java 如何在android中创建可弹跳的滚动视图？

How to create bouncable scrollview in android?

提问by Asif Rafiq

How to create a bounce ScrollViewin Android like iPhone?

如何ScrollView在像 iPhone 一样的 Android 中创建反弹？

回答by Thien Nguyen

Add effect bounce to scrollview in android

在android中为scrollview添加效果反弹

Step 1: Create new file BounceScrollView in package com.base.view

步骤 1：在包 com.base.view 中创建新文件 BounceScrollView

public class BounceScrollView extends ScrollView
{
    private static final int MAX_Y_OVERSCROLL_DISTANCE = 200;

    private Context mContext;
    private int mMaxYOverscrollDistance;

    public BounceScrollView(Context context) 
    {
        super(context);
        mContext = context;
        initBounceScrollView();
    }

    public BounceScrollView(Context context, AttributeSet attrs) 
    {
        super(context, attrs);
        mContext = context;
        initBounceScrollView();
    }

    public BounceScrollView(Context context, AttributeSet attrs, int defStyle) 
    {
        super(context, attrs, defStyle);
        mContext = context;
        initBounceScrollView();
    }

    private void initBounceScrollView()
    {
        //get the density of the screen and do some maths with it on the max overscroll distance
        //variable so that you get similar behaviors no matter what the screen size

        final DisplayMetrics metrics = mContext.getResources().getDisplayMetrics();
            final float density = metrics.density;

        mMaxYOverscrollDistance = (int) (density * MAX_Y_OVERSCROLL_DISTANCE);
    }

    @Override
    protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY, int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent) 
    { 
        //This is where the magic happens, we have replaced the incoming maxOverScrollY with our own custom variable mMaxYOverscrollDistance; 
        return super.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY, maxOverScrollX, mMaxYOverscrollDistance, isTouchEvent);  
    }

}

Step 2:At your layout, please change

第 2 步：在您的布局中，请更改

<ScrollView 
   android:id="@+id/list"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
/>

to

到

<com.base.view.BounceScrollView 
   android:id="@+id/list"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
/>

回答by ultraon

I have improved version of this answer: https://stackoverflow.com/a/13391248/3256989. So my version is (example for HorizontalScrollView):

我已经改进了这个答案的版本：https: //stackoverflow.com/a/13391248/3256989。所以我的版本是（以 Horizo​​ntalScrollView 为例）：

public class HorizontalOverScrollView extends HorizontalScrollView {
    private static final int WIDTH_DEVIDER_OVERSCROLL_DISTANCE = 3;

    private TimeInterpolator mInterpolator;
    private int mMaxOverscrollDistance;
    private int mAnimTime;
    private long mStartTime;

    /**
     * Instantiates {@link HorizontalOverScrollView} object.
     */
    public HorizontalOverScrollView(final Context context) {
        super(context);
        init();
    }

    /**
     * Instantiates {@link HorizontalOverScrollView} object.
     */
    public HorizontalOverScrollView(final Context context, final AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    /**
     * Instantiates {@link HorizontalOverScrollView} object.
     */
    public HorizontalOverScrollView(final Context context, final AttributeSet attrs, final int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        final int widthPixels = getContext().getResources().getDisplayMetrics().widthPixels;
        mMaxOverscrollDistance = widthPixels / WIDTH_DEVIDER_OVERSCROLL_DISTANCE;
        mAnimTime = getContext().getResources().getInteger(android.R.integer.config_mediumAnimTime);
        mInterpolator = new DecelerateInterpolator();
    }

    @Override
    protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY, int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent) {
        int overScrollDistance = mMaxOverscrollDistance;
        if (isTouchEvent) {
            mStartTime = AnimationUtils.currentAnimationTimeMillis();
        } else {
            final long elapsedTime = AnimationUtils.currentAnimationTimeMillis() - mStartTime;
            float interpolation = mInterpolator.getInterpolation((float) elapsedTime / mAnimTime);
            interpolation = interpolation > 1 ? 1 : interpolation;
            overScrollDistance -= overScrollDistance * interpolation;
            overScrollDistance = overScrollDistance < 0 ? 0 : overScrollDistance;
        }

        return super.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY, overScrollDistance, maxOverScrollY, isTouchEvent);
    }
}

回答by Marc Van Daele

It's called overscroll in Android.
See http://developer.android.com/reference/android/widget/OverScroller.htmland (for example) http://developer.android.com/reference/android/widget/ListView.html#setOverscrollFooter(android.graphics.drawable.Drawable)

它在 Android 中称为过度滚动。
请参阅http://developer.android.com/reference/android/widget/OverScroller.html和（例如）http://developer.android.com/reference/android/widget/ListView.html#setOverscrollFooter( android.graphics .drawable.Drawable)

It's only available from API level 9 onward.
However, Samsung devices do seem to support overscroll natively in Android 2.2

它仅从 API 级别 9 开始可用。
但是，三星设备似乎确实在 Android 2.2 中原生支持过度滚动

回答by Eduardo Reis

Just use OverScrollDecoratorHelper

只需使用 OverScrollDecoratorHelper

ScrollView scrollView = (ScrollView) findViewById(R.id.scroll_view);
OverScrollDecoratorHelper.setUpOverScroll(scrollView);

HorizontalScrollView horizontalScrollView = (HorizontalScrollView) findViewById(R.id.horizontal_scroll_view);
OverScrollDecoratorHelper.setUpOverScroll(horizontalScrollView);

https://github.com/EverythingMe/overscroll-decor

https://github.com/EverythingMe/overscroll-decor