form_driver(3X)

NAME
form_driver - command-processing loop of the form system

SYNOPSIS
#include <form.h>
int form_driver(FORM *form, int c);

DESCRIPTION
Once a form has been posted (displayed), you should funnel input events to it through form_driver. This routine has three major input cases: The input is a form navigation request. Navigation request codes are constants defined in <form.h>, which are distinct from the key- and character codes returned by wgetch. The input is a printable character. Printable characters (which must be positive, less than 256) are checked according to the program's locale settings. The input is the KEY_MOUSE special key associated with an mouse event.

The form driver requests are as follows:

REQ_NEXT_PAGE
    Move to the next page.

REQ_PREV_PAGE
    Move to the previous page.

REQ_FIRST_PAGE
    Move to the first page.

REQ_LAST_PAGE
    Move to the last field.

REQ_NEXT_FIELD
    Move to the next field.

REQ_PREV_FIELD
    Move to the previous field.

REQ_FIRST_FIELD
    Move to the first field.

REQ_LAST_FIELD
    Move to the last field.

REQ_SNEXT_FIELD
    Move to the sorted next field.

REQ_SPREV_FIELD
    Move to the sorted previous field.

REQ_SFIRST_FIELD
    Move to the sorted first field.

REQ_SLAST_FIELD
    Move to the sorted last field.

REQ_LEFT_FIELD
    Move left to a field.

REQ_RIGHT_FIELD
    Move right to a field.

REQ_UP_FIELD
    Move up to a field.

REQ_DOWN_FIELD
    Move down to a field.

REQ_NEXT_CHAR
    Move to the next char.

REQ_PREV_CHAR
    Move to the previous char.

REQ_NEXT_LINE
    Move to the next line.

REQ_PREV_LINE
    Move to the previous line.

REQ_NEXT_WORD
    Move to the next word.

REQ_PREV_WORD
    Move to the previous word.

REQ_BEG_FIELD
    Move to the beginning of the field.

REQ_END_FIELD
    Move to the end of the field.

REQ_BEG_LINE
    Move to the beginning of the line.

REQ_END_LINE
    Move to the end of the line.

REQ_LEFT_CHAR
    Move left in the field.

REQ_RIGHT_CHAR
    Move right in the field.

REQ_UP_CHAR
    Move up in the field.

REQ_DOWN_CHAR
    Move down in the field.

REQ_NEW_LINE
    Insert or overlay a new line.

REQ_INS_CHAR
    Insert a blank at the cursor.

REQ_INS_LINE
    Insert a blank line at the cursor.

REQ_DEL_CHAR
    Delete character at the cursor.

REQ_DEL_PREV
    Delete character before the cursor.

REQ_DEL_LINE
    Delete line at the cursor.

REQ_DEL_WORD
    Delete blank-delimited word at the cursor.

REQ_CLR_EOL
    Clear to end of line from cursor.

REQ_CLR_EOF
    Clear to end of field from cursor.

REQ_CLR_FIELD
    Clear the entire field.

REQ_OVL_MODE
    Enter overlay mode.

REQ_INS_MODE
    Enter insert mode.

REQ_SCR_FLINE
    Scroll the field forward a line.

REQ_SCR_BLINE
    Scroll the field backward a line.

REQ_SCR_FPAGE
    Scroll the field forward a page.

REQ_SCR_BPAGE
    Scroll the field backward a page.

REQ_SCR_FHPAGE
    Scroll the field forward half a page.

REQ_SCR_BHPAGE
    Scroll the field backward half a page.

REQ_SCR_FCHAR
    Scroll the field forward a character.

REQ_SCR_BCHAR
    Scroll the field backward a character.

REQ_SCR_HFLINE
    Horizontal scroll the field forward a line.

REQ_SCR_HBLINE
    Horizontal scroll the field backward a line.

REQ_SCR_HFHALF
    Horizontal scroll the field forward half a line.

REQ_SCR_HBHALF
    Horizontal scroll the field backward half a line.

REQ_VALIDATION
    Validate field.

REQ_NEXT_CHOICE
    Display next field choice.

REQ_PREV_CHOICE
    Display previous field choice.

If the second argument is a printable character, the driver places it in the current position in the current field. If it is one of the forms requests listed above, that request is executed.

  MOUSE HANDLING

If the second argument is the KEY_MOUSE special key, the associated mouse event is translated into one of the above pre-defined requests. Currently only clicks in the user window (e.g., inside the form display area or the decoration window) are handled.

If you click above the display region of the form:

    a REQ_PREV_FIELD is generated for a single click,

    a REQ_PREV_PAGE is generated for a double-click and

    a REQ_FIRST_FIELD is generated for a triple-click.

If you click below the display region of the form:

    a REQ_NEXT_FIELD is generated for a single click,

    a REQ_NEXT_PAGE is generated for a double-click and

    a REQ_LAST_FIELD is generated for a triple-click.

If you click at an field inside the display area of the form:
    the form cursor is positioned to that field. If you double-click a field, the form cursor is positioned to that field and E_UNKNOWN_COMMAND is returned. This return value makes sense, because a double click usually means that an field-specific action should be returned. It is exactly the purpose of this return value to signal that an application specific command should be executed. If a translation into a request was done, form_driver returns the result of this request.

If you clicked outside the user window or the mouse event could not be translated into a form request an E_REQUEST_DENIED is returned.

  APPLICATION-DEFINED COMMANDS

If the second argument is neither printable nor one of the above pre-defined form requests, the driver assumes it is an application-specific command and returns E_UNKNOWN_COMMAND. Application-defined commands should be defined relative to MAX_COMMAND, the maximum value of these pre-defined requests.

RETURN VALUE
form_driver returns one of the following error codes:

E_OK
    The routine succeeded.

E_BAD_ARGUMENT
    Routine detected an incorrect or out-of-range argument.

E_BAD_STATE
    Routine was called from an initialization or termination function.

E_NOT_POSTED
    The form has not been posted.

E_INVALID_FIELD
    Contents of field is invalid.

E_REQUEST_DENIED
    The form driver could not process the request.

E_SYSTEM_ERROR
    System error occurred (see errno).

E_UNKNOWN_COMMAND
    The form driver code saw an unknown request code.

SEE ALSO
curses(3X), form(3X), form_variables(3X), getch(3X).

NOTES
The header file <form.h> automatically includes the header files <curses.h>.

PORTABILITY
These routines emulate the System V forms library. They were not supported on Version 7 or BSD versions.

AUTHORS
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S. Raymond.