TControl.OnMouseWheelLeft

Event handler signalled for a leftward movement of the mouse wheel.

Declaration

Source position: controls.pp line 1573

Description

OnMouseWheelLeft is a TMouseWheelUpDownEvent property with the event handler signalled when the mouse wheel is "tilted" towards the left. It is signalled (when assigned) from the DoMouseWheelLeft method, and occurs when the LM_MOUSEHWHEEL message is handled in the WMMouseHWheel method.

Applications can implement and assign a TMouseWheelUpDownEvent to perform actions needed when the event has occurred in the control. The arguments to the event handler include:

Sender

The control for the event notification.

Shift

The shift modifier in effect when the event occurred.

MousePos

The coordinates for the mouse pointer when the event occurred.

Handled

A variable argument which indicates if the wheel event is handled in the routine.

There are several horizontal mouse wheel event handlers, and they are signalled in order until a handler is found that responds to the event notification. These include:

• OnMouseWheelHorz
• Controls handlers added using AddHandler and the chtOnMouseWheelHorz handler type.
• OnMouseWheelLeft or OnMouseWheelRight depending on the WheelDelta - or relative units of movement for the mouse wheel.

OnMouseWheelLeft, and the other horizontal mouse wheel event handlers, require a mouse with a tilting scroll wheel to generate the event notification.

See also