January 1, 2001 FORMS 3

### NAME

form_driver - form library

### LIBRARY

Curses Form Library (libform, -lform)

### SYNOPSIS

```int` form_driver(```FORM *form``, int request`)

### DESCRIPTION

The form_driver(``) is the heart of the forms library, it takes commands in the ```request` parameter that is either a request to the driver to perform some action or is a character to be inserted into the current field. The form driver will attempt to insert any printable character passed to it into the current field. This may or may not succeed depending on the state of the current field. If the character passed is not printable then the driver attempts to process it as a driver request. If the character passed is not a valid request then the driver will return an unknown command error.

### PARAMETERS

The forms driver recognizes the following requests:

REQ_NEXT_PAGE
  Change to the next page in the form.
REQ_PREV_PAGE
  Change to the previous page in the form.
REQ_FIRST_PAGE
  Select the first page in the form.
REQ_LAST_PAGE
  Go to the last page in the form.
REQ_NEXT_FIELD
  Move to the next field in the form field array.
REQ_PREV_FIELD
  Move to the previous field in the form field array.
REQ_FIRST_FIELD
  Go to the first field in the form field array.
REQ_LAST_FIELD
  Go to the last field in the form field array.
REQ_SNEXT_FIELD
  Move to the next sorted field on the form.
REQ_SPREV_FIELD
  Move to the previous sorted field on the form.
REQ_SFIRST_FIELD
  Go to the first field in the sorted list.
REQ_SLAST_FIELD
  Move to the last field in the sorted list.
REQ_LEFT_FIELD
  Go one field to the left on the form page.
REQ_RIGHT_FIELD
  Go one field to the right on the form page.
REQ_UP_FIELD
  Go up one field on the form page.
REQ_DOWN_FIELD
  Go down one field on the form page.
REQ_NEXT_CHAR
  Move one char to the right within the field
REQ_PREV_CHAR
  Move one char to the left within the current field.
REQ_NEXT_LINE
  Go down one line in the current field.
REQ_PREV_LINE
  Go up one line in the current field.
REQ_NEXT_WORD
  Go forward one word in the current field
REQ_PREV_WORD
  Go backward one word in the current field.
REQ_BEG_FIELD
  Move the cursor to the beginning of the current field.
REQ_END_FIELD
  Move the cursor to the end of the current field.
REQ_BEG_LINE
  Move the cursor to the beginning of the line in the current field.
REQ_END_LINE
  Move the cursor to the end of the line.
REQ_LEFT_CHAR
  Move the cursor left one character
REQ_RIGHT_CHAR
  Move the cursor right one character
REQ_UP_CHAR
  Move the cursor up one line.
REQ_DOWN_CHAR
  Move the cursor down one line.
REQ_NEW_LINE
  Insert a new line at the current cursor position.
REQ_INS_CHAR
  Insert a blank character at the current cursor position
REQ_INS_LINE
  Open a blank line at the current cursor position.
REQ_DEL_CHAR
  Delete the character at the current cursor position.
REQ_DEL_PREV
  Delete the character to the left of the current cursor position.
REQ_DEL_LINE
  Delete the current line.
REQ_DEL_WORD
  Delete the word at the current cursor position.
REQ_CLR_EOL
  Clear the field from the current cursor position to the end of the current line.
REQ_CLR_EOF
  Clear the field from the current cursor position to the end of the field.
REQ_CLR_FIELD
  Clear the field.
REQ_OVL_MODE
  Enter overlay mode, characters added to the field will replace the ones already there.
REQ_INS_MODE
  Enter insert mode, characters will be inserted at the current cursor position. Any characters to the right of the cursor will be moved right to accommodate the new characters.
REQ_SCR_FLINE
  Scroll the field forward one line.
REQ_SCR_BLINE
  Scroll the field backward one line.
REQ_SCR_FPAGE
  Scroll the field forward one field page.
REQ_SCR_BPAGE
  Scroll the field backward one field page.
REQ_SCR_FHPAGE
  Scroll the field forward half one field page.
REQ_SCR_BHPAGE
  Scroll the field backward half one field page.
REQ_SCR_FCHAR
  Scroll the field horizontally forward one character
REQ_SCR_BCHAR
  Scroll the field horizontally backward one character
REQ_SCR_HFLINE
  Scroll the field horizontally forward one field line.
REQ_SCR_HBLINE
  Scroll the field horizontally backward one field line.
REQ_SCR_HFHALF
  Scroll the field horizontally forward half a field line.
REQ_SCR_HBHALF
  Scroll the field horizontally backward half a field line.
REQ_VALIDATION
  Request the contents of the current field be validated using any field validation function that has been set for the field. Normally, the field is validated before the current field changes. This request allows the current field to be validated.
REQ_PREV_CHOICE
  Select the previous choice in an enumerated type field.
REQ_NEXT_CHOICE
  Select the next choice in an enumerated type field.

### RETURN VALUES

Functions returning pointers will return ```NULL` if an error is detected. The functions that return an int will return one of the following error values:

```E_OK`
  The function was successful.
```E_REQUEST_DENIED`
  The forms driver request could not be fulfilled
```E_UNKNOWN_COMMAND`
  The passed character is not a printable character and is not a valid forms driver request.
```E_BAD_ARGUMENT`
  A bad argument was passed to the forms driver.
```E_INVALID_FIELD`
  The form passed to the driver has no valid attached fields.
```E_NOT_POSTED`
  The given form is not currently posted to the screen.
```E_BAD_STATE`
  The forms driver was called from within an init or term function.
```E_INVALID_FIELD`
  The character passed to the forms driver fails the character validation for the current field.

### SEE ALSO

curses(3), forms(3)

### NOTES

Field sorting is done by location of the field on the form page, the fields are sorted by position starting with the top-most, left-most field and progressing left to right. For the purposes of sorting, the fields top left corner is used as the sort criteria. The header <```form.h`> automatically includes both <```curses.h`> and <```eti.h`>.