IDLitWindow::OnWheel

IDL Reference Guide: iTools Object Classes

IDLitWindow::OnWheel

The IDLitWindow::OnWheel procedure method handles notification (from the native window device) that a mouse wheel event has occurred, and passes along that notification to all observers in the list of window event observers (as specified by calls to the IDLitWindow::AddWindowEventObserver method). You can also simulate a mouse wheel event by calling this method directly.

Note
Window event observers that handle mouse wheel events must implement the OnWheel method, as described in Implementing the OnWheel Interface.

Syntax

Obj->[IDLitWindow::]OnWheel, X, Y, Delta, Modifiers

Arguments

X

A long integer representing the x-location (in device coordinates) of the mouse event.

Y

A long integer representing the y-location (in device coordinates) of the mouse event.

Delta

A long integer giving the direction and distance that the wheel was rolled. Pushing the wheel generates positive values, pulling the wheel generates negative values. The magnitude of the value depends on the device setting for the individual mouse, but is usually limited to small integer values such as +1, -1, +2, -2, etc.

Modifiers

A long integer containing a bitwise mask indicating which modifier keys are active at the time of the wheel event. If a bit is zero, the key is up; if the bit is set, the key is pressed. The following table describes the bits in this bit mask:

Table 7-20: Modifier Values

Table 7-20: Modifier Values
Bit	Value	Modifier Key
0	1	Shift
1	2	Control
2	4	Caps Lock
3	8	Alt

Keywords

None

Implementing the OnWheel Interface

When defining a window event observer that handles mouse wheel events, you must implement an OnWheel procedure method with the following signature:

PRO MyObject::OnWheel, Window, X, Y, Delta, Modifiers

where the Window argument is an object reference to the IDLitWindow object in which the event was generated, and all of the other arguments are described above.

Version History


6.4	Introduced