自定义ViewGroup--仿QQ5.0侧滑菜单

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说说实现流程：
（1）为了适配效果更好一点，使用一下代码获取屏幕宽度

WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(outMetrics);
mScreenWidth = outMetrics.widthPixels;

(2)设置Menu区域滑动之后距离屏幕右边的padding值

//将dp转化成px
mMenuRightPadding = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 50, context.getResources().getDisplayMetrics());

（3）重写onMeasure，设置menu和content的宽度

@Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        if (!once) {
            mWapper = (LinearLayout) getChildAt(0);
            mMenu = (ViewGroup) mWapper.getChildAt(0);
            mContent = (ViewGroup) mWapper.getChildAt(1);

            //显示设置子View的宽度
            mMenuWidth = mMenu.getLayoutParams().width = mScreenWidth - mMenuRightPadding;
            mContent.getLayoutParams().width = mScreenWidth;
            once = true;
        }

        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

（4）重写onLayout，使得初始状态时，menu隐藏

 /**
     * 通过设置偏移量将menu隐藏
     * @param changed
     * @param l
     * @param t
     * @param r
     * @param b
     */
    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {

        super.onLayout(changed, l, t, r, b);

        if (changed) {
            this.scrollTo(mMenuWidth, 0);
        }
    }

（5）重写onTouchEvent，监听滑动距离，判定是打开menu还是关闭

 @Override
    public boolean onTouchEvent(MotionEvent ev) {

        int action = ev.getAction();

        switch (action) {
            case MotionEvent.ACTION_UP:
                int scrollX = getScrollX();
                if (scrollX >= mMenuWidth/2) {
                    smoothScrollTo(mMenuWidth, 0);
                }else if (scrollX < mMenuWidth) {
                    smoothScrollTo(0, 0);
                }
                return true;
        }

        return super.onTouchEvent(ev);
    }

(6)重写onScrollChanged，监听滑动状态并加上各动画

@Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {

        super.onScrollChanged(l, t, oldl, oldt);

        float scale = 1.0f * l / mMenuWidth; // 1~0,获取一个渐变scale，用于绘制各动画状态

        float scaleContent = 1f - (1 - scale) * 0.3f;// 1~0.7
        ObjectAnimator.ofFloat(mMenu, "translationX", mMenuWidth*scale*0.7f).setDuration(0).start();

        mContent.setPivotX(0);
        mContent.setPivotY(mContent.getHeight() / 2);
        ObjectAnimator.ofFloat(mContent, "scaleX", scaleContent).setDuration(0).start();
        ObjectAnimator.ofFloat(mContent, "scaleY", scaleContent).setDuration(0).start();

        mMenu.setPivotX(0);
        mMenu.setPivotY(mMenu.getHeight() / 2);
        ObjectAnimator.ofFloat(mMenu, "scaleX", 1.7f-scaleContent).setDuration(0).start();
        ObjectAnimator.ofFloat(mMenu, "scaleY", 1.7f-scaleContent).setDuration(0).start();
    }

源码：

package com.example.admin.myapplication.custom;

import android.animation.ObjectAnimator;
import android.content.Context;
import android.support.v4.widget.ViewDragHelper;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.util.TypedValue;
import android.view.MotionEvent;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;

public class MyHorizontalScrollView extends HorizontalScrollView {


    private LinearLayout mWapper;
    private ViewGroup mMenu;
    private ViewGroup mContent;
    private int mScreenWidth; //屏幕宽度
    private int mMenuWidth;

    //dp
    private int mMenuRightPadding = 50;

    private boolean once = false;


    public MyHorizontalScrollView(Context context) {
        this(context, null);
    }

    public MyHorizontalScrollView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public MyHorizontalScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics outMetrics = new DisplayMetrics();
        wm.getDefaultDisplay().getMetrics(outMetrics);
        mScreenWidth = outMetrics.widthPixels;

        //将dp转化成px
        mMenuRightPadding = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 50, context.getResources().getDisplayMetrics());
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        if (!once) {
            mWapper = (LinearLayout) getChildAt(0);
            mMenu = (ViewGroup) mWapper.getChildAt(0);
            mContent = (ViewGroup) mWapper.getChildAt(1);

            //显示设置子View的宽度
            mMenuWidth = mMenu.getLayoutParams().width = mScreenWidth - mMenuRightPadding;
            mContent.getLayoutParams().width = mScreenWidth;
            once = true;
        }

        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    /**
     * 通过设置偏移量将menu隐藏
     * @param changed
     * @param l
     * @param t
     * @param r
     * @param b
     */
    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {

        super.onLayout(changed, l, t, r, b);

        if (changed) {
            this.scrollTo(mMenuWidth, 0);
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {

        int action = ev.getAction();

        switch (action) {
            case MotionEvent.ACTION_UP:
                int scrollX = getScrollX();
                if (scrollX >= mMenuWidth/2) {
                    smoothScrollTo(mMenuWidth, 0);
                }else if (scrollX < mMenuWidth) {
                    smoothScrollTo(0, 0);
                }
                return true;
        }

        return super.onTouchEvent(ev);
    }

    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {

        super.onScrollChanged(l, t, oldl, oldt);

        float scale = 1.0f * l / mMenuWidth; // 1~0

        float scaleContent = 1f - (1 - scale) * 0.3f;// 1~0.7
        ObjectAnimator.ofFloat(mMenu, "translationX", mMenuWidth*scale*0.7f).setDuration(0).start();

        mContent.setPivotX(0);
        mContent.setPivotY(mContent.getHeight() / 2);
        ObjectAnimator.ofFloat(mContent, "scaleX", scaleContent).setDuration(0).start();
        ObjectAnimator.ofFloat(mContent, "scaleY", scaleContent).setDuration(0).start();

        mMenu.setPivotX(0);
        mMenu.setPivotY(mMenu.getHeight() / 2);
        ObjectAnimator.ofFloat(mMenu, "scaleX", 1.7f-scaleContent).setDuration(0).start();
        ObjectAnimator.ofFloat(mMenu, "scaleY", 1.7f-scaleContent).setDuration(0).start();
    }
}

布局文件