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Visual Basic Reference

Visual Studio 6.0

MouseDown, MouseUp Events

See Also    Example    Applies To

Occur when the user presses (MouseDown) or releases (MouseUp) a mouse button.

Syntax

Private Sub Form_MouseDown(button As Integer, shift As Integer, x As Single, y As Single)

Private Sub MDIForm_MouseDown(button As Integer, shift As Integer, x As Single, y As Single)

Private Sub object_MouseDown([index As Integer,]button As Integer, shift As Integer, x As Single, y As Single)

Private Sub Form_MouseUp(button As Integer, shift As Integer, x As Single, y As Single)

Private Sub MDIForm_MouseUp(button As Integer, shift As Integer, x As Single, y As Single)

Private Sub object _MouseUp([index As Integer,]button As Integer, shift As Integer, x As Single, y As Single)

The MouseDown and MouseUp event syntaxes have these parts:

Part Description
object Returns an object expression that evaluates to an object in the Applies To list.
index Returns an integer that uniquely identifies a control if it's in a control array.
button Returns an integer that identifies the button that was pressed (MouseDown) or released (MouseUp) to cause the event. The button argument is a bit field with bits corresponding to the left button (bit 0), right button (bit 1), and middle button (bit 2). These bits correspond to the values 1, 2, and 4, respectively. Only one of the bits is set, indicating the button that caused the event.
shift Returns an integer that corresponds to the state of the SHIFT, CTRL, and ALT keys when the button specified in the button argument is pressed or released. A bit is set if the key is down. The shift argument is a bit field with the least-significant bits corresponding to the SHIFT key (bit 0), the CTRL key (bit 1), and the ALT key (bit 2 ). These bits correspond to the values 1, 2, and 4, respectively. The shift argument indicates the state of these keys. Some, all, or none of the bits can be set, indicating that some, all, or none of the keys are pressed. For example, if both CTRL and ALT were pressed, the value of shift would be 6.
x, y Returns a number that specifies the current location of the mouse pointer. The x and y values are always expressed in terms of the coordinate system set by the ScaleHeight, ScaleWidth, ScaleLeft, and ScaleTop properties of the object.

Remarks

Use a MouseDown or MouseUp event procedure to specify actions that will occur when a given mouse button is pressed or released. Unlike the Click and DblClick events, MouseDown and MouseUp events enable you to distinguish between the left, right, and middle mouse buttons. You can also write code for mouse-keyboard combinations that use the SHIFT, CTRL, and ALT keyboard modifiers.

The following applies to both Click and DblClick events:

  • If a mouse button is pressed while the pointer is over a form or control, that object "captures" the mouse and receives all mouse events up to and including the last MouseUp event. This implies that the x, y mouse-pointer coordinates returned by a mouse event may not always be in the internal area of the object that receives them.

  • If mouse buttons are pressed in succession, the object that captures the mouse after the first press receives all mouse events until all buttons are released.

If you need to test for the button or shift arguments, you can use constants listed in the Visual Basic (VB) object library in the Object Browser to define the bits within the argument:

Constant (Button) Value Description
vbLeftButton 1 Left button is pressed
vbRightButton 2 Right button is pressed
vbMiddleButton 4 Middle button is pressed

Constant (Shift) Value Description
vbShiftMask 1 SHIFT key is pressed.
vbCtrlMask 2 CTRL key is pressed.
vbAltMask 4 ALT key is pressed.

The constants then act as bit masks you can use to test for any combination of buttons without having to figure out the unique bit field value for each combination.

Note   You can use a MouseMove event procedure to respond to an event caused by moving the mouse. The button argument for MouseDown and MouseUp differs from the button argument used for MouseMove. For MouseDown and MouseUp, the button argument indicates exactly one button per event, whereas for MouseMove, it indicates the current state of all buttons.

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