java.awt.event
Class MouseWheelEvent
java.lang.Object
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+--java.util.EventObject
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+--java.awt.AWTEvent
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+--java.awt.event.ComponentEvent
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+--java.awt.event.InputEvent
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+--java.awt.event.MouseEvent
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+--java.awt.event.MouseWheelEvent
This event is generated for a mouse wheel rotation. The wheel (the middle
mouse button on most modern mice) can be rotated towards or away from the
user, and is ofteh used for scrolling.
Because of the special use for scrolling components, MouseWheelEvents
often affect a different component than the one located at the point of
the event. If the component under the mouse cursor does not accept wheel
events, the event is passed to the first ancestor container which does. This
is often a ScrollPane, which knows how to scroll. If an AWT component is
built from a native widget that knows how to use mouse wheel events, that
component will consume the event.
The two most common scroll types are "units" (lines at a time) or
"blocks" (pages at a time). The initial setting is taken from the platform,
although the user can adjust the setting at any time.
Since:Author:- Eric Blake <ebb9@email.byu.edu>
See Also:
MouseWheelEvent(java.awt.Component source, int id, long when, int modifiers, int x, int y, int clickCount, boolean popupTrigger, int scrollType, int scrollAmount, int wheelRotation)
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WHEEL_BLOCK_SCROLL
public static final int WHEEL_BLOCK_SCROLL
Indicates scrolling by blocks (pages).
See Also:
WHEEL_UNIT_SCROLL
public static final int WHEEL_UNIT_SCROLL
Indicates scrolling by units (lines).
See Also:
MouseWheelEvent
public MouseWheelEvent(java.awt.Component source, int id, long when, int modifiers, int x, int y, int clickCount, boolean popupTrigger, int scrollType, int scrollAmount, int wheelRotation)
Initializes a new instance of MouseWheelEvent
with the
specified information. Note that an invalid id leads to unspecified
results.
#WHEEL_BLOCK_SCROLL
Parameters:
Throws:
See Also:
getScrollAmount
public int getScrollAmount()
Returns the number of units to scroll in response to this event. This
only makes sense when the scroll type is WHEEL_UNIT_SCROLL.
Returns:
- the number of scroll units, if defined
See Also:
getScrollType
public int getScrollType()
This method returns the scrolling pattern this event requests. Legal
values are WHEEL_UNIT_SCROLL and WHEEL_BLOCK_SCROLL.
Returns:
See Also:
getUnitsToScroll
public int getUnitsToScroll()
This is a convenience method which aids in a common listener for scrolling
a scrollpane (although this is already built into ScrollPane and
JScrollPane). This method only makes sense when getScrollType() returns
WHEEL_UNIT_SCROLL.
This accounts for direction of scroll and amount of wheel movement, as
interpreted by the platform settings.
Returns:
- the number of units to scroll
See Also:
getWheelRotation
public int getWheelRotation()
Gets the number of "clicks" the wheel was rotated. Negative values move
up (away) from the user, positive values move down (towards) the user.
Returns:
- the number of rotation clicks
paramString
public String paramString()
Returns a string identifying this event. For mouse wheel events, this
is super.paramString() + ",scrollType=WHEEL_" +
(getScrollType() == WHEEL_UNIT_SCROLL ? "UNIT" : "BLOCK")
+ "_SCROLL,scrollAmount=" + getScrollAmount() + ",wheelRotation="
+ getWheelRotation()
.
Returns:
- a string identifying this event
Because of the special use for scrolling components, MouseWheelEvents often affect a different component than the one located at the point of the event. If the component under the mouse cursor does not accept wheel events, the event is passed to the first ancestor container which does. This is often a ScrollPane, which knows how to scroll. If an AWT component is built from a native widget that knows how to use mouse wheel events, that component will consume the event.
The two most common scroll types are "units" (lines at a time) or "blocks" (pages at a time). The initial setting is taken from the platform, although the user can adjust the setting at any time.