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<HTML><HEAD><TITLE>Xlib Programming Manual: Keyboard Encoding</TITLE></HEAD><BODY><H1 ALIGN=center>12.7 Keyboard Encoding</H1>A <B>KeyCode</B> represents a physical (or logical) key. KeyCodes lie in the inclusive range [8,255]. A KeyCode value carries no intrinsic information,although server implementors may attempt to encode geometry (for example, matrix) information in some fashion so that it canbe interpreted in a server-dependent fashion.The mapping between keys and KeyCodes cannot be changed.<A NAME="KeySym"></A><P>A <B>KeySym</B> is an encoding of a symbol on the cap of a key. The set of defined KeySyms includes the ISO Latin character sets (1-4), Katakana, Arabic, Cyrillic, Greek, Technical,Special, Publishing, APL, Hebrew, Thai, Koreanand a miscellany of keys foundon keyboards (Return, Help, Tab, and so on). To the extent possible, these sets are derived from internationalstandards. In areas where no standards exist,some of these sets are derived from Digital Equipment Corporation standards.The list of defined symbols can be found in<B><TT>X11/keysymdef.h</TT></B>.Unfortunately, some C preprocessors havelimits on the number of defined symbols.If you must use KeySyms notin the Latin 1-4, Greek, and miscellaneous classes,you may have to define a symbol for those sets.Most applications usually only include <B><TT>X11/keysym.h</TT></B>,which defines symbols for ISO Latin 1-4, Greek, and miscellaneous.<P>A list of KeySyms is associated with each KeyCode.The list is intended to convey the set of symbols on the corresponding key.If the list (ignoring trailing<B>NoSymbol</B>entries) is a single KeySym ``<I>K</I>'',then the list is treated as if it were the list ``<I>K</I> NoSymbol <I>K</I> NoSymbol''.If the list (ignoring trailing<B>NoSymbol</B>entries) is a pair of KeySyms ``<I>K1 K2</I>'',then the list is treated as if it were the list ``<I>K1 K2 K1 K2</I>''.If the list (ignoring trailing<B>NoSymbol</B>entries) is a triple of KeySyms ``<I>K1 K2 K3</I>'',then the list is treated as if it were the list ``<I>K1 K2 K3</I> NoSymbol''.When an explicit ``void'' element is desired in the list,the value<B>VoidSymbol</B>can be used.<P>The first four elements of the list are split into two groups of KeySyms.Group 1 contains the first and second KeySyms;Group 2 contains the third and fourth KeySyms.Within each group,if the second element of the group is<B>NoSymbol</B> ,then the group should be treated as if the second element were the same as the first element,except when the first element is an alphabetic KeySym ``<I>K</I>'' for which both lowercase and uppercase forms are defined.In that case,the group should be treated as if the first element were the lowercase form of ``<I>K</I>'' and the second element were the uppercase form of ``<I>K</I>.''<P>The standard rules for obtaining a KeySym from a<B><A HREF="../events/keyboard-pointer/keyboard-pointer.html">KeyPress</A></B>event make use of only the Group 1 and Group 2 KeySyms;no interpretation of other KeySyms in the list is given.Which group to use is determined by the modifier state.Switching between groups is controlled by the KeySym named MODE SWITCH,by attaching that KeySym to some KeyCode and attaching that KeyCode to any one of the modifiers<B>Mod1</B>through<B>Mod5</B>.This modifier is called the <I>group modifier</I>.For any KeyCode,Group 1 is used when the group modifier is off,and Group 2 is used when the group modifier is on.<P>The<B>Lock</B>modifier is interpreted as CapsLock when the KeySym named XK_Caps_Lockis attached to some KeyCode and that KeyCode is attached to the<B>Lock</B>modifier. The<B>Lock</B>modifier is interpreted as ShiftLock when the KeySym named XK_Shift_Lockis attached to some KeyCode and that KeyCode is attached to the<B>Lock</B> modifier. If the<B>Lock</B> modifier could be interpreted as bothCapsLock and ShiftLock, the CapsLock interpretation is used.<P>The operation of keypad keys is controlled by the KeySym named XK_Num_Lock,by attaching that KeySym to some KeyCode and attaching that KeyCode to anyone of the modifiers<B>Mod1</B> through<B>Mod5</B> . This modifier is called the<I>numlock modifier</I>. The standard KeySyms with the prefix ``XK_KP_''in theirname are called keypad KeySyms; these are KeySyms with numeric value inthe hexadecimal range 0xFF80 to 0xFFBD inclusive. In addition,vendor-specific KeySyms in the hexadecimal range 0x11000000 to 0x1100FFFFare also keypad KeySyms.<P>Within a group, the choice of KeySym is determined by applying the firstrule that is satisfied from the following list:<UL><P><LI>The numlock modifier is on and the second KeySym is a keypad KeySym. Inthis case, if the<B>Shift</B>modifier is on, or if the<B>Lock</B> modifier is on andis interpreted as ShiftLock, then the first KeySym is used, otherwise thesecond KeySym is used.<P><LI>The<B>Shift</B> and<B>Lock</B> modifiers are both off. In this case, the firstKeySym is used.<P><LI>The<B>Shift</B> modifier is off, and the<B>Lock</B> modifier is on and isinterpreted as CapsLock. In this case, the first KeySym is used, but ifthat KeySym is lowercase alphabetic, then the corresponding uppercaseKeySym is used instead.<P><LI>The<B>Shift</B> modifier is on, and the<B>Lock</B> modifier is on and is interpretedas CapsLock. In this case, the second KeySym is used, but if that KeySymis lowercase alphabetic, then the corresponding uppercase KeySym is usedinstead.<P><LI>The<B>Shift</B> modifier is on, or the<B>Lock</B> modifier is on and is interpretedas ShiftLock, or both. In this case, the second KeySym is used.</UL><P>No spatial geometry of the symbols on the key is defined bytheir order in the KeySym list, although a geometry might be defined on aserver-specific basis.The X server does not use the mapping between KeyCodes and KeySyms.Rather, it merely stores it for reading and writing by clients.<P>To obtain the legal KeyCodes for a display, use<B><A HREF="XDisplayKeycodes.html">XDisplayKeycodes()</A></B>.<P>To obtain the symbols for the specified KeyCodes, use<B><A HREF="XGetKeyboardMapping.html">XGetKeyboardMapping()</A></B>.<P>To change the keyboard mapping, use<B><A HREF="XChangeKeyboardMapping.html">XChangeKeyboardMapping()</A></B>.<A NAME="XModifierKeymap"></A><P>The next six functions make use of the <B>XModifierKeymap</B>data structure, which contains:<P><!.IN "XModifierKeymap" "" "@DEF@"><PRE><CODE>typedef struct { int max_keypermod; /* This server's max number of keys per modifier */ KeyCode *modifiermap; /* An 8 by max_keypermod array of the modifiers */} XModifierKeymap;</PRE></CODE><P>To create an<B>XModifierKeymap()</B>structure, use<B><A HREF="XNewModifiermap.html">XNewModifiermap()</A></B>.<P>To add a new entry to an <B>XModifierKeymap()</B>structure, use<B><A HREF="XInsertModifiermapEntry.html">XInsertModifiermapEntry()</A></B>.<P>To delete an entry from an <B>XModifierKeymap()</B>structure, use<B><A HREF="XDeleteModifiermapEntry.html">XDeleteModifiermapEntry()</A></B>.<P>To destroy an<B>XModifierKeymap</B>structure, use<B><A HREF="XFreeModifiermap.html">XFreeModifiermap()</A></B>.<P>To set the KeyCodes to be used as modifiers, use<B><A HREF="XSetModifierMapping.html">XSetModifierMapping()</A></B>.<P>To obtain the KeyCodes used as modifiers, use<B><A HREF="XGetModifierMapping.html">XGetModifierMapping()</A></B>.<H5 ALIGN=right><I>Next Chapter: <A HREF="../localization/">Locales and Internationalized Text Functions</A></I></H5><HR><ADDRESS><A HREF="http://tronche.com/">Christophe Tronche</A>, <A HREF="mailto:ch.tronche@computer.org">ch.tronche@computer.org</A></ADDRESS></BODY></HTML>⌨️ 快捷键说明
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