-Digilib is a client-server-software that transforms high-resolution images to
-formats that are acceptable for internet network connetions. the client software
-is based on HTML and JavaScript so that everybody can use it with a normal
-browser. To see in full detail which browsers and platforms are supported check
-chapter 4.1. This software provides lots of features like zooming areas of
-pictures, setting marks to the pictures, jumping to different pictures while
-always being able to generate URLs so that people can distibute these and
-everybody can see the same picture with ist marks.
-It has been put lots of attention providing files that are as intependant of
-each other as possible so that embedding it in other kind of pages will be as
-simple as it can be. Stuff like providing modules or a different menubar are
-just some of the stuff you can easily do without having to change the files
-provided.
-
-Some of the the client-files contain JSP code, to do some serverside -configuration. Because of the fact that the serverside software has to use a -java module for the web-server there is no need to install more stuff than what -is needed by the server-scripts. -
--This software is still work in progress and it is quite probable that lots of -stuff will change in the future, so check this file with every new version of -software you downloaded. -
- --There are quite some files the client software needs to run all the interactive -user-interface. To give you a detailed view of the files there is a subsection -provided in this document explaining what each file does and how it interacts -with the others. -
- --This is the file you will request from the server and which will call the -other files. The main purposes of this file are: -
- -
-The crutial point in this file is the way the query on the URL (get-method) is
-made. After digilib.jsp? there is a comma-separated list of parameters. It is
-to say that principally all of them are optional, but the first of them
-describing the url of the image-directory should really be set.
-Here is the list of the diffenent attributes in
-digilib.jsp?[att0]+[att1]+[att2]+[att3]+[att4]+ ... +[att8]:
-
| [att0] | -Directory where the image can be found (check the documentation for - serverside). | -
| [att1] | -The page number (equals the index of the image in the sorted directory). | -
| [att2] | -The dimension relative to the visible height/width in the frame (1.0 means - that the image fits exactly into the frame, while 2.0 means twice that - size). | -
| [att3] | -Attribute to pass extra options to the servlet (for example 'fit' means - that normally not resized gif-images will be scaled). | -
| [att4] | -Here are the marks passed separated by ';', while the coordinates are
- separated with '/'. The cooridnates are in a relative format (0.0 -
- 1.0). - Example ... +0.33/0.5;0.25/0.25+ ... means that there are two marks one a - third from the left and half down the image and the second a quarter from - left and top of the image. |
-
| [att5] | -Relative (0.0 - 1.0) value giving the most left pixels visible in the - zoomed image. | -
| [att6] | -Dito with the topmost pixels. | -
| [att7] | -Gives the visible width of the image (also 0.0 - 1.0). | -
| [att8] | -Same with the height. | -
-It is important to understand that all cooridnates that are used by digilib are -passed as relative values where the width/height of an image is 1. This way it -is possible that the images are displayed the same way on all kind of different -screen-sizes and so making opening the possibility of sharing a url between -people that will see the same on their screens. -
- --The parameterlist in dlImage.jsp is quite the same as in digilib.jsp but is -represented in another format. As in chapter 2.1 we are discussing here the -parameterlist. The parameters are no longer separated with the plus-sign put -with an ampersand '&', which is the official way of passing different parameters -through the URL. The parameters have all a name followed by a value, like -.../dlImage.jsp?fn=histbot/botany&pn=3& ... . I will give you now a list of -parameters dlImage.jsp understands by default by indication the name and its -equivalent in digilib.jsp and if needed some special comments. It is possible -and the somehow the aim of dlImage to pass more parameters to this file for -additional functionality. Check out section 2.5.1 where is a good example of how -to modify dlImage.jsp for adding new functionality. -
- -| fn | -= att0 | -
| pn | -= att1 | -
| ws | -= att2 | -
| mo | -= att3 | -
| mk | -= att4 | -
| wx | -= att5 | -
| wy | -= att6 | -
| ww | -= att7 | -
| wh | -= att8 | -
| dx | -Width of the frame containing the to be displayed image in pixels. | -
| dy | -Dito with the height. | -
-DlImage.jsp can react in two completely different ways on a request. When -requesting the file it checks whether the width and height of the frame are -passed as parameters in the URL. This is not the case on every first view of a -session. If the dimensions are not set, then dlImage sends a dummy page to the -client, calculates the width and height of the frame (which is only possible -with a correct html-file) and resends the request to dlImage.jsp this time with -the indicated dimensions. -
-
-The other way dlImage.jsp reacts is its noraml reaction. This means that it
-parses the parameterslist and fills in some default values if they are missing
-(check out the source-code to see them). Then the file is going to include some
-script files that do offer the functionality. Part of these JavaScript-files are
-browser dependant, some are not. The most important files are named with
-navigation_XX.js where XX is a shortcut for the browser. The other files (the
-ones not browser-dependant) are some sample modules that are discussed in
-section 2.5.
-Then it is time to build the actual HTML for the frame. There is one layer
-holding the picture (the way the parameters should be passed is described in the
-serverside dokumentaion). The layers named 'dotX' are the layers holding the
-marks, the ones named 'eckX' are the corners when zooming a rectangle.
-Last but not least the parameters are passed to the navigation-script or the the
-module using them (<body bgcolor="#666666" onload='init_XXXXX("<%= fn ...
-")'>).
-
-Let's look at the crucail points about navigation_XX.js-files. Most important is -that the parameters passed to the init-function are stored in an array globally -accesible (the code in init shows this). The name of the array is 'att'. There -is also a function called 'loadPicture' that puts together a new URL -(dlImage.jsp?...) for loading a new picture or another part of the same. Then we -have lots of functions dealing with different parts of the digilib -functionality: -
- -| backPage | -Loading the previous picture in the directory. | -
| nextPage | -Loading the next picture in the directory. | -
| page | -Loading a picture in the same directory by index. | -
| digicat | -Loading a new window containing thumbnails of images in the directoy (some - closely related project called 'digicat'). | -
| ref | -Generating HTML- or LaTeX-style links for the special part of picture - including marks to build into other documents. The URL is made with - digilib.jsp?...+... . | -
| mark | -Sets a mark to the current picture. | -
| zoomArea | -Zooms an area of the current picture. | -
| zoomPoint | -Zooms in around the selected point on the picture. | -
| moveTo | -Moves the center of a image area to this point while maintaining the same - zooming grade (sometimes this is known as 'pan'). | -
| scale | -Scales an image relative to the dimensions of the image-frame (normally - the image fits right into it). | -
-The other functions are helpers that are should not be directly accessed from -outside the frame. -
- -
-This file generates the navigation-frame with buttons and menus. From this point
-the calls are made to navigation_XX.js. Please consider this frame as a sample
-the we at the University of Berne are currently using. If you are good in
-graphics design feel free to create your own buttons.
-The files related to dlMenu.html are in a subdirectory called 'buttons' where
-the gif-images are stored and also the menu.js-scripts handling the menus.
-
-The modules form a very important part of the whole project. This software aims -to be easy to upgrade with new functionality. Because of the fact that -JavaScript is not a full featured programming language modularisation in so -that intuitive and simple. Still we have found a way of providing enough freedom -to build new modules and adding features to digilib. The example of two sample -modules (that are nevertheless useful), we would like to show how we think one -should implement another module to add new functionality. -
- -
-In the subdirectory 'modules' is a very simple module called pdfMaker.js. This
-very basic module only has one function (makePDF) that does nothing more than
-giving a prompt where one can enter a number of image-indices and call a
-serverside script that creates a PDF-file with the different picures. To make
-this module work it has first to be loaded by dlImage.jsp. Because it is
-browser-independant there is only one version of it. Aften being loaded it has
-access to the whole 'att'-array which is quite stupidely shown in makePDF by
-giving the index of the currently displayed image as default value.
-One other thing that has to be done is to enter a new button to navigation.html
-so that the new function can be called... quite logic i know.
-
-'pagesTotal.js' is a lot more complicated than the first module and shows some
-more things to think of when making a module. It aims to show the current
-pagenumber (index) and the total number of images in the directory in a
-separated frame. The first thing that has to be done is implementing a new frame
-in diglib.jsp to provide space to write down the information.
-As we know the current index is stored in the parameter 'pn' in dlImage.jsp and
-easily accessible in the scripts with 'att[1]', where as the total number of
-pages is only known by the server. To get this information one has to make a
-call to a server function. This is done in digilib.jsp (query += "&pt=" +
-DB.getNumPages(request);) the resulting number that should not cheange during a
-session is stored in a new parameter 'pt' that is sent in the parameter-list to
-dlImage.jsp.
-In dlImage we have to load the module (configure 2.5.1). Next thing is to make
-the 'pt' accessible through all the scripts (adding a new cell to the
-'att'-array) by creating an init'function in the module. While the original
-function is called 'init' the one in pagesTotal is called 'init_pagesTotal' and
-acception the additional parameter 'pt'. In 'init_pagesTotal' there is a call to
-the original 'init' with all parameters but 'pt' and so filling the first nine
-cells of the att-array. Then it's time to add a new cell with 'pt' as its value.
-Further on there is a call to function 'pagesTotal' that writes the data into
-the new frame.
-As you can see there are some functions overriding the original ones.
-'nextPage', 'page' and 'loadPicture' are rewritten in the module to make use of
-the new functionality. In the first two functions we can make now some
-additional checks that we cannot run past the last image. 'loadPicture' has to
-be improved so that 'pt' will be in the URL sent when loading a new picture or
-area.
-
-There are some future plans concerning the cilent software. While there is no -actual list of things that have to be done, but some vague ideas of -improvements: -
- --Here is a very incomplete list of browsers and platforms known to work with -digilib. We provide three different navigation-scripts to work with different -implementations of JavaScript in different browsers. These are Netscape 4, -Internet Explorer (working on versions 4 - 6), Opera 6 and the Mozilla5-engine. Due to -some bugs in the browsers and special behaviours of different platforms we -cannot garantee that digilib works on every platform supported by for example -the Mozilla5-engine. Anyone having success on a different platform than the ones -indicated below, please send a note. -
- -