實現類似QQ側滑的SlidingLayout

SlidingLayout的側滑效果通過ViewDragHelper來實現；
ViewDragHelper使用詳解參考：http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2014/0911/1680.html

package com.zkr.cn.slidinglayout;

import android.content.Context;
import android.support.v4.view.ViewCompat;
import android.support.v4.widget.ViewDragHelper;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;

/**
 * @PackageName: ---------com.zkr.cn.slidinglayout
 * @Description: ---------描述這個類的作用
 * @author: ---------------LF
 * @date: -----------------2016/11/9 17:15
 */
public class SlidingLayout extends FrameLayout {

    private ViewDragHelper mViewDragHelper;
    private View mMenuView,mMainView;
    private int mWidth;
    private float startX,startY;

    public SlidingLayout(Context context) {
        super(context);
        initView();
    }

    public SlidingLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        initView();
    }

    public SlidingLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initView();
    }

    private void initView() {
        mViewDragHelper=ViewDragHelper.create(this,callBack);
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        mMenuView=getChildAt(0);
        mMainView=getChildAt(1);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        mWidth=mMenuView.getMeasuredWidth();
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return mViewDragHelper.shouldInterceptTouchEvent(ev);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        //將觸摸事件傳遞給mViewDragHelper
        mViewDragHelper.processTouchEvent(event);
        return true;
    }

    private ViewDragHelper.Callback callBack=new ViewDragHelper.Callback(){

        //該條件下開始檢測觸摸事件
        @Override
        public boolean tryCaptureView(View child, int pointerId) {
            return mMainView==child;//當觸摸的view爲MainView則檢測該事件
        }
        //不斷返回水平滑動的距離
        @Override
        public int clampViewPositionHorizontal(View child, int left, int dx) {
            if(left>0){
                return left;
            }else{//禁止左滑
                return 0;
            }

        }

        //不斷返回豎直滑動的距離
        @Override
        public int clampViewPositionVertical(View child, int top, int dy) {
            return 0;
        }

        //拖動結束後調用
        @Override
        public void onViewReleased(View releasedChild, float xvel, float yvel) {
            super.onViewReleased(releasedChild, xvel, yvel);
            //關閉菜單
            if(mMainView.getLeft()<300){
                mViewDragHelper.smoothSlideViewTo(mMainView,0,0);
                //invalidate方法類似
                ViewCompat.postInvalidateOnAnimation(SlidingLayout.this);
            }
            //打開菜單
            else{
                mViewDragHelper.smoothSlideViewTo(mMainView,300,0);
                ViewCompat.postInvalidateOnAnimation(SlidingLayout.this);
            }
        }
    };

    @Override
    public void computeScroll() {
       if(mViewDragHelper.continueSettling(true)){
            ViewCompat.postInvalidateOnAnimation(this);
       }
    }
}

demo地址：http://download.csdn.net/detail/qq1377399077/9678510