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Event handler for mouse wheel turned.
Source position: controls.pp line 1602
protected property TControl.OnMouseWheel : TMouseWheelEvent |
OnMouseWheel is a TMouseWheelEvent property with the event handler signalled when a mouse wheel movement occurs in for the control. By default all mouse wheel actions are translated into scroll events. Write an OnMouseWheel handler to react when the mouse wheel is rotated.
Arguments for the event handler routine include:
OnMouseWheel is signalled (when assigned) from the DoMouseWheel method, and occurs when the LM_MOUSEWHEEL message is handled in the WMMouseWheel method. If the event handler does not set the Handled argument to True, other assigned handler routines are signalled. These include control handlers added using the AddHandler method, as well as OnMouseWheelDown and OnMouseWheelUp.
The value in WheelDelta argument is used to determine the handler signalled. OnMouseWheelUp is used when the delta value (or the relative number of units of movement) is 0 (zero) or a positive number. OnMouseWheelDown is used when the delta value is a negative number.
Neither OnMouseWheelUp nor OnMouseWheelDown include the wheel delta value; they are simple notifications that the event has occurred at a given position.
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Event handler signalled for a downward movement of the mouse wheel. |
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Event handler signalled for a leftward movement of the mouse wheel. |
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Event handler signalled for a rightward movement of the mouse wheel. |
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Event handler signalled for an upward movement of the mouse wheel. |
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Signals the OnMouseWheel handlers, when the mouse wheel has been turned. |
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Handles horizontal mouse wheel messages for the control. |
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Executes assigned mouse wheel events until a handler is found for the event notifications. |
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Specifies an event handler used to respond to mouse wheel events. |
| Version 3.2 | Generated 2024-02-25 | Home |