TouchScroller (Google Web Toolkit Javadoc)

java.lang.Object
- com.google.gwt.touch.client.TouchScroller

```
public class TouchScroller
extends java.lang.Object
```
Adds touch based scrolling to a scroll panel.
Touch based scrolling is only supported on devices that support touch events and do not implement native touch based scrolling.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

(package private) static class TouchScroller.TemporalPoint
A point associated with a time.

Nested Classes
Modifier and Type	Class and Description
`(package private) static class`	`TouchScroller.TemporalPoint` A point associated with a time.

Constructor Summary

Constructors
Modifier Constructor and Description

protected TouchScroller()
Construct a new TouchScroller.

Constructors
Modifier	Constructor and Description
`protected`	`TouchScroller()` Construct a new `TouchScroller`.

Method Summary

Methods
Modifier and Type	Method and Description
`(package private) Point`	`calculateEndVelocity(TouchScroller.TemporalPoint from, TouchScroller.TemporalPoint to)` Calculate the end velocity.
`static TouchScroller`	`createIfSupported()` Return a new `TouchScroller`.
`static TouchScroller`	`createIfSupported(HasScrolling widget)` Return a new `TouchScroller` that augments the specified scrollable widget if supported, and null otherwise.
`(package private) TouchScroller.TemporalPoint`	`getLastTouchPosition()` Visible for testing.
`Momentum`	`getMomentum()` Get the `Momentum` that controls scrolling after the user completes a gesture.
`(package private) TouchScroller.TemporalPoint`	`getRecentTouchPosition()` Visible for testing.
`HasScrolling`	`getTargetWidget()` Get the target `HasScrolling` widget that this scroller affects.
`protected Touch`	`getTouchFromEvent(TouchEvent<?> event)` Get touch from event.
`(package private) boolean`	`isDragging()` Visible for testing.
`(package private) boolean`	`isMomentumActive()` Check if momentum is currently active.
`static boolean`	`isSupported()` Runtime check for whether touch scrolling is supported in this browser.
`(package private) boolean`	`isTouching()` Visible for testing.
`protected void`	`onDragEnd(TouchEvent<?> event)` Called when the object's drag sequence is complete.
`protected void`	`onDragMove(TouchEvent<?> event)` Called when the object has been dragged to a new position.
`protected void`	`onDragStart(TouchEvent<?> event)` Called when the object has started dragging.
`protected void`	`onTouchCancel(TouchEvent<?> event)` Called when the user cancels a touch.
`protected void`	`onTouchEnd(TouchEvent<?> event)` Called when the user releases a touch.
`protected void`	`onTouchMove(TouchEvent<?> event)` Called when the user moves a touch.
`protected void`	`onTouchStart(TouchEvent<?> event)` Called when the user starts a touch.
`(package private) void`	`removeAttachHandler()` Removes the attach handler.
`(package private) void`	`removeBustClickHandler()` Removes the bust click handler.
`void`	`setMomentum(Momentum momentum)` Set the `Momentum` that controls scrolling after the user completes a gesture.
`void`	`setTargetWidget(HasScrolling widget)` Set the target `HasScrolling` widget that this scroller affects.
`(package private) void`	`setupBustClickHandler()` Sets up the bust click handler.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - TouchScroller
```
protected TouchScroller()
```
    Construct a new TouchScroller. This constructor should be called using the static method createIfSupported().
    
    See Also:
    createIfSupported()
- Method Detail
  - createIfSupported
```
public static TouchScroller createIfSupported()
```
    Return a new TouchScroller.
    
    Returns:
    a new TouchScroller if supported, and null otherwise
  - createIfSupported
```
public static TouchScroller createIfSupported(HasScrolling widget)
```
    Return a new TouchScroller that augments the specified scrollable widget if supported, and null otherwise.
    
    Parameters:
    widget - the scrollable widget
    
    Returns:
    a new TouchScroller if supported, and null otherwise
  - isSupported
```
public static boolean isSupported()
```
    Runtime check for whether touch scrolling is supported in this browser. Returns true if touch events are supported but touch based scrolling is not natively supported.
    
    Returns:
    true if touch scrolling is supported, false if not
  - getMomentum
```
public Momentum getMomentum()
```
    Get the Momentum that controls scrolling after the user completes a gesture.
    
    Returns:
    the scrolling Momentum, or null if disabled
  - getTargetWidget
```
public HasScrolling getTargetWidget()
```
    Get the target HasScrolling widget that this scroller affects.
    
    Returns:
    the target widget
  - setMomentum
```
public void setMomentum(Momentum momentum)
```
    Set the Momentum that controls scrolling after the user completes a gesture.
    
    Parameters:
    momentum - the scrolling Momentum, or null to disable
  - setTargetWidget
```
public void setTargetWidget(HasScrolling widget)
```
    Set the target HasScrolling widget that this scroller affects.
    
    Parameters:
    widget - the target widget, or null to disbale
  - getTouchFromEvent
```
protected Touch getTouchFromEvent(TouchEvent<?> event)
```
    Get touch from event.
    
    Parameters:
    event - the event
    
    Returns:
    the touch object
  - onDragEnd
```
protected void onDragEnd(TouchEvent<?> event)
```
    Called when the object's drag sequence is complete.
    
    Parameters:
    event - the touch event
  - onDragMove
```
protected void onDragMove(TouchEvent<?> event)
```
    Called when the object has been dragged to a new position.
    
    Parameters:
    event - the touch event
  - onDragStart
```
protected void onDragStart(TouchEvent<?> event)
```
    Called when the object has started dragging.
    
    Parameters:
    event - the touch event
  - onTouchCancel
```
protected void onTouchCancel(TouchEvent<?> event)
```
    Called when the user cancels a touch. This can happen if the user touches the screen with too many fingers.
    
    Parameters:
    event - the touch event
  - onTouchEnd
```
protected void onTouchEnd(TouchEvent<?> event)
```
    Called when the user releases a touch.
    
    Parameters:
    event - the touch event
  - onTouchMove
```
protected void onTouchMove(TouchEvent<?> event)
```
    Called when the user moves a touch.
    
    Parameters:
    event - the touch event
  - onTouchStart
```
protected void onTouchStart(TouchEvent<?> event)
```
    Called when the user starts a touch.
    
    Parameters:
    event - the touch event
  - calculateEndVelocity
```
Point calculateEndVelocity(TouchScroller.TemporalPoint from,
                         TouchScroller.TemporalPoint to)
```
    Calculate the end velocity. Visible for testing.
    
    Parameters:
    from - the starting point
    to - the ending point
    
    Returns:
    the end velocity, or null if it cannot be calculated
  - getLastTouchPosition
```
TouchScroller.TemporalPoint getLastTouchPosition()
```
    Visible for testing.
  - getRecentTouchPosition
```
TouchScroller.TemporalPoint getRecentTouchPosition()
```
    Visible for testing.
  - isDragging
```
boolean isDragging()
```
    Visible for testing.
  - isMomentumActive
```
boolean isMomentumActive()
```
    Check if momentum is currently active. Visible for testing.
    
    Returns:
    true if active, false if not
  - isTouching
```
boolean isTouching()
```
    Visible for testing.
  - removeAttachHandler
```
void removeAttachHandler()
```
    Removes the attach handler. Visible for testing.
  - removeBustClickHandler
```
void removeBustClickHandler()
```
    Removes the bust click handler. Visible for testing.
  - setupBustClickHandler
```
void setupBustClickHandler()
```
    Sets up the bust click handler. Visible for testing.

Class TouchScroller

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

TouchScroller

Method Detail

createIfSupported

createIfSupported

isSupported

getMomentum

getTargetWidget

setMomentum

setTargetWidget

getTouchFromEvent

onDragEnd

onDragMove

onDragStart

onTouchCancel

onTouchEnd

onTouchMove

onTouchStart

calculateEndVelocity

getLastTouchPosition

getRecentTouchPosition

isDragging

isMomentumActive

isTouching

removeAttachHandler

removeBustClickHandler

setupBustClickHandler