com.google.gwt.touch.client
Class TouchScroller

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.

TouchScroller

protected TouchScroller()

Construct a new TouchScroller. This constructor should be called using the static method createIfSupported().

See Also:

createIfSupported()

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.