java.awt.event
class MouseEvent

java.lang.Object java.util.EventObject java.awt.AWTEvent java.awt.event.ComponentEvent java.awt.event.InputEvent java.awt.event.MouseEvent

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

MenuDragMouseEvent, MouseWheelEvent

public class MouseEvent
extends InputEvent

An event which indicates that a mouse action occurred in a component. A mouse action is considered to occur in a particular component if and only if the mouse cursor is over the unobscured part of the component's bounds when the action happens. For lightweight components, such as Swing's components, mouse events are only dispatched to the component if the mouse event type has been enabled on the component. A mouse event type is enabled by adding the appropriate mouse-based {@code EventListener} to the component ({@link MouseListener} or {@link MouseMotionListener}), or by invoking {@link Component#enableEvents(long)} with the appropriate mask parameter ({@code AWTEvent.MOUSE_EVENT_MASK} or {@code AWTEvent.MOUSE_MOTION_EVENT_MASK}). If the mouse event type has not been enabled on the component, the corresponding mouse events are dispatched to the first ancestor that has enabled the mouse event type.

For example, if a {@code MouseListener} has been added to a component, or {@code enableEvents(AWTEvent.MOUSE_EVENT_MASK)} has been invoked, then all the events defined by {@code MouseListener} are dispatched to the component. On the other hand, if a {@code MouseMotionListener} has not been added and {@code enableEvents} has not been invoked with {@code AWTEvent.MOUSE_MOTION_EVENT_MASK}, then mouse motion events are not dispatched to the component. Instead the mouse motion events are dispatched to the first ancestors that has enabled mouse motion events.

This low-level event is generated by a component object for:

• Mouse Events
  • a mouse button is pressed
  • a mouse button is released
  • a mouse button is clicked (pressed and released)
  • the mouse cursor enters the unobscured part of component's geometry
  • the mouse cursor exits the unobscured part of component's geometry
• Mouse Motion Events
  • the mouse is moved
  • the mouse is dragged

A MouseEvent object is passed to every MouseListener or MouseAdapter object which is registered to receive the "interesting" mouse events using the component's addMouseListener method. (MouseAdapter objects implement the MouseListener interface.) Each such listener object gets a MouseEvent containing the mouse event.

A MouseEvent object is also passed to every MouseMotionListener or MouseMotionAdapter object which is registered to receive mouse motion events using the component's addMouseMotionListener method. (MouseMotionAdapter objects implement the MouseMotionListener interface.) Each such listener object gets a MouseEvent containing the mouse motion event.

When a mouse button is clicked, events are generated and sent to the registered MouseListeners. The state of modal keys can be retrieved using {@link InputEvent#getModifiers} and {@link InputEvent#getModifiersEx}. The button mask returned by {@link InputEvent#getModifiers} reflects only the button that changed state, not the current state of all buttons. (Note: Due to overlap in the values of ALT_MASK/BUTTON2_MASK and META_MASK/BUTTON3_MASK, this is not always true for mouse events involving modifier keys). To get the state of all buttons and modifier keys, use {@link InputEvent#getModifiersEx}. The button which has changed state is returned by {@link MouseEvent#getButton}

For example, if the first mouse button is pressed, events are sent in the following order:

    id              modifiers    button           
    MOUSE_PRESSED:  BUTTON1_MASK BUTTON1
    MOUSE_RELEASED: BUTTON1_MASK BUTTON1
    MOUSE_CLICKED:  BUTTON1_MASK BUTTON1
 

For example, if the user presses button 1 followed by button 2, and then releases them in the same order, the following sequence of events is generated:

    id              modifiers    button           
    MOUSE_PRESSED:  BUTTON1_MASK BUTTON1
    MOUSE_PRESSED:  BUTTON2_MASK BUTTON2
    MOUSE_RELEASED: BUTTON1_MASK BUTTON1
    MOUSE_CLICKED:  BUTTON1_MASK BUTTON1
    MOUSE_RELEASED: BUTTON2_MASK BUTTON2
    MOUSE_CLICKED:  BUTTON2_MASK BUTTON2
 

MOUSE_DRAGGED events are delivered to the Component in which the mouse button was pressed until the mouse button is released (regardless of whether the mouse position is within the bounds of the Component). Due to platform-dependent Drag&Drop implementations, MOUSE_DRAGGED events may not be delivered during a native Drag&Drop operation. In a multi-screen environment mouse drag events are delivered to the Component even if the mouse position is outside the bounds of the GraphicsConfiguration associated with that Component. However, the reported position for mouse drag events in this case may differ from the actual mouse position:

• In a multi-screen environment without a virtual device:
  The reported coordinates for mouse drag events are clipped to fit within the bounds of the GraphicsConfiguration associated with the Component.
• In a multi-screen environment with a virtual device:
  The reported coordinates for mouse drag events are clipped to fit within the bounds of the virtual device associated with the Component.

BUTTON1

public static final int BUTTON1

Indicates mouse button #1; used by {@link #getButton}.

BUTTON2

public static final int BUTTON2

Indicates mouse button #2; used by {@link #getButton}.

BUTTON3

public static final int BUTTON3

Indicates mouse button #3; used by {@link #getButton}.

MOUSE_CLICKED

public static final int MOUSE_CLICKED

The "mouse clicked" event. This MouseEvent occurs when a mouse button is pressed and released.

MOUSE_DRAGGED

public static final int MOUSE_DRAGGED

The "mouse dragged" event. This MouseEvent occurs when the mouse position changes while a mouse button is pressed.

MOUSE_ENTERED

public static final int MOUSE_ENTERED

The "mouse entered" event. This MouseEvent occurs when the mouse cursor enters the unobscured part of component's geometry.

MOUSE_EXITED

public static final int MOUSE_EXITED

The "mouse exited" event. This MouseEvent occurs when the mouse cursor exits the unobscured part of component's geometry.

MOUSE_FIRST

public static final int MOUSE_FIRST

The first number in the range of ids used for mouse events.

MOUSE_LAST

public static final int MOUSE_LAST

The last number in the range of ids used for mouse events.

MOUSE_MOVED

public static final int MOUSE_MOVED

The "mouse moved" event. This MouseEvent occurs when the mouse position changes.

MOUSE_PRESSED

public static final int MOUSE_PRESSED

The "mouse pressed" event. This MouseEvent occurs when a mouse button is pushed down.

MOUSE_RELEASED

public static final int MOUSE_RELEASED

The "mouse released" event. This MouseEvent occurs when a mouse button is let up.

MOUSE_WHEEL

public static final int MOUSE_WHEEL

The "mouse wheel" event. This is the only MouseWheelEvent. It occurs when a mouse equipped with a wheel has its wheel rotated.

NOBUTTON

public static final int NOBUTTON

Indicates no mouse buttons; used by {@link #getButton}.

MouseEvent

public MouseEvent(Component source,
                  int id,
                  long when,
                  int modifiers,
                  int x,
                  int y,
                  int clickCount,
                  boolean popupTrigger)

Constructs a MouseEvent object with the specified source component, type, modifiers, coordinates, and click count.

Note that passing in an invalid id results in unspecified behavior. An invocation of the form MouseEvent(source, id, when, modifiers, x, y, clickCount, popupTrigger) behaves in exactly the same way as the invocation {@link #MouseEvent(Component, int, long, int, int, int, int, int, int, boolean, int) MouseEvent}(source, id, when, modifiers, x, y, xAbs, yAbs, clickCount, popupTrigger, MouseEvent.NOBUTTON) where xAbs and yAbs defines as source's location on screen plus relative coordinates x and y. xAbs and yAbs are set to zero if the source is not showing. This method throws an IllegalArgumentException if source is null.

Parameters:

source - the Component that originated the event

id - the integer that identifies the event

when - a long int that gives the time the event occurred

modifiers - the modifier keys down during event (e.g. shift, ctrl, alt, meta) Either extended _DOWN_MASK or old _MASK modifiers should be used, but both models should not be mixed in one event. Use of the extended modifiers is preferred.

x - the horizontal x coordinate for the mouse location

y - the vertical y coordinate for the mouse location

clickCount - the number of mouse clicks associated with event

popupTrigger - a boolean, true if this event is a trigger for a popup menu

MouseEvent

public MouseEvent(Component source,
                  int id,
                  long when,
                  int modifiers,
                  int x,
                  int y,
                  int clickCount,
                  boolean popupTrigger,
                  int button)

Constructs a MouseEvent object with the specified source component, type, modifiers, coordinates, and click count.

Note that passing in an invalid id results in unspecified behavior. Creating an invalid event (such as by using more than one of the old _MASKs, or modifier/button values which don't match) results in unspecified behavior. An invocation of the form MouseEvent(source, id, when, modifiers, x, y, clickCount, popupTrigger, button) behaves in exactly the same way as the invocation {@link #MouseEvent(Component, int, long, int, int, int, int, int, int, boolean, int) MouseEvent}(source, id, when, modifiers, x, y, xAbs, yAbs, clickCount, popupTrigger, button) where xAbs and yAbs defines as source's location on screen plus relative coordinates x and y. xAbs and yAbs are set to zero if the source is not showing. This method throws an IllegalArgumentException if source is null.

Parameters:

source - the Component that originated the event

id - the integer that identifies the event

when - a long int that gives the time the event occurred

modifiers - the modifier keys down during event (e.g. shift, ctrl, alt, meta) Either extended _DOWN_MASK or old _MASK modifiers should be used, but both models should not be mixed in one event. Use of the extended modifiers is preferred.

x - the horizontal x coordinate for the mouse location

y - the vertical y coordinate for the mouse location

clickCount - the number of mouse clicks associated with event

popupTrigger - a boolean, true if this event is a trigger for a popup menu

button - which of the mouse buttons has changed state. NOBUTTON, BUTTON1, BUTTON2 or BUTTON3.

MouseEvent

public MouseEvent(Component source,
                  int id,
                  long when,
                  int modifiers,
                  int x,
                  int y,
                  int xAbs,
                  int yAbs,
                  int clickCount,
                  boolean popupTrigger,
                  int button)

Constructs a MouseEvent object with the specified source component, type, modifiers, coordinates, absolute coordinates, and click count.

Note that passing in an invalid id results in unspecified behavior. Creating an invalid event (such as by using more than one of the old _MASKs, or modifier/button values which don't match) results in unspecified behavior. Even if inconsistent values for relative and absolute coordinates are passed to the constructor, the mouse event instance is still created and no exception is thrown. This method throws an IllegalArgumentException if source is null.

Parameters:

source - the Component that originated the event

id - the integer that identifies the event

when - a long int that gives the time the event occurred

modifiers - the modifier keys down during event (e.g. shift, ctrl, alt, meta) Either extended _DOWN_MASK or old _MASK modifiers should be used, but both models should not be mixed in one event. Use of the extended modifiers is preferred.

x - the horizontal x coordinate for the mouse location

y - the vertical y coordinate for the mouse location

xAbs - the absolute horizontal x coordinate for the mouse location

yAbs - the absolute vertical y coordinate for the mouse location

clickCount - the number of mouse clicks associated with event

popupTrigger - a boolean, true if this event is a trigger for a popup menu

button - which of the mouse buttons has changed state. NOBUTTON, BUTTON1, BUTTON2 or BUTTON3.

getButton

public int getButton()

Returns which, if any, of the mouse buttons has changed state.

Returns:

one of the following constants: NOBUTTON, BUTTON1, BUTTON2 or BUTTON3.

getClickCount

public int getClickCount()

Returns the number of mouse clicks associated with this event.

Returns:

integer value for the number of clicks

getLocationOnScreen

public Point getLocationOnScreen()

Returns the absolute x, y position of the event. In a virtual device multi-screen environment in which the desktop area could span multiple physical screen devices, these coordinates are relative to the virtual coordinate system. Otherwise, these coordinates are relative to the coordinate system associated with the Component's GraphicsConfiguration.

Returns:

a Point object containing the absolute x and y coordinates.

getMouseModifiersText

public static String getMouseModifiersText(int modifiers)

Returns a String describing the modifier keys and mouse buttons that were down during the event, such as "Shift", or "Ctrl+Shift". These strings can be localized by changing the awt.properties file.

Note that InputEvent.ALT_MASK and InputEvent.BUTTON2_MASK have the same value, so the string "Alt" is returned for both modifiers. Likewise, InputEvent.META_MASK and InputEvent.BUTTON3_MASK have the same value, so the string "Meta" is returned for both modifiers.

Parameters:

modifiers - a modifier mask describing the modifier keys and mouse buttons that were down during the event

Returns:

string a text description of the combination of modifier keys and mouse buttons that were down during the event

getPoint

public Point getPoint()

Returns the x,y position of the event relative to the source component.

Returns:

a Point object containing the x and y coordinates relative to the source component

getX

public int getX()

Returns the horizontal x position of the event relative to the source component.

Returns:

x an integer indicating horizontal position relative to the component

getXOnScreen

public int getXOnScreen()

Returns the absolute horizontal x position of the event. In a virtual device multi-screen environment in which the desktop area could span multiple physical screen devices, this coordinate is relative to the virtual coordinate system. Otherwise, this coordinate is relative to the coordinate system associated with the Component's GraphicsConfiguration.

Returns:

x an integer indicating absolute horizontal position.

getY

public int getY()

Returns the vertical y position of the event relative to the source component.

Returns:

y an integer indicating vertical position relative to the component

getYOnScreen

public int getYOnScreen()

Returns the absolute vertical y position of the event. In a virtual device multi-screen environment in which the desktop area could span multiple physical screen devices, this coordinate is relative to the virtual coordinate system. Otherwise, this coordinate is relative to the coordinate system associated with the Component's GraphicsConfiguration.

Returns:

y an integer indicating absolute vertical position.

isPopupTrigger

public boolean isPopupTrigger()

Returns whether or not this mouse event is the popup menu trigger event for the platform.

Note: Popup menus are triggered differently on different systems. Therefore, isPopupTrigger should be checked in both mousePressed and mouseReleased for proper cross-platform functionality.

Returns:

boolean, true if this event is the popup menu trigger for this platform

paramString

public String paramString()

Returns a parameter string identifying this event. This method is useful for event-logging and for debugging.

Overrides:

paramString in class ComponentEvent

Returns:

a string identifying the event and its attributes

translatePoint

public synchronized void translatePoint(int x,
                                        int y)

Translates the event's coordinates to a new position by adding specified x (horizontal) and y (vertical) offsets.

Parameters:

x - the horizontal x value to add to the current x coordinate position

y - the vertical y value to add to the current y coordinate position