Scroller (library 2.4.13 API)

java.lang.Object
- com.shawnlin.numberpicker.Scroller

```
public class Scroller
extends Object
```
This class encapsulates scrolling. You can use scrollers (Scroller 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();
    ...
 }
```

Constructor Summary

Constructors
Constructor and Description
`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.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`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.
`void`	`forceFinished(boolean finished)` Force the finished field to a particular value.
`float`	`getCurrVelocity()` Returns the current velocity.
`int`	`getCurrX()` Returns the current X offset in the scroll.
`int`	`getCurrY()` Returns the current Y offset in the scroll.
`int`	`getDuration()` Returns how long the scroll event will take, in milliseconds.
`int`	`getFinalX()` Returns where the scroll will end.
`int`	`getFinalY()` Returns where the scroll will end.
`int`	`getStartX()` Returns the start X offset in the scroll.
`int`	`getStartY()` Returns the start Y offset in the scroll.
`boolean`	`isFinished()` Returns whether the scroller has finished scrolling.
`boolean`	`isScrollingInDirection(float xvel, float yvel)`
`void`	`setFinalX(int newX)` Sets the final position (X) for this scroller.
`void`	`setFinalY(int newY)` Sets the final position (Y) for this scroller.
`void`	`setFriction(float friction)` The amount of friction applied to flings.
`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, the distance to travel, and the duration of the scroll.
`int`	`timePassed()` Returns the time elapsed since the beginning of the scrolling.

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

- Constructor Detail
  - Scroller
```
public Scroller(Context context)
```
    Create a Scroller with the default duration and interpolator.
  - Scroller
```
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.
  - Scroller
```
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.
- Method Detail
  - setFriction
```
public final void setFriction(float friction)
```
    The amount of friction applied to flings. The default value is ViewConfiguration.getScrollFriction().
    
    Parameters:
    
    friction - A scalar dimension-less value representing the coefficient of friction.
  - isFinished
```
public final boolean isFinished()
```
    Returns whether the scroller has finished scrolling.
    
    Returns:
    
    True if the scroller has finished scrolling, false otherwise.
  - forceFinished
```
public final void forceFinished(boolean finished)
```
    Force the finished field to a particular value.
    
    Parameters:
    
    finished - The new finished value.
  - getDuration
```
public final int getDuration()
```
    Returns how long the scroll event will take, in milliseconds.
    
    Returns:
    
    The duration of the scroll in milliseconds.
  - getCurrX
```
public final int getCurrX()
```
    Returns the current X offset in the scroll.
    
    Returns:
    
    The new X offset as an absolute distance from the origin.
  - getCurrY
```
public final int getCurrY()
```
    Returns the current Y offset in the scroll.
    
    Returns:
    
    The new Y offset as an absolute distance from the origin.
  - getCurrVelocity
```
public float getCurrVelocity()
```
    Returns the current velocity.
    
    Returns:
    
    The original velocity less the deceleration. Result may be negative.
  - getStartX
```
public final int getStartX()
```
    Returns the start X offset in the scroll.
    
    Returns:
    
    The start X offset as an absolute distance from the origin.
  - getStartY
```
public final int getStartY()
```
    Returns the start Y offset in the scroll.
    
    Returns:
    
    The start Y offset as an absolute distance from the origin.
  - getFinalX
```
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.
  - getFinalY
```
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.
  - computeScrollOffset
```
public boolean computeScrollOffset()
```
    Call this when you want to know the new location. If it returns true, the animation is not yet finished.
  - startScroll
```
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.
  - startScroll
```
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 - 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.
  - fling
```
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.
  - abortAnimation
```
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)
  - extendDuration
```
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 - Additional time to scroll in milliseconds.
    
    See Also:
    
    setFinalX(int), setFinalY(int)
  - timePassed
```
public int timePassed()
```
    Returns the time elapsed since the beginning of the scrolling.
    
    Returns:
    
    The elapsed time in milliseconds.
  - setFinalX
```
public void setFinalX(int newX)
```
    Sets the final position (X) for this scroller.
    
    Parameters:
    
    newX - The new X offset as an absolute distance from the origin.
    
    See Also:
    
    extendDuration(int), setFinalY(int)
  - setFinalY
```
public void setFinalY(int newY)
```
    Sets the final position (Y) for this scroller.
    
    Parameters:
    
    newY - The new Y offset as an absolute distance from the origin.
    
    See Also:
    
    extendDuration(int), setFinalX(int)
  - isScrollingInDirection
```
public boolean isScrollingInDirection(float xvel,
                                      float yvel)
```

Class Scroller

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Scroller

Scroller

Scroller

Method Detail

setFriction

isFinished

forceFinished

getDuration

getCurrX

getCurrY

getCurrVelocity

getStartX

getStartY

getFinalX

getFinalY

computeScrollOffset

startScroll

startScroll

fling

abortAnimation

extendDuration

timePassed

setFinalX

setFinalY

isScrollingInDirection