javafx.scene.input

Class ScrollEvent

java.lang.Object

java.util.EventObject
- javafx.event.Event
- - javafx.scene.input.InputEvent
  - - javafx.scene.input.GestureEvent
    - - javafx.scene.input.ScrollEvent

All Implemented Interfaces:

public final class ScrollEvent
extends GestureEvent

Scroll event indicates that user performed scrolling by mouse wheel, track pad, touch screen or other similar device.

When the scrolling is produced by a touch gesture (such as dragging a finger over a touch screen), it is surrounded by the SCROLL_STARTED and SCROLL_FINISHED events. Changing number of involved touch points during the scrolling is considered a new gesture, so the pair of SCROLL_FINISHED and SCROLL_STARTED notifications is delivered each time the touchCount changes. When the scrolling is caused by a mouse wheel rotation, only a one-time SCROLL event is delivered, without the started/finished surroundings. If scrolling inertia is active on the given platform, some SCROLL events with isInertia() returning true can come after SCROLL_FINISHED.

The event is delivered to the top-most node picked on the gesture coordinates in time of the gesture start - the whole gesture is delivered to the same node even if the coordinates change during the gesture. For mouse wheel rotation the event is delivered to the top-most node picked on mouse cursor location. The delivery is independent of current focus owner.

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 (The totalDeltaX and totalDeltaY contain the cumulative values for the whole gesture, zeros for mouse wheel). 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.

As all gestures, scrolling can be direct (performed directly at the concrete coordinates as on touch screen - the center point among all the touches is usually used as the gesture coordinates) or indirect (performed indirectly as on track pad or with mouse - the mouse cursor location is usually used as the gesture coordinates).

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;
    }

Since:

JavaFX 2.0

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 or dragging a finger over touch screen.
`static EventType<ScrollEvent>`	`SCROLL_FINISHED` This event occurs when a scrolling gesture ends.
`static EventType<ScrollEvent>`	`SCROLL_STARTED` This event occurs when a scrolling gesture is detected.

Fields inherited from class javafx.event.Event
consumed, eventType, NULL_SOURCE_TARGET, target

Fields inherited from class java.util.EventObject
source

Constructor Summary

Constructors
Constructor and Description
ScrollEvent(EventType<ScrollEvent> eventType, double x, double y, double screenX, double screenY, boolean shiftDown, boolean controlDown, boolean altDown, boolean metaDown, boolean direct, boolean inertia, double deltaX, double deltaY, double totalDeltaX, double totalDeltaY, double multiplierX, double multiplierY, ScrollEvent.HorizontalTextScrollUnits textDeltaXUnits, double textDeltaX, ScrollEvent.VerticalTextScrollUnits textDeltaYUnits, double textDeltaY, int touchCount, PickResult pickResult) Constructs new ScrollEvent event with null source and target
`ScrollEvent(EventType<ScrollEvent> eventType, double x, double y, double screenX, double screenY, boolean shiftDown, boolean controlDown, boolean altDown, boolean metaDown, boolean direct, boolean inertia, double deltaX, double deltaY, double totalDeltaX, double totalDeltaY, ScrollEvent.HorizontalTextScrollUnits textDeltaXUnits, double textDeltaX, ScrollEvent.VerticalTextScrollUnits textDeltaYUnits, double textDeltaY, int touchCount, PickResult pickResult)` Constructs new ScrollEvent event with null source and target
ScrollEvent(Object source, EventTarget target, EventType<ScrollEvent> eventType, double x, double y, double screenX, double screenY, boolean shiftDown, boolean controlDown, boolean altDown, boolean metaDown, boolean direct, boolean inertia, double deltaX, double deltaY, double totalDeltaX, double totalDeltaY, ScrollEvent.HorizontalTextScrollUnits textDeltaXUnits, double textDeltaX, ScrollEvent.VerticalTextScrollUnits textDeltaYUnits, double textDeltaY, int touchCount, PickResult pickResult) Constructs new ScrollEvent event.

Method Summary

All MethodsInstance MethodsConcrete Methods
Modifier and Type	Method and Description
`ScrollEvent`	`copyFor(Object newSource, EventTarget newTarget)` Creates and returns a copy of this event with the specified event source and target.
`ScrollEvent`	`copyFor(Object newSource, EventTarget newTarget, EventType<ScrollEvent> type)` Creates a copy of the given event with the given fields substituted.
`double`	`getDeltaX()` Gets the horizontal scroll amount.
`double`	`getDeltaY()` Gets the vertical scroll amount.
`EventType<ScrollEvent>`	`getEventType()` Gets the event type of this event.
`double`	`getMultiplierX()` Gets the multiplier used to convert mouse wheel rotation units to pixels
`double`	`getMultiplierY()` Gets the multiplier used to convert mouse wheel rotation units to pixels
`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`	`getTotalDeltaX()` Gets the cumulative horizontal scroll amount for the whole gesture.
`double`	`getTotalDeltaY()` Gets the cumulative vertical scroll amount for the whole gesture.
`int`	`getTouchCount()` Gets number of touch points that caused this event.
`String`	`toString()` Returns a string representation of this `ScrollEvent` object.

Methods inherited from class javafx.scene.input.GestureEvent
getPickResult, getSceneX, getSceneY, getScreenX, getScreenY, getX, getY, getZ, isAltDown, isControlDown, isDirect, isInertia, isMetaDown, isShiftDown, isShortcutDown

Methods inherited from class javafx.event.Event
clone, consume, fireEvent, 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
- ANY
```
public static final EventType<ScrollEvent> ANY
```
  Common supertype for all scroll event types.
- SCROLL
```
public static final EventType<ScrollEvent> SCROLL
```
  This event occurs when user performs a scrolling action such as rotating mouse wheel or dragging a finger over touch screen.
- SCROLL_STARTED
```
public static final EventType<ScrollEvent> SCROLL_STARTED
```
  This event occurs when a scrolling gesture is detected. It doesn't occur for mouse wheel scrolling.
  
  Since:
  
  JavaFX 2.2
- SCROLL_FINISHED
```
public static final EventType<ScrollEvent> SCROLL_FINISHED
```
  This event occurs when a scrolling gesture ends. It doesn't occur for mouse wheel scrolling.
  
  Since:
  
  JavaFX 2.2

Constructor Detail

ScrollEvent

public ScrollEvent(Object source,
                   EventTarget target,
                   EventType<ScrollEvent> eventType,
                   double x,
                   double y,
                   double screenX,
                   double screenY,
                   boolean shiftDown,
                   boolean controlDown,
                   boolean altDown,
                   boolean metaDown,
                   boolean direct,
                   boolean inertia,
                   double deltaX,
                   double deltaY,
                   double totalDeltaX,
                   double totalDeltaY,
                   ScrollEvent.HorizontalTextScrollUnits textDeltaXUnits,
                   double textDeltaX,
                   ScrollEvent.VerticalTextScrollUnits textDeltaYUnits,
                   double textDeltaY,
                   int touchCount,
                   PickResult pickResult)

Constructs new ScrollEvent event.

Parameters:

source - the source of the event. Can be null.

Since:

JavaFX 8.0

ScrollEvent

public ScrollEvent(EventType<ScrollEvent> eventType,
                   double x,
                   double y,
                   double screenX,
                   double screenY,
                   boolean shiftDown,
                   boolean controlDown,
                   boolean altDown,
                   boolean metaDown,
                   boolean direct,
                   boolean inertia,
                   double deltaX,
                   double deltaY,
                   double totalDeltaX,
                   double totalDeltaY,
                   ScrollEvent.HorizontalTextScrollUnits textDeltaXUnits,
                   double textDeltaX,
                   ScrollEvent.VerticalTextScrollUnits textDeltaYUnits,
                   double textDeltaY,
                   int touchCount,
                   PickResult pickResult)

Constructs new ScrollEvent event with null source and target

Parameters:

eventType - The type of the event.

Since:

JavaFX 8.0

ScrollEvent

public ScrollEvent(EventType<ScrollEvent> eventType,
                   double x,
                   double y,
                   double screenX,
                   double screenY,
                   boolean shiftDown,
                   boolean controlDown,
                   boolean altDown,
                   boolean metaDown,
                   boolean direct,
                   boolean inertia,
                   double deltaX,
                   double deltaY,
                   double totalDeltaX,
                   double totalDeltaY,
                   double multiplierX,
                   double multiplierY,
                   ScrollEvent.HorizontalTextScrollUnits textDeltaXUnits,
                   double textDeltaX,
                   ScrollEvent.VerticalTextScrollUnits textDeltaYUnits,
                   double textDeltaY,
                   int touchCount,
                   PickResult pickResult)

Constructs new ScrollEvent event with null source and target

Parameters:

eventType - The type of the event.

Since:

JavaFX 8.0

Method Detail
- 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.
- getTotalDeltaX
```
public double getTotalDeltaX()
```
  Gets the cumulative horizontal scroll amount for the whole gesture. This value should be interpreted as a number of pixels to scroll relatively to the state at the beginning of the gesture. Contains zeros for mouse wheel scrolling.
  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 scrolled horizontally during the gesture
  
  Since:
  
  JavaFX 2.2
- getTotalDeltaY
```
public double getTotalDeltaY()
```
  Gets the cumulative vertical scroll amount for the whole gesture. This value should be interpreted as a number of pixels to scroll relatively to the state at the beginning of the gesture. Contains zeros for mouse wheel scrolling.
  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 scrolled vertically during the gesture
  
  Since:
  
  JavaFX 2.2
- 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
- getTouchCount
```
public int getTouchCount()
```
  Gets number of touch points that caused this event. For non-touch source devices as mouse wheel and for inertia events after gesture finish it returns zero.
  
  Returns:
  
  Number of touch points that caused this event
  
  Since:
  
  JavaFX 2.2
- getMultiplierX
```
public double getMultiplierX()
```
  Gets the multiplier used to convert mouse wheel rotation units to pixels
  
  Returns:
  
  the x multiplier
  
  Since:
  
  JavaFX 8.0
- getMultiplierY
```
public double getMultiplierY()
```
  Gets the multiplier used to convert mouse wheel rotation units to pixels
  
  Returns:
  
  the y multiplier
  
  Since:
  
  JavaFX 8.0
- toString
```
public String toString()
```
  Returns a string representation of this ScrollEvent object.
  
  Overrides:
  
  toString in class GestureEvent
  
  Returns:
  
  a string representation of this ScrollEvent object.
- copyFor
```
public ScrollEvent copyFor(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 GestureEvent
  
  Parameters:
  
  newSource - the new source of the copied event
  
  Returns:
  
  the event copy with the new source and target
- copyFor
```
public ScrollEvent copyFor(Object newSource,
                           EventTarget newTarget,
                           EventType<ScrollEvent> type)
```
  Creates a copy of the given event with the given fields substituted.
  
  Parameters:
  
  source - the new source of the copied event
  
  Returns:
  
  the event copy with the fields substituted
  
  Since:
  
  JavaFX 8.0
- getEventType
```
public EventType<ScrollEvent> getEventType()
```
  Description copied from class: Event
  
  Gets the event type of this event. Objects of the same Event class can have different event types. These event types further specify what kind of event occurred.
  
  Overrides:
  
  getEventType in class GestureEvent
  
  Returns:
  
  the event type

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Documentation extracted from JavaFX API Documentation.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Java, JavaFX and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.

Class ScrollEvent

Nested Class Summary

Field Summary

Fields inherited from class javafx.event.Event

Fields inherited from class java.util.EventObject

Constructor Summary

Method Summary

Methods inherited from class javafx.scene.input.GestureEvent

Methods inherited from class javafx.event.Event

Methods inherited from class java.util.EventObject

Methods inherited from class java.lang.Object

Field Detail

ANY

SCROLL

SCROLL_STARTED

SCROLL_FINISHED

Constructor Detail

ScrollEvent

ScrollEvent

ScrollEvent

Method Detail

getDeltaX

getDeltaY

getTotalDeltaX

getTotalDeltaY

getTextDeltaXUnits

getTextDeltaYUnits

getTextDeltaX

getTextDeltaY

getTouchCount

getMultiplierX

getMultiplierY

toString

copyFor

copyFor

getEventType