstruct from scratch the Beatles collection that you have just looked at. We develop the collection using a small subset of the material, purely to speed up the repeated rebuilding that is involved.

  1. Start a new collection (FileNew...) called small beatles, basing it on the default -- New Collection --. (Basing it on the existing Advanced Beatles collection would make your life far easier, but we want you to learn how to build it from scratch!)

  1. Copy the files provided in

    sample_files → beatles → advbeat_small

    into your new collection. Do this by opening up advbeat_small, selecting the eight items within it (from discography to beatles_midi.zip), and dragging them across. Because some of these files are in MP3 and MARC formats you will be asked whether to include MP3Plug and MARCPlug in your collection. Click <Add Plugin>.

  1. Change to the Enrich panel and browse around the files. There is no metadata—yet. Recall that you can double-click files to view them.

    (There are no MIDI files in the collection: these require more advanced customisation because there is no MIDI plugin. We will deal with them later.)

  1. Change to the Create panel and build the collection.

  1. Preview the result.

Manually correcting metadata

  1. You might want to correct some of the metadata—for example, the atrocious misspelling in the titles "MAGICAL MISTERY TOUR." These documents are in the discography section, with filenames that contain the same misspelling. Locate one of them in the Enrich panel. Notice that the extracted metadata element ex.Title is now filled in, and misspelt. You cannot correct this element, for it is extracted from the file and will be re-extracted every time the collection is re-built.

  1. Instead, add dc.Title metadata for these two files: "Magical Mystery Tour." Change to the Enrich panel, open the discography folder and drill down to the individual files. Set the dc.Title value for the two offending items.

Now there's a twist. The dc.Title metadata won't appear in Titles because the classifier has been instructed to use ex.Title. But changing the classifier to use dc.Title would miss out all the extracted titles! Fortunately, there's a way of dealing with this by specifying a list of metadata names in the classifier.

  1. Change to the Design panel and select the Browsing Classifiers section. Double-click the ex.Title classifier (the first one) to edit its configuration settings.

    Build the collection again, and preview it.

    Extracted metadata is unreliable. But it is very cheap! On the other hand, manually assigned metadata is reliable, but expensive. The previous section of this exercise has shown how to aim for the best of both worlds by using extracted metadata but correcting it when it is wrong. While this may not satisfy the professional librarian, it could provide a useful compromise for the music teacher who wants to get their collection together with a minimum of effort.

Browsing by media type

  1. First let's remove the AZList classifier for filenames, which isn't very useful, and replace it with a browsing structure that groups documents by category (discography, lyrics, audio etc.). Categories are defined by manually assigned metadata.

    Build the collection again and preview it.

Note how we assigned dc.Format metadata to all documents in the collection with a minimum of labour. We did this by capitalizing on the folder structure of the original information. Even though we complained earlier about how messy this folder structure is, you can still take advantage of it when assigning metadata.

Suppressing dummy text

  1. Alongside the Audio files there is an MP3 icon, which plays the audio when you click it, and also a text document that contains some dummy text. Image files also have dummy documents. These dummy documents aren't supposed to be seen, but to suppress them you have to fiddle with a format statement.

    To make this easier for you we have prepared a plain text file that contains the new text. In WordPad open the following file:

    sample_files → beatles → format_tweaks → audio_tweak.txt

    (Be sure to use WordPad rather than Notepad, because Notepad does not display the line breaks correctly.) Place it in the copy buffer by highlighting the text in WordPad and selecting Edit → Copy. Now move back to the Librarian Interface, highlight all the text that makes up the current VList format statement, and use EditPaste (ctrl-v) to transform the old statement to the new one.

    Preview the result. You may need to click the browser's <Reload> button to force it to re-load the page.

  1. While we're at it, let's remove the source filename from where it appears after each document.

    Preview the result (you don't need to rebuild the collection.)

Using AZCompactList rather than AZList

  1. There are sometimes several documents with the same title. For example, All My Loving appears both as lyrics and tablature (under ALL MY LOVING). The Titles browser might be improved by grouping these together under a bookshelf icon. This is a job for an AZCompactList.

    Build the collection again and preview it. Both items for All My Loving now appear under the same bookshelf. However, many entries haven't been amalgamated because of non-uniform titles: for example A Hard Day's Night appears as four different variants. We will learn below how to amalgamate these.

Making bookshelves show how many items they contain

  1. Make the bookshelves show how many documents they contain by inserting a line in the VList format statement in the Format Features section of the Format panel. The added line is shown highlighted below. The complete format statement can be copied from sample_files → beatles → format_tweaks → show_num_docs.txt.

    <td valign=top>
    {If}{[dc.Format] eq 'Audio',
    [srclink][srcicon][/srclink],
    {If}{[dc.Format] eq 'Images',
    [srclink][thumbicon][/srclink],
    [link][icon][/link]}}</td>
    <td>{If}{[numleafdocs],([numleafdocs])}</td>
    <td valign=top>[highlight]
    {Or}{[dls.Title],[dc.Title],[Title],Untitled}
    [/highlight]</td>

    Preview the result (you don't need to build the collection.) Bookshelves in the titles and browse classifiers should show how many documents they contain.

Adding a Phind phrase browser

  1. In the Browsing Classifiers section on the Design panel, add a Phind classifier. Leave the settings at their defaults: this generates a phrase browsing classifier that sources its phrases from Title and text.

    Build the collection again and preview it. Select the new Phrases option from the navigation bar. Enter a single word in the text box, such as band. The phrase browser will present you with phrases found in the collection containing the search term. This can provide a useful way of browsing a very large collection. Note that even though it is called a phrase browser, only single terms can be used as the starting point for browsing.

Branding the collection with an image

  1. To complete the collection, lets give it a new image for the top left corner of the page. Go to the General section of the Format panel. Use the browse button of URL to 'about page' image: to select the following image:

    sample_files → beatles → advbeat_large → images → beatlesmm.png

    Preview the collection, and make sure the new image appears.

Using UnknownPlug

In this section we incorporate the MIDI files. Greenstone has no MIDI plugin (yet). But that doesn't mean you can't use MIDI files!

  1. UnknownPlug is a useful generic plugin. It knows nothing about any given format but can be tailored to process particular document types—like MIDI—based on their filename extension, and set basic metadata.

    In the Document Plugins section of the Design panel:

    In this collection, all MIDI files are contained in the file beatles_midi.zip. ZIPPlug (already in the list of default plugins) is used to unpack the files and pass them down the list of plugins until they reach UnknownPlug.

  1. Build the collection and preview it. Unfortunately the MIDI files don't appear as Audio under the browse button. That's because they haven't been assigned dc.Format metadata.

Cleaning up a title browser using regular expressions

We now clean up the Titles browser.

To do this we must put the Librarian Interface into a different mode. The interface supports four levels of user: Library Assistant, who can add documents and metadata to collections, and create new ones whose structure mirrors that of existing collections; Librarian, who can, in addition, design new collections, but cannot use specialist IT features (e.g. regular expressions); Library Systems Specialist, who can use all design features, but cannot perform troubleshooting tasks (e.g. interpreting debugging output from Perl programs); and Expert, who can perform all functions.

So far you have mostly been operating in Librarian mode. We switch to Library Systems Specialist mode for the next exercise.

  1. To switch modes, click FilePreferences...Mode and change to Library Systems Specialist. Note from the description that appears that you need to be able to formulate regular expressions to use this mode fully. That is what we do below.

  1. Next we return to our Titles browser and clean it up. The aim is to amalgamate variants of titles by stripping away extraneous text. For example, we would like to treat "ANTHOLOGY 1", "ANTHOLOGY 2" and "ANTHOLOGY 3" the same for grouping purposes. To achieve this:

    Build the collection and preview the result. Observe how many more times similar titles have been amalgamated under the same bookshelf. Test your understanding of regular expressions by trying to rationalize the amalgamations. (Note: [[:punct:]] stands for any punctuation character.) The icons beside the Word and PDF documents are not the correct ones, but that will be fixed in the next format statement.

The previous exercise was done in Library Systems Specialist mode because it requires the use of regular expressions, something librarians are not normally trained in.

One powerful use of regular expressions in the exercise was to clean up the Titles browser. Perhaps the best way of doing this would be to have proper title metadata. The metadata extracted from HTML files is messy and inconsistent, and this was reflected in the original Titles browser. Defining proper title metadata would be simple but rather laborious. Instead, we have opted to use regular expressions in the AZCompactList classifier to clean up the title metadata. This is difficult to understand, and a bit fiddly to do, but if you can cope with its idiosyncrasies it provides a quick way to clean up the extracted metadata and avoid having to enter a large amount of metadata.

Using non-standard macro files

To put finishing touches to our collection, we add some decorative features

  1. Close the collection in the Librarian Interface (FileClose).

  1. Using your Windows file browser outside Greenstone, locate the folder

    sample_files → beatles → advbeat_large

  1. Open up another file browser, and locate the small beatles collection in your Greenstone installation:

    Greenstone → collect → smallbea

    smallbea is the folder name generated by Greenstone for this collection. You can determine what the folder name is for a collection by looking at the title bar of the Librarian Interface: the folder name is displayed in brackets after the collection name.

  1. Using the file browser, copy the images and macros folders from the advbeat_large folder into the smallbea folder. (It's OK to overwrite the existing images folder: the image in it is included in the folder being copied.) The images folder includes some useful icons, and the macros folder defines some macro names that use these images.

    To see the macro definitions, open the collection in the LIbrarian Interface (FileOpen...) and view the Collection Specific Macros section in the Format panel.

Using different icons for different media types

  1. Re-edit your VList format statement to be the following (in Format Features on the Format panel). You can copy this text from the file sample_files → beatles → format_tweaks → multi_icons.txt.

    <td valign=top>
      {If}{[numleafdocs],[link][icon][/link]}
      {If}{[dc.Format] eq 'Lyrics',[link]_iconlyrics_[/link]}
      {If}{[dc.Format] eq 'Discography',[link]_icondisc_[/link]}
      {If}{[dc.Format] eq 'Tablature',[link]_icontab_[/link]}
      {If}{[dc.Format] eq 'MARC',[link]_iconmarc_[/link]}
      {If}{[dc.Format] eq 'Images',[srclink][thumbicon][/srclink]}
      {If}{[dc.Format] eq 'Supplementary',[srclink][srcicon][/srclink]}
      {If}{[dc.Format] eq 'Audio',[srclink]{If}{[FileFormat] eq 'MIDI',_iconmidi_,_iconmp3_}[/srclink]}
    </td>
    <td>
    {If}{[numleafdocs],([numleafdocs])}
    </td>
    <td valign=top>
    [highlight]
    {Or}{[dc.Title],[Title],Untitled}
    [/highlight]
    </td>

  1. Preview your collection as before. Now different icons are used for discography, lyrics, tablature, and MARC metadata. Even MP3 and MIDI audio file types are distinguished. If you let the mouse hover over one of these images a "tool tip" appears explaining what file type the icon represents in the current interface language (note: extra.dm only defines English and French).

Changing the collection's background image

  1. Go to the Collection Specific Macros section in the Format panel.

  1. The content is fairly brief, specifying only what needs to be overridden from the default behaviour for this collection. Near the top you should see:

    _collectionspecificstyle_ {
    <style>
    body.bgimage \{ background-image: url("_httpcimages_/beat_margin.gif"); \}
    \#page \{ margin-left: 120px; \}
    </style>
    }

    Replace the text beat_margin.gif with tile.jpg.

    This line relates to the background image used. The new image tile.jpg was in the images folder that was copied across previously.

  1. Preview the collection's home page. The page background is now the new graphic.

    Other features can be altered by editing the macros—for example, the headers and footers used on each page, and the highlighting style used for search terms (specify a different colour, use bold etc.).

Building a full-size version of the collection

  1. To finish, let's now build a larger version of the collection. To do this:

Adding an image collage browser

  1. Switch to the Design panel and select the Browsing Classifiers section. Pull down the Select classifier to add: menu and select Collage. Click <Add Classifier...>. There is no need to customize the options, so click <OK> at the bottom of the resulting popup.

  1. Now change to the Create panel and build and preview the collection.

4.3. Scanned image collection

Here we build a small replica of Niupepa, the Maori Newspaper collection, using five newspapers taken from two newspaper series. It allows full text searching and browsing by title and date. When a newspaper is viewed, a preview image and its corresponding plain text are presented side by side, with a "go to page" navigation feature at the top of the page.

The collection involves a mixture of plugins, classifiers, and format statements. The bulk of the work is done by PagedImgPlug, a plugin designed precisely for the kind of data we have in this example. For each document, an "item" file is prepared that specifies a list of image files that constitute the document, tagged with their page number and (optionally) accompanied by a text file containing the machine-readable version of the image, which is used for full text searching. Three newspapers in our collection (all from the series "Te Whetu o Te Tau") have text representations, and two (from "Te Waka o Te Iwi") have images only. Item files can also specify metadata. In our example the newspaper series is recorded as ex.Title and its date of publication as ex.Date. Issue ex.Volume and ex.Number metadata is also recorded, where appropriate. This metadata is extracted as part of the building process.

  1. Start a new collection called Paged Images and fill out the fields with appropriate information: it is a collection sourced from an excerpt of Niupepa documents.

  1. In the Gather panel, open the sample_files → niupepa → sample_items folder and drag the two subfolders into your collection on the right-hand side. A popup window asks whether you want to add PagedImgPlug to the collection: click <Add Plugin>, because this plugin will be needed to process the item files.

  1. Some of the files you have just dragged in are the newspaper images; others are text files that contain the text extracted from these images. We want these to be processed by PagedImgPlug, not ImagePlug or TEXTPlug. Switch to the Document Plugins section of the Design panel and delete ImagePlug and TEXTPlug. While you are at it, you could tidy things up by deleting ZIPPlug and all plugins from HTMLPlug to NULPlug as well, since they will not be used. GAPlug and PagedImgPlug remain.

  1. Open up the configuration window for PagedImgPlug by double-clicking on the plugin. Switch on its screenview configuration option by checking the box. The source images we use were scanned at high resolution and are large files for a browser to download. The screenview option generates smaller screen-resolution images of each page when the collection is built. Click <OK>.

  1. In the Search Indexes section, check the section checkbox to build the indexes on section level as well as document level.

  1. Now go to the Create panel, build the collection and preview the result. Search for "waka" and view one of the titles listed (all three appear as Te Whetu o Te Tau). Browse by Titles and view one of the Te Waka o Te Iwi newspapers. Note that only the Te Whetu o Te Tau newspapers have text; Te Waka o Te Iwi papers don't.

This collection was built with Greenstone's default settings. You can locate items of interest, but the information is less clearly and attractively presented than in the full Niupepa collection.

Grouping documents by series title and displaying dates within each group

Under Titles documents from the same series are repeated without any distinguishing features such as date, volume or number. It would be better to group them by series title and display other information within each group. This can be accomplished using an AZCompactList classifier rather than AZList, and tuning the classifier's format statement.

  1. In the Design panel, under the Browsing Classifiers section, delete the AZList classifiers for ex.Source and ex.Title.

  1. Now add an AZCompactList classifier, setting its metadata option to ex.Title, and add a DateList classifier, setting its metadata option to ex.Date.

  1. In the Format Features section of the Format panel, select the ex.Title classifier in the Choose Feature list, and VList in the Affected Component list. Click <Add Format> to add this format statment to your collection. Delete the contents of the HTML Format String box, and add the following text. (This format statement can be copied and pasted from the file sample_files → niupepa → formats → titles_tweak.txt.)

    <td valign="top">[link][icon][/link]</td>
    <td valign="top">
    {If}{[numleafdocs],[ex.Title] ([numleafdocs]),
    {If}{[ex.Volume],Volume [ex.Volume] }
    {If}{[ex.Number],Number [ex.Number] }
    {If}{[ex.Date], [ex.Date]}}
    </td>

  1. Build the collection, and preview the new Titles list.

    As a consequence of using the AZCompactList classifier, bookshelf icons appear when titles are browsed. This revised format statement has the effect of specifying in brackets how many items are contained within a bookshelf. It works by exploiting the fact that only bookshelf icons define [numleafdocs] metadata. For document nodes, Title is not displayed. Instead, Volume, Number and Date information are displayed if present.

Displaying scanned images and suppressing dummy text

When you reach a newspaper, only its associated text is displayed. When either of the Te Waka o Te Iwi newspapers is accessed, the document view presents the message "This document has no text.". No scanned image information (screen-view resolution or otherwise) is shown, even though it has been computed and stored with the document. This can be fixed by a format statement that modifies the default behaviour for DocumentText.

  1. In the Format Features section of the Format panel, select the DocumentText format statement. The default format string displays the document's plain text, which, if there is none, is set to "This document has no text.". Change this to the following text. (This format statement can be copied and pasted from the file sample_files → niupepa → formats → doc_tweak.txt)

    <table><tr>
    <td valign=top>[srclink][screenicon][/srclink]</td>
    <td valign=top>[Text]</td>
    </tr></table>

    Including [screenicon] has the effect of embedding the screen-sized image generated by switching the screenview option on in PagedImgPlug. It is hyperlinked to the original image by the construct [srclink]...[/srclink].

    This modification will display screenview image, but does nothing about the dummy text "This document has no text.", which will still be displayed. To get rid of this, edit the DocumentText format statement again and replace

    <td valign=top>[Text]</td>

    with

    {If}{[Text] ne "This document has no text. ",<td valign=top>[Text]</td>}

  1. Preview the collection and view one of the Te Waka o Te Iwi documents. The line "This document has no text." should now be gone. (Note that it important to get the text exactly right for this to work, including the space after the ".".)

Searching at page level

  1. The newspaper documents are split into sections, one per page. For large documents, it is useful to be able to search on sections rather than documents. This allows users to more easily locate the relevant information in the document.

  1. Go to the Search Indexes section of the Design panel. Remove the ex.Source index. Check the section checkbox to build the indexes on section level as well as document level. Make section level the default by selecting its Default radio button.

  1. Set the display text used for the level drop-down menu by going to the Search section on the Format panel. Set the document level text to "newspaper", and the section level text to "page".

  1. Build and preview the collection. Compare searching at "newspaper" level compared to "page" level. A useful search term for this collection is "aroha".

  1. You will notice that when searching for individual pages, the newspaper image is displayed in the search results. As these images are very large, this is not very useful. Go to Format Features section of the Format panel in the Librarian Interface and select the VList format statement from the list of assigned format statements. Remove the second line from the HTML Format String:

    <td valign="top">[ex.srclink]{Or}{[ex.thumbicon],[ex.srcicon]}[ex./srclink]</td>

    While we are here, lets remove the filename from the display. Remove the following from the last line:

    {If}{[ex.Source],<br><i>([ex.Source])</i>}

    Preview the collection—the search results should be back to normal.

  1. Now you will notice that page level search results only show the Title of the page (the page number), and not the Title of the newspaper. We'll modify the format statement to show the newspaper title as well as the page number. Also, lets add in Volume and Number information too.

    In the Format Features section, select Search in Choose Feature, and VList in Affected Component. Click <Add Format> to add this format to the collection. The previous changes modified VList, so they will apply to all VLists that don't have specific format statements. These next changes are made to SearchVList so will only apply to search results.

    The extracted Title for the current section is specified as [ex.Title] while the Title for the parent section is [parent:ex.Title]. Since the same SearchVList format statement is used when searching both whole newspapers and newspaper pages, we need to make sure it works in both cases.

    Set the format statement to the following text (it can be copied and pasted from the file sample_files → niupepa → formats → search_tweak.txt):

    <td valign="top">[link][icon][/link]</td>
    <td valign="top">
    {If}{[parent:ex.Title],[parent:ex.Title]
    {If}{[parent:ex.Volume],Volume [parent:ex.Volume] }
    {If}{[parent:ex.Number],Number [parent:ex.Number]}: Page [ex.Title],
    [ex.Title] {If}{[ex.Volume], Volume [ex.Volume] }
    {If}{[ex.Number], Number [ex.Number] }}
    <br/><i>({Or}{[parent:ex.Date],[ex.Date]})</i></td>
    </td>

    Preview the search results. Items display newspaper title, Volume, Number and Date if available, and pages also display the page number.

In the collection you have just built, newspapers are grouped by series title, and dates are supplied alongside each one to distinguish it from others in the same series. Users can browse chronologically by date, and when a newspaper page is viewed a preview image is shown on the left that displays the original high-resolution version when clicked, accompanied on the right by the plain-text version of that newspaper (if available).

4.4. Advanced scanned image collection

In this exercise we build upon the collection created in the Scanned image collection exercise. We add a new newspaper by creating an item file for it, add a new newspaper using the extended XML item file format, and modify the formatting.

Adding another newspaper to the collection

Another newspaper has been scanned and OCRed, but has no item file. We will add this newspaper into the collection, and create an item file for it.

  1. In the Librarian Interface, open up the Paged Image collection that was created in exercise Scanned image collection if it is not already open (FileOpen...).

  1. In the Gather panel, add the folder sample_files → niupepa → new_papers → 12 to your collection.

    Inside the 12 folder you can see that there are 4 images and 4 text files.

  1. Create an item file for the collection. Have a look at an existing item file to see the format. Start up a text editor (e.g. WordPad) to open a new document. Add some metadata. The Title for this newspaper is "Te Haeata 1859-1862". The Volume is 3, Number is 6, and the Date is "18610902". (Greenstone's date format is yyyymmdd.) Metadata must be added in the form:

    <Metadata name>Metadata value

    For this document, the metadata looks like:

    <Title>Te Haeata 1859-1862
    <Date>18610902
    <Volume>3
    <Number>6

  1. For each page, add a line in the file in the following format:

    pagenum:imagefile:textfile

    For example, the first page entry would look like

    1:images/12_3_6_1.gif:text/12_3_6_1.txt

    Note that if there is no text file, you can leave that space blank. You need to add a line for each page in the document. Make sure you increment the page number for each line.

  1. Save the file using Filename 12_3_6.item, and save as a plain text document. (If you are using Windows, make sure the file isn't saved as 12_3_6.item.txt.) Back in the Gather panel of the Librarian Interface, locate the new file in the Workspace tree, and drag it into the collection, adding it to the 12 folder.

  1. Build the collection and preview. Check that your new document has been added.

XML based item file

There are two styles of item files. The first, which was used in the previous section, uses a simple text based format, and consists of a list of metadata for the document, and a list of pages. This format allows specification of document level metadata, and a single list of pages.

The second style is an extended format, and uses XML. It allows a hierarchy of pages, and metadata specification at the page level as well as at the document level. In this section, we add in two newspapers which use XML-based item files.

  1. In the Gather panel, add the folder sample_files → niupepa → new_papers → xml to your collection.

  1. Open up the file xml → 23 → 23__2.item and have a look at the XML. This is Number 2 of the newspaper titled Matariki 1881. The contents of this document have been grouped into two sections: Supplementary Material, which contains an Abstract, and Newspaper Pages, which contains the page images (and OCR text).

  1. Build and preview the collection. The xml style items have been included, but the document display for these items is not very nice.

Using process_exp to control document processing

  1. Paged documents can be presented with a hierarchical table of contents, or with next and previous page arrows, and a "go to page" box (like we have done so far). The display type is specified by the documenttype (hierarchy|paged) option to PagedImgPlug. The next and previous arrows suit the linear sequence documents, while the table of contents suits the hierarchically organised document.

    Ordinarily, a Greenstone collection would have one plugin per document type, and all documents of that type get the same processing. In this case, we want to treat the XML-based item files differently from the text-based item files. We can achieve this by adding two PagedImgPlug plugins to the collection, and configuring them differently.

  1. Change the mode in the Librarian Interface to Library Systems Specialist (or Expert) mode (using FilePreferences...Mode), because you will need to change the order of plugins, and use regular expressions in the plugin options.

    For version 2.71, you'll need to close GLI now then restart it to get the list of plugins to update properly.

  1. Go to the Document Plugins section of the Design panel, and add a new PagedImgPlug plugin. Enable the screenview option, set the documenttype option to hierarchy and set the process_exp option to xml.*.item$.

  1. Move this PagedImgPlug plugin above the original one in the Assigned Plugins list.

  1. The XML based newspapers have been grouped into a folder called xml. This enables us to process these files differently, by utilizing the process_exp option which all plugins support. The first PagedImgPlug in the list looks for item files underneath the xml folder. These documents will be processed as 'hierarchical' documents. Item files that don't match the process expression (i.e. aren't underneath the xml folder) will be passed onto the second PagedImgPlug, and these are treated as 'paged' documents.

    Rebuild and preview the collection. Compare the document display for a paged document e.g. Te Waka o Te Iwi, Vol. 1, No. 1 with a hierarchical document, e.g. Matariki 1881, No. 1.

Switching between images and text

We can modify the document display to switch between the text version and the screenview and full size versions. We do this using a combination of format statements and macro files.

  1. First of all we will add a macro file to the collection. Close the collection in the Librarian Interface. In a file browser outside of Greenstone, locate the Paged Image collection in your Greenstone installation: Greenstone → collect → pagedima.

    Also in a file browser, locate the file sample_files → niupepa → macros → extra.dm. Copy this file and paste it into the macros folder inside the pagedima collection.

  1. Back in the Librarian Interface, open up the collection again, and go to the Format Features section of the Format panel.

  1. Select AllowExtendedOptions in the Choose Feature list, and click <Add Format>. Tick the Enabled checkbox. This gives us more control over the layout of the page—in this case, we want to replace the standard DETACH and NO HIGHLIGHTING buttons with buttons that switch between images and text.

  1. Select the DocumentHeading format item and set it to the following text (which can copied from sample_files → niupepa → formats → adv_doc_heading.txt).

    <div class="heading_title">{Or}{[parent(Top):ex.Title],[ex.Title]}</div>
    <div class="buttons" id="toc_buttons">
    {If}{[srcicon],_document:viewfullsize_}
    {If}{[screenicon],_document:viewpreview_}
    {If}{[Text] ne 'This document has no text. ',_document:viewtext_}
    </div>
    <div class="toc">[DocTOC]</div>

    {Or}{[parent(Top):ex.Title],[ex.Title]} outputs the newspaper Title metadata. This is only stored at the top level of the document, so if we are at a subsection, we need to get it from the top ([parent(Top):ex.Title]). Note that we can't just use [parent:ex.Title] as this retrieves the Title from the immediate parent node, which may not be the top node of the document.

    _document:viewpreview_, _document:viewfullsize_, _document:viewtext_ are macros defined in extra.dm which output buttons for preview, fullsize and text versions, respectively. We choose which buttons to display based on what metadata and text the document has. Note you can view the macros by going to the Collection Specific Macros section of the Format panel.

    [DocTOC] is the document table of contents or "go to page" navigation element. Since we are using extended options, we need to explicitly specify this for it to appear in the page.

    The different pieces are surrounded by <div> elements, so that the appropriate styling information can be used.

  1. Select the DocumentText format statement and set it to the following text (which can be copied from sample_files → niupepa → formats → adv_doc_text.txt):

    {If}{_cgiargp_ eq 'fullsize',[srcicon],
    {If}{_cgiargp_ eq 'preview',[screenicon],
    {If}{[Text] ne \'This document has no text. \',[Text],[screenicon]}}}

    This format statement changes the display based on the "p" argument (_cgiargp_). This is not used normally for document display, so we can use it here to switch between full size image ([srcicon]), preview size image ([screenicon]) and text ([Text]) versions of each page.

  1. Preview the collection. View some of the documents—once you have reached a newspaper page, you should get fullsize, preview and text options.