Reference Manual Reference ManualThese functions control the look and feel of the user interface objects of Power-4gl, and are expected to be modified by the programmer to integrate Power-4gl with the individual system. These functions must be present in the system, typically in a module called "interf.4gl". A default set of interface functions is supplied which the programmer can alter to fit his/her particular needs.
Converts an integer keyboard key code to a logical name, as used in Power-4gl. Keyboard mapping is thus contained in one function which the programmer can easily modify by assigning appropriate keyboard values (i.e. "f8") to logical values (i.e. "exit").
1 parameters:
Keycode: An integer value representing a
keyboard key code (as produced by fgl_lastkey).
1 return value:
Logical value: A string containing a
logical keyboard name. The logical values used by Power-4gl functions, and their
standard purposes are as follows:
'exit' = Exit without change or
action.
'accept' = Perform operation and exit.
'enter' = Enter into a list
item or next field in an input form.
'help' = Open the appropriate help
window.
'insert' = Insert a new pick-list row.
'delete' = Delete a
pick-list row.
'filter' = Edit the search criteria for a pick-list or
report.
'refresh' = Refresh the current window data.
'toggle' = View
report list/coversheet. Mark/unmark pick-list rows.
'search' = In an input
field, open an appropriate pick-list.
'other' = Other operations, perhaps a
menu offering some possibilities.
'tab' = Move far left.
'sh-tab' = Move
far right.
'up' = Move up.
'down' = Move down.
'left' = Move
left.
'right' = Move right.
'prevpage' = Page upward.
'nextpage' = Page
downward.
'home' = First page of a list.
'end' = Last page of a
list.
'print' = Output the current list to a printer (pipe).
'file' =
Output the current list to a file.
'prtscr' = Print screen to a
pipe.
'opsys' = Call up an operating system shell.
Display text of a logical type with an appropriate attribute. Power-4gl uses these definitions to display text of types such as titles, listings and messages. Display attributes are thus contained in one function which the programmer can easily modify by assigning appropriate display attributes (i.e. "bold") to logical display types (i.e. "title").
4 parameters:
Text: The text to be
displayed.
Type: The logical display type of the text. The
logical types used by Power-4gl functions, and their standard purposes are as
follows:
'list' = Normal list line (pick-list lines, menu items, report lines
etc.)
'listcurr' = The current list line, i.e. the cursor.
'listmark' = A
marked list line (used in pick-lists).
'listcurrmark' = The current list line
which has also been marked.
'listinact' = An inactive list line (used in
menus).
'titlefirst' = The first title line of a window, i.e. the window
label.
'title' = A middle title line or header.
'titlelast' = The last
title line or header (usually underlined).
'message' = Messages or
prompts.
'error' = Error messages.
Row: The window row
which the text is to be displayed at.
Column: The window
column which the text is to be displayed at.
Converts a value using a specified translation method, reducing translations and conversions to a single function.
2 parameters:
Method: Character string identifying the
translation or conversion method.
Value: The value to be
converted.
1 return value:
Value: The converted value.
Obtain the name of the default printer.
1 return value:
Printer name: A string containing the
logical name of the default printer.
Search for a printer. This function typically calls a pick-list containing a selection of available printers and returns a selected printer along with configuration values.
2 parameters:
Printer name: The currently selected
printer name (if any).
Output width: The expected width of
the printed output (number of characters).
12 return value:
Printer name: The newly selected printer
name.
Pipe: String containing the output pipe
description.
Page length: The page length of the appropriate
page setup (number of lines).
Page width: The page width of
the appropriate page setup (number of characters).
Setup:
The page setup escape sequence.
Reset: Character sequence
between pages.
Bold: Sequence that produces bold
output.
Nonbold: Sequence that ends bold
output.
Underline: Sequence that produces underlined
output.
Nonunderline: Sequence that ends underlined
output.
Italic: Sequence that produces italic
output.
Nonitalic: Sequence that ends underlined output.
Validate a printer name and return configuration values.
2 parameters:
Printer name: The currently selected
printer name (if any).
Output width: The expected width of
the printed output (number of characters).
13 return value:
Printer name: The newly selected printer
name.
Pipe: String containing the output pipe
description.
Page length: The page length of the appropriate
page setup (number of lines).
Page width: The page width of
the appropriate page setup (number of characters).
Setup:
The page setup escape sequence.
Reset: Character sequence
between pages.
Bold: Sequence that produces bold
output.
Nonbold: Sequence that ends bold
output.
Underline: Sequence that produces underlined
output.
Nonunderline: Sequence that ends underlined
output.
Italic: Sequence that produces italic
output.
Nonitalic: Sequence that ends underlined
output.
Valid: True if the printer is valid, otherwise
false.
Handle a program error without program termination. Typically, the function displays error information, possibly notifying the system administrator via email, before continuing.
3 parameters:
Location: Character string identifying
where in the program the error occurred.
Status: An integer
status code, e.g. sqlca.sqlcode.
Message: Additional
comments or messages.
Handle a program error and terminate the program. Typically, the function notifies the system administrator via email before terminating the program as gracefully as possible.
3 parameters:
Location: Character string identifying
where in the program the error occurred.
Status: An integer
status code, e.g. sqlca.sqlcode.
Message: Additional
comments or messages.