source: vbox/trunk/src/VBox/RDP/client/doc/keymapping.txt@ 8497

Keyboard mapping
================
This release of rdesktop uses a new, portable keyboard mapping
implementation. It should hopefully work on all X11 systems. This new
implementation only looks at X11 keysyms: Not on (nonportable)
keycodes or modifier status. This means that rdesktop will obey your
local keyboard configuration. For example, if you have swapped
CapsLock and Control, rdesktop will use this mapping. 

XKB is currently not used. It seems like a good idea to me, but since
some X servers (like Xvnc) does not support XKB, we still need to use
the plain old interface as well, at least. 

There are still some small problems.

* CapsLock: CapsLock changes are never sent to the RDP
  server. rdesktop does not know which keys that are modified by
  CapsLock and which are not. So, the CapsLock indicator in Wordpad
  etc will always be off.

Composing/Multi_key is supported. For more information, see:

  MIT:              $SRC/xc/nls/X11/locale/Compose/iso8859-1
  XFree86:          /usr/X11R6/lib/X11/locale/*/Compose
  Solaris' Openwin: /usr/openwin/include/X11/Suncompose.h
                    /usr/openwin/lib/locale/*/Compose
  Irix6:            compose(5)


Keymap files
============
The names of the keymaps follows RFC1766. 

(You can find a translation from Windows keyboard layout numbers to
keymap names by looking at
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\MIME\Database\RFC1766 in the
registry.)


Contents of keymap files
========================
The keymaps are line based. There are four different types of lines:

1) include lines
Syntax:
include <another-map-file>

Example:
include common


2) map lines
Syntax:
map <hex-number>

Example:
map 0x41d

Map-lines specifies how the remote RDP server should interpret the
sent scancodes. 


3) Translation lines
Syntax:
<keysym-name> <scancode> [flags..]

Example:
onehalf 0x29 shift

The scancode can be found in scancodes.h. Note: The scancode value for
extended keys can be calculated by OR:ing with 0x80. Example: The
Delete key have the scancode sequence 0xe0, 0x52. You can get the
scancode value to put into the map file by running:

python -c "print hex(0x80 | 0x52)"

If flags are "altgr", "shift", the scancode sent for this keysym will
be prefixed with AltGr, or Shift.

If flags includes "addupper", a translation for this keysyms uppercase
name will be added as well, in addition to the non-uppercase
name. Example:

x 2d addupper

...will add an translation for "X" automatically, just like if you
would specify:

X 2d shift

If flags include "localstate", the modifier to send will be determined
by the local modifier state. 

If flags is "inhibit", nothing will be sent to the server. 

If flags is "numlock", rdesktop will make sure that the remote NumLock
state is on before generating the key event. Otherwise, it will make
sure NumLock is off.


4) enable_compose

If any line starts with the keyword "enable_compose", rdesktop will
enable local Compose/Multi_key handling. Enabling this will often make
it impossible to compose characters with dead keys (on the remote
side). This is because when local compose support is enabled, dead
keys will not be sent to the remote side. 


5) sequence lines
Syntax:
sequence <event-keysym-name> <keysym-name1> <keysym-name2> ...

Examples:
sequence eacute dead_acute e
sequence F12 f o o at e x a m p l e period c o m

Sequence lines allows you to specify that multiple scancodes should be
sent to the RDP server, in response to one X11 keyboard event. Note:
The sequence is sent at the X11 KeyPress event. Nothing is sent at
KeyRelease.


6) keyboard_type lines
Syntax:
keyboard_type <hex-number>
 
keyboard_type lines specifies the keyboard type. Default value is 0x4
(en-us 101/104 keys keyboard).


7) keyboard_subtype lines
Syntax:
keyboard_subtype <hex-number>

keyboard_subtype lines specifies the keyboard subtype. Default value
is 0x0 (en-us 101/104 keys keyboard).


8) keyboard_functionkeys lines
Syntax:
keyboard_functionkeys <hex-number>

keyboard_functionkeys specifies the number of keyboard function
keys. Default value is 0xc (12, for standard 101/104 keys keyboard).




Suggested X11 keysym mapping on PCs
===================================
Unfortunately, there is no standard for which keysyms a given key
should generate. If you have a PC-keyboard with Windows keys, I suggest this mapping:

Keyboard keys:
CtrlLeft WinLeft AltLeft Space AltGr WinRight Menu CtrlRight

...should generate keysyms:
Control_L Super_L Alt_L space Mode_switch Super_R Menu Control_R

Additionally:
Shift-Alt should produce Meta_L
Shift-AltGr should produce Multi_Key. 

Use a modifier-map like this:

shift       Shift_L (0x32),  Shift_R (0x3e)
lock        Caps_Lock (0x25)
control     Control_L (0x42),  Control_R (0x6d)
mod1        Alt_L (0x40)
mod2        Num_Lock (0x4d)
mod3        Mode_switch (0x71)
mod4        Super_L (0x73),  Super_R (0x74)
mod5        Scroll_Lock (0x4e)


Updating / writing keymap files
===============================
When writing new or updating keymap files, please use comments and
blanks, to increase readability. The "sv" keymap is a good template. 

When you need to add a translation to a keymap file, do:

    1. Get the "key number" for this key, by looking at keynums.png. 

    2. Take a look at scancodes.h, and look for
    SCANCODE_KEY_<my-key-number>. The scancode value is at the end of
    the line. If the line contains (SCANCODE_EXTENDED | 0xsomething),
    then you should OR 0x80 to this value. For example, you can do:
    
    python -c "print hex(0x80 | 0xsomething)"

    3. Put the scancode (from step 2) and keysym name (found in the
    error message) into the keymap file. 


Special keys
============

* The combination Ctrl-Alt-Enter toggles between fullscreen and
  non-fullscreen mode. 

* Meta, Hyper and Super are treated as windows keys. RDP4 does not
  support the windows keys though, so if you are running RDP4, these
  keys will translate to Ctrl-Esc. 


Links
=====
http://www.win.tue.nl/~aeb/linux/kbd/scancodes.html


Test cases
==========
When changing the keyboard code, make sure all these tests in Notepad
works:

1. Ctrl+f should bring up Find dialog, with CapsLock both on and off. 

2. Ctrl+Shift+arrows should mark text, with CapsLock both on and off. 

3. Test a sequence, like egrave. 

4. Test a char generated with AltGr, such as @ on a swedish keyboard. 

5. Test Ctrl-Alt-Delete. 

6. Ctrl-Alt-Enter should toggle fullscreen. 

7. Test NumLock synchronization using the -N option. Excel is able to
   indicate the current NumLock state. Verify that the status is
   updated correctly on reconnects. 

8. Test the Windows keys, standalone as well as in combination with,
   say, E.

9. Make sure the system menu (via Alt-space) cannot be accessed in
   single app mode.

10. Make sure keymaps can be loaded from ~/.rdesktop/keymaps,
    KEYMAP_PATH, $CWD/keymaps, and from an absolute path.