path: root/fpcdocs/keyboard.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<fpdoc-descriptions>
<!--  

   $Id: keyboard.xml,v 1.3 2005/03/16 07:54:10 michael Exp $ 
   This file is part of the FPC documentation. 
   Copyright (C) 1997, by Michael Van Canneyt 
 
   The FPC documentation is free text; you can redistribute it and/or 
   modify it under the terms of the GNU Library General Public License as 
   published by the Free Software Foundation; either version 2 of the 
   License, or (at your option) any later version. 
 
   The FPC Documentation is distributed in the hope that it will be useful, 
   but WITHOUT ANY WARRANTY; without even the implied warranty of 
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU 
   Library General Public License for more details. 
 
   You should have received a copy of the GNU Library General Public 
   License along with the FPC documentation; see the file COPYING.LIB.  If not, 
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, 
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 -->
<package name="rtl">
<module name="keyboard">
<short>Access to low-level keyboard functions</short>
<!-- \FPCexampledir{kbdex} -->
<descr>
<p>
The <file>Keyboard</file> unit implements a keyboard access layer which is system
independent. It can be used to poll the keyboard state and wait for certain
events. Waiting for a keyboard event can be done with the <link id="GetKeyEvent"/>
function, which will return a driver-dependent key event. This key event can
be translated to a interpretable event by the <link id="TranslateKeyEvent"/>
function. The result of this function can be used in the other event
examining functions.
</p>
<p>
A custom keyboard driver can be installed using the <link id="SetKeyboardDriver"/>
function. The current keyboard driver can be retrieved using the
<link id="GetKeyboardDriver"/> function. The last section of this chapter
demonstrates how to make a keyboard driver.
</p>
</descr>

<element name="errKbdBase">
<short>Base of keyboard routine error reporting constants.</short>
</element>

<element name="errKbdInitError">
<short>Failed to initialize keyboard driver</short>
</element>

<element name="errKbdNotImplemented">
<short>Keyboard driver not implemented.</short>
</element>

<element name="kbdApps">
<short>Application key (popup-menu) pressed.</short>
</element>

<element name="kbdLWin">
<short>Left windows key pressed.</short>
</element>

<element name="kbdRWin">
<short>Right windows key pressed.</short>
</element>

<element name="kbdF1">
<short>F1 function key pressed.</short>
</element>

<element name="kbdF2">
<short>F2 function key pressed.</short>
</element>

<element name="kbdF3">
<short>F3 function key pressed.</short>
</element>

<element name="kbdF4">
<short>F4 function key pressed.</short>
</element>

<element name="kbdF5">
<short>F5 function key pressed.</short>
</element>

<element name="kbdF6">
<short>F6 function key pressed.</short>
</element>

<element name="kbdF7">
<short>F7 function key pressed.</short>
</element>

<element name="kbdF8">
<short>F8 function key pressed.</short>
</element>

<element name="kbdF9">
<short>F9 function key pressed.</short>
</element>

<element name="kbdF10">
<short>F10 function key pressed.</short>
</element>

<element name="kbdF11">
<short>F12 function key pressed.</short>
</element>

<element name="kbdF12">
<short>F12 function key pressed.</short>
</element>

<element name="kbdF13">
<short>F13 function key pressed.</short>
</element>

<element name="kbdF14">
<short>F14 function key pressed.</short>
</element>

<element name="kbdF15">
<short>F15 function key pressed.</short>
</element>

<element name="kbdF16">
<short>F16 function key pressed.</short>
</element>

<element name="kbdF17">
<short>F17 function key pressed.</short>
</element>

<element name="kbdF18">
<short>F18 function key pressed.</short>
</element>

<element name="kbdF19">
<short>F19 function key pressed.</short>
</element>

<element name="kbdF20">
<short>F20 function key pressed.</short>
</element>

<element name="kbFnKey">
<short>function key pressed.</short>
</element>

<element name="ShiftPrefix">
<short>Shift key name index.</short>
</element>

<element name="AltPrefix">
<short>Keycode for alternate prefix key for Alt key. Unix Only</short>
</element>


<element name="CtrlPrefix">
<short>Keycode for alternate prefix key for Ctrl key. Unix only</short>
</element>



<element name="ShiftPrefix">
<short>Keycode for alternate prefix key for Shift key. Unix Only</short>
</element>



<element name="kbdHome">
<short>Home key pressed</short>
</element>

<element name="kbdUp">
<short>Arrow up key pressed</short>
</element>

<element name="kbdDown">
<short>Arrow down key pressed</short>
</element>

<element name="kbdPgUp">
<short>Page Up key pressed</short>
</element>

<element name="kbdLeft">
<short>Arrow left key pressed</short>
</element>

<element name="kbdMiddle">
<short>Middle key pad key pressed (numerical 5)</short>
</element>

<element name="kbdRight">
<short>Arrow right key pressed</short>
</element>

<element name="kbdEnd">
<short>End key pressed</short>
</element>

<element name="kbdPgDn">
<short>Page down key pressed</short>
</element>


<element name="kbdInsert">
<short>Insert key pressed</short>
</element>

<element name="kbdDelete">
<short>Delete key pressed</short>
</element>

<element name="kbASCII">
<short>Ascii code key event</short>
</element>

<element name="kbUniCode">
<short>Unicode code key event</short>
</element>

<element name="kbPhys">
<short>Physical key code event</short>
</element>

<element name="kbReleased">
<short>Key release event (not implemented in FPC)</short>
</element>

<element name="kbLeftShift">
<short>Left shift key modifier</short>
</element>

<element name="kbRightShift">
<short>Right shift key modifier</short>
</element>

<element name="kbShift">
<short>Shift key modifier</short>
</element>

<element name="kbCtrl">
<short>Control key modifier</short>
</element>

<element name="kbAlt">
<short>Alt key modifier</short>
</element>

<element name="SShift">
<short>Names of modifier keys</short>
<descr>
This constant describes the various modifier keys.
This constant is used by the key event description routines.
It can be changed to localize the key descriptions when needed.
</descr>
<seealso>
<link id="KeyEventToString"/>
<link id="FunctionKeyName"/>
</seealso>
</element>

<element name="SLeftRight">
<short>Names for left-right keys</short>
<descr>
This constant contains strings to describe left and right keys.
This constant is used by the key event description routines.
It can be changed to localize the key descriptions when needed.
</descr>
<seealso>
<link id="KeyEventToString"/>
<link id="FunctionKeyName"/>
</seealso>
</element>

<element name="SUnicodeChar">
<short>Unicode character string.</short>
<descr>
This constant contains a string to denote a unicode key event.
This constant is used by the key event description routines.
It can be changed to localize the key descriptions when needed.
</descr>
<seealso>
<link id="KeyEventToString"/>
<link id="FunctionKeyName"/>
</seealso>
</element>

<element name="SScanCode">
<short>Scancode key</short>
<descr>
This constant contains a string to denote a scancode key event.
This constant is used by the key event description routines.
It can be changed to localize the key descriptions when needed.
</descr>
<seealso>
<link id="KeyEventToString"/>
<link id="FunctionKeyName"/>
</seealso>
</element>

<element name="SUnknownFunctionKey">
<short>Unknown function key</short>
<descr>
This constant contains a string to denote that an  unknown function key was
found. This constant is used by the key event description routines.
It can be changed to localize the key descriptions when needed.
</descr>
<seealso>
<link id="KeyEventToString"/>
<link id="FunctionKeyName"/>
</seealso>
</element>

<element name="SAnd">
<short>'And' description string</short>
<descr>
This constant is used as the 'And' word in key descriptions.
This constant is used by the key event description routines.
It can be changed to localize the key descriptions when needed.
</descr>
<seealso>
<link id="KeyEventToString"/>
<link id="FunctionKeyName"/>
</seealso>
</element>

<element name="SKeyPad">
<short>Names of keypad keys</short>
<descr>
This constant describes all keypad keys.
This constant is used by the key event description routines.
It can be changed to localize the key descriptions when needed.
</descr>
<seealso>
<link id="KeyEventToString"/>
<link id="FunctionKeyName"/>
</seealso>
</element>

<element name="TKeyEvent">
<short>Base type to describe all key events.</short>
<descr>
<p>
The <var>TKeyEvent</var> type is the base type for all keyboard events.
</p>
<p>
The key stroke is encoded in the 4 bytes of the <var>TKeyEvent</var> type. 
The various fields of the key stroke encoding can be obtained by typecasting
the <var>TKeyEvent</var> type to the <link id="TKeyRecord"/> type.
</p>
</descr>
</element>

<element name="TKeyRecord">
<short>Key event decoding type.</short>
<descr>
<p>
The structure of a <var>TKeyRecord</var> structure is explained in the
following table:
</p>
<table>
<caption>Structure of TKeyRecord</caption>
<th><td>Field</td><td>Meaning</td></th>
<tr><td>KeyCode</td><td>
Depending on <var>flags</var> either the physical representation of a key
(under DOS scancode, ascii code pair), or the translated
ASCII/unicode character.
</td></tr>
<tr>
<td>ShiftState</td>
<td>
Shift-state when this key was pressed (or shortly after) 
</td></tr>
<tr><td>Flags</td>
<td>
Determine how to interpret <var>KeyCode</var>
</td></tr>
</table>
<p>
The shift-state can be checked using the various shift-state constants, 
and the flags in the last byte can be checked using one of the
kbASCII, kbUniCode, kbFnKey, kbPhys, kbReleased constants.
</p>
<p>
If there are two keys returning the same char-code, there's no way to find
out which one was pressed (Gray+ and Simple+). If it needs to be known which
was pressed, the untranslated keycodes must be used, but these are system
dependent. System dependent constants may be defined to cover those, with
possibily having the same name (but different value).
</p>
</descr>
<seealso>
<link id="kbdscancode"/>
<link id="TKeyEvent"/>
</seealso>
</element>

<element name="TKeyboardDriver">
<short>Keyboard driver structure</short>
<descr>
<p>
The <var>TKeyboardDriver</var> record can be used to install a custom keyboard
driver with the <link id="SetKeyboardDriver"/> function.
</p>
<p>
The various fields correspond to the different functions of the keyboard unit 
interface. For more information about this record see <link id="kbddriver"/>
</p>
</descr>
<seealso>
<link id="SetKeyboardDriver"/>
<link id="kbddriver"/>
</seealso>
</element>

<element name="DoneKeyboard">
<short>Deactivate keyboard driver.</short>
<descr>
<p>
<var>DoneKeyboard</var> de-initializes the keyboard interface if the keyboard
driver is active. If the keyboard driver is not active, the function does
nothing.
</p>
<p>
This will cause the keyboard driver to clear up any allocated memory, 
or restores the console or terminal the program was running in to its 
initial state before the call to <link id="InitKeyBoard"/>. This function should 
be called on program exit. Failing to do so may leave the terminal or
console window in an unusable state. Its exact action depends on the 
platform on which the program is running.
</p>
<p>
On Unix the default keyboard driver restores the line ending of system.output to
#10.
</p>
<p>
For an example, see most other functions.
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="InitKeyBoard"/>
</seealso>
</element>


<element name="FunctionKeyName">
<short>Return string representation of a function key code.</short>
<descr>
<var>FunctionKeyName</var> returns a string representation of the function key
with code <var>KeyCode</var>. This can be an actual function key, or one of the
cursor movement keys.
</descr>
<errors>
In case <var>KeyCode</var> does not contain a function code, the
<var>SUnknownFunctionKey</var> string is returned, appended with the
<var>KeyCode</var>.
</errors>
<seealso>
<link id="ShiftStateToString"/>
<link id="KeyEventToString"/>
</seealso>
<example file="kbdex/ex8"/>
</element>


<element name="GetKeyboardDriver">
<short>Return the current keyboard driver record.</short>
<descr>
<p>
<var>GetKeyBoardDriver</var> returns in <var>Driver</var> the currently active
keyboard driver. This function can be used to enhance an existing
keyboarddriver.
</p>
<p>
For more information on getting and setting the keyboard driver
<link id="kbddriver"/>.
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="SetKeyboardDriver"/>
</seealso>
</element>

<element name="GetKeyEvent">
<short>Get the next raw key event, wait if needed.</short>
<descr>
<p>
<var>GetKeyEvent</var> returns the last keyevent if it is available, 
or waits for one if none is available.
A non-blocking version is available in <link id="PollKeyEvent"/>.
</p>
<p>
The returned key is encoded as a <var>TKeyEvent</var> type variable, and
is normally the physical key scan code, (the scan code is driver 
dependent) which can be translated with one of the translation 
functions <link id="TranslateKeyEvent"/> or <link id="TranslateKeyEventUniCode"/>. 
See the types section for a description of how the key is described.
</p>
</descr>
<errors>
If no key became available (e.g. when the driver does not support it), 0 is returned.
</errors>
<seealso>
<link id="PutKeyEvent"/>
<link id="PollKeyEvent"/>
<link id="TranslateKeyEvent"/>,
<link id="TranslateKeyEventUniCode"/>
</seealso>
<example file="kbdex/ex1"/>
</element>


<element name="GetKeyEventChar">
<short>Get the character key part of a key event.</short>
<descr>
<p>
<var>GetKeyEventChar</var> returns the charcode part of the given 
<var>KeyEvent</var>, if it contains a translated character key 
keycode. The charcode is simply the ascii code of the 
character key that was pressed.
</p>
<p>
It returns the null character if the key was not a character key, but e.g. a
function key.
</p>
<p>
For an example, see <link id="GetKeyEvent"/>
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetKeyEventUniCode"/>,
<link id="GetKeyEventShiftState"/>, 
<link id="GetKeyEventFlags"/>,
<link id="GetKeyEventCode"/>,
<link id="GetKeyEvent"/>
</seealso>
</element>


<element name="GetKeyEventCode">
<short>Translate function key  part of a key event code.</short>
<descr>
<p>
<var>GetKeyEventCode</var> returns the translated function keycode part of 
the given KeyEvent, if it contains a translated function key.
</p>
<p>
If the key pressed was not a function key, the null character is returned.
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetKeyEventUniCode"/>,
<link id="GetKeyEventShiftState"/>, 
<link id="GetKeyEventFlags"/>,
<link id="GetKeyEventChar"/>,
<link id="GetKeyEvent"/>
</seealso>
<example file="kbdex/ex2"/>
</element>

<element name="GetKeyEventFlags">
<short>Extract the flags from a key event.</short>
<descr>
<p>
<var>GetKeyEventFlags</var> returns the flags part of the given 
<var>KeyEvent</var>. 
</p>
<p>
For an example, see <link id="GetKeyEvent"/>
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetKeyEventUniCode"/>,
<link id="GetKeyEventShiftState"/>, 
<link id="GetKeyEventCode"/>,
<link id="GetKeyEventChar"/>,
<link id="GetKeyEvent"/>
</seealso>
</element>


<element name="GetKeyEventShiftState">
<short>Return the current state of the shift keys.</short>
<descr>
<p>
<var>GetKeyEventShiftState</var> returns the shift-state values of 
the given <var>KeyEvent</var>. This can be used to detect which of the modifier
keys <var>Shift</var>, <var>Alt</var> or <var>Ctrl</var> were pressed. If none were
pressed, zero is returned.
</p>
<p>
Note that this function does not always return expected results;
In a unix X-Term, the modifier keys do not always work.
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetKeyEventUniCode"/>,
<link id="GetKeyEventFlags"/>, 
<link id="GetKeyEventCode"/>,
<link id="GetKeyEventChar"/>,
<link id="GetKeyEvent"/>
</seealso>
<example file="kbdex/ex3"/>
</element>


<element name="GetKeyEventUniCode">
<short>Return the unicode key event.</short>
<descr>
<var>GetKeyEventUniCode</var> returns the unicode part of the 
given <var>KeyEvent</var> if it contains a translated unicode 
character.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetKeyEventShiftState"/>,
<link id="GetKeyEventFlags"/>, 
<link id="GetKeyEventCode"/>,
<link id="GetKeyEventChar"/>,
<link id="GetKeyEvent"/>
</seealso>
</element>

<element name="InitKeyBoard">
<short>Initialize the keyboard driver.</short>
<descr>
<p>
<var>InitKeyboard</var> initializes the keyboard driver. 
If the driver is already active, it does nothing. When the driver is
initialized, it will do everything necessary to ensure the functioning of
the keyboard, including allocating memory, initializing the terminal etc.
</p>
<p>
This function should be called once, before using any of the
keyboard functions. When it is called, the <link id="DoneKeyboard"/> function
should also be called before exiting the program or changing the keyboard
driver with <link id="SetKeyboardDriver"/>.
</p>
<p>
On Unix, the default keyboard driver sets terminal in raw mode. In raw mode the
line feed behaves as an actual linefeed, i.e. the cursor is moved down one line.
while the x coordinate does not change. To compensate, the default keyboard 
sets driver line ending of system.output to #13#10.
</p>
<p>
For an example, see most other functions.
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="DoneKeyboard"/>
<link id="SetKeyboardDriver"/>
</seealso>
</element>

<element name="AddSequence" skip="1"/>
<element name="FindSequence" skip="1"/>
<element name="RawReadKey" skip="1"/>
<element name="RawReadString" skip="1"/>
<element name="RestoreStartMode" skip="1"/>


<element name="IsFunctionKey">
<short>Check whether a given event is a function key event.</short>
<descr>
<var>IsFunctionKey</var> returns <var>True</var> if the given key event
in <var>KeyEvent</var> was a function key or not.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetKeyEvent"/>
</seealso>
<example file="kbdex/ex7"/>
</element>


<element name="KeyEventToString">
<short>Return a string describing the key event.</short>
<descr>
<p>
<var>KeyEventToString</var> translates the key event in <var>KeyEvent</var> to a
human-readable description of the pressed key. It will use the constants
described in the constants section to do so.
</p>
<p>
For an example, see most other functions.
</p>
</descr>
<errors>
If an unknown key is passed, the scancode is returned, prefixed with the 
<var>SScanCode</var> string.
</errors>
<seealso>
<link id="FunctionKeyName"/>
<link id="ShiftStateToString"/>
</seealso>
</element>

<element name="KeyPressed">
<short>Check event queue for key press</short>
<descr>
<var>KeyPressed</var> checks the keyboard event queue to see whether a key
event is present, and returns <var>True</var> if a key event is available.
This function simply calls <link id="PollKeyEvent"/> and checks for a valid
result.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="PollKeyEvent"/>
<link id="GetKeyEvent"/>
</seealso>
</element>



<element name="PollKeyEvent">
<short>Get next key event, but does not wait.</short>
<descr>
<p>
<var>PollKeyEvent</var> checks whether a key event is available, 
and returns it if one is found. If no event is pending, 
it returns 0. 
</p>
<p>
Note that this does not remove the key from the pending keys. 
The key should still be retrieved from the pending key events 
list with the <link id="GetKeyEvent"/> function.
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="PutKeyEvent"/>
<link id="GetKeyEvent"/>
</seealso>
<example file="kbdex/ex4"/>
</element>


<element name="PollShiftStateEvent">
<short>Check current shift state. </short>
<descr>
<var>PollShiftStateEvent</var> returns the current shiftstate in a 
keyevent. This will return 0 if there is no key event pending.
</descr>
<errors>
None.
</errors>
<seealso>
<link id="PollKeyEvent"/>
<link id="GetKeyEvent"/>
</seealso>
<example file="kbdex/ex6"/>
</element>


<element name="PutKeyEvent">
<short>Put a key event in the event queue.</short>
<descr>
<var>PutKeyEvent</var> adds the given <var>KeyEvent</var> to the input 
queue. Please note that depending on the implementation this 
can hold only one value, i.e. when calling <var>PutKeyEvent</var>
multiple times, only the last pushed key will be remembered.
</descr>
<errors>
None
</errors>
<seealso>
<link id="PollKeyEvent"/>
<link id="GetKeyEvent"/>
</seealso>
<example file="kbdex/ex5"/>
</element>


<element name="SetKeyboardDriver">
<short>Set a new keyboard driver.</short>
<descr>
<p>
<var>SetKeyBoardDriver</var> sets the keyboard driver to <var>Driver</var>, if the
current keyboard driver is not yet initialized. If the current
keyboard driver is initialized, then <var>SetKeyboardDriver</var> does 
nothing. Before setting the driver, the currently active driver should
be disabled with a call to <link id="DoneKeyboard"/>.
</p>
<p>
The function returns <var>True</var> if the driver was set, <var>False</var> if not.
</p>
<p>
For more information on setting the keyboard driver, see <link id="kbddriver"/>.
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="GetKeyboardDriver"/>
<link id="DoneKeyboard"/>.
</seealso>
</element>

<element name="ShiftStateToString">
<short>Return description of key event shift state</short>
<descr>
<p>
<var>ShiftStateToString</var> returns a string description of the shift state
of the key event <var>KeyEvent</var>. This can be an empty string. 
</p>
<p>
The shift state is described using the strings in the <var>SShift</var> constant.
</p>
<p>
For an example, see <link id="PollShiftStateEvent"/>.
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="FunctionKeyName"/>
<link id="KeyEventToString"/>
</seealso>
</element>


<element name="TranslateKeyEvent">
<short>Translate raw event to ascii key event</short>
<descr>
<p>
<var>TranslateKeyEvent</var> performs ASCII translation of the <var>KeyEvent</var>.
It translates a physical key to a function key if the key is a function key,
and translates the physical key to the ordinal of the ascii character if 
there is an equivalent character key.
</p>
<p>
For an example, see <link id="GetKeyEvent"/>
</p>
</descr>
<errors>
None.
</errors>
<seealso>
<link id="TranslateKeyEventUniCode"/>
</seealso>
</element>


<element name="TranslateKeyEventUniCode">
<short>Translate raw event to UNICode key event</short>
<descr>
<var>TranslateKeyEventUniCode</var> performs Unicode translation of the 
<var>KeyEvent</var>. It is not yet implemented for all platforms.
</descr>
<errors>
If the function is not yet implemented, then the <var>ErrorCode</var> of the 
<file>system</file> unit will be set to <var>errKbdNotImplemented</var>
</errors>
<seealso>
<link id="TranslateKeyEvent"/>
</seealso>
</element>

<!-- variable Visibility: default -->
<element name="TKeyRecord.KeyCode">
<short>Key code</short>
</element>

<!-- variable Visibility: default -->
<element name="TKeyRecord.ShiftState">
<short>State of shift keys</short>
</element>

<!-- variable Visibility: default -->
<element name="TKeyRecord.Flags">
<short>Additional flags</short>
</element>

<!-- variable Visibility: default -->
<element name="TKeyboardDriver.InitDriver">
<short>Handler called when initializing keyboard driver</short>
</element>

<!-- variable Visibility: default -->
<element name="TKeyboardDriver.DoneDriver">
<short>Handler called when unloading keyboard driver</short>
</element>

<!-- variable Visibility: default -->
<element name="TKeyboardDriver.GetKeyEvent">
<short>Blocking handler called when a key event is requested</short>
</element>

<!-- variable Visibility: default -->
<element name="TKeyboardDriver.PollKeyEvent">
<short>Non blocking handler when checking for presence of a key event</short>
</element>

<!-- variable Visibility: default -->
<element name="TKeyboardDriver.GetShiftState">
<short>Handler called to request the current shift state</short>
</element>

<!-- variable Visibility: default -->
<element name="TKeyboardDriver.TranslateKeyEvent">
<short>Translate key event to a suitable ASCII representation</short>
</element>

<!-- variable Visibility: default -->
<element name="TKeyboardDriver.TranslateKeyEventUniCode">
<short>Translate key event to a suitable Unicode representation</short>
</element>

<topic name="kbdscancode">
<short>Keyboard scan codes</short>
<descr>
<p>
Special physical keys are encoded with the DOS scan codes for these keys
in the second byte of the <link id="TKeyEvent"/> type.
A complete list of scan codes can be found in the below table. 
This is the list of keys that is used by the default key event translation mechanism.
When writing a keyboard driver, either these constants should be returned
by the various key event functions, or the <var>TranslateKeyEvent</var> hook
should be implemented by the driver.
</p>
<table border="1">
<caption>Key Scancodes</caption>
<th><td>Code</td><td>Key</td><td>Code</td><td>Key</td><td>Code</td><td>Key</td></th>
<tr><td>00 </td><td> NoKey </td><td> 3D </td><td> F3 </td><td> 70 </td><td> ALT-F9 </td></tr>
<tr><td>01 </td><td> ALT-Esc </td><td> 3E </td><td> F4 </td><td> 71 </td><td> ALT-F10 </td></tr>
<tr><td>02 </td><td> ALT-Space </td><td> 3F </td><td> F5 </td><td> 72 </td><td> CTRL-PrtSc </td></tr>
<tr><td>04 </td><td> CTRL-Ins </td><td> 40 </td><td> F6 </td><td> 73 </td><td> CTRL-Left </td></tr>
<tr><td>05 </td><td> SHIFT-Ins </td><td> 41 </td><td> F7 </td><td> 74 </td><td> CTRL-Right </td></tr>
<tr><td>06 </td><td> CTRL-Del </td><td> 42 </td><td> F8 </td><td> 75 </td><td> CTRL-end </td></tr>
<tr><td>07 </td><td> SHIFT-Del </td><td> 43 </td><td> F9 </td><td> 76 </td><td> CTRL-PgDn </td></tr>
<tr><td>08 </td><td> ALT-Back </td><td> 44 </td><td> F10 </td><td> 77 </td><td> CTRL-Home </td></tr>
<tr><td>09 </td><td> ALT-SHIFT-Back </td><td> 47 </td><td> Home </td><td> 78 </td><td> ALT-1 </td></tr>
<tr><td>0F </td><td> SHIFT-Tab </td><td> 48 </td><td> Up </td><td> 79 </td><td> ALT-2 </td></tr>
<tr><td>10 </td><td> ALT-Q </td><td> 49 </td><td> PgUp </td><td> 7A </td><td> ALT-3 </td></tr>
<tr><td>11 </td><td> ALT-W </td><td> 4B </td><td> Left </td><td> 7B </td><td> ALT-4 </td></tr>
<tr><td>12 </td><td> ALT-E </td><td> 4C </td><td> Center </td><td> 7C </td><td> ALT-5 </td></tr>
<tr><td>13 </td><td> ALT-R </td><td> 4D </td><td> Right </td><td> 7D </td><td> ALT-6 </td></tr>
<tr><td>14 </td><td> ALT-T </td><td> 4E </td><td> ALT-GrayPlus </td><td> 7E </td><td> ALT-7 </td></tr>
<tr><td>15 </td><td> ALT-Y </td><td> 4F </td><td> end </td><td> 7F </td><td> ALT-8 </td></tr>
<tr><td>16 </td><td> ALT-U </td><td> 50 </td><td> Down </td><td> 80 </td><td> ALT-9 </td></tr>
<tr><td>17 </td><td> ALT-I </td><td> 51 </td><td> PgDn </td><td> 81 </td><td> ALT-0 </td></tr>
<tr><td>18 </td><td> ALT-O </td><td> 52 </td><td> Ins </td><td> 82 </td><td> ALT-Minus </td></tr>
<tr><td>19 </td><td> ALT-P </td><td> 53 </td><td> Del </td><td> 83 </td><td> ALT-Equal </td></tr>
<tr><td>1A </td><td> ALT-LftBrack </td><td> 54 </td><td> SHIFT-F1 </td><td> 84 </td><td> CTRL-PgUp </td></tr>
<tr><td>1B </td><td> ALT-RgtBrack </td><td> 55 </td><td> SHIFT-F2 </td><td> 85 </td><td> F11 </td></tr>
<tr><td>1E </td><td> ALT-A </td><td> 56 </td><td> SHIFT-F3 </td><td> 86 </td><td> F12 </td></tr>
<tr><td>1F </td><td> ALT-S </td><td> 57 </td><td> SHIFT-F4 </td><td> 87 </td><td> SHIFT-F11 </td></tr>
<tr><td>20 </td><td> ALT-D </td><td> 58 </td><td> SHIFT-F5 </td><td> 88 </td><td> SHIFT-F12 </td></tr>
<tr><td>21 </td><td> ALT-F </td><td> 59 </td><td> SHIFT-F6 </td><td> 89 </td><td> CTRL-F11 </td></tr>
<tr><td>22 </td><td> ALT-G </td><td> 5A </td><td> SHIFT-F7 </td><td> 8A </td><td> CTRL-F12 </td></tr>
<tr><td>23 </td><td> ALT-H </td><td> 5B </td><td> SHIFT-F8 </td><td> 8B </td><td> ALT-F11 </td></tr>
<tr><td>24 </td><td> ALT-J </td><td> 5C </td><td> SHIFT-F9 </td><td> 8C </td><td> ALT-F12 </td></tr>
<tr><td>25 </td><td> ALT-K </td><td> 5D </td><td> SHIFT-F10 </td><td> 8D </td><td> CTRL-Up </td></tr>
<tr><td>26 </td><td> ALT-L </td><td> 5E </td><td> CTRL-F1 </td><td> 8E </td><td> CTRL-Minus </td></tr>
<tr><td>27 </td><td> ALT-SemiCol </td><td> 5F </td><td> CTRL-F2 </td><td> 8F </td><td> CTRL-Center </td></tr>
<tr><td>28 </td><td> ALT-Quote </td><td> 60 </td><td> CTRL-F3 </td><td> 90 </td><td> CTRL-GreyPlus </td></tr>
<tr><td>29 </td><td> ALT-OpQuote </td><td> 61 </td><td> CTRL-F4 </td><td> 91 </td><td> CTRL-Down </td></tr>
<tr><td>2B </td><td> ALT-BkSlash </td><td> 62 </td><td> CTRL-F5 </td><td> 94 </td><td> CTRL-Tab </td></tr>
<tr><td>2C </td><td> ALT-Z </td><td> 63 </td><td> CTRL-F6 </td><td> 97 </td><td> ALT-Home </td></tr>
<tr><td>2D </td><td> ALT-X </td><td> 64 </td><td> CTRL-F7 </td><td> 98 </td><td> ALT-Up </td></tr>
<tr><td>2E </td><td> ALT-C </td><td> 65 </td><td> CTRL-F8 </td><td> 99 </td><td> ALT-PgUp </td></tr>
<tr><td>2F </td><td> ALT-V </td><td> 66 </td><td> CTRL-F9 </td><td> 9B </td><td> ALT-Left </td></tr>
<tr><td>30 </td><td> ALT-B </td><td> 67 </td><td> CTRL-F10 </td><td> 9D </td><td> ALT-Right </td></tr>
<tr><td>31 </td><td> ALT-N </td><td> 68 </td><td> ALT-F1 </td><td> 9F </td><td> ALT-end </td></tr>
<tr><td>32 </td><td> ALT-M </td><td> 69 </td><td> ALT-F2 </td><td> A0 </td><td> ALT-Down </td></tr>
<tr><td>33 </td><td> ALT-Comma </td><td> 6A </td><td> ALT-F3 </td><td> A1 </td><td> ALT-PgDn </td></tr>
<tr><td>34 </td><td> ALT-Period </td><td> 6B </td><td> ALT-F4 </td><td> A2 </td><td> ALT-Ins </td></tr>
<tr><td>35 </td><td> ALT-Slash </td><td> 6C </td><td> ALT-F5 </td><td> A3 </td><td> ALT-Del </td></tr>
<tr><td>37 </td><td> ALT-GreyAst </td><td> 6D </td><td> ALT-F6 </td><td> A5 </td><td> ALT-Tab </td></tr>
<tr><td>3B </td><td> F1 </td><td> 6E </td><td> ALT-F7 </td><td> </td><td>  </td></tr>
<tr><td>3C </td><td> F2 </td><td> 6F </td><td> ALT-F8 </td><td> </td><td>  </td></tr> 
</table>
<p>
A list of scan codes for special keys and combinations with the SHIFT, ALT
and CTRL keys can be found in the following table: They are for quick reference
only.
</p>
<table border="1">
<caption>Special keys scan codes</caption>
<th><td>Key  </td><td> Code </td><td> SHIFT-Key </td><td> CTRL-Key </td><td> Alt-Key</td></th>
<tr><td>NoKey </td><td> 00 </td><td> </td><td> </td><td> </td></tr>
<tr><td>F1  </td><td> 3B </td><td> 54 </td><td> 5E </td><td> 68 </td></tr>
<tr><td>F2  </td><td> 3C </td><td> 55 </td><td> 5F </td><td> 69 </td></tr>
<tr><td>F3  </td><td> 3D </td><td> 56 </td><td> 60 </td><td> 6A </td></tr>
<tr><td>F4  </td><td> 3E </td><td> 57 </td><td> 61 </td><td> 6B </td></tr>
<tr><td>F5  </td><td> 3F </td><td> 58 </td><td> 62 </td><td> 6C </td></tr>
<tr><td>F6  </td><td> 40 </td><td> 59 </td><td> 63 </td><td> 6D </td></tr>
<tr><td>F7  </td><td> 41 </td><td> 5A </td><td> 64 </td><td> 6E </td></tr>
<tr><td>F8  </td><td> 42 </td><td> 5B </td><td> 65 </td><td> 6F </td></tr>
<tr><td>F9  </td><td> 43 </td><td> 5C </td><td> 66 </td><td> 70 </td></tr>
<tr><td>F10  </td><td> 44 </td><td> 5D </td><td> 67 </td><td> 71 </td></tr>
<tr><td>F11  </td><td> 85 </td><td> 87 </td><td> 89 </td><td> 8B </td></tr>
<tr><td>F12  </td><td> 86 </td><td> 88 </td><td> 8A </td><td> 8C </td></tr>
<tr><td>Home </td><td> 47 </td><td> </td><td> 77 </td><td> 97 </td></tr> 
<tr><td>Up  </td><td> 48 </td><td> </td><td> 8D </td><td> 98 </td></tr>
<tr><td>PgUp </td><td> 49 </td><td> </td><td> 84 </td><td> 99 </td></tr>
<tr><td>Left </td><td> 4B </td><td> </td><td> 73 </td><td> 9B </td></tr>
<tr><td>Center </td><td> 4C </td><td> </td><td> 8F </td><td> </td></tr>
<tr><td>Right </td><td> 4D </td><td> </td><td> 74 </td><td> 9D </td></tr>
<tr><td>end  </td><td> 4F </td><td> </td><td> 75 </td><td> 9F </td></tr>
<tr><td>Down </td><td> 50 </td><td> </td><td> 91 </td><td> A0 </td></tr>
<tr><td>PgDn </td><td> 51 </td><td> </td><td> 76 </td><td> A1 </td></tr>
<tr><td>Ins  </td><td> 52 </td><td> 05 </td><td> 04 </td><td> A2 </td></tr>
<tr><td>Del  </td><td> 53 </td><td> 07 </td><td> 06 </td><td> A3 </td></tr>
<tr><td>Tab  </td><td> 8 </td><td> 0F </td><td> 94 </td><td> A5 </td></tr>
<tr><td>GreyPlus </td><td> </td><td> </td><td> 90 </td><td> 4E </td></tr>
</table>
</descr>
</topic>

<topic name="kbddriver">
<short>Writing a keyboard driver</short>
<descr>
<p>
Writing a keyboard driver means that hooks must be created for most of the 
keyboard unit functions. The <var>TKeyBoardDriver</var> record contains a field
for each of the possible hooks:
</p>
<code>
TKeyboardDriver = Record
  InitDriver : Procedure;
  DoneDriver : Procedure;
  GetKeyEvent : Function : TKeyEvent;
  PollKeyEvent : Function : TKeyEvent;
  GetShiftState : Function : Byte;
  TranslateKeyEvent : Function (KeyEvent: TKeyEvent): TKeyEvent;
  TranslateKeyEventUniCode: Function (KeyEvent: TKeyEvent): TKeyEvent;
end;
</code>
<p>
The meaning of these hooks is explained below:
</p>
<dl>
<dt>InitDriver</dt>
<dd> Called to initialize and enable the driver. 
Guaranteed to be called only once. This should initialize all needed things
for the driver.
</dd>
<dt>DoneDriver</dt>
<dd> Called to disable and clean up the driver. Guaranteed to be
called after a call to <var>initDriver</var>. This should clean up all
things initialized by <var>InitDriver</var>.
</dd>
<dt>GetKeyEvent</dt>
<dd> Called by <link id="GetKeyEvent"/>. Must wait for and return the
next key event. It should NOT store keys.
</dd>
<dt>PollKeyEvent</dt>
<dd> Called by <link id="PollKeyEvent"/>. It must return the next key
event if there is one. Should not store keys. 
</dd>
<dt>GetShiftState</dt>
<dd> Called by <link id="PollShiftStateEvent"/>.  Must return the current
shift state.
</dd>
<dt>TranslateKeyEvent</dt>
<dd> Should translate a raw key event to a cOrrect
key event, i.e. should fill in the shiftstate and convert function key
scancodes to function key keycodes. If the
<var>TranslateKeyEvent</var> is not filled in, a default translation function
will be called which converts the known scancodes from the tables in the
previous section to a correct keyevent.
</dd>
<dt>TranslateKeyEventUniCode</dt>
<dd> Should translate a key event to a unicode key
representation. 
</dd>
</dl>
<p>
Strictly speaking, only the <var>GetKeyEvent</var> and <var>PollKeyEvent</var>
hooks must be implemented for the driver to function correctly. 
</p>
<p>
The example unit demonstrates how a keyboard driver can be installed.
It takes the installed driver, and hooks into the <var>GetKeyEvent</var>
function to register and log the key events in a file. This driver
can work on top of any other driver, as long as it is inserted in the 
<var>uses</var> clause <em> after</em> the real driver unit, and the real driver unit
should set the driver record in its initialization section.
</p>
<p>
Note that with a simple extension of this unit could be used to make a
driver that is capable of recording and storing a set of keyboard strokes,
and replaying them at a later time, so a 'keyboard macro' capable driver.
This driver could sit on top of any other driver.
</p>
</descr>
<example file="kbdex/logkeys"/>
<example file="kbdex/ex9"/>
</topic>

<topic name="kbdunix">
<short>Unix specific notes</short>
<descr>
<p>
On Unix, applications run on a "terminal", and the application writes to the
screen and reads from the keyboard by communicating with the terminal. Unix
keyboard handling is mostly backward compatible with the DEC vt100 and vt220
terminals from tens of years ago. The vt100 and vt220 had very different
keyboards than todays PC's and this is where the problems start. To make it
worse the protocol of both terminals has not been very well designed.
</p><p>
Because of this, the keyboard unit on Unix operating systems does a best effort
to provide keyboard functionality. An implementation with full keyboard
facilities like on other operating systems is not possible.
</p><p>
The exception is the Linux kernel. The terminal emulation of the Linux kernel
is from a PC keyboard viewpoint hopeless as well, but unlike other terminal
emulators it is configurable. On the Linux console, the Free Pascal keyboard
unit tries to implement full functionality.
</p><p>
Users of applications using the keyboard unit should expect the following:
</p>
<ul>
<li>Full functionality on the Linux console. It must be the bare console,
SSH into another machine will kill the full functionality.</li>
<li>Limited functionality otherwise.</li>
</ul>
<p>
Notes about Linux full functionality:
</p>
<ul>
<li>The keyboard is reprogrammed. If the keyboard is for whatever reason not
restored in its original state, please load your keymap to reinitialize it.</li>
<li>Alt+function keys generate keycodes for those keys. To switch virtual
consoles, use ctrl+alt+function key.</li>
<li>Unlike what you're used to with other Unix software, escape works as you
intuitively expect, it generates the keycode for an escape key
<b>without a delay.</b></li>
</ul>
<p>
The limited functionality does include these quirks:
</p>
<ul>
<li>Escape must be pressed two times before it has effect.</li>
<li><p>On the Linux console, when the users runs the program by logging 
   into another machine:
   </p>
  <ul>
  <li>Shift+F1 and Shift+F12 will generate keycodes for F11 and F12.</li>
  <li>Shift+arrow keys, shift+ins, shift+del, shift+home, shift+end do not work.
      The same is true about the control and alt combinations.</li>
  <li>Alt+function keys will switch virtual consoles instead of generating the
      right key sequences.</li>
  <li>Ctrl+function keys will generate the keycodes for the function keys
      without ctrl</li>
  </ul></li>
<li>
  <p>In Xterm:</p>
  <ul>
  <li>Shift+insert pastes the x clipboard, no keycode will be generated.</li>
  </ul></li>
<li>
  <p>In Konsole:</p>
  <ul>
  <li>Shift+insert pastes the x clipboard, no keycode will be generated.</li>
  <li>Shift+arrow keys doesn't work, nor does ctrl+arrow keys</li>
  </ul></li>
</ul>
<p>
If you have a non-standard terminal, some keys may not work at all. When in
limited functionality mode, the user can work around using an escape prefix:
</p>
<ul>
<li>Esc+1 = F1, Esc+2 = F2.</li>
<li>Esc before another key is equal to alt+key.</li>
</ul>
<p>
In such cases, if the terminal does output an escape sequence for those keys,
please submit a bug report so we can add them.
</p>
</descr>
</topic>
<!-- procedure type Visibility: default -->
<element name="Tprocedure">
<short>Procedure prototype</short>
</element>

<!-- pointer type Visibility: default -->
<element name="PTreeElement">
<short>Pointer to <link id="#rtl.keyboard.TTreeElement">TTreeElement</link> record</short>
</element>

<!-- record type Visibility: default -->
<element name="TTreeElement" skip="1">
<short>Tree element</short>
<descr>
<var>TTreeELement</var> is used to describe key scancode sequences, and is
used to handle special key combinations in <link id="AddSpecialSequence"/>
on unix platforms. There should be no need to handle records of this type.
</descr>
<seealso>
<link id="AddSpecialSequence"/>
</seealso>
</element>

<!-- variable Visibility: default -->
<element name="TTreeElement.Next">
<short>Reference to next scancode in the tree</short>
</element>

<!-- variable Visibility: default -->
<element name="TTreeElement.Parent">
<short>Reference to parent scancode in the tree</short>
</element>

<!-- variable Visibility: default -->
<element name="TTreeElement.Child">
<short>Reference to child scancode in the tree</short>
</element>

<!-- variable Visibility: default -->
<element name="TTreeElement.CanBeTerminal">
<short>This scancode is possibly the last of a sequence scancode</short>
</element>

<!-- variable Visibility: default -->
<element name="TTreeElement.char">
<short>Key Character</short>
</element>

<!-- variable Visibility: default -->
<element name="TTreeElement.ScanValue">
<short>Key scancode</short>
</element>

<!-- variable Visibility: default -->
<element name="TTreeElement.CharValue">
<short>Character value for scancode</short>
</element>

<!-- variable Visibility: default -->
<element name="TTreeElement.SpecialHandler">
<short>Procedure to handle this sequence</short>
</element>

<!-- function Visibility: default -->
<element name="AddSpecialSequence" skip="1">
<short>Add a handler for a special key sequence</short>
<descr>
<var>AddSpecialSequence</var> adds a sequence of key combinations to the
keyboard handler. When the key combination specified in <var>st</var>
is encountered, then <var>Proc</var> will be executed. The function returns
the element in the special key sequence handling tree which handles
<var>st</var>.
</descr>
<seealso>
<link id="AddSequence"/>
</seealso>
</element>

</module>
</package>
</fpdoc-descriptions>