Event

A data structure that provides information about the state of the system and the most recent event.

The Event data structure provides information about the most recent event and about the state of the system when that event occurred.

The components of the Event data structure are set when an event occurs in the user interface. An application program can use the information in the fields to determine what action, if any, to take.

The fields in the Event structure are

AltKey, CtrlKey, EventName, EventTag, EventType, FieldTag, FormTag, KeyPressed , MenuItemTag, MenuTag, MouseClick , ScrollingKey, ShiftKey, WindowTag

Syntax #1 - AltKey, CtrlKey, ShiftKey

Provides information about the state of the Alt, Ctrl, or Shift key during the last event

event.altkey

event.ctrlkey

event.shiftkey

Return Value

Character string (binary). Can be reset by the application program.

Description

The variables provide information about the state of the Alt, Ctrl, and Shift keys during the last event.

The string is set to '1' ($True) if the indicated key was down when the last event occurred. Otherwise, it is set to '0' ($False).

Syntax #2 - EventName

event.eventname

Where eventname is one of

Return Value

Character string (alpha). Can be reset by the application program.

Description

The Event data structure provides information about the most recent event and about the state of the system when that event occurred.

The components of the Event data structure are set when an event occurs in the user interface. An application program can use the information in the fields to determine what action, if any, to take.

Syntax #3 - EventTag

event.eventtag

Return Value

Character string (ALPHA). Can be reset by the application program.

Description

The variable identifies, by its tag, the object in which the last user interface event occurred. The variable can be

EventType Setting

EventTag Value Taken From

Window

Event.WindowTag

Menu

Event.MenuTag

Menuitem

Event.MenuItemTag

Form

Event.FormTag

Formfield

Event.FieldTag

Accelerator

Event.FieldTag

System

Event.FieldTag

Syntax #4 - EventType

event.eventtype

Return Value

Character string (ALPHA). Can be reset by the application program.

Description

The variable identifies the type of user interface event that last occurred.

Syntax #5 - FieldTag

event.fieldtag

Return Value

Character string (ALPHA). Can be reset by the application program.

Description

The variable identifies, by its tag, the current field at the time of the last event.

Syntax #6 - FormTag

event.formtag

Return Value

Character string (ALPHA). Can be reset by the application program.

Description

The variable, identifies, by its tag, the current form at the time of the last event.

Syntax #7 - KeyPressed

event.keypressed

Return Value

Character string (CHAR). Can be reset by the application program.

Description

The variable indicates, by name, the pressed key that caused the last event to occur.

Note: The keynames associated with accelerator events, such as F1, are recorded in EventName.

Example

If the user presses the a key in a form field and a Modified event is intercepted by the application program, then Event.KeyPressed is set to a.

Syntax #8 - MenuItemTag

event.menuitemtag

Return Value

Character string (ALPHA). Can be reset by the application program.

Description

The variable identifies, by its tag, the selected item on the menu in the current window at the time of the last event.

Syntax #9 - MenuTag

event.menutag

Return Value

Character string (ALPHA). Can be reset by the application program.

Description

The variable identifies, by its tag, the current menu at the time of the last event.

Syntax #10 - MouseClick

event.mouseclick

Return Value

Character string (binary). Can be reset by the application program.

Description

The variable indicates if a mouse button acceleration caused an event to occur.

It is set to '1' ($True) if the event was caused by pressing a mouse button that is defined as an accelerator for the window. Otherwise, it is set to '0' ($False).

Syntax #11 - ScrollingKey

event.scrollingkey

Return Value

Character string (ALPHA). Can be reset by the application program.

Description

The variable indicates if an event corresponds to a defined SCROLL key.

It is set to '1' ($True) if an event corresponds to an accelerator key that is also a defined SCROLL key for the window. Otherwise, it is set to '0' ($False).

Accelerators and SCROLL keys are defined using WINDOW SET commands.

Example

The application fragment that follows enables employee records to be scrolled through a form and the data to be updated. The combined actions are accomplished by defining certain keys both as accelerators and SCROLL keys. When one of these keys is pressed, the corresponding accelerator event occurs. The application program uses ScrollingKey to detect that a SCROLL key was pressed and performs the scrolling action after saving the updated data.

window set scroll Up F7 Down F8
window set accelerator F7 F8 escape
form open fEmployee
form set scroll fEmployee from EmpSet
form display
while
 form input
 if event.scrollingkey = $true
  if thisform.formchanged = $true
   change EmpSet from fEmployee
    endif
  form scroll
  continue
   endif
 ... other commands ...
endwhile

Syntax #12 - WindowTag

event.windowtag

Return Value

Character string (ALPHA). Can be reset by the application program.

Description

The variable identifies, by its tag, the current window at the time of the last event.

 

Related Topics