ru.noties.scrollable

Class ScrollableScroller

java.lang.Object

ru.noties.scrollable.ScrollableScroller

public class ScrollableScroller
extends java.lang.Object

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();
    ...
 }

Constructor Summary

Constructors

Constructor and Description
ScrollableScroller(android.content.Context context, android.view.animation.Interpolator interpolator, boolean flywheel) Create a Scroller with the specified interpolator.

Method Summary

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	fling(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY) Start scrolling based on a fling gesture.
float	getCurrVelocity() Returns the current velocity.
int	getCurrY() Returns the current Y offset in the scroll.
int	getDuration() Returns how long the scroll event will take, in milliseconds.
int	getFinalY() Returns where the scroll will end.
void	setFinalY(int newY) Sets the final position (Y) for this scroller.
void	setFriction(float friction) The amount of friction applied to flings.
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

ScrollableScroller

public ScrollableScroller(android.content.Context context,
                  android.view.animation.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.

getDuration

public final int getDuration()

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

Returns:

The duration of the scroll in milliseconds.

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.

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.

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 forceFinished(boolean)

timePassed

public int timePassed()

Returns the time elapsed since the beginning of the scrolling.

Returns:

The elapsed time in milliseconds.

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. extendDuration(int) setFinalX(int)