xserver xkeyboard-config libX11 pixman mesa git update 2011

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--- a/xorg-server/xkeyboard-config/docs/README.enhancing
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@@ -1,525 +1,520 @@
-                  How to further enhance XKB configuration
-
-                         Kamil Toman, Ivan U. Pascal
-
-                              25 November 2002
-
-                                  Abstract
-
-     This guide is aimed to relieve one's labour to create a new (inter-
-     nationalized) keyboard layout. Unlike other documents this guide
-     accents the keymap developer's point of view.
-
-1.  Overview
-
-The developer of a new layout should read the xkb protocol specification (The
-X Keyboard Extension: Protocol Specification 
-<URL:http://xfree86.org/current/XKBproto.pdf>) at least to clarify for
-himself some xkb-specific terms used in this document and elsewhere in xkb
-configuration. Also it shows wise to understand how the X server and a client
-digest their keyboard inputs (with and without xkb).
-
-A useful source is also Ivan  Pascal's text about xkb configuration
-<URL:http://www.tsu.ru/~pascal/en/xkb> often referenced throughout this docu-
-ment.
-
-Note that this document covers only enhancements which are to be made to
-XFree86 version 4.3.x and above.
-
-2.  The Basics
-
-At the startup (or at later at user's command) X server starts its xkb key-
-board module extension and reads data from a compiled configuration file.
-
-This compiled configuration file is prepared by the program xkbcomp which
-behaves altogether as an ordinary compiler (see man xkbcomp).  Its input are
-human readable xkb configuration files which are verified and then composed
-into a useful xkb configuration. Users don't need to mess with xkbcomp them-
-selves, for them it is invisible. Usually, it is started upon X server
-startup.
-
-As you probably already know, the xkb configuration consists of five main
-modules:
-
-      Keycodes
-            Tables that defines translation from keyboard scan codes into
-            reasonable symbolic names, maximum, minimum legal keycodes, sym-
-            bolic aliases and description of physically present LED-indica-
-            tors. The primary sence of this component is to allow definitions
-            of maps of symbols (see below) to be independent of physical key-
-            board scancodes. There are two main naming conventions for sym-
-            bolic names (always four bytes long):
-
-               o  names which express some traditional meaning like <SPCE>
-                 (stands for space bar) or
-
-               o  names which express some relative positioning on a key-
-                 board, for example <AE01> (an exclamation mark on US key-
-                 boards), on the right there are keys <AE02>, <AE03> etc.
-
-      Types
-            Types describe how the produced key is changed by active modi-
-            fiers (like Shift, Control, Alt, ...). There are several prede-
-            fined types which cover most of used combinations.
-
-      Compat
-            Compatibility component defines internal behaviour of modifiers.
-            Using compat component you can assign various actions (elabo-
-            rately described in xkb specification) to key events. This is
-            also the place where LED-indicators behaviour is defined.
-
-      Symbols
-            For i18n purposes, this is the most important table. It defines
-            what values (=symbols) are assigned to what keycodes (represented
-            by their symbolic name, see above). There may be defined more
-            than one value for each key and then it depends on a key type and
-            on modifiers state (respective compat component) which value will
-            be the resulting one.
-
-      Geometry
-            Geometry files aren't used by xkb itself but they may be used by
-            some external programs to depict a keyboard image.
-
-All these components have the files located in xkb configuration tree in sub-
-directories with the same names (usually in /usr/lib/X11/xkb).
-
-3.  Enhancing XKB Configuration
-
-Most of xkb enhancements concerns a need to define new output symbols for the
-some input key events. In other words, a need to define a new symbol map (for
-a new language, standard or just to feel more comfortable when typing text).
-
-What do you need to do? Generally, you have to define following things:
-
-   o  the map of symbols itself
-
-   o  the rules to allow users to select the new mapping
-
-   o  the description of the new layout
-
-First of all, it is good to go through existing layouts and to examine them
-if there is something you could easily adjust to fit your needs.  Even if
-there is nothing similar you may get some ideas about basic concepts and used
-tricks.
-
-3.1  Levels And Groups
-
-Since XFree86 4.3.0 you can use multi-layout concept of xkb configuration.
-Though it is still in boundaries of xkb protocol and general ideas, the
-keymap designer must obey new rules when creating new maps. In exchange we
-get a more powerful and cleaner configuration system.
-
-Remember that it is the application which must decide which symbol matches
-which keycode according to effective modifier state. The X server itself
-sends only an input event message to. Of course, usually the general inter-
-pretation is processed by Xlib, Xaw, Motif, Qt, Gtk and similar libraries.
-The X server only supplies its mapping table (usually upon an application
-startup).
-
-You can think of the X server's symbol table as of a irregular table where
-each keycode has its row and where each combination of modifiers determines
-exactly one column. The resulting cell then gives the proper symbolic value.
-Not all keycodes need to bind different values for different combination of
-modifiers.  <ENTER> key, for instance, usually doesn't depend on any modi-
-fiers so it its row has only one column defined.
-
-Note that in XKB there is no prior assumption that certain modifiers are
-bound to certain columns. By editing proper files (see keytypes (section 4.2,
-page 1)) this mapping can be changed as well.
-
-Unlike the original X protocol the XKB approach is far more flexible. It is
-comfortable to add one additional XKB term - group. You can think of a group
-as of a vector of columns per each keycode (naturally the dimension of this
-vector may differ for different keycodes). What is it good for? The group is
-not very useful unless you intend to use more than one logically different
-set of symbols (like more than one alphabet) defined in a single mapping ta-
-ble. But then, the group has a natural meaning - each symbol set has its own
-group and changing it means selecting a different one.  XKB approach allows
-up to four different groups. The columns inside each group are called (shift)
-levels. The X server knows the current group and reports it together with
-modifier set and with a keycode in key events.
-
-To sum it up:
-
-   o  for each keycode XKB keyboard map contains up to four one-dimensional
-     tables - groups (logically different symbol sets)
-
-   o  for each group of a keycode XKB keyboard map contains some columns -
-     shift levels (values reached by combinations of Shift, Ctrl, Alt, ...
-     modifiers)
-
-   o  different keycodes can have different number of groups
-
-   o  different groups of one keycode can have different number of shift lev-
-     els
-
-   o  the current group number is tracked by X server
-
-It is clear that if you sanely define levels, groups and sanely bind modi-
-fiers and associated actions you can have simultaneously loaded up to four
-different symbol sets where each of them would reside in its own group.
-
-The multi-layout concept provides a facility to manipulate xkb groups and
-symbol definitions in a way that allows almost arbitrary composition of pre-
-defined symbol tables. To keep it fully functional you have to:
-
-   o  define all symbols only in the first group
-
-   o  (re)define any modifiers with extra care to avoid strange (anisometric)
-     behaviour
-
-4.  Defining New Layouts
-
-See Some Words  About XKB internals <URL:http://www.tsu.ru/~pas-
-cal/en/xkb/internals.html> for explanation of used xkb terms and problems
-addressed by XKB extension.
-
-See Common  notes about XKB configuration files language
-<URL:http://www.tsu.ru/~pascal/en/xkb/gram-common.html> for more precise
-explanation of syntax of xkb configuration files.
-
-4.1  Predefined XKB Symbol Sets
-
-If you are about to define some European symbol map extension, you might want
-to use on of four predefined latin alphabet layouts.
-
-Okay, let's assume you want extend an existing keymap and you want to over-
-ride a few keys. Let's take a simple U.K. keyboard as an example (defined in
-pc/gb):
-
-     partial default alphanumeric_keys
-     xkb_symbols "basic" {
-       include "pc/latin"
-
-       name[Group1]="Great Britain";
-
-       key <AE02>  { [         2,   quotedbl,  twosuperior,    oneeighth ] };
-       key <AE03>  { [         3,   sterling, threesuperior,    sterling ] };
-       key <AC11>  { [apostrophe,         at, dead_circumflex, dead_caron] };
-       key <TLDE>  { [     grave,    notsign,          bar,          bar ] };
-       key <BKSL>  { [numbersign, asciitilde,   dead_grave,   dead_breve ] };
-       key <RALT>  { type[Group1]="TWO_LEVEL",
-                     [ ISO_Level3_Shift, Multi_key ]   };
-
-       modifier_map Mod5   { <RALT> };
-     };
-
-It defines a new layout in basic variant as an extension of common latin
-alphabet layout. The layout (symbol set) name is set to "Great Britain".
-Then there are redefinitions of a few keycodes and a modifiers binding. As
-you can see the number of shift levels is the same for <AE02>, <AE03>,
-<AC11>, <TLDE> and <BKSL> keys but it differs from number of shift levels of
-<RALT>.
-
-Note that the <RALT> key itself is a binding key for Mod5 and that it serves
-like a shift modifier for LevelThree, together with Shift as a multi-key. It
-is a good habit to respect this rule in a new similar layout.
-
-Okay, you could now define more variants of your new layout besides basic
-simply by including (augmenting/overriding/...) the basic definition and
-altering what may be needed.
-
-4.2  Key Types
-
-The differences in the number of columns (shift levels) are caused by a dif-
-ferent types of keys (see the types definition in section basics).  Most key-
-codes have implicitly set the keytype in the included "pc/latin" file to
-"FOUR_LEVEL_ALPHABETIC". The only exception is <RALT> keycode which is
-explicitly set "TWO_LEVEL" keytype.
-
-All those names refer to pre-defined shift level schemes. Usually you can
-choose a suitable shift level scheme from default types scheme list in proper
-xkb component's subdirectory.
-
-The most used schemes are:
-
-      ONE_LEVEL
-            The key does not depend on any modifiers. The symbol from first
-            level is always chosen.
-
-      TWO_LEVEL
-            The key uses a modifier Shift and may have two possible values.
-            The second level may be chosen by Shift modifier. If Lock modi-
-            fier (usually Caps-lock) applies the symbol is further processed
-            using system-specific capitalization rules. If both Shift+Lock
-            modifier apply the symbol from the second level is taken and cap-
-            italization rules are applied (and usually have no effect).
-
-      ALPHABETIC
-            The key uses modifiers Shift and Lock. It may have two possible
-            values. The second level may be chosen by Shift modifier. When
-            Lock modifier applies, the symbol from the first level is taken
-            and further processed using system-specific capitalization rules.
-            If both Shift+Lock modifier apply the symbol from the first level
-            is taken and no capitalization rules applied. This is often
-            called shift-cancels-caps behaviour.
-
-      THREE_LEVEL
-            Is the same as TWO_LEVEL but it considers an extra modifier -
-            LevelThree which can be used to gain the symbol value from the
-            third level. If both Shift+LevelThree modifiers apply the value
-            from the third level is also taken. As in TWO_LEVEL, the Lock
-            modifier doesn't influence the resulting level. Only Shift and
-            LevelThree are taken into that consideration. If the Lock modi-
-            fier is active capitalization rules are applied on the resulting
-            symbol.
-
-      FOUR_LEVEL
-            Is the same as THREE_LEVEL but unlike LEVEL_THREE if both
-            Shift+LevelThree modifiers apply the symbol is taken from the
-            fourth level.
-
-      FOUR_LEVEL_ALPHABETIC
-            Is similar to FOUR_LEVEL but also defines shift-cancels-caps
-            behaviour as in ALPHABETIC. If Lock+LevelThree apply the symbol
-            from the third level is taken and the capitalization rules are
-            applied.  If Lock+Shift+LevelThree apply the symbol from the
-            third level is taken and no capitalization rules are applied.
-
-      KEYPAD
-            As the name suggest this scheme is primarily used for numeric
-            keypads.  The scheme considers two modifiers - Shift and NumLock.
-            If none of modifiers applies the symbol from the first level is
-            taken. If either Shift or NumLock modifiers apply the symbol from
-            the second level is taken.  If both Shift+NumLock modifiers apply
-            the symbol from the first level is taken. Again, shift-cancels-
-            caps variant.
-
-      FOUR_LEVEL_KEYPAD
-            Is similar to KEYPAD scheme but considers also LevelThree modi-
-            fier.  If LevelThree modifier applies the symbol from the third
-            level is taken.  If Shift+LevelThree or NumLock+LevelThree apply
-            the symbol from the fourth level is taken. If all Shift+Num-
-            Lock+LevelThree modifiers apply the symbol from the third level
-            is taken. This also, shift-cancels-caps variant.
-
-      FOUR_LEVEL_MIXED_KEYPAD
-	    A four-level keypad scheme where the first two levels are similar
-            to the KEYPAD scheme (NumLock+Shift)
-            LevelThree acts as an override providing access to two Shift-ed
-            levels. When LevelThree is active we totally ignore NumLock state
-            Intended for the digit area of the keypad
-
-      FOUR_LEVEL_X
-            A four-level scheme where the base level accepts no modifier,
-            LevelThree provides two more Shift-ed levels like in the previous
-            scheme, and Ctrl+Alt controls the fourth level
-            Intended for the operator part of a keypad, though since NumLock
-            plays no part, it is not keypad-specific
-
-Besides that, there are several schemes for special purposes:
-
-      PC_CONTROL_LEVEL2
-            It is similar to TWO_LEVEL scheme but it considers the Control
-            modifier rather than Shift. That means, the symbol from the sec-
-            ond level is chosen by Control rather than by Shift.
-
-      PC_ALT_LEVEL2
-            It is similar to TWO_LEVEL scheme but it considers the Alt modi-
-            fier rather than Shift. That means, the symbol from the second
-            level is chosen by Alt rather than by Shift.
-
-      CTRL+ALT
-            The key uses modifiers Alt and Control. It may have two possible
-            values. If only one modifier (Alt or Control) applies the symbol
-            from the first level is chosen. Only if both Alt+Control modi-
-            fiers apply the symbol from the second level is chosen.
-
-      SHIFT+ALT
-            The key uses modifiers Shift and Alt. It may have two possible
-            values.  If only one modifier (Alt or Shift) applies the symbol
-            from the first level is chosen. Only if both Alt+Shift modifiers
-            apply the symbol from the second level is chosen.
-
-If needed, special caps schemes may be used. They redefine the standard
-behaviour of all *ALPHABETIC types. The layouts (maps of symbols) with keys
-defined in respective types then automatically change their behaviour accord-
-ingly. Possible redefinitions are:
-
-   o internal
-
-   o internal_nocancel
-
-   o shift
-
-   o shift_nocancel
-
-None of these schemes should be used directly. They are defined merely for
-'caps:' xkb options (used to globally change the layouts behaviour).
-
-Don't alter any of existing key types. If you need a different behaviour cre-
-ate a new one.
-
-4.2.1  More On Definitions Of Types
-
-When the XKB software deals with a separate type description it gets a com-
-plete list of modifiers that should be taken into account from the 'modi-
-fiers=<list of modifiers>' list and expects that a set of 'map[<combination
-of modifiers>]=<list of modifiers>' instructions that contain the mapping for
-each combination of modifiers mentioned in that list. Modifiers that are not
-explicitly listed are NOT taken into account when the resulting shift level
-is computed.  If some combination is omitted the program (subroutine) should
-choose the first level for this combination (a quite reasonable behavior).
-
-Lets consider an example with two modifiers ModOne and ModTwo:
-
-     type "..." {
-         modifiers = ModOne+ModTwo;
-         map[None] = Level1;
-         map[ModOne] = Level2;
-     };
-
-In this case the map statements for ModTwo only and ModOne+ModTwo are omit-
-ted.  It means that if the ModTwo is active the subroutine can't found
-explicit mapping for such combination an will use the default level i.e.
-Level1.
-
-But in the case the type described as:
-
-     type "..." {
-         modifiers = ModOne;
-         map[None] = Level1;
-         map[ModOne] = Level2;
-     };
-
-the ModTwo will not be taken into account and the resulting level depends on
-the ModOne state only. That means, ModTwo alone produces the Level1 but the
-combination ModOne+ModTwo produces the Level2 as well as ModOne alone.
-
-What does it mean if the second modifier is the Lock? It means that in the
-first case (the Lock itself is included in the list of modifiers but combina-
-tions with this modifier aren't mentioned in the map statements) the internal
-capitalization rules will be applied to the symbol from the first level. But
-in the second case the capitalization will be applied to the symbol chosen
-accordingly to he first modifier - and this can be the symbol from the first
-as well as from the second level.
-
-Usually, all modifiers introduced in 'modifiers=<list of modifiers>' list are
-used for shift level calculation and then discarded. Sometimes this is not
-desirable. If you want to use a modifier for shift level calculation but you
-don't want to discard it, you may list in 'preserve[<combination of modi-
-fiers>]=<list of modifiers>'. That means, for a given combination all listed
-modifiers will be preserved. If the Lock modifier is preserved then the
-resulting symbol is passed to internal capitalization routine regardless
-whether it has been used for a shift level calculation or not.
-
-Any key type description can use both real and virtual modifiers. Since real
-modifiers always have standard names it is not necessary to explicitly
-declare them. Virtual modifiers can have arbitrary names and can be declared
-(prior using them) directly in key type definition:
-
-     virtual_modifiers <comma-separated list of modifiers>  ;
-
-as seen in for example basic, pc or mousekeys key type definitions.
-
-4.3  Rules
-
-Once you are finished with your symbol map you need to add it to rules file.
-The rules file describes how all the five basic keycodes, types, compat, sym-
-bols and geometry components should be composed to give a sensible resulting
-xkb configuration.
-
-The main advantage of rules over formerly used keymaps is a possibility to
-simply parameterize (once) fixed patterns of configurations and thus to ele-
-gantly allow substitutions of various local configurations into predefined
-templates.
-
-A pattern in a rules file (often located in /usr/lib/X11/xkb/rules) can be
-parameterized with four other arguments: Model, Layout, Variant and Options.
-For most cases parameters model and layout should be sufficient for choosing
-a functional keyboard mapping.
-
-The rules file itself is composed of pattern lines and lines with rules. The
-pattern line starts with an exclamation mark ('!') and describes how will the
-xkb interpret the following lines (rules). A sample rules file looks like
-this:
-
-     ! model                   =   keycodes
-       macintosh_old                     =   macintosh
-       ...
-       *                       =   xfree86
-
-     ! model                        =   symbols
-       hp                      =   +inet(%m)
-       microsoftpro                 =   +inet(%m)
-       geniuscomfy                  =   +inet(%m)
-
-     ! model       layout[1]          = symbols
-       macintosh    us           = macintosh/us%(v[1])
-       *             *               =       pc/pc(%m)+pc/%l[1]%(v[1])
-
-     ! model     layout[2]            = symbols
-       macintosh     us              =  +macintosh/us[2]%(v[2]):2
-       *       *               =   +pc/%l[2]%(v[2]):2
-
-     ! option            =    types
-       caps:internal               =    +caps(internal)
-       caps:internal_nocancel =    +caps(internal_nocancel)
-
-Each rule defines what certain combination of values on the left side of
-equal sign ('=') results in. For example a (keyboard) model macintosh_old
-instructs xkb to take definitions of keycodes from file keycodes/macintosh
-while the rest of models (represented by a wild card '*') instructs it to
-take them from file keycodes/xfree86. The wild card represents all possible
-values on the left side which were not found in any of the previous rules.
-The more specialized (more complete) rules have higher precedence than gen-
-eral ones, i.e. the more general rules supply reasonable default values.
-
-As you can see some lines contain substitution parameters - the parameters
-preceded by the percent sign ('%'). The first alphabetical character after
-the percent sign expands to the value which has been found on the left side.
-For example +%l%(v) expands into +cz(bksl) if the respective values on the
-left side were cz layout in its bksl variant. More, if the layout resp. vari-
-ant  parameter is followed by a pair of brackets ('[', ']') it means that xkb
-should place the layout resp. variant into specified xkb group. If the brack-
-ets are omitted the first group is the default value.
-
-So the second block of rules enhances symbol definitions for some particular
-keyboard models with extra keys (for internet, multimedia, ...) . Other mod-
-els are left intact. Similarly, the last block overrides some key type defi-
-nitions, so the common global behaviour ''shift cancels caps'' or ''shift
-doesn't cancel caps'' can be selected. The rest of rules produces special
-symbols for each variant us layout of macintosh keyboard and standard pc sym-
-bols in appropriate variants as a default.
-
-4.4  Descriptive Files of Rules
-
-Now you just need to add a detailed description to <rules>.xml description
-file so the other users (and external programs which often parse this file)
-know what is your work about.
-
-4.4.1  Old Descriptive Files
-
-The formerly used descriptive files were named <rules>.lst Its structure is
-very simple and quite self descriptive but such simplicity had also some cav-
-ities, for example there was no way how to describe local variants of layouts
-and there were problems with the localization of descriptions. To preserve
-compatibility with some older programs, new XML descriptive files can be con-
-verted to old format '.lst'.
-
-For each parameter of rules file should be described its meaning. For the
-rules file described above the .lst file could look like:
-
-     ! model
-       pc104        Generic 104-key PC
-       microsoft    Microsoft Natural
-       pc98         PC-98xx Series
-       macintosh     Original Macintosh
-       ...
-
-     ! layout
-       us      U.S. English
-       cz      Czech
-       de      German
-       ...
-
-     ! option
-       caps:internal           uses internal capitalization. Shift cancels Caps
-       caps:internal_nocancel uses internal capitalization. Shift doesn't cancel Caps
-
-And that should be it. Enjoy creating your own xkb mapping.
-
-     Generated from XFree86: xc/programs/Xserver/hw/xfree86/doc/sgml/XKB-Enhancing.sgml,v 1.2 dawes Exp $
-
-
-$XFree86: xc/programs/xkbcomp/README.enhancing,v 1.5 2003/10/19 19:57:44 dawes Exp $
+                  How to further enhance XKB configuration

+

+                         Kamil Toman, Ivan U. Pascal

+

+                              25 November 2002

+

+                                  Abstract

+

+     This guide is aimed to relieve one's labour to create a new (inter-

+     nationalized) keyboard layout. Unlike other documents this guide

+     accents the keymap developer's point of view.

+

+1.  Overview

+

+The developer of a new layout should read the xkb protocol specification (The

+X Keyboard Extension: Protocol Specification 

+<URL:http://xfree86.org/current/XKBproto.pdf>) at least to clarify for

+himself some xkb-specific terms used in this document and elsewhere in xkb

+configuration. Also it shows wise to understand how the X server and a client

+digest their keyboard inputs (with and without xkb).

+

+A useful source is also Ivan  Pascal's text about xkb configuration

+<URL:http://www.tsu.ru/~pascal/en/xkb> often referenced throughout this docu-

+ment.

+

+Note that this document covers only enhancements which are to be made to

+XFree86 version 4.3.x and above.

+

+2.  The Basics

+

+At the startup (or at later at user's command) X server starts its xkb key-

+board module extension and reads data from a compiled configuration file.

+

+This compiled configuration file is prepared by the program xkbcomp which

+behaves altogether as an ordinary compiler (see man xkbcomp).  Its input are

+human readable xkb configuration files which are verified and then composed

+into a useful xkb configuration. Users don't need to mess with xkbcomp them-

+selves, for them it is invisible. Usually, it is started upon X server

+startup.

+

+As you probably already know, the xkb configuration consists of five main

+modules:

+

+      Keycodes

+            Tables that defines translation from keyboard scan codes into

+            reasonable symbolic names, maximum, minimum legal keycodes, sym-

+            bolic aliases and description of physically present LED-indica-

+            tors. The primary sence of this component is to allow definitions

+            of maps of symbols (see below) to be independent of physical key-

+            board scancodes. There are two main naming conventions for sym-

+            bolic names (always four bytes long):

+

+               o  names which express some traditional meaning like <SPCE>

+                 (stands for space bar) or

+

+               o  names which express some relative positioning on a key-

+                 board, for example <AE01> (an exclamation mark on US key-

+                 boards), on the right there are keys <AE02>, <AE03> etc.

+

+      Types

+            Types describe how the produced key is changed by active modi-

+            fiers (like Shift, Control, Alt, ...). There are several prede-

+            fined types which cover most of used combinations.

+

+      Compat

+            Compatibility component defines internal behaviour of modifiers.

+            Using compat component you can assign various actions (elabo-

+            rately described in xkb specification) to key events. This is

+            also the place where LED-indicators behaviour is defined.

+

+      Symbols

+            For i18n purposes, this is the most important table. It defines

+            what values (=symbols) are assigned to what keycodes (represented

+            by their symbolic name, see above). There may be defined more

+            than one value for each key and then it depends on a key type and

+            on modifiers state (respective compat component) which value will

+            be the resulting one.

+

+      Geometry

+            Geometry files aren't used by xkb itself but they may be used by

+            some external programs to depict a keyboard image.

+

+All these components have the files located in xkb configuration tree in sub-

+directories with the same names (usually in /usr/lib/X11/xkb).

+

+3.  Enhancing XKB Configuration

+

+Most of xkb enhancements concerns a need to define new output symbols for the

+some input key events. In other words, a need to define a new symbol map (for

+a new language, standard or just to feel more comfortable when typing text).

+

+What do you need to do? Generally, you have to define following things:

+

+   o  the map of symbols itself

+

+   o  the rules to allow users to select the new mapping

+

+   o  the description of the new layout

+

+First of all, it is good to go through existing layouts and to examine them

+if there is something you could easily adjust to fit your needs.  Even if

+there is nothing similar you may get some ideas about basic concepts and used

+tricks.

+

+3.1  Levels And Groups

+

+Since XFree86 4.3.0 you can use multi-layout concept of xkb configuration.

+Though it is still in boundaries of xkb protocol and general ideas, the

+keymap designer must obey new rules when creating new maps. In exchange we

+get a more powerful and cleaner configuration system.

+

+Remember that it is the application which must decide which symbol matches

+which keycode according to effective modifier state. The X server itself

+sends only an input event message to. Of course, usually the general inter-

+pretation is processed by Xlib, Xaw, Motif, Qt, Gtk and similar libraries.

+The X server only supplies its mapping table (usually upon an application

+startup).

+

+You can think of the X server's symbol table as of a irregular table where

+each keycode has its row and where each combination of modifiers determines

+exactly one column. The resulting cell then gives the proper symbolic value.

+Not all keycodes need to bind different values for different combination of

+modifiers.  <ENTER> key, for instance, usually doesn't depend on any modi-

+fiers so it its row has only one column defined.

+

+Note that in XKB there is no prior assumption that certain modifiers are

+bound to certain columns. By editing proper files (see keytypes (section 4.2,

+page 1)) this mapping can be changed as well.

+

+Unlike the original X protocol the XKB approach is far more flexible. It is

+comfortable to add one additional XKB term - group. You can think of a group

+as of a vector of columns per each keycode (naturally the dimension of this

+vector may differ for different keycodes). What is it good for? The group is

+not very useful unless you intend to use more than one logically different

+set of symbols (like more than one alphabet) defined in a single mapping ta-

+ble. But then, the group has a natural meaning - each symbol set has its own

+group and changing it means selecting a different one.  XKB approach allows

+up to four different groups. The columns inside each group are called (shift)

+levels. The X server knows the current group and reports it together with

+modifier set and with a keycode in key events.

+

+To sum it up:

+

+   o  for each keycode XKB keyboard map contains up to four one-dimensional

+     tables - groups (logically different symbol sets)

+

+   o  for each group of a keycode XKB keyboard map contains some columns -

+     shift levels (values reached by combinations of Shift, Ctrl, Alt, ...

+     modifiers)

+

+   o  different keycodes can have different number of groups

+

+   o  different groups of one keycode can have different number of shift lev-

+     els

+

+   o  the current group number is tracked by X server

+

+It is clear that if you sanely define levels, groups and sanely bind modi-

+fiers and associated actions you can have simultaneously loaded up to four

+different symbol sets where each of them would reside in its own group.

+

+The multi-layout concept provides a facility to manipulate xkb groups and

+symbol definitions in a way that allows almost arbitrary composition of pre-

+defined symbol tables. To keep it fully functional you have to:

+

+   o  define all symbols only in the first group

+

+   o  (re)define any modifiers with extra care to avoid strange (anisometric)

+     behaviour

+

+4.  Defining New Layouts

+

+See Some Words  About XKB internals <URL:http://www.tsu.ru/~pas-

+cal/en/xkb/internals.html> for explanation of used xkb terms and problems

+addressed by XKB extension.

+

+See Common  notes about XKB configuration files language

+<URL:http://www.tsu.ru/~pascal/en/xkb/gram-common.html> for more precise

+explanation of syntax of xkb configuration files.

+

+4.1  Predefined XKB Symbol Sets

+

+If you are about to define some European symbol map extension, you might want

+to use on of four predefined latin alphabet layouts.

+

+Okay, let's assume you want extend an existing keymap and you want to over-

+ride a few keys. Let's take a simple U.K. keyboard as an example (defined in

+pc/gb):

+

+     partial default alphanumeric_keys

+     xkb_symbols "basic" {

+       include "pc/latin"

+

+       name[Group1]="Great Britain";

+

+       key <AE02>  { [         2,   quotedbl,  twosuperior,    oneeighth ] };

+       key <AE03>  { [         3,   sterling, threesuperior,    sterling ] };

+       key <AC11>  { [apostrophe,         at, dead_circumflex, dead_caron] };

+       key <TLDE>  { [     grave,    notsign,          bar,          bar ] };

+       key <BKSL>  { [numbersign, asciitilde,   dead_grave,   dead_breve ] };

+       key <RALT>  { type[Group1]="TWO_LEVEL",

+                     [ ISO_Level3_Shift, Multi_key ]   };

+

+       modifier_map Mod5   { <RALT> };

+     };

+

+It defines a new layout in basic variant as an extension of common latin

+alphabet layout. The layout (symbol set) name is set to "Great Britain".

+Then there are redefinitions of a few keycodes and a modifiers binding. As

+you can see the number of shift levels is the same for <AE02>, <AE03>,

+<AC11>, <TLDE> and <BKSL> keys but it differs from number of shift levels of

+<RALT>.

+

+Note that the <RALT> key itself is a binding key for Mod5 and that it serves

+like a shift modifier for LevelThree, together with Shift as a multi-key. It

+is a good habit to respect this rule in a new similar layout.

+

+Okay, you could now define more variants of your new layout besides basic

+simply by including (augmenting/overriding/...) the basic definition and

+altering what may be needed.

+

+4.2  Key Types

+

+The differences in the number of columns (shift levels) are caused by a dif-

+ferent types of keys (see the types definition in section basics).  Most key-

+codes have implicitly set the keytype in the included "pc/latin" file to

+"FOUR_LEVEL_ALPHABETIC". The only exception is <RALT> keycode which is

+explicitly set "TWO_LEVEL" keytype.

+

+All those names refer to pre-defined shift level schemes. Usually you can

+choose a suitable shift level scheme from default types scheme list in proper

+xkb component's subdirectory.

+

+The most used schemes are:

+

+      ONE_LEVEL

+            The key does not depend on any modifiers. The symbol from first

+            level is always chosen.

+

+      TWO_LEVEL

+            The key uses a modifier Shift and may have two possible values.

+            The second level may be chosen by Shift modifier. If Lock modi-

+            fier (usually Caps-lock) applies the symbol is further processed

+            using system-specific capitalization rules. If both Shift+Lock

+            modifier apply the symbol from the second level is taken and cap-

+            italization rules are applied (and usually have no effect).

+

+      ALPHABETIC

+            The key uses modifiers Shift and Lock. It may have two possible

+            values. The second level may be chosen by Shift modifier. When

+            Lock modifier applies, the symbol from the first level is taken

+            and further processed using system-specific capitalization rules.

+            If both Shift+Lock modifier apply the symbol from the first level

+            is taken and no capitalization rules applied. This is often

+            called shift-cancels-caps behaviour.

+

+      THREE_LEVEL

+            Is the same as TWO_LEVEL but it considers an extra modifier -

+            LevelThree which can be used to gain the symbol value from the

+            third level. If both Shift+LevelThree modifiers apply the value

+            from the third level is also taken. As in TWO_LEVEL, the Lock

+            modifier doesn't influence the resulting level. Only Shift and

+            LevelThree are taken into that consideration. If the Lock modi-

+            fier is active capitalization rules are applied on the resulting

+            symbol.

+

+      FOUR_LEVEL

+            Is the same as THREE_LEVEL but unlike LEVEL_THREE if both

+            Shift+LevelThree modifiers apply the symbol is taken from the

+            fourth level.

+

+      FOUR_LEVEL_ALPHABETIC

+            Is similar to FOUR_LEVEL but also defines shift-cancels-caps

+            behaviour as in ALPHABETIC. If Lock+LevelThree apply the symbol

+            from the third level is taken and the capitalization rules are

+            applied.  If Lock+Shift+LevelThree apply the symbol from the

+            third level is taken and no capitalization rules are applied.

+

+      KEYPAD

+            As the name suggest this scheme is primarily used for numeric

+            keypads.  The scheme considers two modifiers - Shift and NumLock.

+            If none of modifiers applies the symbol from the first level is

+            taken. If either Shift or NumLock modifiers apply the symbol from

+            the second level is taken.  If both Shift+NumLock modifiers apply

+            the symbol from the first level is taken. Again, shift-cancels-

+            caps variant.

+

+      FOUR_LEVEL_KEYPAD

+            Is similar to KEYPAD scheme but considers also LevelThree modi-

+            fier.  If LevelThree modifier applies the symbol from the third

+            level is taken.  If Shift+LevelThree or NumLock+LevelThree apply

+            the symbol from the fourth level is taken. If all Shift+Num-

+            Lock+LevelThree modifiers apply the symbol from the third level

+            is taken. This also, shift-cancels-caps variant.

+

+      FOUR_LEVEL_MIXED_KEYPAD

+	    A four-level keypad scheme where the first two levels are similar

+            to the KEYPAD scheme (NumLock+Shift)

+            LevelThree acts as an override providing access to two Shift-ed

+            levels. When LevelThree is active we totally ignore NumLock state

+            Intended for the digit area of the keypad

+

+      FOUR_LEVEL_X

+            A four-level scheme where the base level accepts no modifier,

+            LevelThree provides two more Shift-ed levels like in the previous

+            scheme, and Ctrl+Alt controls the fourth level

+            Intended for the operator part of a keypad, though since NumLock

+            plays no part, it is not keypad-specific

+

+Besides that, there are several schemes for special purposes:

+

+      PC_CONTROL_LEVEL2

+            It is similar to TWO_LEVEL scheme but it considers the Control

+            modifier rather than Shift. That means, the symbol from the sec-

+            ond level is chosen by Control rather than by Shift.

+

+      PC_ALT_LEVEL2

+            It is similar to TWO_LEVEL scheme but it considers the Alt modi-

+            fier rather than Shift. That means, the symbol from the second

+            level is chosen by Alt rather than by Shift.

+

+      CTRL+ALT

+            The key uses modifiers Alt and Control. It may have two possible

+            values. If only one modifier (Alt or Control) applies the symbol

+            from the first level is chosen. Only if both Alt+Control modi-

+            fiers apply the symbol from the second level is chosen.

+

+      SHIFT+ALT

+            The key uses modifiers Shift and Alt. It may have two possible

+            values.  If only one modifier (Alt or Shift) applies the symbol

+            from the first level is chosen. Only if both Alt+Shift modifiers

+            apply the symbol from the second level is chosen.

+

+If needed, special caps schemes may be used. They redefine the standard

+behaviour of all *ALPHABETIC types. The layouts (maps of symbols) with keys

+defined in respective types then automatically change their behaviour accord-

+ingly. Possible redefinitions are:

+

+   o internal

+

+   o internal_nocancel

+

+   o shift

+

+   o shift_nocancel

+

+None of these schemes should be used directly. They are defined merely for

+'caps:' xkb options (used to globally change the layouts behaviour).

+

+Don't alter any of existing key types. If you need a different behaviour cre-

+ate a new one.

+

+4.2.1  More On Definitions Of Types

+

+When the XKB software deals with a separate type description it gets a com-

+plete list of modifiers that should be taken into account from the 'modi-

+fiers=<list of modifiers>' list and expects that a set of 'map[<combination

+of modifiers>]=<list of modifiers>' instructions that contain the mapping for

+each combination of modifiers mentioned in that list. Modifiers that are not

+explicitly listed are NOT taken into account when the resulting shift level

+is computed.  If some combination is omitted the program (subroutine) should

+choose the first level for this combination (a quite reasonable behavior).

+

+Lets consider an example with two modifiers ModOne and ModTwo:

+

+     type "..." {

+         modifiers = ModOne+ModTwo;

+         map[None] = Level1;

+         map[ModOne] = Level2;

+     };

+

+In this case the map statements for ModTwo only and ModOne+ModTwo are omit-

+ted.  It means that if the ModTwo is active the subroutine can't found

+explicit mapping for such combination an will use the default level i.e.

+Level1.

+

+But in the case the type described as:

+

+     type "..." {

+         modifiers = ModOne;

+         map[None] = Level1;

+         map[ModOne] = Level2;

+     };

+

+the ModTwo will not be taken into account and the resulting level depends on

+the ModOne state only. That means, ModTwo alone produces the Level1 but the

+combination ModOne+ModTwo produces the Level2 as well as ModOne alone.

+

+What does it mean if the second modifier is the Lock? It means that in the

+first case (the Lock itself is included in the list of modifiers but combina-

+tions with this modifier aren't mentioned in the map statements) the internal

+capitalization rules will be applied to the symbol from the first level. But

+in the second case the capitalization will be applied to the symbol chosen

+accordingly to he first modifier - and this can be the symbol from the first

+as well as from the second level.

+

+Usually, all modifiers introduced in 'modifiers=<list of modifiers>' list are

+used for shift level calculation and then discarded. Sometimes this is not

+desirable. If you want to use a modifier for shift level calculation but you

+don't want to discard it, you may list in 'preserve[<combination of modi-

+fiers>]=<list of modifiers>'. That means, for a given combination all listed

+modifiers will be preserved. If the Lock modifier is preserved then the

+resulting symbol is passed to internal capitalization routine regardless

+whether it has been used for a shift level calculation or not.

+

+Any key type description can use both real and virtual modifiers. Since real

+modifiers always have standard names it is not necessary to explicitly

+declare them. Virtual modifiers can have arbitrary names and can be declared

+(prior using them) directly in key type definition:

+

+     virtual_modifiers <comma-separated list of modifiers>  ;

+

+as seen in for example basic, pc or mousekeys key type definitions.

+

+4.3  Rules

+

+Once you are finished with your symbol map you need to add it to rules file.

+The rules file describes how all the five basic keycodes, types, compat, sym-

+bols and geometry components should be composed to give a sensible resulting

+xkb configuration.

+

+The main advantage of rules over formerly used keymaps is a possibility to

+simply parameterize (once) fixed patterns of configurations and thus to ele-

+gantly allow substitutions of various local configurations into predefined

+templates.

+

+A pattern in a rules file (often located in /usr/lib/X11/xkb/rules) can be

+parameterized with four other arguments: Model, Layout, Variant and Options.

+For most cases parameters model and layout should be sufficient for choosing

+a functional keyboard mapping.

+

+The rules file itself is composed of pattern lines and lines with rules. The

+pattern line starts with an exclamation mark ('!') and describes how will the

+xkb interpret the following lines (rules). A sample rules file looks like

+this:

+

+     ! model                   =   keycodes

+       macintosh_old                     =   macintosh

+       ...

+       *                       =   xfree86

+

+     ! model                        =   symbols

+       hp                      =   +inet(%m)

+       microsoftpro                 =   +inet(%m)

+       geniuscomfy                  =   +inet(%m)

+

+     ! model       layout[1]          = symbols

+       macintosh    us           = macintosh/us%(v[1])

+       *             *               =       pc/pc(%m)+pc/%l[1]%(v[1])

+

+     ! model     layout[2]            = symbols

+       macintosh     us              =  +macintosh/us[2]%(v[2]):2

+       *       *               =   +pc/%l[2]%(v[2]):2

+

+     ! option            =    types

+       caps:internal               =    +caps(internal)

+       caps:internal_nocancel =    +caps(internal_nocancel)

+

+Each rule defines what certain combination of values on the left side of

+equal sign ('=') results in. For example a (keyboard) model macintosh_old

+instructs xkb to take definitions of keycodes from file keycodes/macintosh

+while the rest of models (represented by a wild card '*') instructs it to

+take them from file keycodes/xfree86. The wild card represents all possible

+values on the left side which were not found in any of the previous rules.

+The more specialized (more complete) rules have higher precedence than gen-

+eral ones, i.e. the more general rules supply reasonable default values.

+

+As you can see some lines contain substitution parameters - the parameters

+preceded by the percent sign ('%'). The first alphabetical character after

+the percent sign expands to the value which has been found on the left side.

+For example +%l%(v) expands into +cz(bksl) if the respective values on the

+left side were cz layout in its bksl variant. More, if the layout resp. vari-

+ant  parameter is followed by a pair of brackets ('[', ']') it means that xkb

+should place the layout resp. variant into specified xkb group. If the brack-

+ets are omitted the first group is the default value.

+

+So the second block of rules enhances symbol definitions for some particular

+keyboard models with extra keys (for internet, multimedia, ...) . Other mod-

+els are left intact. Similarly, the last block overrides some key type defi-

+nitions, so the common global behaviour ''shift cancels caps'' or ''shift

+doesn't cancel caps'' can be selected. The rest of rules produces special

+symbols for each variant us layout of macintosh keyboard and standard pc sym-

+bols in appropriate variants as a default.

+

+4.4  Descriptive Files of Rules

+

+Now you just need to add a detailed description to <rules>.xml description

+file so the other users (and external programs which often parse this file)

+know what is your work about.

+

+4.4.1  Old Descriptive Files

+

+The formerly used descriptive files were named <rules>.lst Its structure is

+very simple and quite self descriptive but such simplicity had also some cav-

+ities, for example there was no way how to describe local variants of layouts

+and there were problems with the localization of descriptions. To preserve

+compatibility with some older programs, new XML descriptive files can be con-

+verted to old format '.lst'.

+

+For each parameter of rules file should be described its meaning. For the

+rules file described above the .lst file could look like:

+

+     ! model

+       pc104        Generic 104-key PC

+       microsoft    Microsoft Natural

+       pc98         PC-98xx Series

+       macintosh     Original Macintosh

+       ...

+

+     ! layout

+       us      U.S. English

+       cz      Czech

+       de      German

+       ...

+

+     ! option

+       caps:internal           uses internal capitalization. Shift cancels Caps

+       caps:internal_nocancel uses internal capitalization. Shift doesn't cancel Caps

+

+And that should be it. Enjoy creating your own xkb mapping.