Change Event

PLBCMP GUI Only

The Change event occurs when the contents or value of an object is altered. This event provides the first opportunity to respond to modifications that the user makes.

Note the following:

1. The Change event is referenced using an event value of three (3). The equated label in PLBEQU.INC for this event is $CHANGE.

2. If the object is an EDITTEXT or COMBOBOX, the data contained within the edit box has changed.

3. For COMBOBOXes, the COMBOSTYLE property must be set to $EDIT for this event to occur. Selection of a item from the list will result in a CLICK event.

4. If the object is a HSCROLLBAR, VSCROLLBAR, or SLIDER, the event occurs when the position is changed by the user.

5. If the object is a TABCONTROL, this event occurs when the selected tab has changed and is always preceded by a CLICK event.

6. If the object is a TREEVIEW, this event occurs when an item selection changes. The Event Modifier indicates whether the left or right mouse button caused the change. The Event Result is the handle of the newly selected item.

7. The Event Result is set to the value of the current position for HSCROLLBAR, VSCROLLBAR or SLIDER objects. It is set to the current tab number for TABCONTROL objects.

8. The Event Modifier is set to set zero for a TABCONTROL or one of the following for HSCROLLBAR, VSCROLLBAR, or SLIDER:

 

Value	Meaning
1	Line Down
2	Line Up
4	Page Down
8	Page Up
16	Set Slide Box
32	At Min (SLIDER - Home key pressed)
64	At Max (SLIDER - End key pressed)

 

9. If the object is a BUTTON and the program is executing on a PL/B web server, a CHANGE event that is generated when a BUTTONTYPE=$FILEINPUT' is being used and an end-user has made a selection from the client browser 'File Upload' selection dialog. (9.7A)

1. The CHANGE event for a BUTTON object is only generated when executing under a PL/B Web Server and a file has been selected by an end-user using the client browser 'File Upload' selection dialog. For this event; the event character is always 0x20; the event result and event modifier are always zero (0).

2. When this CHANGE event for a BUTTON object is processed, the PL/B logic can use the BUTTON GetFileCount and GetFileItem methods to retrieve the end-user file selection information.

10. This event is not supported for an IMAGELIST when using the PL/B Web Server.

11. If the object is a LISTVIEW, this event occurs when an item selection changes. The Event Result is the item number of the newly selected item.

See Also: EVENTREGISTER, Object Events, Object Instructions, Object Definitions