BrlAPI: Entering & leaving tty mode

BrlAPI 0.8

Macros | Functions
Entering & leaving tty mode

How to take control of ttys for direct braille display / read. More...

## Macros
#define | BRLAPI_TTY_DEFAULT -1

## Functions
int BRLAPI_STDCALL | brlapi_enterTtyMode (int tty, const char *driver)
int BRLAPI_STDCALL | brlapi__enterTtyMode (brlapi_handle_t *handle, int tty, const char *driver)
int BRLAPI_STDCALL | brlapi_enterTtyModeWithPath (const int *ttys, int count, const char *driver)
int BRLAPI_STDCALL | brlapi__enterTtyModeWithPath (brlapi_handle_t *handle, const int *ttys, int count, const char *driver)
int BRLAPI_STDCALL | brlapi_leaveTtyMode (void)
int BRLAPI_STDCALL | brlapi__leaveTtyMode (brlapi_handle_t *handle)
int BRLAPI_STDCALL | brlapi_setFocus (int tty)
int BRLAPI_STDCALL | brlapi__setFocus (brlapi_handle_t *handle, int tty)

## Detailed Description

Before being able to write on the braille display, the application must tell the server which tty it will handle.

The application must also specify how braille keys will be delivered to it. Two ways are possible:

- driver-specific keycodes: applications will get values specific to each braille driver, since the keycode, as defined in the driver will be given for each key event (press or release). Using them leads to building highly driver-dependent applications, which can yet sometimes be useful to mimic existing proprietary applications for instance.
- commands: applications will get exactly the same values as brltty. This allows driver-independent clients, which will hopefully be nice to use with a lot of different terminals.
  See also
    brlapi_readKey()

## Macro Definition Documentation

## ◆ BRLAPI_TTY_DEFAULT

#define BRLAPI_TTY_DEFAULT -1

Select the default tty.

The library takes the following steps:

1. Try to get the tty number from the `WINDOWID` environment variable (for the `xterm` case).
2. Try to get the tty number from the `CONTROLVT` environment variable.
3. Read `/proc/self/stat` (on `Linux`).

See also
  brlapi_enterTtyMode()

## Function Documentation

## ◆ brlapi__enterTtyMode()

int BRLAPI_STDCALL brlapi__enterTtyMode | ( | brlapi_handle_t * | handle,
|  | int | tty,
|  | const char * | driver )

## ◆ brlapi__enterTtyModeWithPath()

int BRLAPI_STDCALL brlapi__enterTtyModeWithPath | ( | brlapi_handle_t * | handle,
|  | const int * | ttys,
|  | int | count,
|  | const char * | driver )

## ◆ brlapi__leaveTtyMode()

int BRLAPI_STDCALL brlapi__leaveTtyMode | ( | brlapi_handle_t * | handle | ) |

## ◆ brlapi__setFocus()

int BRLAPI_STDCALL brlapi__setFocus | ( | brlapi_handle_t * | handle,
|  | int | tty )

## ◆ brlapi_enterTtyMode()

int BRLAPI_STDCALL brlapi_enterTtyMode | ( | int | tty,
|  | const char * | driver )

Ask for some tty, with some key mechanism

Parameters

  tty | If tty>=0 then take control of the specified tty. If tty==BRLAPI_TTY_DEFAULT then take control of the default tty.
  driver | tells how the application wants brlapi_readKey() to return key presses. NULL or "" means BRLTTY commands are required, whereas a driver name means that driver-specific keycodes are expected.

Returns
  the used tty number on success, -1 on error

WINDOWPATH and WINDOWID should be propagated when running remote applications via ssh, for instance, along with BRLAPI_HOST and the authorization key (see SendEnv in ssh_config(5) and AcceptEnv in sshd_config(5))

Once brlapi_enterTtyMode() is called, brlapi_leaveTtyMode() has to be called before calling brlapi_enterTtyMode() again.

If the application does not want to take control of a particular tty, but keep control on all ttys, brlapi_enterTtyModeWithPath should be called instead with nttys equal to 0. This is usually what a screen reader wants to use.

TODO: document which functions work in TTY mode only.

See also
  brlapi_leaveTtyMode() brlapi_readKey()

## ◆ brlapi_enterTtyModeWithPath()

int BRLAPI_STDCALL brlapi_enterTtyModeWithPath | ( | const int * | ttys,
|  | int | count,
|  | const char * | driver )

Ask for some tty specified by its path in the tty tree, with some key mechanism

Parameters

  ttys | points on the array of ttys representing the tty path to be got. Can be NULL if nttys is 0.
  count | gives the number of elements in ttys.
  driver | has the same meaning as in brlapi_enterTtyMode()

Providing nttys == 0 means to get the root, which is usually what a screen readers wants to use.

The content of WINDOWPATH or XDG_VTNR will always be prepended to the given `ttys` array, so the application does not need to determine by itself where it is running.

Returns
  0 on success, -1 on error.

See also
  brlapi_enterTtyMode()

## ◆ brlapi_leaveTtyMode()

int BRLAPI_STDCALL brlapi_leaveTtyMode | ( | void |  | ) |

Stop controlling the tty

Returns
  0 on success, -1 on error.

See also
  brlapi_enterTtyMode()

## ◆ brlapi_setFocus()

int BRLAPI_STDCALL brlapi_setFocus | ( | int | tty | ) |

Tell the current tty to brltty

This is intended for focus tellers, such as brltty, xbrlapi, screen, ... brlapi_enterTtyMode() must have been called beforehand to tell where this focus applies in the tty tree.

Returns
  0 on success, -1 on error.

See also
  brlapi_enterTtyMode() brlapi_leaveTtyMode()