ScrollView阻尼效果

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical"

    tools:context="com.example.scrollviewdemo.MainActivity" >

    <com.example.scrollviewdemo.CustomScrollView

        android:id="@+id/scrollview"

        android:layout_width="fill_parent"

        android:layout_height="fill_parent" >

        <LinearLayout

            android:layout_width="fill_parent"

            android:layout_height="fill_parent"

            android:orientation="vertical" >

            <TextView

                android:layout_width="fill_parent"

                android:layout_height="100dp"

                android:text="AAA" >

            </TextView>

            <TextView

                android:layout_width="fill_parent"

                android:layout_height="100dp"

                android:text="AAA" >

            </TextView>

            <TextView

                android:layout_width="fill_parent"

                android:layout_height="100dp"

                android:text="AAA" >

            </TextView>

            <TextView

                android:layout_width="fill_parent"

                android:layout_height="100dp"

                android:text="AAA" >

            </TextView>

            <TextView

                android:layout_width="fill_parent"

                android:layout_height="100dp"

                android:text="AAA" >

            </TextView>

             <TextView

                android:layout_width="fill_parent"

                android:layout_height="100dp"

                android:text="AAA" >

            </TextView>

             <TextView

                android:layout_width="fill_parent"

                android:layout_height="100dp"

                android:text="AAA" >

            </TextView>

             <TextView

                android:layout_width="fill_parent"

                android:layout_height="100dp"

                android:text="AAA" >

            </TextView>

             <TextView

                android:layout_width="fill_parent"

                android:layout_height="100dp"

                android:text="AAA" >

            </TextView>

        </LinearLayout>

    </com.example.scrollviewdemo.CustomScrollView

>

</LinearLayout>

MainActivity

package com.example.scrollviewdemo;

import android.app.Activity;

import android.os.Bundle;

import android.os.Handler;

import android.os.Message;

import android.view.MotionEvent;

import android.view.View;

import android.view.View.OnTouchListener;

import android.widget.ScrollView;

public class MainActivity extends Activity {

	ScrollView scrollView;

	private static final int TOUCH_EVENT_ID = 1;

	@Override

	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_main);

		scrollView = (ScrollView) findViewById(R.id.scrollview);

	}

}

方式一

ElasticScrollView

package com.example.scrollviewdemo;

import android.annotation.SuppressLint;

import android.content.Context;

import android.util.AttributeSet;

import android.widget.ScrollView;

import android.graphics.Rect;

import android.view.MotionEvent;

import android.view.View;

import android.view.animation.TranslateAnimation;

public class ElasticScrollView extends ScrollView {

	//scrollView下的控件

	private View inner;

	private float y;

	//保存状态的矩形框

	private Rect normal = new Rect();

	//是否要计算

	private boolean isCount = false;

	@SuppressLint("NewApi")

	public ElasticScrollView(Context context, AttributeSet attrs) {

		super(context, attrs);

	}

	//载入完布局文件之后调用

	@Override

	protected void onFinishInflate() {

		if (getChildCount() > 0) {

			//获取控件

			inner = getChildAt(0);

		}

	}

	@SuppressLint("ClickableViewAccessibility")

	@Override

	public boolean onTouchEvent(MotionEvent ev) {

		if (inner != null) {

			commOnTouchEvent(ev);

		}

		return super.onTouchEvent(ev);

	}

	//处理触摸事件

	public void commOnTouchEvent(MotionEvent ev) {

		int action = ev.getAction();

		switch (action) {

		case MotionEvent.ACTION_DOWN:

			break;

		case MotionEvent.ACTION_UP:

			//是不是须要动画

			if (isNeedAnimation()) {

				animation();

				isCount = false;

			}

			break;

		case MotionEvent.ACTION_MOVE:

			final float preY = y;

			float nowY = ev.getY();

			int deltaY = (int) (preY - nowY);

			if (!isCount) {

				deltaY = 0;

			}

			y = nowY;

			if (isNeedMove()) {

				if (normal.isEmpty()) {

					normal.set(inner.getLeft(), inner.getTop(),inner.getRight(), inner.getBottom());

				}

				inner.layout(inner.getLeft(), inner.getTop() - deltaY / 2,inner.getRight(), inner.getBottom() - deltaY / 2);

			}

			isCount = true;

			break;

		default:

			break;

		}

	}

	public void animation() {

		TranslateAnimation ta = new TranslateAnimation(0, 0, inner.getTop(),normal.top);

		ta.setDuration(200);

		inner.startAnimation(ta);

		inner.layout(normal.left, normal.top, normal.right, normal.bottom);

		normal.setEmpty();

	}

	// return left >= right || top >= bottom;

	public boolean isNeedAnimation() {

		return !normal.isEmpty();

	}

	public boolean isNeedMove() {

		int offset = inner.getMeasuredHeight() - getHeight();

		int scrollY = getScrollY();

		if (scrollY == 0 || scrollY == offset) {

			return true;

		}

		return false;

	}

}

——————————————————————————方式二——————————————————————————

CustomScrollView

package com.example.scrollviewdemo;

import android.content.Context;

import android.graphics.Rect;

import android.util.AttributeSet;

import android.view.MotionEvent;

import android.view.View;

import android.view.animation.AccelerateInterpolator;

import android.view.animation.TranslateAnimation;

import android.widget.ScrollView;

public class CustomScrollView extends ScrollView {

	// y方向上当前触摸点的前一次记录位置

		private int previousY = 0;

		// y方向上的触摸点的起始记录位置

		private int startY = 0;

		// y方向上的触摸点当前记录位置

		private int currentY = 0;

		// y方向上两次移动间移动的相对距离

		private int deltaY = 0;

		// 第一个子视图

		private View childView;

		// 用于记录childView的初始位置

		private Rect topRect = new Rect();

		public CustomScrollView(Context context) {

			super(context);

			;

		}

		public CustomScrollView(Context context, AttributeSet attrs) {

			super(context, attrs);

			;

		}

		public CustomScrollView(Context context, AttributeSet attrs, int defStyle) {

			super(context, attrs, defStyle);

			;

		}

		@Override

		protected void onFinishInflate() {

			if (getChildCount() > 0) {

				childView = getChildAt(0);

			}

		}

		@Override

		public boolean dispatchTouchEvent(MotionEvent event) {

			if (null == childView) {

				return super.dispatchTouchEvent(event);

			}

			switch (event.getAction()) {

			case MotionEvent.ACTION_DOWN:

				startY = (int) event.getY();

				previousY = startY;

				break;

			case MotionEvent.ACTION_MOVE:

				currentY = (int) event.getY();

				deltaY = previousY - currentY;

				previousY = currentY;

				if (0 == getScrollY()

						|| childView.getMeasuredHeight() - getHeight() <= getScrollY()) {

					// 记录childView的初始位置

					if (topRect.isEmpty()) {

						topRect.set(childView.getLeft(), childView.getTop(),

								childView.getRight(), childView.getBottom());

					}

					// 更新childView的位置

					childView.layout(childView.getLeft(), childView.getTop()

							- deltaY / 3, childView.getRight(),

							childView.getBottom() - deltaY / 3);

				}

				break;

			case MotionEvent.ACTION_UP:

				if (!topRect.isEmpty()) {

					upDownMoveAnimation();

					// 子控件回到初始位置

					childView.layout(topRect.left, topRect.top, topRect.right,

							topRect.bottom);

				}

				startY = 0;

				currentY = 0;

				topRect.setEmpty();

				break;

			default:

				break;

			}

			return super.dispatchTouchEvent(event);

		}

		// 初始化上下回弹的动画效果

		private void upDownMoveAnimation() {

			TranslateAnimation animation = new TranslateAnimation(0.0f, 0.0f,

					childView.getTop(), topRect.top);

			animation.setDuration(200);

			animation.setInterpolator(new AccelerateInterpolator());

			childView.setAnimation(animation);

		}

}