NAME
Writing on the braille display -
Write text to the braille display.
Data Structures
struct brlapi_writeArguments_t
Defines
#define BRLAPI_DISPLAY_DEFAULT -1
#define BRLAPI_CURSOR_LEAVE -1
#define BRLAPI_CURSOR_OFF 0
#define BRLAPI_WRITEARGUMENTS_INITIALIZER { BRLAPI_DISPLAY_DEFAULT,
0, 0, NULL, -1, NULL, NULL, BRLAPI_CURSOR_LEAVE, NULL }
Functions
int BRLAPI_STDCALL brlapi_writeText (int cursor, const char *text)
int BRLAPI_STDCALL brlapi__writeText (brlapi_handle_t *handle, int
cursor, const char *text)
int BRLAPI_STDCALL brlapi_writeDots (const unsigned char *dots)
int BRLAPI_STDCALL brlapi__writeDots (brlapi_handle_t *handle, const
unsigned char *dots)
int BRLAPI_STDCALL brlapi_write (const brlapi_writeArguments_t
*arguments)
int BRLAPI_STDCALL brlapi__write (brlapi_handle_t *handle, const
brlapi_writeArguments_t *arguments)
Detailed Description
After brlapi_enterTtyMode() has been called, the application can call
one of these functions to write things on the braille display.
Note:
Be sure to call brlapi_enterTtyMode() before calling
brlapi_write(), or else you'll get an error. This is particularly
not always trivial when writing multithreaded applications.
Dots are coded as described in ISO/TR 11548-1: a dot pattern is
coded by a byte in which bit 0 is set iff dot 1 is up, bit 1 is set
iff dot 2 is up, ... bit 7 is set iff dot 8 is up. This also
corresponds to the low-order byte of the coding of unicode's
braille row U+2800.
Text is translated by the server one to one, by just using a simple
wchar_t to pattern table, i.e. no contraction/expansion is
performed, because the client would then have no way to know how
wide the output would be and thus the quantity of text to feed. If
contraction/expansion is desired, the client should perform it
itself (e.g. thanks to liblouis or gnome-braille) and send the
resulting dot patterns. This is actually exactly the same problem
as font rendering on a graphical display: for better control,
nowadays all font rasterization is performed on the client side,
and mere pixmaps are sent to the X server.
Define Documentation
#define BRLAPI_CURSOR_LEAVE -1 Do not change the cursor's state or
position.
See also:
brlapi_writeText() brlapi_write() brlapi_writeArguments_t
#define BRLAPI_CURSOR_OFF 0 Do not display the cursor.
See also:
brlapi_writeText() brlapi_write() brlapi_writeArguments_t
#define BRLAPI_DISPLAY_DEFAULT -1 Write to the default display on the
braille device.
See also:
brlapi_write() brlapi_writeArguments_t
#define BRLAPI_WRITEARGUMENTS_INITIALIZER { BRLAPI_DISPLAY_DEFAULT, 0, 0,
NULL, -1, NULL, NULL, BRLAPI_CURSOR_LEAVE, NULL } Allows to initialize
a structure of type brlapi_writeArguments_t * with default values:
displayNumber = BRLAPI_DISPLAY_DEFAULT; (unspecified) regionBegin =
regionSize = 0; (update the whole display, DEPRECATED and will be
forbidden in next release. You must always express the region you wish
to update) text = andMask = orMask = NULL; (no text, no attribute)
cursor = BRLAPI_CURSOR_LEAVE; (don't touch cursor)
Function Documentation
int BRLAPI_STDCALL brlapi__write (brlapi_handle_t * handle, const
brlapi_writeArguments_t * arguments)
int BRLAPI_STDCALL brlapi__writeDots (brlapi_handle_t * handle, const
unsigned char * dots)
int BRLAPI_STDCALL brlapi__writeText (brlapi_handle_t * handle, int cursor,
const char * text)
int BRLAPI_STDCALL brlapi_write (const brlapi_writeArguments_t * arguments)
Update a specific region of the braille display and apply and/or masks
Parameters:
arguments gives information necessary for the update
regionBegin and regionSize must be filled for specifying which part of
the display will be updated, as well as the size (in characters, not
bytes) of the text, andMask and orMask members.
If given, the 'text' field holds the text that will be displayed in the
region. The char string must hold exactly as many characters as the
region fields express. For multibyte text, this is the number of
multibyte caracters. Notably, combining and double-width caracters
count for 1.
The actual length of the text in bytes may be specified thanks to
textSize. If -1 is given, it will be computed thanks to strlen(), so
'text' must then be a NUL-terminated string.
The 'andMask' and 'orMask' masks, if present, are then applied on top
of the text, one byte per character. This hence permits the
superimposing of attributes over the text. For instance, setting an
andMask mask full of BRLAPI_DOTS(1,1,1,1,1,1,0,0) will only keep
(logical AND) dots 1-6, hence dropping dots 7 and 8. On the contrary,
setting an orMask full of BRLAPI_DOT7|BRLAPI_DOT8 will add (logical OR)
dots 7 and 8.
The 'charset' field, if present, specifies the charset of the 'text'
field. If it is '', the current locale's charset (if any) is assumed.
Else, the 8-bit charset of the server is assumed.
A special invocation is with an unmodified initialized structure: this
clears the client's whole display, letting the display of other
applications on the same tty or of applications 'under' the tty appear.
See Concurrency management section of the BrlAPI documentation for more
details.
Returns:
0 on success, -1 on error.
int BRLAPI_STDCALL brlapi_writeDots (const unsigned char * dots) Write the
given dots array to the display
Parameters:
dots points on an array of dot information, one per character. Its
size must hence be the same as what brlapi_getDisplaySize()
returns.
Returns:
0 on success, -1 on error.
int BRLAPI_STDCALL brlapi_writeText (int cursor, const char * text) Write
the given -terminated string to the braille display
If the string is too long, it is cut. If it's too short, spaces are
appended. The current LC_CTYPE locale is considered, unless it is left
as default 'C', in which case the charset is assumed to be 8bits, and
the same as the server's.
Parameters:
cursor gives the cursor position; if equal to BRLAPI_CURSOR_OFF, no
cursor is shown at all; if cursor==BRLAPI_CURSOR_LEAVE, the cursor
is left where it is
text points to the string to be displayed.
Returns:
0 on success, -1 on error.
Author
Generated automatically by Doxygen for BrlAPI from the source code.
Version 1.0 Wed Aug 11 20Writing on the braille display(3)