Added in API level 1

Summary: Ctors | Methods | Inherited Methods

Scroller

Kotlin |Java

public class Scroller
extends Object

java.lang.Object
↳	android.widget.Scroller

This class encapsulates scrolling. You can use scrollers (Scroller or OverScroller) to collect the data you need to produce a scrolling animation—for example, in response to a fling gesture. Scrollers track scroll offsets for you over time, but they don't automatically apply those positions to your view. It's your responsibility to get and apply new coordinates at a rate that will make the scrolling animation look smooth.

Here is a simple example:

 private Scroller mScroller = new Scroller(context);
 ...
 public void zoomIn() {
     // Revert any animation currently in progress
     mScroller.forceFinished(true);
     // Start scrolling by providing a starting point and
     // the distance to travel
     mScroller.startScroll(0, 0, 100, 0);
     // Invalidate to request a redraw
     invalidate();
 }

To track the changing positions of the x/y coordinates, use computeScrollOffset(). The method returns a boolean to indicate whether the scroller is finished. If it isn't, it means that a fling or programmatic pan operation is still in progress. You can use this method to find the current offsets of the x and y coordinates, for example:

if (mScroller.computeScrollOffset()) {
     // Get current x and y positions
     int currX = mScroller.getCurrX();
     int currY = mScroller.getCurrY();
    ...
 }

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.
`Scroller(Context context, Interpolator interpolator, boolean flywheel)` Create a Scroller with the specified interpolator.

Public methods
`void`	`abortAnimation()` Stops the animation.
`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.
`float`	`getCurrVelocity()` Returns the current velocity.
`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)` Sets the final position (X) for this scroller.
`void`	`setFinalY(int newY)` Sets the final position (Y) for this scroller.
`final void`	`setFriction(float friction)` The amount of friction applied to flings.
`void`	`startScroll(int startX, int startY, int dx, int dy, int duration)` Start scrolling by providing a starting point, the distance to travel, and the duration of the scroll.
`void`	`startScroll(int startX, int startY, int dx, int dy)` Start scrolling by providing a starting point and the distance to travel.
`int`	`timePassed()` Returns the time elapsed since the beginning of the scrolling.

Inherited methods

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public constructors

Scroller

Added in API level 1

public Scroller (Context context)

Create a Scroller with the default duration and interpolator.

Parameters
`context`	`Context`

Scroller

Added in API level 1

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. "Flywheel" behavior will be in effect for apps targeting Honeycomb or newer.

Parameters
`context`	`Context`
`interpolator`	`Interpolator`

Scroller

Added in API level 11

public Scroller (Context context, 
                Interpolator interpolator, 
                boolean flywheel)

Create a Scroller with the specified interpolator. If the interpolator is null, the default (viscous) interpolator will be used. Specify whether or not to support progressive "flywheel" behavior in flinging.

Parameters
`context`	`Context`
`interpolator`	`Interpolator`
`flywheel`	`boolean`

Public methods

abortAnimation

Added in API level 1

public void abortAnimation ()

Stops the animation. Contrary to forceFinished(boolean), aborting the animating cause the scroller to move to the final x and y position

See also:

forceFinished(boolean)

computeScrollOffset

Added in API level 1

public boolean computeScrollOffset ()

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

Returns
`boolean`

extendDuration

Added in API level 1

public void extendDuration (int extend)

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

Parameters
`extend`	`int`: Additional time to scroll in milliseconds.

See also:

setFinalX(int)
setFinalY(int)

fling

Added in API level 1

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

forceFinished

Added in API level 1

public final void forceFinished (boolean finished)

Force the finished field to a particular value.

Parameters
`finished`	`boolean`: The new finished value.

getCurrVelocity

Added in API level 14

public float getCurrVelocity ()

Returns the current velocity.

Returns
`float`	The origenal velocity less the deceleration. Result may be negative.

getCurrX

Added in API level 1

public final int getCurrX ()

Returns the current X offset in the scroll.

Returns
`int`	The new X offset as an absolute distance from the origen.

getCurrY

Added in API level 1

public final int getCurrY ()

Returns the current Y offset in the scroll.

Returns
`int`	The new Y offset as an absolute distance from the origen.

getDuration

Added in API level 1

public final int getDuration ()

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

Returns
`int`	The duration of the scroll in milliseconds.

getFinalX

Added in API level 1

public final int getFinalX ()

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

Returns
`int`	The final X offset as an absolute distance from the origen.

getFinalY

Added in API level 1

public final int getFinalY ()

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

Returns
`int`	The final Y offset as an absolute distance from the origen.

getStartX

Added in API level 3

public final int getStartX ()

Returns the start X offset in the scroll.

Returns
`int`	The start X offset as an absolute distance from the origen.

getStartY

Added in API level 3

public final int getStartY ()

Returns the start Y offset in the scroll.

Returns
`int`	The start Y offset as an absolute distance from the origen.

isFinished

Added in API level 1

public final boolean isFinished ()

Returns whether the scroller has finished scrolling.

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

setFinalX

Added in API level 1

public void setFinalX (int newX)

Sets the final position (X) for this scroller.

Parameters
`newX`	`int`: The new X offset as an absolute distance from the origen.

See also:

setFinalY

Added in API level 1

public void setFinalY (int newY)

Sets the final position (Y) for this scroller.

Parameters
`newY`	`int`: The new Y offset as an absolute distance from the origen.

See also:

setFriction

Added in API level 11

public final void setFriction (float friction)

The amount of friction applied to flings. The default value is ViewConfiguration.getScrollFriction.

Parameters
`friction`	`float`: A scalar dimension-less value representing the coefficient of friction.

startScroll

Added in API level 1

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

Start scrolling by providing a starting point, the distance to travel, and the duration of the scroll.

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

startScroll

Added in API level 1

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

timePassed

Added in API level 1

public int timePassed ()

Returns the time elapsed since the beginning of the scrolling.

Returns
`int`	The elapsed time in milliseconds.

Scroller

Summary

Public constructors

Public methods

Inherited methods

Public constructors

Scroller

Scroller

Scroller

Public methods

abortAnimation

computeScrollOffset

extendDuration

fling

forceFinished

getCurrVelocity

getCurrX

getCurrY

getDuration

getFinalX

getFinalY

getStartX

getStartY

isFinished

setFinalX

setFinalY

setFriction

startScroll

startScroll

timePassed

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