java.awt.event
Class MouseWheelEvent

java.lang.Object
  |
  +--java.util.EventObject
        |
        +--java.awt.AWTEvent
              |
              +--java.awt.event.ComponentEvent
                    |
                    +--java.awt.event.InputEvent
                          |
                          +--java.awt.event.MouseEvent
                                |
                                +--java.awt.event.MouseWheelEvent
All Implemented Interfaces:
Serializable

public class MouseWheelEvent
extends MouseEvent

Safe:

See Also:
Serialized Form

Field Summary
private static sun.awt.DebugHelper dbg
           
(package private)  int scrollAmount
          Only valid for scrollType WHEEL_UNIT_SCROLL.
(package private)  int scrollType
          Indicates what sort of scrolling should take place in response to this event, based on platform settings.
static int WHEEL_BLOCK_SCROLL
          Enabled: Constant representing scrolling by a "block" (like scrolling with page-up, page-down keys)
static int WHEEL_UNIT_SCROLL
          Enabled: Constant representing scrolling by "units" (like scrolling with the arrow keys)
(package private)  int wheelRotation
          Indicates how far the mouse wheel was rotated.
 
Fields inherited from class java.awt.event.MouseEvent
button, BUTTON1, BUTTON2, BUTTON3, clickCount, MOUSE_CLICKED, MOUSE_DRAGGED, MOUSE_ENTERED, MOUSE_EXITED, MOUSE_FIRST, MOUSE_LAST, MOUSE_MOVED, MOUSE_PRESSED, MOUSE_RELEASED, MOUSE_WHEEL, NOBUTTON, popupTrigger, x, y
 
Fields inherited from class java.awt.event.InputEvent
ALT_DOWN_MASK, ALT_GRAPH_DOWN_MASK, ALT_GRAPH_MASK, ALT_MASK, BUTTON1_DOWN_MASK, BUTTON1_MASK, BUTTON2_DOWN_MASK, BUTTON2_MASK, BUTTON3_DOWN_MASK, BUTTON3_MASK, CTRL_DOWN_MASK, CTRL_MASK, JDK_1_3_MODIFIERS, META_DOWN_MASK, META_MASK, modifiers, SHIFT_DOWN_MASK, SHIFT_MASK, when
 
Fields inherited from class java.awt.event.ComponentEvent
COMPONENT_FIRST, COMPONENT_HIDDEN, COMPONENT_LAST, COMPONENT_MOVED, COMPONENT_RESIZED, COMPONENT_SHOWN
 
Fields inherited from class java.awt.AWTEvent
ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, COMPONENT_EVENT_MASK, consumed, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, HIERARCHY_BOUNDS_EVENT_MASK, HIERARCHY_EVENT_MASK, id, INPUT_METHOD_EVENT_MASK, INVOCATION_EVENT_MASK, ITEM_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, MOUSE_WHEEL_EVENT_MASK, PAINT_EVENT_MASK, RESERVED_ID_MAX, TEXT_EVENT_MASK, WINDOW_EVENT_MASK, WINDOW_FOCUS_EVENT_MASK, WINDOW_STATE_EVENT_MASK
 
Fields inherited from class java.util.EventObject
source
 
Constructor Summary
MouseWheelEvent(Component source, int id, long when, int modifiers, int x, int y, int clickCount, boolean popupTrigger, int scrollType, int scrollAmount, int wheelRotation)
          Suppressed: Constructs a MouseWheelEvent object with the specified source component, type, modifiers, coordinates, scroll type, scroll amount, and wheel rotation.
 
Method Summary
 int getScrollAmount()
          Enabled: Returns the number of units that should be scrolled in response to this event.
 int getScrollType()
          Enabled: Returns the type of scrolling that should take place in response to this event.
 int getUnitsToScroll()
          Enabled: This is a convenience method to aid in the implementation of the common-case MouseWheelListener - to scroll a ScrollPane or JScrollPane by an amount which conforms to the platform settings.
 int getWheelRotation()
          Enabled: Returns the number of "clicks" the mouse wheel was rotated.
 String paramString()
          Suppressed: Returns a parameter string identifying this event.
 
Methods inherited from class java.awt.event.MouseEvent
getButton, getClickCount, getMouseModifiersText, getPoint, getX, getY, isPopupTrigger, translatePoint
 
Methods inherited from class java.awt.event.InputEvent
consume, getModifiers, getModifiersEx, getModifiersExText, getWhen, isAltDown, isAltGraphDown, isConsumed, isControlDown, isMetaDown, isShiftDown
 
Methods inherited from class java.awt.event.ComponentEvent
getComponent
 
Methods inherited from class java.awt.AWTEvent
getID, setSource, toString
 
Methods inherited from class java.util.EventObject
getSource
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

dbg

private static final sun.awt.DebugHelper dbg

WHEEL_UNIT_SCROLL

public static final int WHEEL_UNIT_SCROLL
Enabled: Constant representing scrolling by "units" (like scrolling with the arrow keys)

See Also:
getScrollType()

WHEEL_BLOCK_SCROLL

public static final int WHEEL_BLOCK_SCROLL
Enabled: Constant representing scrolling by a "block" (like scrolling with page-up, page-down keys)

See Also:
getScrollType()

scrollType

int scrollType
Indicates what sort of scrolling should take place in response to this event, based on platform settings. Legal values are:

See Also:
getScrollType()

scrollAmount

int scrollAmount
Only valid for scrollType WHEEL_UNIT_SCROLL. Indicates number of units that should be scrolled per click of mouse wheel rotation, based on platform settings.

See Also:
getScrollAmount(), getScrollType()

wheelRotation

int wheelRotation
Indicates how far the mouse wheel was rotated.

See Also:
getWheelRotation()
Constructor Detail

MouseWheelEvent

public MouseWheelEvent(Component source,
                       int id,
                       long when,
                       int modifiers,
                       int x,
                       int y,
                       int clickCount,
                       boolean popupTrigger,
                       int scrollType,
                       int scrollAmount,
                       int wheelRotation)
Suppressed: Constructs a MouseWheelEvent object with the specified source component, type, modifiers, coordinates, scroll type, scroll amount, and wheel rotation.

Note that passing in an invalid id results in unspecified behavior.

Parameters:
source - the Component that originated the event
id - the integer that identifies the event
when - a long that gives the time the event occurred
modifiers - the modifier keys down during event (shift, ctrl, alt, meta)
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
scrollType - the type of scrolling which should take place in response to this event; valid values are WHEEL_UNIT_SCROLL and WHEEL_BLOCK_SCROLL
scrollAmount - for scrollType WHEEL_UNIT_SCROLL, the number of units to be scrolled
wheelRotation - the amount that the mouse wheel was rotated (the number of "clicks")
See Also:
MouseEvent.MouseEvent(java.awt.Component, int, long, int, int, int, int, boolean)
Method Detail

getScrollType

public int getScrollType()
Enabled: Returns the type of scrolling that should take place in response to this event. This is determined by the native platform. Legal values are:

Returns:
either MouseWheelEvent.WHEEL_UNIT_SCROLL or MouseWheelEvent.WHEEL_BLOCK_SCROLL, depending on the configuration of the native platform.
See Also:
java.awt.Adjustable#getUnitIncrement, java.awt.Adjustable#getBlockIncrement, javax.swing.Scrollable#getScrollableUnitIncrement, javax.swing.Scrollable#getScrollableBlockIncrement

getScrollAmount

public int getScrollAmount()
Enabled: Returns the number of units that should be scrolled in response to this event. Only valid if getScrollType returns MouseWheelEvent.WHEEL_UNIT_SCROLL

Returns:
number of units to scroll, or an undefined value if getScrollType returns MouseWheelEvent.WHEEL_BLOCK_SCROLL
See Also:
getScrollType()

getWheelRotation

public int getWheelRotation()
Enabled: Returns the number of "clicks" the mouse wheel was rotated.

Returns:
negative values if the mouse wheel was rotated up/away from the user, and positive values if the mouse wheel was rotated down/ towards the user

getUnitsToScroll

public int getUnitsToScroll()
Enabled: This is a convenience method to aid in the implementation of the common-case MouseWheelListener - to scroll a ScrollPane or JScrollPane by an amount which conforms to the platform settings. (Note, however, that ScrollPane and JScrollPane already have this functionality built in.)

This method returns the number of units to scroll when scroll type is MouseWheelEvent.WHEEL_UNIT_SCROLL, and should only be called if getScrollType returns MouseWheelEvent.WHEEL_UNIT_SCROLL.

Direction of scroll, amount of wheel movement, and platform settings for wheel scrolling are all accounted for. This method does not and cannot take into account value of the Adjustable/Scrollable unit increment, as this will vary among scrolling components.

A simplified example of how this method might be used in a listener:

 
  mouseWheelMoved(MouseWheelEvent event) {
      ScrollPane sp = getScrollPaneFromSomewhere(); 
      Adjustable adj = sp.getVAdjustable()
      if (MouseWheelEvent.getScrollType() == WHEEL_UNIT_SCROLL) {
          int totalScrollAmount =
              event.getUnitsToScroll() *
              adj.getUnitIncrement();
          adj.setValue(adj.getValue() + totalScrollAmount);
      }
  }
 

Returns:
the number of units to scroll based on the direction and amount of mouse wheel rotation, and on the wheel scrolling settings of the native platform
See Also:
getScrollType(), getScrollAmount(), MouseWheelListener, java.awt.Adjustable, java.awt.Adjustable#getUnitIncrement, javax.swing.Scrollable, javax.swing.Scrollable#getScrollableUnitIncrement, java.awt.ScrollPane, java.awt.ScrollPane#setWheelScrollingEnabled, javax.swing.JScrollPane, javax.swing.JScrollPane#setWheelScrollingEnabled

paramString

public String paramString()
Suppressed: Returns a parameter string identifying this event. This method is useful for event-logging and for debugging.

Overrides:
paramString in class MouseEvent
Returns:
a string identifying the event and its attributes


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