Receiving and handling mouse input is an important part of every Windows application. You can handle mouse events to carry out an action in your application, or use mouse location information to perform hit testing or other actions. Also, you can change the way the controls in your application handle mouse input. This article describes these mouse events in detail, and how to obtain and change system settings for the mouse.

In Windows Forms, user input is sent to applications in the form ofWindows messages. A series of overridable methods process these messages at the application, form, and control level. When these methods receive mouse messages, they raise events that can be handled to get information about the mouse input. In many cases, Windows Forms applications can process all user input simply by handling these events. In other cases, an application can override one of the methods that process messages to intercept a particular message before it's received by the application, form, or control.

Mouse Events

All Windows Forms controls inherit a set of events related to mouse and keyboard input. For example, a control can handle theMouseClick event to determine the location of a mouse click. For more information on the mouse events, seeUsing mouse events.

Mouse location and hit-testing

When the user moves the mouse, the operating system moves the mouse pointer. The mouse pointer contains a single pixel, called the hot spot, which the operating system tracks and recognizes as the position of the pointer. When the user moves the mouse or presses a mouse button, theControl that contains theHotSpot raises the appropriate mouse event.

You can obtain the current mouse position with theLocation property of theMouseEventArgs when handling a mouse event or by using thePosition property of theCursor class. You can then use mouse location information to carry out hit-testing, and then perform an action based on the location of the mouse. Hit-testing capability is built in to several controls in Windows Forms such as theListView,TreeView,MonthCalendar, andDataGridView controls.

Hit-testing is useful for determining when your application should do a specific action, when used with the appropriate mouse event, such asMouseHover.

Changing mouse input settings

You can detect and change the way a control handles mouse input by deriving from the control and using theGetStyle andSetStyle methods. TheSetStyle method takes a bitwise combination ofControlStyles values to determine whether the control has standard click, double-click behavior, or if the control handles its own mouse processing. Also, theSystemInformation class includes properties that describe the capabilities of the mouse and specify how the mouse interacts with the operating system. The following table summarizes these properties.

Methods that process user input messages

Forms and controls have access to theIMessageFilter interface and a set of overridable methods that process Windows messages at different points in the message queue. These methods all have aMessage parameter, which encapsulates the low-level details of Windows messages. You can implement or override these methods to examine the message and then either consume the message or pass it on to the next consumer in the message queue. The following table presents the methods that process all Windows messages in Windows Forms.

See also

• Using mouse events
• Drag-and-drop mouse behavior overview
• Manage mouse pointers