Event
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Event
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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
- Break, Canceled, Click, Closed, DoubleClick, GotFocus, HangUp, LostFocus, LostFocusModified, Modified, PanicExit, RightClick, Timeout, WindowFocusSwitch, or
- the name of an accelerator key, such as F1, if the event type was accelerator
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.
– window
– menu
– menuitem
– form
– formfield
– accelerator
– system
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.
See Also
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