javafx.scene.input

Class ScrollEvent

java.lang.Object

java.util.EventObject

javafx.event.Event

javafx.scene.input.InputEvent

javafx.scene.input.ScrollEvent

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

public class ScrollEvent
extends InputEvent

Scroll event indicates that user performed scrolling by mouse wheel, touchpad or other similar device. It is always delivered to the node under cursor regardless of current focus owner (similarly to mouse events).

The event provides two different types of scrolling values: pixel-based and character/line-based. The basic deltaX and deltaY values give reasonable results when used as number of pixels to scroll. For scrolling text (or other line-based content as tables) the textDelta values should be used if they are available. The textDeltaXUnits and textDeltaYUnits determine how to interpret the textDeltaX and textDeltaY values. If the units are set to NONE, the text-based values are not available (not provided by the underlying platform) and the pixel-based values need to be used.

For example, scrolling a graphical node can be achieved by following code:

    node.setOnScroll(new EventHandler() {
        @Override public void handle(ScrollEvent event) {
            node.setTranslateX(node.getTranslateX() + event.getDeltaX());
            node.setTranslateY(node.getTranslateY() + event.getDeltaY());
        }
    });

A scroll event handler on text-based component behaving according to system settings on all platforms should contain following logic:

    switch(event.getTextDeltaYUnits()) {
        case LINES:
            // scroll about event.getTextDeltaY() lines 
            break;
        case PAGES:
            // scroll about event.getTextDeltaY() pages
            break;
        case NONE:
            // scroll about event.getDeltaY() pixels
            break;
    }
 

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ScrollEvent.HorizontalTextScrollUnits Horizontal text-based scrolling units.
static class	ScrollEvent.VerticalTextScrollUnits Vertical text-based scrolling units.

Field Summary

Fields

Modifier and Type	Field and Description
static EventType<ScrollEvent>	ANY Common supertype for all scroll event types.
static EventType<ScrollEvent>	SCROLL This event occurs when user performs a scrolling action such as rotating mouse wheel.

Fields inherited from class javafx.event.Event

consumed, eventType, NULL_SOURCE_TARGET, target

Fields inherited from class java.util.EventObject

source

Method Summary

Methods

Modifier and Type	Method and Description
Event	copyFor(java.lang.Object newSource, EventTarget newTarget) Creates and returns a copy of this event with the specified event source and target.
double	getDeltaX() Gets the horizontal scroll amount.
double	getDeltaY() Gets the vertical scroll amount.
double	getSceneX() Gets the horizontal position of the event relative to the origin of the Scene that contains the ScrollEvent's source.
double	getSceneY() Gets the vertical position of the event relative to the origin of the Scene that contains the ScrollEvent's source.
double	getScreenX() Gets the absolute horizontal position of the event.
double	getScreenY() Gets the absolute vertical position of the event.
double	getTextDeltaX() Gets the horizontal text-based scroll amount.
ScrollEvent.HorizontalTextScrollUnits	getTextDeltaXUnits() Gets the horizontal scrolling units for text-based scrolling.
double	getTextDeltaY() Gets the vertical text-based scroll amount.
ScrollEvent.VerticalTextScrollUnits	getTextDeltaYUnits() Gets the vertical scrolling units for text-based scrolling.
double	getX() Gets the horizontal position of the event relative to the origin of the ScrollEvent's source.
double	getY() Gets the vertical position of the event relative to the origin of the ScrollEvent's source.
boolean	isAltDown() Indicates whether or not the Alt modifier is down on this event.
boolean	isControlDown() Indicates whether or not the Control modifier is down on this event.
boolean	isMetaDown() Indicates whether or not the Meta modifier is down on this event.
boolean	isShiftDown() Indicates whether or not the Shift modifier is down on this event.
boolean	isShortcutDown() Indicates whether or not the host platform common shortcut modifier is down on this event.
java.lang.String	toString() Returns a string representation of this ScrollEvent object.

Methods inherited from class javafx.event.Event

clone, consume, fireEvent, getEventType, getTarget, isConsumed

Methods inherited from class java.util.EventObject

getSource

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

SCROLL

public static final EventType<ScrollEvent> SCROLL

This event occurs when user performs a scrolling action such as rotating mouse wheel.

ANY

public static final EventType<ScrollEvent> ANY

Common supertype for all scroll event types.

Method Detail

copyFor

public Event copyFor(java.lang.Object newSource,
            EventTarget newTarget)

Description copied from class: Event

Creates and returns a copy of this event with the specified event source and target. If the source or target is set to null, it is replaced by the NULL_SOURCE_TARGET value.

Overrides:

copyFor in class Event

Parameters:

newSource - the new source of the copied event

newTarget - the new target of the copied event

Returns:

the event copy with the new source and target

getDeltaX

public double getDeltaX()

Gets the horizontal scroll amount. This value should be interpreted as a number of pixels to scroll. When scrolling a text-based content, the textDeltaX and textDeltaXUnits values should be considered first.

The sign of the value is reversed compared to the coordinate system (when you scroll right, the content actually needs to go left). So the returned value can be simply added to the content's X coordinate.

Returns:

Number of pixels to scroll horizontally.

getDeltaY

public double getDeltaY()

Gets the vertical scroll amount. This value should be interpreted as a number of pixels to scroll. When scrolling a line-based content, the textDeltaY and textDeltaYUnits values should be considered first.

The sign of the value is reversed compared to the coordinate system (when you scroll down, the content actually needs to go up). So the returned value can be simply added to the content's Y coordinate.

Returns:

Number of pixels to scroll vertically.

getTextDeltaXUnits

public ScrollEvent.HorizontalTextScrollUnits getTextDeltaXUnits()

Gets the horizontal scrolling units for text-based scrolling. The returned value indicates how to interpret the getTextDeltaX() value. If the returned value is NONE, the text-based scrolling value is not available and the pixel-based getDeltaX() value needs to be used.

Returns:

the horizontal scrolling units for text-based scrolling

getTextDeltaYUnits

public ScrollEvent.VerticalTextScrollUnits getTextDeltaYUnits()

Gets the vertical scrolling units for text-based scrolling. The returned value indicates how to interpret the getTextDeltaY() value. If the returned value is NONE, the text-based scrolling value is not available and the pixel-based getDeltaY() value needs to be used.

Returns:

the vertical scrolling units for text-based scrolling

getTextDeltaX

public double getTextDeltaX()

Gets the horizontal text-based scroll amount. This value should be interpreted according to the getTextDeltaXUnits() value.

Returns:

Number of units to scroll horizontally, zero if the text-based horizontal scrolling data is not available getTextDeltaXUnits() returns NONE

getTextDeltaY

public double getTextDeltaY()

Gets the vertical text-based scroll amount. This value should be interpreted according to the getTextDeltaYUnits() value.

Returns:

Number of units to scroll vertically, zero if the text-based vertical scrolling data is not available getTextDeltaYUnits() returns NONE

getX

public final double getX()

Gets the horizontal position of the event relative to the origin of the ScrollEvent's source.

Returns:

the horizontal position of the event relative to the origin of the ScrollEvent's source.

getY

public final double getY()

Gets the vertical position of the event relative to the origin of the ScrollEvent's source.

Returns:

the vertical position of the event relative to the origin of the ScrollEvent's source.

getScreenX

public final double getScreenX()

Gets the absolute horizontal position of the event.

Returns:

the absolute horizontal position of the event

getScreenY

public final double getScreenY()

Gets the absolute vertical position of the event.

Returns:

the absolute vertical position of the event

getSceneX

public final double getSceneX()

Gets the horizontal position of the event relative to the origin of the Scene that contains the ScrollEvent's source. If the node is not in a Scene, then the value is relative to the boundsInParent of the root-most parent of the ScrollEvent's node.

Returns:

the horizontal position of the event relative to the origin of the Scene that contains the ScrollEvent's source

getSceneY

public final double getSceneY()

Gets the vertical position of the event relative to the origin of the Scene that contains the ScrollEvent's source. If the node is not in a Scene, then the value is relative to the boundsInParent of the root-most parent of the ScrollEvent's node.

Returns:

the vertical position of the event relative to the origin of the Scene that contains the ScrollEvent's source

isShiftDown

public final boolean isShiftDown()

Indicates whether or not the Shift modifier is down on this event.

Returns:

true if the Shift modifier is down on this event

isControlDown

public final boolean isControlDown()

Indicates whether or not the Control modifier is down on this event.

Returns:

true if the Control modifier is down on this event

isAltDown

public final boolean isAltDown()

Indicates whether or not the Alt modifier is down on this event.

Returns:

true if the Alt modifier is down on this event

isMetaDown

public final boolean isMetaDown()

Indicates whether or not the Meta modifier is down on this event.

Returns:

true if the Meta modifier is down on this event

isShortcutDown

public final boolean isShortcutDown()

Indicates whether or not the host platform common shortcut modifier is down on this event. This common shortcut modifier is a modifier key which is used commonly in shortcuts on the host platform. It is for example control on Windows and meta (command key) on Mac.

Returns:

true if the shortcut modifier is down, false otherwise

toString

public java.lang.String toString()

Returns a string representation of this ScrollEvent object.

Overrides:

toString in class java.util.EventObject

Returns:

a string representation of this ScrollEvent object.