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Control Events
User-driven events cluster into five types of activities: focus, mouse movement, mouse clicking, drag-and-drop, and keyboard use. In addition, an event can signal an error.
Focus Change
The Enter event occurs before a control receives the focus from a control on the same form.
The Exit event occurs just before a control loses the focus to another control on the same form.
Mouse Movement
The MouseMove Event occurs when the user moves the mouse.
Mouse Clicking
The MouseDown event occurs when the user presses any mouse button.
The MouseUp occurs when the user releases any mouse button.
Drag And Drop
The BeforeDragOver event occurs when a drag-and-drop operation is in progress. Use this event to monitor the mouse pointer as it enters, leaves, or rests directly over a valid target. When a drag-and-drop operation is in progress, the system initiates this event when the user moves the mouse, or presses or releases the mouse button or buttons. The mouse pointer position determines the target object that receives this event. Determine the state of the mouse pointer by examining the DragState argument. Use the Effect argument to identify the drag-and-drop action is to be Copy, Move, or None.
The BeforeDropOrPaste event occurs when the user is about to drop or paste data onto an object.
Most controls do not support drag-and-drop while Cancel is False, which is the default setting. This means the control rejects attempts to drag or drop anything on the control, and the control does not initiate the BeforeDropOrPaste event. The TextBox and ComboBox controls are exceptions to this, since they support drag-and-drop operations even when Cancel is False.
Keyboard Keystrokes
The KeyPress event occurs when the user presses an ANSI key, and returns the ANSI key value. ANSI codes typically cover printable characters and some special characters such as BACKSPACE, ESC. TAB, ENTER, DELETE, and arrow keys do not trigger KeyPress
The KeyDown event occurs when the user presses a key and the KeyUp event occurs when the user releases a key. KeyDown and KeyUp identify what key was pressed, and which of SHIFT, CTRL, and/or ALT were pressed. Special keys, such as the function keys, navigation keys, and keys on the numeric keypad, will trigger KeyDown and KeyUp. These two events return a different code than KeyPress, and it can change depending on the type of physical keyboard in use. Care must be taken if a macro is to work with keyboards of different countries.
The sequence of keyboard-related events is:
When the user presses and holds a key, KeyDown and KeyPress alternate, at the keyboard repeat rate specified in the Control Panel Keyboard properties. KeyUp occurs only once, when the key is released.
Error
The Error Event occurs when a control detects an error and cannot return the error information to a calling program.
ByVal References in Microsoft Forms
The ByVal keyword in Microsoft Forms indicates that an argument is passed as a value; this is the standard meaning of ByVal in Visual Basic. However, in Microsoft Forms, you can use ByVal with a ReturnBoolean, ReturnEffect, ReturnInteger, or ReturnString object. When you do, the value passed is not a simple data type; it is a pointer to the object.
When used with these objects, ByVal refers to the object, not the method of passing parameters. Each of the objects listed above has a Value property that you can set. You can also pass that value into and out of a function. Because you can change the values of the object's members, events produce results consistent with ByRef behavior, even though the event syntax says the parameter is ByVal.
Assigning a value to an argument associated with a ReturnBoolean, ReturnEffect, ReturnInteger, or ReturnString is no different from setting the value of any other argument. For example, if the event syntax indicates a Cancel argument used with the ReturnBoolean object, the statement Cancel=True is still valid, just as it is with other data types.
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Control |
Short Description |
Default Property |
Default Event |
|
Label |
Displays fixed text |
Caption |
Click |
|
TextBox |
Displays entered text or for edit |
Value |
Change |
|
ListBox |
Displays a list of selectable items |
Value |
Click |
|
ComboBox |
Combines TextBox and ListBox. |
Value |
Change |
|
CheckBox |
For selecting any number of items |
Value |
Click |
|
Frame |
Used to group OptionButtons |
(none) |
Click |
|
OptionButton |
For selecting only one item |
Value |
Click |
|
CommandButton |
Click to execute code |
Value |
Click |
|
ToggleButton |
A two-state CommandButton |
Value |
Click |
|
TabStrip |
Displays tabs of the same limited info |
SelectedItem |
Change |
|
MultiPage |
Splits large amounts of info into pages |
Value |
Change |
|
ScrollBar |
Displays a vertical or horizontal scrollbar |
Value |
Change |
|
SpinButton |
Increments and decrements numbers |
Value |
Change |
|
Image |
Displays an image. |
(none) |
Click |
Control Events
Each control on a UserForm has its own set of events. The default event for most controls, as seen in the above table, is the Click event or the Change event. The quickest and easiest way to find out the default event for a particular control is to place it on a UserForm and then simply double-click it. Excel will create the default event procedure in the UserForm code module, and put the cursor in it ready for editing.
The order of events for a control depends on user movement of the mouse and user clicking of the left button. Most of the time, it doesn’t matter, since the Click and Change events cover most needs, so order of events is not important.
EXAMPLE
On a UserForm place two TextBox controls. Double-click each to create the Change event procedures, then place in each the code below.
Private Sub TextBox1_Change()
If TextBox1.Value = VBNullString then Exit Sub
If Not IsNumeric(TextBox1.Value) Then
MsgBox "No text please", vbCritical
TextBox1.Text = vbNullString
End If
End Sub
Private Sub TextBox2_Change()
If TextBox2.Value = VBNullString then Exit Sub
If IsNumeric(TextBox2.Value) Then
MsgBox "No numbers please", vbCritical
TextBox1.Text = vbNullString
End If
End Sub
These Change event handlers ensure the user enters something, and correctly enters text or numbers. For example, the user would be informed immediately if text is entered into TextBox1, or if a number is entered into Textbox2. The Change event fires for each keystroke, which means the first character entered in Textbox2 cannot be a number, though numbers can be entered later and still have the contents register as text.
Note that the IF statement as the first line of code in the procedure above checks and exits if the TextBox is empty. If this code was not in there, and a bad entry is reported, the code setting the TextBox to VBNullString will itself fire the Change event and cause a second error to be reported.
Unfortunately, development and validation of UserForms is rarely this simple. For the code below, intended for finding the @ in an email address, will not work in a Change event because the @ doesn’t occur until the middle of the address.
Private Sub TextBox3_Change()
' this code doesn’t work in a Change handler
If TextBox3.Value = VBNullString then Exit Sub
If InStr(1, TextBox3, "@", vbTextCompare) = 0 Then
MsgBox "Not an email address, vbCritical"
End If
End Sub
In cases like this, another event must run our validation check. One event which can be used for this type of check is the Exit event. Before looking at the Exit event though, it is important that the meaning of Focus is understood. According to Microsoft Excel's VBE Help:
focus
The ability to receive mouse clicks or keyboard input at any one time. In the Microsoft Windows environment, only one window, form, or control can have this ability at a time. The object that "has the focus" is normally indicated by a highlighted caption or title bar. The focus can be set by the user or by the application.
EXAMPLE
The Exit event will fire immediately before a control loses Focus to another control on the same form.
Private Sub TextBox3_Exit(ByVal Cancel As MSForms.ReturnBoolean)
' this code now works in an Exit handler
If TextBox3.Value = VBNullString then Exit Sub
If InStr(1, TextBox3, "@", vbTextCompare) = 0 Then
MsgBox "Not an email address", vbCritical
Cancel = True
End If
End Sub
A new argument in this handler is Cancel. For this example, it is set to True when an error occurs. Once a string is typed that includes @, it is easy to click in another control on the same UserForm and shift focus. If the @ is not found, and the error is posted, Cancel = True cancels shifting the focus away from the control. As the code is above, @ must be typed before focus is allowed to leave. Rather than trap the user in an endless loop, the MsgBox message should tell the user why focus is unable to leave the control, and include what to do to get out.
There is a caveat, that if the control is in a Frame control, the Exit event doesn’t occur.
If this code is copied for a real project, be sure to change TextBox3 to the new TextBox name.
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