Unit Keymap

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Description

Keymaps

Keymaps define the translation of a keyboard scan code (the SCAN_CODE_* values) to a key code value (the KEY_CODE_* values) and provide the ability to handle different keyboard layouts in different countries and regions.

The keyboard scan codes are based on the values in Section 10 of the Universal Serial Bus HID Usage Tables v1.12 and are the actual values returned by the keyboard when a key is pressed.

The key code values are based on the Unicode standard with each key code mapped to the code point for that character.

This allows almost infinite flexibility in the way keyboard scan codes are mapped to actual characters and avoids the need to make unreliable assumptions about ASCII characters and upper or lower case handling.

Since the output of the keyboard is a stream of TKeyboardData structures containing both the scan code and the key code then higher level functions can retranslate the data in any way required.

Caps Keys

Caps keys account for the set of keys which are affected by Caps Lock in any given keyboard layout.

In some layouts only the alphabetic keys are affected, in other layouts some or all of the numeric and punctuation keys are also affected.

The caps keys data for any keyboard layout allows defining ranges of keys that are affected by the Caps Lock state.

Dead Keys

Dead keys account for the set of keys which behave as dead keys in any given keyboard layout.

On pressing a deadkey it will be recognized by the keyboard as such and stored until the next key press occurs. If the next keypress is one of the resolves for the pressed dead key then theoutput character will be the key code value of the resolve not for the key itself.

If the next keypress after a dead key is not one of the resolves that the dead key and the pressed key will both be output to the keyboard buffer.

Setting the default keymap for the system

Additional keymaps are provided as units which can be included in a program and will auto load themselves if included.

All keymap units are configured to check for both the environment variable KEYMAP_DEFAULT and the global configuration variable KEYMAP_DEFAULT to determine if either of them is set to the name of that keymap. If either is set to the keymap name then that keymap will also set itself as the default during system startup.

The environment variable KEYMAP_DEFAULT can be set by adding KEYMAP_DEFAULT=XX (where XX is the name of the keymap, eg DE for Keymap_DE) to the command line of the application (dependant onthe system, for a Raspberry Pi use the cmdline.txt file on the SD card).

The global configuration variable KEYMAP_DEFAULT can be set in code by including the GlobalConfig unit in a program and setting the variable during startup.

At any time after startup the default keymap can be changed by call the KeymapSetDefault function.

Constants

To be documented

Type definitions

To be documented

Public variables

To be documented

Function declarations


Initialization functions 

procedure KeymapInit;
Description: Initialize the keymap unit, keymap table and default keymap
Note Called only during system startup


Keymap functions 

function KeymapLoad(Header:PKeymapHeader; Data:PKeymapData; Size:LongWord):TKeymapHandle;
Description: Load a Keymap from a keymap data block and add to the Keymap table
Header Pointer to the keymap header
Data Pointer to the keymap data
Size Size of the keymap data
Return Handle of the newly loaded keymap or INVALID_HANDLE_VALUE on failure 


function KeymapLoadEx(Header:PKeymapHeader; Data:PKeymapData; Capskeys:PKeymapCapskeys; Deadkeys:PKeymapDeadkeys; Size:LongWord; Properties:PKeymapProperties):TKeymapHandle;
Description: Load a Keymap from a keymap data block and add to the Keymap table
Header Pointer to the keymap header (See TKeymapHeader)
Data Pointer to the keymap data (See TKeymapData)
Capskeys Pointer to the capskeys table (Optional)
Deadkeys Pointer to the deadkeys table (Optional)
Size Size of the keymap data
Properties Pointer to a keymap properties record to use instead of the header (Optional)
Return Handle of the newly loaded keymap or INVALID_HANDLE_VALUE on failure 


function KeymapUnload(Handle:TKeymapHandle):LongWord;
Description: Unload an existing keymap and remove from the Keymap table
Handle The handle of the keymap to unload
Return ERROR_SUCCESS if completed or another error code on failure 


function KeymapGetName(Handle:TKeymapHandle):String;
Description: Get the name of the specified keymap
Handle The handle of the keymap to get the name for
Return The name of the keymap (eg US) 


function KeymapGetDescription(Handle:TKeymapHandle):String;
Description: Get the description of the specified keymap
Handle The handle of the keymap to get the description for
Return The description of the keymap (eg US English) 


function KeymapCheckFlag(Handle:TKeymapHandle; Flag:LongWord):Boolean;
Description: Check if a specified keymap has a particular flag set or not
Handle The handle of the keymap to check the flag for
Flag The flag value to check (eg KEYMAP_FLAG_CAPS_ASCII)
Return True if the flag is set and False if not set 


function KeymapGetKeyCode(Handle:TKeymapHandle; ScanCode:Word; Index:Byte):Word;
Description: Resolve a scan code and index value to a key code using the specified keymap
Handle The handle of the keymap to use for translation
ScanCode The keyboard scan code value to resolve (eg SCAN_CODE_A)
Index The keymap index to use for the translation (eg KEYMAP_INDEX_SHIFT)
Return The translated key code value (eg KEY_CODE_A) or KEY_CODE_NONE on failure 


function KeymapGetCharCode(Handle:TKeymapHandle; KeyCode:Word):Char;
Description: Resolve a key code value to an ANSI character code using the specified keymap
Handle The handle of the keymap to use for translation
KeyCode The key code value to resolve (eg KEY_CODE_A)
Return The ANSI character value for the keycode or 0 on failure 


function KeymapGetCharUnicode(Handle:TKeymapHandle; KeyCode:Word):WideChar;
Description: Resolve a key code value to a Unicode character code using the specified keymap
Handle The handle of the keymap to use for translation
KeyCode The key code value to resolve (eg KEY_CODE_A)
Return The Unicode character value for the keycode or 0 on failure 


function KeymapCheckCapskey(Handle:TKeymapHandle; ScanCode:Word):Boolean;
Description: Check if a scan code is affected by the Caps Lock key in the specified keymap
Handle The handle of the keymap to check
ScanCode The scan code value to check (eg SCAN_CODE_A)
Return True if affected by Caps Lock, False if not 


function KeymapCheckDeadkey(Handle:TKeymapHandle; ScanCode:Word; Index:Byte):Boolean;
Description: Check if a scan code represents a Dead Key in the specified keymap
Handle The handle of the keymap to check
ScanCode The scan code value to check (eg SCAN_CODE_A)
Index The keymap index to check (eg KEYMAP_INDEX_SHIFT)
Return True if the scan key is a Dead Key, False if not 


function KeymapResolveDeadkey(Handle:TKeymapHandle; DeadCode,ScanCode:Word; DeadIndex,ScanIndex:Byte; var KeyCode:Word):Boolean;
Description: Resolve a Dead Key and the next scan code to a key code value
Handle The handle of the keymap to use for resolution
DeadCode The scan code value of the dead key (eg SCAN_CODE_GRAVE)
ScanCode The scan code value of the next key (eg (SCAN_CODE_A)
DeadIndex The keymap index of the dead key (eg KEYMAP_INDEX_SHIFT)
ScanIndex The keymap index of the next key (eg KEYMAP_INDEX_SHIFT)
KeyCode Return value for the key code represented by the dead key / next key combination (or KEY_CODE_NONE)
Return True if the dead key / next key combination resolves to a key code or False if not 


function KeymapGetProperties(Handle:TKeymapHandle; Properties:PKeymapProperties):LongWord;
Description: Get the properties of the specified keymap
Handle The handle of the keymap to get the properties for
Properties Pointer to a keymap properties structure to return the properties
Return ERROR_SUCCESS if completed or another error code on failure 


function KeymapFindByName(const Name:String):TKeymapHandle;
Description: Find a keymap by name
Name The name of the keymap to find (eg US)
Return The handle of the matching keymap or INVALID_HANDLE_VALUE if not found 


function KeymapFindByDescription(const Description:String):TKeymapHandle;
Description: Find a keymap by description
Description The description of the keymap to find (eg US English)
Return The handle of the matching keymap or INVALID_HANDLE_VALUE if not found 


function KeymapEnumerate(Callback:TKeymapEnumerate; Data:Pointer):LongWord;
Description: Enumerate all loaded keymaps
Callback The function to call for each loaded keymap
Data A private data pointer to pass to callback for each loaded keymap


Keymap helper functions 

function KeymapGetCount:LongWord; inline;
Description: Get the current keymap count
Note To be documented 


function KeymapGetDefault:TKeymapHandle; inline;
Description: Get the current default keymap
Note To be documented 


function KeymapSetDefault(Handle:TKeymapHandle):LongWord;
Description: Set the current default keymap
Note To be documented 


function KeymapCheck(Keymap:PKeymapEntry):PKeymapEntry;
Description: Check if the supplied Keymap is in the Keymap table
Note To be documented


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