public class

Scroller

extends Object
java.lang.Object
   ↳ android.widget.Scroller

Class Overview

This class encapsulates scrolling. The duration of the scroll can be passed in the constructor and specifies the maximum time that the scrolling animation should take. Past this time, the scrolling is automatically moved to its final stage and computeScrollOffset() will always return false to indicate that scrolling is over.

Summary

Public Constructors
Scroller(Context context)
Create a Scroller with the default duration and interpolator.
Scroller(Context context, Interpolator interpolator)
Create a Scroller with the specified interpolator.
Public Methods
void abortAnimation()
boolean computeScrollOffset()
Call this when you want to know the new location.
void extendDuration(int extend)
Extend the scroll animation.
void fling(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY)
Start scrolling based on a fling gesture.
final void forceFinished(boolean finished)
Force the finished field to a particular value.
final int getCurrX()
Returns the current X offset in the scroll.
final int getCurrY()
Returns the current Y offset in the scroll.
final int getDuration()
Returns how long the scroll event will take, in milliseconds.
final int getFinalX()
Returns where the scroll will end.
final int getFinalY()
Returns where the scroll will end.
final int getStartX()
Returns the start X offset in the scroll.
final int getStartY()
Returns the start Y offset in the scroll.
final boolean isFinished()
Returns whether the scroller has finished scrolling.
void setFinalX(int newX)
void setFinalY(int newY)
void startScroll(int startX, int startY, int dx, int dy)
Start scrolling by providing a starting point and the distance to travel.
void startScroll(int startX, int startY, int dx, int dy, int duration)
Start scrolling by providing a starting point and the distance to travel.
int timePassed()
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public Scroller (Context context)

Create a Scroller with the default duration and interpolator.

public Scroller (Context context, Interpolator interpolator)

Create a Scroller with the specified interpolator. If the interpolator is null, the default (viscous) interpolator will be used.

Public Methods

public void abortAnimation ()

public boolean computeScrollOffset ()

Call this when you want to know the new location. If it returns true, the animation is not yet finished. loc will be altered to provide the new location.

public void extendDuration (int extend)

Extend the scroll animation. This allows a running animation to scroll further and longer, when used with setFinalX() or setFinalY().

Parameters
extend Additional time to scroll in milliseconds.

public void fling (int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY)

Start scrolling based on a fling gesture. The distance travelled will depend on the initial velocity of the fling.

Parameters
startX Starting point of the scroll (X)
startY Starting point of the scroll (Y)
velocityX Initial velocity of the fling (X) measured in pixels per second.
velocityY Initial velocity of the fling (Y) measured in pixels per second
minX Minimum X value. The scroller will not scroll past this point.
maxX Maximum X value. The scroller will not scroll past this point.
minY Minimum Y value. The scroller will not scroll past this point.
maxY Maximum Y value. The scroller will not scroll past this point.

public final void forceFinished (boolean finished)

Force the finished field to a particular value.

Parameters
finished The new finished value.

public final int getCurrX ()

Returns the current X offset in the scroll.

Returns
  • The new X offset as an absolute distance from the origin.

public final int getCurrY ()

Returns the current Y offset in the scroll.

Returns
  • The new Y offset as an absolute distance from the origin.

public final int getDuration ()

Returns how long the scroll event will take, in milliseconds.

Returns
  • The duration of the scroll in milliseconds.

public final int getFinalX ()

Returns where the scroll will end. Valid only for "fling" scrolls.

Returns
  • The final X offset as an absolute distance from the origin.

public final int getFinalY ()

Returns where the scroll will end. Valid only for "fling" scrolls.

Returns
  • The final Y offset as an absolute distance from the origin.

public final int getStartX ()

Returns the start X offset in the scroll.

Returns
  • The start X offset as an absolute distance from the origin.

public final int getStartY ()

Returns the start Y offset in the scroll.

Returns
  • The start Y offset as an absolute distance from the origin.

public final boolean isFinished ()

Returns whether the scroller has finished scrolling.

Returns
  • True if the scroller has finished scrolling, false otherwise.

public void setFinalX (int newX)

public void setFinalY (int newY)

public void startScroll (int startX, int startY, int dx, int dy)

Start scrolling by providing a starting point and the distance to travel. The scroll will use the default value of 250 milliseconds for the duration.

Parameters
startX Starting horizontal scroll offset in pixels. Positive numbers will scroll the content to the left.
startY Starting vertical scroll offset in pixels. Positive numbers will scroll the content up.
dx Horizontal distance to travel. Positive numbers will scroll the content to the left.
dy Vertical distance to travel. Positive numbers will scroll the content up.

public void startScroll (int startX, int startY, int dx, int dy, int duration)

Start scrolling by providing a starting point and the distance to travel.

Parameters
startX Starting horizontal scroll offset in pixels. Positive numbers will scroll the content to the left.
startY Starting vertical scroll offset in pixels. Positive numbers will scroll the content up.
dx Horizontal distance to travel. Positive numbers will scroll the content to the left.
dy Vertical distance to travel. Positive numbers will scroll the content up.
duration Duration of the scroll in milliseconds.

public int timePassed ()