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-rw-r--r--doc/white-papers/calendar/calendar.sgml209
-rw-r--r--doc/white-papers/mail/camel.sgml356
-rw-r--r--doc/white-papers/mail/ibex.sgml158
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diff --git a/doc/white-papers/calendar/calendar.sgml b/doc/white-papers/calendar/calendar.sgml
deleted file mode 100644
index 2cb3132e2b..0000000000
--- a/doc/white-papers/calendar/calendar.sgml
+++ /dev/null
@@ -1,209 +0,0 @@
-<!doctype article PUBLIC "-//Davenport//DTD DocBook V3.0//EN" [
-<!entity Evolution "<application>Evolution</application>">
-<!entity CUA "<acronym>CUA</acronym>">
-<!entity PCS "<acronym>PCS</acronym>">
-<!entity Bonobo "<application>Bonobo</application>">
-<!entity CORBA "<acronym>CORBA</acronym>">
-<!entity GTK "<acronym>GTK+</acronym>">
-]>
-
-<article class="whitepaper" id="calendar">
-
- <artheader>
- <title>&Evolution; Calendaring Framework</title>
-
- <authorgroup>
- <author>
- <firstname>Federico</firstname>
- <surname>Mena Quintero</surname>
- <affiliation>
- <address>
- <email>federico@helixcode.com</email>
- </address>
- </affiliation>
- </author>
- </authorgroup>
-
- <copyright>
- <year>2000</year>
- <holder>Helix Code, Inc.</holder>
- </copyright>
-
- <abstract>
- <para>
- The &Evolution; groupware suite provides a framework for
- developing calendaring applications, as well as a graphical
- calendar client and a personal calendar server. This white
- paper describes the architecture of the &Evolution;
- calendaring framework.
- </para>
- </abstract>
- </artheader>
-
- <!-- Introduction -->
-
- <sect1 id="introduction">
- <title>Introduction</title>
-
- <para>
- Calendaring is an important part of a groupware suite. A
- calendaring framework will allow a user to keep a personal
- calendar and have several applications use it. Such
- applications could be a graphical calendar client that the user
- employs to schedule appointments and keep track of his time, a
- <productname>Palm Pilot</productname> synchronization client, or
- a simple alarm or reminder utility. A comprehensive calendaring
- framework will also allow multiple users to schedule
- appointments between each other; for example, a project director
- may want to schedule a weekly meeting with the rest of the
- project members, or a person who owns a large house may want to
- schedule a big party with his friends. The attendees will then
- want to reply with messages such as, &ldquo;I will
- attend&rdquo;, or &ldquo;I will attend only if the proposed time
- is changed&rdquo;.
- </para>
-
- <para>
- The &Evolution; groupware suite provides a framework for
- developing calendaring applications, as well as a graphical
- calendar client or calendar user agent (&CUA;) and a personal
- calendar server (&PCS;).
- </para>
-
- <para>
- The following sections explain the basic calendaring framework,
- the functions of the calendar user agent and the personal
- calendar server, and the relationship between the two.
- </para>
- </sect1>
-
- <!-- Personal Calendar Server -->
-
- <sect1 id="pcs">
- <title>Personal Calendar Server</title>
-
- <para>
- The personal calendar server (&PCS;) provides centralized
- management and storage of a user's personal calendar. Multiple
- clients can connect to the &PCS; simultaneously to query and
- modify the user's calendar in a synchronized fashion. The main
- features of the &PCS; are as follows:
- </para>
-
- <formalpara>
- <title>Storage</title>
-
- <para>
- The &PCS; is responsible for loading and saving calendars.
- Centralizing the loading and saving functionality allows
- multiple clients to use the same calendar at the same time
- without having to worry about each other.
- </para>
- </formalpara>
-
- <formalpara>
- <title>Basic Queries</title>
-
- <para>
- The &PCS; provides functions to do basic queries on a
- calendar, for example, a client can ask the server for a list
- of all the appointments in the calendar, or for all the data
- for a specific appointment.
- </para>
- </formalpara>
-
- <formalpara>
- <title>Recurrence and Alarm Queries</title>
-
- <para>
- Clients can ask the &PCS; for a list of the appointments that
- occur within a specified time range; for example a graphical
- client that has a per-week view could ask the &PCS; for all
- the appointments that occur in a particular week. This
- includes multiple occurrences of a single recurring event; for
- example, the object for &ldquo;a 1-hour meeting that occurs on
- every Tuesday and Thursday&rdquo; is represented inside the
- &PCS; as a single event with a recurrence rule. Similarly,
- clients can ask the &PCS; for a list of events that have
- alarms that trigger within a specified time range.
- </para>
- </formalpara>
-
- <formalpara>
- <title>Notification of Changes</title>
-
- <para>
- This is the most important function of the &PCS;, as it allows
- multiple calendar clients to maintain a unified view of the
- calendar between the server and themselves. When a client
- asks the &PCS; to modify or remove an event, the &PCS;
- notifies all the clients that are connected to it about the
- change. The policy is that &ldquo;the server is always
- right&rdquo;; clients can act as dumb views onto the
- calendar's data and they will be notified by the &PCS; when
- something changes.
- </para>
- </formalpara>
- </sect1>
-
- <!-- Calenar User Agent -->
-
- <sect1 id="cua">
- <title>Calendar User Agent</title>
-
- <para>
- A calendar user agent (&CUA;) is a program that lets a user
- manipulate a calendar. &Evolution; provides an attractive,
- graphical calendar client that communicates with the &Evolution;
- personal calendar server.
- </para>
-
- <para>
- The &Evolution; calendar client just provides a view onto the
- data that is stored and managed by the personal calendar server.
- The calendar client does not perform direct manipulations on a
- calendar's data; instead it offloads those requests to the
- calendar server, which takes care of making the appropriate
- modifications in the calendar and then notifies all the clients
- about the changes.
- </para>
- </sect1>
-
- <!-- Calendar Client Library -->
-
- <sect1 id="client-lib">
- <title>Calendar Client Library</title>
-
- <para>
- Communication between the personal calendar server and calendar
- clients is defined by a set of &Bonobo; &CORBA; interfaces.
- Clients can be written by implementing the client-side
- <classname>Listener</classname> interface, which defines the
- notification callbacks that the PCS uses to inform clients about
- changes to the calendar.
- </para>
-
- <para>
- As a convenience for &GTK; programmers, &Evolution; also
- includes a library which provides a
- <classname>CalClient</classname> class which can be used for
- communication with the personal calendar server. Objects of
- this class automatically contact the PCS when they are created.
- <classname>CalClient</classname> provides functions to request
- changes in the calendar, and it also emits signals when it gets
- notification about changes from the PCS. This makes it easy and
- convenient to write calendar clients for &Evolution; using
- &GTK;.
- </para>
-
- <para>
- The implementation of the <classname>CalClient</classname> class
- simply wraps the &Evolution; &CORBA; interfaces for calendaring
- with a familiar-looking &GTK; object. Calls to the
- <classname>Listener</classname> interface get translated to
- signal emissions from the <classname>CalClient</classname>, thus
- shielding programmers from the details of the &CORBA;
- interfaces.
- </para>
- </sect1>
-</article>
diff --git a/doc/white-papers/mail/camel.sgml b/doc/white-papers/mail/camel.sgml
deleted file mode 100644
index 5f5ea27a98..0000000000
--- a/doc/white-papers/mail/camel.sgml
+++ /dev/null
@@ -1,356 +0,0 @@
-<!doctype article PUBLIC "-//Davenport//DTD DocBook V3.0//EN" [
-<!entity Evolution "<application>Evolution</application>">
-<!entity Camel "Camel">
-]>
-
-<article class="whitepaper" id="camel">
-
- <artheader>
- <title>The &Camel; Messaging Library</title>
-
- <authorgroup>
- <author>
- <firstname>Jeffrey</firstname>
- <surname>Stedfast</surname>
- <affiliation>
- <address>
- <email>fejj@helixcode.com</email>
- </address>
- </affiliation>
- </author>
-
- <author>
- <firstname>Michael</firstname>
- <surname>Zucchi</surname>
- <affiliation>
- <address>
- <email>notzed@helixcode.com</email>
- </address>
- </affiliation>
- </author>
-
- <author>
- <firstname>Dan</firstname>
- <surname>Winship</surname>
- <affiliation>
- <address>
- <email>danw@helixcode.com</email>
- </address>
- </affiliation>
- </author>
-
- <author>
- <firstname>Bertrand</firstname>
- <surname>Guiheneuf</surname>
- <affiliation>
- <address>
- <email>bertrand@helixcode.com</email>
- </address>
- </affiliation>
- </author>
- </authorgroup>
-
- <copyright>
- <year>2000, 2001</year>
- <holder>Ximian, Inc.</holder>
- </copyright>
-
- </artheader>
-
- <sect1 id="introduction">
- <title>Introduction</title>
-
- <para>
- &Camel; is a generic messaging library. It is being used as the
- back end for the mail component of &Evolution;. The name
- "&Camel;" is an acronym; it refers to the fact that the
- library is capable of going several days without food or water.
- It means : Camel's Acronym Makes Everyone Laugh.
- </para>
-
- <para>
- &Camel;'s initial design is heavily based on Sun's
- <trademark>JavaMail</trademark> API. It uses the Gtk+ object
- system, and many of its classes are direct analags of JavaMail
- classes. Its design has also been influenced by the features of
- IMAP, and the limitations of the standard UNIX mbox mail store,
- which set some of the boundaries on its requirements and
- extensibility.
- </para>
-
- <para>
- &Camel; sees all message repositories as stores containing
- folders. These folders in turn contain the messages the client
- actually accesses. The use of such a unified interface allows
- the client applications to be very extensible. &Camel; includes
- an external provider mechanism which allows applications to
- dynamically load and use protocols which were not available when
- the application was initially written.
- </para>
-
- <para>
- The abstract store/folder mechanism is a powerful and versatile
- way of accessing messages. No particular asumptions are made on
- the client side, thus allowing new ways of managing the
- messages. For example, the messages stored in the folders don't
- necessarily have to share some common physical location. The
- folder can be a purely virtual folder, containing only
- references to the actual messages. This is used by the "vFolder"
- provider, which allows you select messages meeting particular
- criteria and deal with them as a group.
- </para>
-
- <para>
- In addition to these possibilities, &Camel; has full MIME
- support. &Camel; MIME messages are lightweight objects
- representing the MIME skeleton of the actual message. The data
- contained in the subparts are never stored in memory except when
- they are actually needed. The application, when accessing the
- various MIME objects contained in the message (text parts,
- attachments, embedded binary objects ...) asks &Camel; for a
- stream that it can read data from. This scheme is particularly
- useful with the IMAP provider. IMAP has strong MIME support
- built-in, which allows &Camel; to download only the parts of
- messages that it actually needs: attachments need not be
- downloaded until they are viewed, and unnecessary
- "multipart/alternative" parts will never be read off the server.
- </para>
- </sect1>
-
- <sect1 id="overview">
- <title>Overview</title>
-
- <graphic format="gif" fileref="camel"></graphic>
-
- <para>
- To begin using &Camel;, an application first creates subclassed
- <classname>CamelSession</classname> object. This object is used
- to store application defaults, and to coordinate communication
- between providers and the application.
- </para>
-
- <para>
- A <classname>CamelProvider</classname> is a dynamically-loadable
- module that provides functionality associated with a specific
- service. Examples of providers are POP, IMAP and SMTP. Providers
- include subclasses of the various other &Camel; classes for
- accessing and manipulating messages.
- </para>
-
- <para>
- <classname>CamelService</classname> is an abstract class for
- describing a connection to a local or remote service. It
- currently has two subclasses: <classname>CamelStore</classname>,
- for services that store messages (such as IMAP servers and mbox
- files), and <classname>CamelTransport</classname>, for services
- that deliver messages (such as SMTP or a local MTA). A provider
- could also be both a store and a transport, as in the case of
- NNTP.
- </para>
-
- <para>
- A <classname>CamelStore</classname> contains some number of
- <classname>CamelFolder</classname> objects, which in turn
- contain messages. A <classname>CamelFolder</classname> provides
- a <classname>CamelFolderSummary</classname> object, which
- includes details about the subject, date, and sender of each
- message in the folder. The folder also includes the messages
- themselves, as subclasses of <classname>CamelMedium</classname>.
- </para>
-
- <para>
- Email messages are represented by the
- <classname>CamelMimeMessage</classname> class, a subclass of
- <classname>CamelMedium</classname>. This class includes
- operations for accessing RFC822 and MIME headers, accessing
- subparts of MIME messages, encoding and decoding Base64 and
- Quoted-Printable, etc.
- </para>
-
- <para>
- <classname>CamelTransport</classname> includes methods for
- delivering messages. While the abstract
- <function>CamelTransport::send</function> method takes a
- <classname>CamelMedium</classname>, its subclasses may only be
- able to deliver messages of specific
- <classname>CamelMedium</classname> subclasses. For instance,
- <classname>CamelSendmailTransport</classname> requires a
- <classname>CamelMimeMessage</classname>, because it needs a
- message that includes a "To:" header. A hypothetical
- <classname>CamelNNTPTransport</classname> would need a
- <classname>CamelNewsMessage</classname>, which would have a
- "Newsgroups:" header.
- </para>
-
- <para>
- The content of messages are referred to using
- <classname>CamelStream</classname> and its subclasses. In the
- case of an mbox-based store, the
- <classname>CamelStream</classname> would abstract the operation
- of reading the correct section of the mbox file. For IMAP,
- reading off the <classname>CamelStream</classname> might result
- in commands being issued to the remote IMAP server and data
- being read off a socket.
- </para>
-
- <para>
- The final major class in &Camel; is
- <classname>CamelException</classname>, which is used to
- propagate information about errors. Many methods take a
- <classname>CamelException</classname> as an argument, which the
- caller can then check if an error occurs. It includes both a
- numeric error code which can be interpreted by the program, and
- a text error message that can be displayed to the user.
- </para>
- </sect1>
-
- <sect1 id="classes">
- <title>Major Subcomponents</title>
-
- <sect2 id="store">
- <title>The Message Store</title>
-
- <para>
- A <classname>CamelStore</classname> inherits the ability to
- connect and authenticate to a service from its parent class,
- <classname>CamelService</classname>. It then adds the ability
- to retrieve folders. A store must contain at least one folder,
- which can be retrieved with
- <function>CamelStore::get_default_folder</function>. There are
- also methods to retrieve the "top-level" folder (for
- hieararchical stores), and to retrieve an arbitrary folder by
- name.
- </para>
-
- <para>
- All <classname>CamelFolder</classname>s must implement certain
- core operations, most notably generating a summary and
- retrieving and deleting messages. A
- <classname>CamelFolder</classname> must assign a permanently
- unique identifier to each message it contains. Messages can
- then be retrieved via
- <function>CamelFolder::get_message</function>.
- </para>
-
- <para>
- Folders must also implement the
- <function>get_parent_folder</function> and
- <function>list_subfolders</function> methods. For stores that
- don't allow multiple folders, they would return NULL and an
- empty list, respectively. Stores that do allow multiple
- folders will also define methods for creating and deleting
- folders, and for moving messages between them (assuming the
- folders are writable).
- </para>
-
- <para>
- Folders that support searching can define the
- <function>search_by_expression</function> method. For mbox
- folders, this is implemented by indexing the messages with the
- ibex library and using that to search them later. For IMAP
- folders, this uses the IMAP SEARCH command. Other folder types
- might not be able to implement this functionality, in which
- case users would not be able to do full-content searches on
- them.
- </para>
- </sect2>
-
- <sect2 id="messages">
- <title>Messages</title>
-
- <para>
- As mentioned before, messages are represented by subclasses of
- <classname>CamelMedium</classname>.
- <classname>CamelMedium</classname> itself is a subclass of
- <classname>CamelDataWrapper</classname>, a generic class for
- connecting a typed data source to a data sink.
- <classname>CamelMedium</classname> adds the concept of message
- headers versus message body.
- (<classname>CamelDataWrapper</classname> has one other
- important subclass, <classname>CamelMultipart</classname>,
- which is used to provide separate access to the multiple
- independent parts of a multipart MIME type.)
- <classname>CamelMedium</classname>'s subclasses provide more
- specialized handling of various headers:
- <classname>CamelMimePart</classname> adds special handling for
- the &ldquot;Content-*&rdquot; headers in MIME messages, and
- its subclass <classname>CamelMimeMessage</classname> adds
- handling for the RFC822 headers.
- </para>
-
- <graphic format="gif" fileref="mimemessage"></graphic>
-
- <para>
- Consider a message with two parts: a text part (in both plain
- text and HTML), and an attached image:
-
- <programlisting>
-
- From: Dan Winship &lt;danw@helixcode.com&gt;
- To: Matt Loper &lt;matt@helixcode.com&gt;
- Subject: the Camel white paper
- MIME-Version: 1.0
- Content-Type: multipart/mixed;
- boundary="jhTYrnsRrdhDFGa"
-
- This is a multi-part message in MIME format.
- --jhTYrnsRrdhDFGa
- Content-Type: multipart/alternative;
- boundary="sFSenbAFDSgDfg"
-
- --sFSenbAFDSgDfg
- Content-Type: text/plain
-
- Hey, Matt
-
- Check out this graphic...
-
- -- Dan
-
- --sFSenbAFDSgDfg
- Content-Type: text/html
-
- Hey, Matt&lt;br&gt;
- &lt;br&gt;
- Check out this graphic...&lt;br&gt;
- &lt;br&gt;
- -- Dan&lt;br&gt;
- &lt;br&gt;
- --sFSenbAFDSgDfg--
-
- --jhTYrnsRrdhDFGa
- Content-Type: image/png
- Content-Transfer-Encoding: base64
-
- F4JLw0ORrkRa8AwAMQJLAaI3UDIGsco9RAaB92...
- --jhTYrnsRrdhDFGa--
- </programlisting>
-
- <para>
- In &Camel;, this would be represented as follows:
- </para>
-
- <graphic fileref="samplemsg"></graphic>
- </sect2>
-
- <sect2 id="streams">
- <title>Streams</title>
-
- <para>
- Streams are a generic data transport layer. Two basic stream
- classes are <classname>CamelStreamFs</classname>, for
- reading and writing files, and
- <classname>CamelStreamMem</classname>, for reading from and
- writing to objects that are already in memory.
- </para>
-
- <para>
- Streams can also be filtered. So a CamelMimePart
- containing base64-encoded data can filter its output through
- CamelMimeFilterBasic. Other parts of the application that want
- to read its data will never need to even realize that the
- original data was encoded.
- </para>
- </sect2>
-
-</article>
diff --git a/doc/white-papers/mail/ibex.sgml b/doc/white-papers/mail/ibex.sgml
deleted file mode 100644
index dcb8f5ca4b..0000000000
--- a/doc/white-papers/mail/ibex.sgml
+++ /dev/null
@@ -1,158 +0,0 @@
-<!doctype article PUBLIC "-//Davenport//DTD DocBook V3.0//EN" [
-<!entity Evolution "<application>Evolution</application>">
-<!entity Camel "Camel">
-<!entity Ibex "Ibex">
-]>
-
-<article class="whitepaper" id="ibex">
-
- <artheader>
- <title>Ibex: an Indexing System</title>
-
- <authorgroup>
- <author>
- <firstname>Dan</firstname>
- <surname>Winship</surname>
- <affiliation>
- <address>
- <email>danw@helixcode.com</email>
- </address>
- </affiliation>
- </author>
- </authorgroup>
-
- <copyright>
- <year>2000</year>
- <holder>Helix Code, Inc.</holder>
- </copyright>
-
- </artheader>
-
- <sect1 id="introduction">
- <title>Introduction</title>
-
- <para>
- &Ibex; is a library for text indexing. It is being used by
- &Camel; to allow it to quickly search locally-stored messages,
- either because the user is looking for a specific piece of text,
- or because the application is contructing a vFolder or filtering
- incoming mail.
- </para>
- </sect1>
-
- <sect1 id="goals">
- <title>Design Goals and Requirements for Ibex</title>
-
- <para>
- The design of &Ibex; is based on a number of requirements.
-
- <itemizedlist>
- <listitem>
- <para>
- First, obviously, it must be fast. In particular, searching
- the index must be appreciably faster than searching through
- the messages themselves, and constructing and maintaining
- the index must not take a noticeable amount of time.
- </para>
- </listitem>
-
- <listitem>
- <para>
- The indexes must not take up too much space. Many users have
- limited filesystem quotas on the systems where they read
- their mail, and even users who read mail on private machines
- have to worry about running out of space on their disks. The
- indexes should be able to do their job without taking up so
- much space that the user decides he would be better off
- without them.
- </para>
-
- <para>
- Another aspect of this problem is that the system as a whole
- must be clever about what it does and does not index:
- accidentally indexing a "text" mail message containing
- uuencoded, BinHexed, or PGP-encrypted data will drastically
- affect the size of the index file. Either the caller or the
- indexer itself has to avoid trying to index these sorts of
- things.
- </para>
- </listitem>
-
- <listitem>
- <para>
- The indexing system must allow data to be added to the index
- incrementally, so that new messages can be added to the
- index (and deleted messages can be removed from it) without
- having to re-scan all existing messages.
- </para>
- </listitem>
-
- <listitem>
- <para>
- It must allow the calling application to explain the
- structure of the data however it wants to, rather than
- requiring that the unit of indexing be individual files.
- This way, &Camel; can index a single mbox-format file and
- treat it as multiple messages.
- </para>
- </listitem>
-
- <listitem>
- <para>
- It must support non-ASCII text, given that many people send
- and receive non-English email, and even people who only
- speak English may receive email from people whose names
- cannot be written in the US-ASCII character set.
- </para>
- </listitem>
- </itemizedlist>
-
- <para>
- While there are a number of existing indexing systems, none of
- them met all (or even most) of our requirements.
- </para>
- </sect1>
-
- <sect1 id="implementation">
- <title>The Implementation</title>
-
- <para>
- &Ibex; is still young, and many of the details of the current
- implementation are not yet finalized.
- </para>
-
- <para>
- With the current index file format, 13 megabytes of Info files
- can be indexed into a 371 kilobyte index file&mdash;a bit under
- 3% of the original size. This is reasonable, but making it
- smaller would be nice. (The file format includes some simple
- compression, but <application>gzip</application> can compress an
- index file to about half its size, so we can clearly do better.)
- </para>
-
- <para>
- The implementation has been profiled and optimized for speed to
- some degree. But, it has so far only been run on a 500MHz
- Pentium III system with very fast disks, so we have no solid
- benchmarks.
- </para>
-
- <para>
- Further optimization (of both the file format and the in-memory
- data structures) awaits seeing how the library is most easily
- used by &Evolution;: if the indexes are likely to be kept in
- memory for long periods of time, the in-memory data structures
- need to be kept small, but the reading and writing operations
- can be slow. On the other hand, if the indexes will only be
- opened when they are needed, reading and writing must be fast,
- and memory usage is less critical.
- </para>
-
- <para>
- Of course, to be useful for other applications that have
- indexing needs, the library should provide several options, so
- that each application can use the library in the way that is
- most suited for its needs.
- </para>
- </sect1>
-</article>
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-<!doctype article PUBLIC "-//Davenport//DTD DocBook V3.0//EN" [
-<!entity Evolution "<application>Evolution</application>">
-<!entity ETable "<classname>ETable</classname>">
-<!entity ETableModel "<classname>ETableModel</classname>">
-<!entity ETableSimple "<classname>ETableSimple</classname>">
-<!entity ETableHeader "<classname>ETableHeader</classname>">
-<!entity ETableSpecification "<classname>ETableSpecification</classname>">
-<!entity ETableCol "<classname>ETableCol</classname>">
-]>
-
-<article class="whitepaper" id="e-table">
-
- <artheader>
- <title>The ETable Widget</title>
-
- <authorgroup>
- <author>
- <firstname>Chris</firstname>
- <surname>Lahey</surname>
- <affiliation>
- <address>
- <email>clahey@helixcode.com</email>
- </address>
- </affiliation>
- </author>
- <author>
- <firstname>Miguel</firstname>
- <surname>de Icaza</surname>
- <affiliation>
- <address>
- <email>miguel@helixcode.com</email>
- </address>
- </affiliation>
- </author>
- </authorgroup>
-
- <copyright>
- <year>2000</year>
- <holder>Helix Code, Inc.</holder>
- </copyright>
-
- </artheader>
-
- <sect1 id="introduction">
- <title>Introduction</title>
-
- <para>
- &ETable; is a table widget on steroids. It is intended to provide
- all the table functionality needed throughout &Evolution;, and
- hopefully be general purpose enough to be used in other projects.
- </para>
-
- <para>
- &ETable; provides a lot of interactive control over the data in the
- table. Without any work from the programmer, &ETable; provides
- rearrangeable columns and editable data. When finished, &ETable; will
- also provide, again with no programmer intervention, easy interactive
- sorting and grouping.
- </para>
-
- <para>
- &ETable; gives you a great deal of functionality, flexibility, and
- power. Most of this power is internal to the widget, but some of
- the flexibility requires a bit of work by the programmer.
- However, once you learn it, &ETable; is not very hard at all to
- use.
- </para>
-
- <para>
- &ETable;'s power comes from the fact that it is fully
- model/view/controller based. Various models are involved into
- the process of rendering the information, and various views are
- provided. The programmer has a wide range of options: from the
- most finely hand-tuned table to a generic all-encompasing widget
- that takes over most of tasks. It is up to the programmer: he
- can use the simple to use &ETable; widget that takes care of
- everything in a generic way, or he can use the various
- components to roll his own tabular display.
- </para>
-
- <para>
- &ETable; ships with a standard set of information renderers:
- strings, bitmaps, toggle-buttons, check-boxes, and multi-line
- strings. But the programmer can write and implement his own
- renderer for his information. This means that by default
- &ETable; provides the basic display facilities that programmers
- required, but they offer the programmer a complete freedom to
- incorporate new cell renderers.
- </para>
-
- </sect1>
-
- <sect1 id="model">
- <title>ETableModel</title>
-
- <para>
- The data back end for the &ETable; is an &ETableModel;. The
- &ETableModel is an abstract interface that acts as the
- information repository for the various &ETable components.
- </para>
-
- <para>
- To use &ETable; you have to create a subclass of the abstract
- &ETableModel; class. However, to save you the work of defining
- a new <classname>GtkClass</classname> every time you use
- &ETable, there is a predefined subclass of &ETableModel; called
- &ETableSimple; which simply takes a list of function callbacks
- to perform the various operations.
- </para>
-
- </sect1>
-
- <sect1 id="columns">
- <title>Columns</title>
-
- <para>
- There are two different meanings to the word "column". The first
- is the model column (defined by the &ETableCol: object). A model
- column describes how it maps to the column in the &ETableModel;
- as well as containing information about its properties (name,
- resizability, resize dimensions, and a renderer for this
- specific columns).
- </para>
-
- <para>
- &ETable; distinguishes between a model column index, and a view
- column index. The former reflects the column in which the data
- is stored in the &ETableModel; The later represents the actual
- location at which the column is being displayed in the screen.
- </para>
-
- <para>
- Each view column index corresponds to a specific model column,
- though a model column may have any number of view columns
- associated with it (including zero). For example the same
- column might be rendered twice, or the data from one column
- could be used to display different bits of information
- </para>
-
- <para>
- The view column does not necessarily depend on only one model
- column. In some cases, the view column renderer can be given a
- reference to another model column to get extra information about
- its display. For example, a mail program could display deleted
- messages with a line through them by creating a model column
- with no corresponding view column that told whether or not the
- message is deleted, and then having the text column
- strikethrough the display if the invisible column had a value
- corresponding to "deleted".
- </para>
-
- <para>
- The view column also specifies a few other pieces of
- information. One piece of information is the renderer. &ETable;
- provides a number of renderers to choose from, or you can write
- your own. Currently, there are renderers for text, image sets,
- and checkboxes.
- </para>
-
- <para>
- The view column also includes information about the header.
- There are two types of headers: text, and pixbuf. The first
- allows you to specify a string which is rendered in the header.
- The second allows you to specify an image to copy into the
- header.
- </para>
- </sect1>
-
- <sect1 id="header">
- <title>Header</title>
-
- <para>
- The &ETableHeader; represents the header information for the
- table. The &ETableHeader; is used in two different ways. The
- first is the in the <structfield>full_header</structfield>
- element of an &ETable;. This is the list of possible columns in
- the view. You add each of your columns to this &ETableHeader;
- and then pass it into the &ETable;.
- </para>
-
- <para>
- The second use is completely internal. &ETable; uses another
- &ETableHeader; to store the actual displayed columns. Many of
- the &ETableHeader; functions are for this purpose. The only
- functions that users of the library should need to use are
- <function>e_table_header_new</function> and
- <function>e_table_header_add_col</function>.
- </para>
- </sect1>
-
- <sect1 id="layout">
- <title>Layout Specification</title>
-
- <para>
- &ETable; uses an &ETableSpecification; to layout the columns of
- the widget. The &ETableSpecification; is specified as XML data
- passed into the &ETable; as a string.
- </para>
-
- <para>
- The most powerful part of the &ETableSpecification; is that when
- finished, &ETable; will allow you to get a copy of an
- &ETableSpecification; that describes the current view of the
- tree. This allows the developer to save the current view so that
- next time the user opens this table, they find it in exactly the
- state that they left it.
- </para>
-
- <para>
- The XML specification allows for a number of things. First, it
- allows you to pick a set of default columns to be shown. Thus,
- even if you had hundreds of pieces of data, you could choose to
- only display a few that fit on the screen by default.
- </para>
-
- <para>
- The second major thing that the &ETableSpecification; allows you
- to specify is the column grouping and sorting. &ETable; has a
- powerful mechanism for allowing the user to choose columns to
- group by, thus allowing multiple columns of sorting, as well as
- visual grouping of similar elements and interactive selection of
- what data to display.
- </para>
-
- <para>
- The grouping in &ETableSpecification; is specified as a
- hierarchy of columns to group by. Each level of the hierarchy
- lets you sort by a particular column, either ascending or
- descending. All levels except the last cause the canvas to group
- by the given column.
- </para>
-
- <para>
- An example &ETableSpecification; follows.
- </para>
-
- <programlisting>
- &lt;ETableSpecification&gt;
- &lt;columns-shown frozen_columns="2"&gt;
- &lt;column&gt; 0 &lt;/column&gt;
- &lt;column&gt; 1 &lt;/column&gt;
- &lt;column&gt; 2 &lt;/column&gt;
- &lt;column&gt; 3 &lt;/column&gt;
- &lt;column&gt; 4 &lt;/column&gt;
- &lt;/columns-shown&gt;
- &lt;grouping&gt;
- &lt;group column="3" ascending="1"&gt;
- &lt;group column="4" ascending="0"&gt;
- &lt;leaf column="2" ascending="1"/&gt;
- &lt;/group&gt;
- &lt;/group&gt;
- &lt;/grouping&gt;
- &lt;/ETableSpecification&gt;
- </programlisting>
-
- <para>
- This example has 5 columns which are initially in order. It has
- 2 levels of grouping. The first is grouped by the 4th column
- (all indexes are 0 based) and sorts those groups in ascending
- order. Inside those groups, the data is grouped by the fifth
- column and sorted in descending order of the fifth column.
- Finally, the data in those groups is sorted by the third column
- in ascending order. Due to the "frozen_columns" attribute on the
- columns-shown element, the user will not be
- able to rearrange the first two columns. They will always be the
- first two.
- </para>
- </sect1>
-
- <sect1 id="conclusion">
- <title>Conclusion</title>
-
- <para>
- All in all, &ETable; is a very powerful widget. Once you learn
- to use it, you have access to a vast amount of power requiring a
- comparatively small amount of work.
- </para>
- </sect1>
-</article>