android开发教程之使用线程实现视图平滑滚动示例

package com.melonsapp.messenger.ui.popupuser;

import android.os.Handler;
import android.view.View;
import android.view.WindowManager;
import android.view.animation.DecelerateInterpolator;

import java.util.Timer;

/**
 * Created by lidaqiang on 17/5/3.
 */

public class SmoothScroll {
    private Handler mHandler = new Handler();
    SmoothScrollThread smoothScrollThread;
    public static int noData = 0;

    /**
     * @param v       需要操控的视图
     * @param fromX   起始Y坐标
     * @param toX     终止Y坐标
     * @param fps     帧率
     * @param durtion 动画完成时间（毫秒）
     * @desc 平滑滚动
     */
    public SmoothScroll(View v, WindowManager windowManager, WindowManager.LayoutParams windowParams, int fromX, int toX, int fps, long durtion) {
        this(v, windowManager, windowParams, fromX, toX, noData, noData, 60, durtion);
    }

    public SmoothScroll(View v, WindowManager windowManager, WindowManager.LayoutParams windowParams, int fromX, int toX, int fromY, int toY, long durtion) {
        this(v, windowManager, windowParams, fromX, toX, fromY, toY, 60, durtion);
    }

    public SmoothScroll(View v, WindowManager windowManager, WindowManager.LayoutParams windowParams, int fromX, int toX, int fromY, int toY, int fps, long durtion) {
        smoothScrollThread = new SmoothScrollThread(v, windowManager, windowParams, fromX, toX, fromY, toY, durtion, fps);
    }

    public void start() {
        if (smoothScrollThread == null) {
            return;
        }
        smoothScrollThread.run();
    }

    public void stop() {
        if (smoothScrollThread == null) {
            return;
        }
        smoothScrollThread.stop();
    }

    /**
     * @desc 平滑滚动线程，用于递归调用自己来实现某个视图的平滑滚动
     */
    class SmoothScrollThread implements Runnable {
        WindowManager mWindowManager;
        WindowManager.LayoutParams mWindowParams;
        //需要操控的视图
        private View v = null;
        //原X坐标
        private int fromX = noData;
        //目标X坐标
        private int toX = noData;

        //原Y坐标
        private int fromY = noData;
        //目标Y坐标
        private int toY = noData;
        //动画执行时间（毫秒）
        private long durtion = 0;
        //帧率
        private int fps = 60;
        //间隔时间（毫秒），间隔时间 = 1000 / 帧率
        private int interval = 0;
        //启动时间，-1 表示尚未启动
        private long startTime = -1;
        //        /减速插值器
        private DecelerateInterpolator decelerateInterpolator = null;

        private int mChangeState = 0;  // 0 x,y都不变   1 x变      2 y变   3 x,y都变

        /**
         * @desc 构造方法，做好*次配置
         */
        public SmoothScrollThread(View v, WindowManager windowManager, WindowManager.LayoutParams windowParams, int fromX, int toX, int fromY, int toY, long durtion, int fps) {
            mWindowManager = windowManager;
            mWindowParams = windowParams;
            this.v = v;
            this.fromX = fromX;
            this.toX = toX;
            this.fromY = fromY;
            this.toY = toY;
            this.durtion = durtion;
            this.fps = fps;
            this.interval = 1000 / this.fps;
            decelerateInterpolator = new DecelerateInterpolator();
            mChangeState = 0;

            if (fromX != toX && fromY == toY) {
                mChangeState = 1;
            } else if (fromX == toX && fromY != toY) {
                mChangeState = 2;
            } else if (fromX != toX && fromY != toY) {
                mChangeState = 3;
            }
        }

        @Override
        public void run() {

            if (mChangeState == 0) {
                return;
            }

            //先判断是否是*次启动，是*次启动就记录下启动的时间戳，该值仅此一次赋值
            if (startTime == -1) {
                startTime = System.currentTimeMillis();
            }
            //得到当前这个瞬间的时间戳
            long currentTime = System.currentTimeMillis();
            //放大倍数，为了扩大除法计算的浮点精度
            int enlargement = 1000;
            //算出当前这个瞬间运行到整个动画时间的百分之多少
            float rate = (currentTime - startTime) * enlargement / durtion;
            //这个比率不可能在 0 - 1 之间，放大了之后即是 0 - 1000 之间
            rate = Math.min(rate, 1000);
            //将动画的进度通过插值器得出响应的比率，乘以起始与目标坐标得出当前这个瞬间，视图应该滚动的距离。

            int currentX = fromX;
            if (mChangeState == 1 || mChangeState == 3) {
                int changeDistanceX = (int) ((fromX - toX) * decelerateInterpolator.getInterpolation(rate / enlargement));
                currentX = fromX - changeDistanceX;
            }

            int currentY = fromY;
            if (mChangeState == 2 || mChangeState == 3) {
                int changeDistanceY = (int) ((fromY - toY) * decelerateInterpolator.getInterpolation(rate / enlargement));
                currentY = fromY - changeDistanceY;
            }


            notifyViewLayout(currentX, currentY);

            if (currentX != toX || currentY != toY) {


                mHandler.postDelayed(this, this.interval);
            } else {
                return;
            }
        }


        private void notifyViewLayout(int currentX, int currentY) {
//            v.scrollTo(0, currentY);
            if (mWindowParams == null || mWindowParams == null || v == null) {
                return;
            }

            if (mChangeState == 1 || mChangeState == 3) {
                mWindowParams.x = currentX;
            }


            if (mChangeState == 2 || mChangeState == 3) {
                mWindowParams.y = currentY;
            }


            if (v.getParent() != null) {
                mWindowManager.updateViewLayout(v, mWindowParams);
            }

        }

        public void stop() {
            mHandler.removeCallbacks(this);
        }
    }


}