1Writing on the braille display(3) BrlAPI Writing on the braille display(3)
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6 Writing on the braille display - Write text to the braille display.
7 Data Structures
10 struct brlapi_writeArguments_t
11 Defines
13 #define BRLAPI_DISPLAY_DEFAULT -1
14 #define BRLAPI_CURSOR_LEAVE -1
15 #define BRLAPI_CURSOR_OFF 0
16 #define BRLAPI_WRITEARGUMENTS_INITIALIZER { BRLAPI_DISPLAY_DEFAULT,
17 0, 0, NULL, -1, NULL, NULL, BRLAPI_CURSOR_LEAVE, NULL }
18 Functions
20 int BRLAPI_STDCALL brlapi_writeText (int cursor, const char *text)
21 int BRLAPI_STDCALL brlapi__writeText (brlapi_handle_t *handle, int
22 cursor, const char *text)
23 int BRLAPI_STDCALL brlapi_writeDots (const unsigned char *dots)
24 int BRLAPI_STDCALL brlapi__writeDots (brlapi_handle_t *handle, const
25 unsigned char *dots)
26 int BRLAPI_STDCALL brlapi_write (const brlapi_writeArguments_t
27 *arguments)
28 int BRLAPI_STDCALL brlapi__write (brlapi_handle_t *handle, const
29 brlapi_writeArguments_t *arguments)
30
32 After brlapi_enterTtyMode() has been called, the application can call
33 one of these functions to write things on the braille display.
34 Note:
36 Be sure to call brlapi_enterTtyMode() before calling
37 brlapi_write(), or else you'll get an error. This is particularly
38 not always trivial when writing multithreaded applications.
39 Dots are coded as described in ISO/TR 11548-1: a dot pattern is
41 coded by a byte in which bit 0 is set iff dot 1 is up, bit 1 is set
42 iff dot 2 is up, ... bit 7 is set iff dot 8 is up. This also
43 corresponds to the low-order byte of the coding of unicode's
44 braille row U+2800.
45 Text is translated by the server one to one, by just using a simple
47 wchar_t to pattern table, i.e. no contraction/expansion is
48 performed, because the client would then have no way to know how
49 wide the output would be and thus the quantity of text to feed. If
50 contraction/expansion is desired, the client should perform it
51 itself (e.g. thanks to liblouis or gnome-braille) and send the
52 resulting dot patterns. This is actually exactly the same problem
53 as font rendering on a graphical display: for better control,
54 nowadays all font rasterization is performed on the client side,
55 and mere pixmaps are sent to the X server.
56
58 #define BRLAPI_CURSOR_LEAVE -1
59 Do not change the cursor's state or position.
60 See also:
62 brlapi_writeText() brlapi_write() brlapi_writeArguments_t
63 #define BRLAPI_CURSOR_OFF 0
65 Do not display the cursor.
66 See also:
68 brlapi_writeText() brlapi_write() brlapi_writeArguments_t
69 #define BRLAPI_DISPLAY_DEFAULT -1
71 Write to the default display on the braille device.
72 See also:
74 brlapi_write() brlapi_writeArguments_t
75 #define BRLAPI_WRITEARGUMENTS_INITIALIZER { BRLAPI_DISPLAY_DEFAULT, 0, 0,
77 NULL, -1, NULL, NULL, BRLAPI_CURSOR_LEAVE, NULL }
78 Allows to initialize a structure of type brlapi_writeArguments_t * with
79 default values: displayNumber = BRLAPI_DISPLAY_DEFAULT; (unspecified)
80 regionBegin = regionSize = 0; (update the whole display, DEPRECATED and
81 will be forbidden in next release. You must always express the region
82 you wish to update) text = andMask = orMask = NULL; (no text, no
83 attribute) cursor = BRLAPI_CURSOR_LEAVE; (don't touch cursor)
84
86 int BRLAPI_STDCALL brlapi__write (brlapi_handle_t * handle, const
87 brlapi_writeArguments_t * arguments)
88 int BRLAPI_STDCALL brlapi__writeDots (brlapi_handle_t * handle, const
89 unsigned char * dots)
90 int BRLAPI_STDCALL brlapi__writeText (brlapi_handle_t * handle, int cursor,
91 const char * text)
92 int BRLAPI_STDCALL brlapi_write (const brlapi_writeArguments_t * arguments)
93 Update a specific region of the braille display and apply and/or masks
94 Parameters:
96 arguments gives information necessary for the update
97 regionBegin and regionSize must be filled for specifying which part of
99 the display will be updated, as well as the size (in characters, not
100 bytes) of the text, andMask and orMask members.
101 If given, the 'text' field holds the text that will be displayed in the
103 region. The char string must hold exactly as many characters as the
104 region fields express. For multibyte text, this is the number of
105 multibyte caracters. Notably, combining and double-width caracters
106 count for 1.
107 The actual length of the text in bytes may be specified thanks to
109 textSize. If -1 is given, it will be computed thanks to strlen(), so
110 'text' must then be a NUL-terminated string.
111 The 'andMask' and 'orMask' masks, if present, are then applied on top
113 of the text, one byte per character. This hence permits the
114 superimposing of attributes over the text. For instance, setting an
115 andMask mask full of BRLAPI_DOTS(1,1,1,1,1,1,0,0) will only keep
116 (logical AND) dots 1-6, hence dropping dots 7 and 8. On the contrary,
117 setting an orMask full of BRLAPI_DOT7|BRLAPI_DOT8 will add (logical OR)
118 dots 7 and 8.
119 The 'charset' field, if present, specifies the charset of the 'text'
121 field. If it is '', the current locale's charset (if any) is assumed.
122 Else, the 8-bit charset of the server is assumed.
123 A special invocation is with an unmodified initialized structure: this
125 clears the client's whole display, letting the display of other
126 applications on the same tty or of applications 'under' the tty appear.
127 See Concurrency management section of the BrlAPI documentation for more
128 details.
129 Returns:
131 0 on success, -1 on error.
132 int BRLAPI_STDCALL brlapi_writeDots (const unsigned char * dots)
134 Write the given dots array to the display
135 Parameters:
137 dots points on an array of dot information, one per character. Its
138 size must hence be the same as what brlapi_getDisplaySize()
139 returns.
140 Returns:
142 0 on success, -1 on error.
143 int BRLAPI_STDCALL brlapi_writeText (int cursor, const char * text)
145 Write the given \0-terminated string to the braille display
146 If the string is too long, it is cut. If it's too short, spaces are
148 appended. The current LC_CTYPE locale is considered, unless it is left
149 as default 'C', in which case the charset is assumed to be 8bits, and
150 the same as the server's.
151 Parameters:
153 cursor gives the cursor position; if equal to BRLAPI_CURSOR_OFF, no
154 cursor is shown at all; if cursor==BRLAPI_CURSOR_LEAVE, the cursor
155 is left where it is
156 text points to the string to be displayed.
157 Returns:
159 0 on success, -1 on error.
160Version 1.0 7 Oct 2009 Writing on the braille display(3)