Entering & leaving tty mode(3)

NAME
Entering & leaving tty mode - How to take control of ttys for direct braille display / read.

  Defines
#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 (int *ttys, int count, const char *driver)
int BRLAPI_STDCALL brlapi__enterTtyModeWithPath (brlapi_handle_t *handle, 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: key codes and commands:

•   key codes are specific to each braille driver, since the raw key code, as defined in the driver will be given for each key press. Using them leads to building highly driver-dependent applications, which can yet sometimes be useful to mimic existing proprietary applications for instance.

•   commands means that 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()

Define Documentation

  #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

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

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

  int BRLAPI_STDCALL brlapi__leaveTtyMode (brlapi_handle_t * handle)

  int BRLAPI_STDCALL brlapi__setFocus (brlapi_handle_t * handle, int tty)

  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 raw key codes returned by this driver are expected.

In an X window environment, WINDOWPATH might be useful. XFree86 >=4.4 defines an XFree86_VT root window property which exactly holds the used VT, so that it should be given to brlapi_enterTtyMode. If it isn't available, one may, right into .xsession and .xinitrc, grep X's log, for instance:

WINDOWPATH='$(grep 'using VT number' '/var/log/Xorg.$(echo '$DISPLAY' | sed -e 's/^.*::*\([0-9]*\).*$/\1/').log' | sed -e 's/^.*using VT number \([0-9]*\).*$/\1/')'

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))

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

See also:
    brlapi_leaveTtyMode() brlapi_readKey()

  int BRLAPI_STDCALL brlapi_enterTtyModeWithPath (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.

See also:
    brlapi_enterTtyMode()

  int BRLAPI_STDCALL brlapi_leaveTtyMode (void)

Stop controlling the tty

Returns:
    0 on success, -1 on error.

See also:
    brlapi_enterTtyMode()

  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()

Author

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