利用ViewDragHelper做滑动效果，侧滑的布局整体是一个LinearLayout，里面包含3个TextView分别是，已读，删除，置顶。 运行之后，LinearLayout布局只出现已读和删除这2个TextView。

public class SlideMenuView extends ViewGroup {
    private static final String TAG = "SlideMenuView";
    private int mFunction;
    private View mContentView;
    private TextView mRead;
    private TextView mDelete;
    private TextView mTop;
    private int DEFAULT_LEFT = 0;
    private ViewDragHelper mViewDragHelper;
    private int mWidthSize;
    private LinearLayout mLinearLayout;

    public int getDEFAULT_LEFT() {
        return DEFAULT_LEFT;
    }

    public void setDEFAULT_LEFT(int DEFAULT_LEFT) {
        this.DEFAULT_LEFT = DEFAULT_LEFT;
    }

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

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

    public SlideMenuView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.SlideMenuView);
        mFunction = ta.getInt(R.styleable.SlideMenuView_function, 0);
        Log.d(TAG, "function  -->  " + mFunction);
        ta.recycle();

        mViewDragHelper = ViewDragHelper.create(this, new ViewDragHelper.Callback() {
            @Override
            public boolean tryCaptureView(@NonNull View child, int pointerId) {
                Log.d(TAG, "child " + child.getMeasuredWidth());
                Log.d(TAG, "pointerId " + pointerId);
                return child == mContentView;
                //|| child == mLinearLayout
            }

            @Override
            public void onViewCaptured(@NonNull View capturedChild, int activePointerId) {
                super.onViewCaptured(capturedChild, activePointerId);
                Log.d(TAG, "capturedChild " + capturedChild);
                Log.d(TAG, "activePointerId " + activePointerId);
            }

            @Override
            public int clampViewPositionHorizontal(@NonNull View child, int left, int dx) {
                //可以设置移动范围，不限制就无限
                Log.d(TAG, "child " + child);
                Log.d(TAG, "left " + left);
                Log.d(TAG, "dx " + dx);
                if (left <= -(mContentView.getMeasuredWidth() * 3 / 4)) {
                    //Log.d(TAG, "small left " + left);
                    //Log.d(TAG, "-(3 / 4 * mWidthSize) " + -(mContentView.getMeasuredWidth() * 3 / 4));
                    //Log.d(TAG, "mContentView.getMeasuredWidth()  " + mContentView.getMeasuredWidth());
                    return left = -(mContentView.getMeasuredWidth() * 3 / 4);
                }
                if (left > 0) {
                    return left = 0;
                }
                return left;
            }

            @Override
            public void onViewPositionChanged(@NonNull View changedView, int left, int top, int dx, int dy) {
                invalidate();
                //super.onViewPositionChanged(changedView, left, top, dx, dy);
                Log.d(TAG, "onViewPositionChanged -- changedView " + changedView);
                Log.d(TAG, "onViewPositionChanged -- left " + left);
                Log.d(TAG, "onViewPositionChanged -- top " + top);
                Log.d(TAG, "onViewPositionChanged -- dx " + dx);
                Log.d(TAG, "onViewPositionChanged -- dy " + dy);
                if (changedView == mContentView) {
                    mContentView.layout(left, 0, left + mContentView.getMeasuredWidth(), mContentView.getMeasuredHeight());
                    Log.d(TAG, "mContentView.getMeasuredWidth()  " + mContentView.getMeasuredWidth());
                    Log.d(TAG, "left + mContentView.getMeasuredWidth() " + left + mContentView.getMeasuredWidth());
                    mLinearLayout.layout(left + mContentView.getMeasuredWidth(), 0, left + mContentView.getMeasuredWidth() + mLinearLayout.getMeasuredWidth(), mLinearLayout.getMeasuredHeight());
                }
            }
        });

    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Log.d(TAG, "event " + event.getAction());
        mViewDragHelper.processTouchEvent(event);
        return true;//true才能监听其他手势
        //return super.onTouchEvent(event);
    }

    @Override
    public boolean onInterceptHoverEvent(MotionEvent event) {
        mViewDragHelper.shouldInterceptTouchEvent(event);
        return true;
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        //构造方法获取不了孩子个数
        int childCount = getChildCount();
        Log.d(TAG, "childCount  -->  " + childCount);
        //加个判断只能有一个孩子
        if (childCount > 1) {
            throw new IllegalArgumentException("no more than one child");
        }
        //内容部分
        mContentView = getChildAt(0);
        //根据属性继续添加子View
        mLinearLayout = new LinearLayout(getContext());
        mLinearLayout.setBackgroundColor(getResources().getColor(R.color.colorPrimaryDark));
        LayoutParams layoutParams = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);
        mLinearLayout.setLayoutParams(layoutParams);
        mLinearLayout.setGravity(Gravity.CENTER);
        String s[] = {"已读", "删除", "置顶"};
        for (int i = 0; i < 3; i++) {
            TextView tv = new TextView(getContext());
            tv.setGravity(Gravity.CENTER);
            tv.setTextColor(getResources().getColor(R.color.mainColor));
            tv.setBackgroundColor(getResources().getColor(R.color.text_grey));
            tv.setText(s[i]);
            mLinearLayout.addView(tv);
        }
        addView(mLinearLayout);
       /* mRead = new TextView(getContext());
        mRead.setGravity(Gravity.CENTER);
        mRead.setTextColor(getResources().getColor(R.color.mainColor));
        mRead.setBackgroundColor(getResources().getColor(R.color.text_grey));
        mRead.setText("已读");
        addView(mRead);
        mDelete = new TextView(getContext());
        mDelete.setGravity(Gravity.CENTER);
        mDelete.setTextColor(getResources().getColor(R.color.mainColor));
        mDelete.setBackgroundColor(getResources().getColor(R.color.colorAccent));
        mDelete.setText("删除");
        addView(mDelete);
        mTop = new TextView(getContext());
        mTop.setGravity(Gravity.CENTER);
        mTop.setTextColor(getResources().getColor(R.color.mainColor));
        mTop.setBackgroundColor(getResources().getColor(R.color.colorPrimaryDark));
        mTop.setText("置顶");
        addView(mTop);*/
        int afterCount = getChildCount();
        Log.d(TAG, "afterCount  -->  " + afterCount);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);

    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int left = DEFAULT_LEFT;
        int top = 0;
        int bottom = top + mContentView.getMeasuredHeight();
        //摆放内容
        // mContentView.layout(left, top, right, bottom);
        Log.d(TAG, "childCount layout -->  " + getChildCount());
        for (int i = 0; i < getChildCount(); i++) {
            View childAt = getChildAt(i);
            Log.d(TAG, "childAt Height -->  " + childAt.getMeasuredHeight());
            Log.d(TAG, "childAt Width -->  " + childAt.getMeasuredWidth());
            int right = left + childAt.getMeasuredWidth();
            Log.d(TAG, "right -->  " + right);
            childAt.layout(left, top, right, bottom);
            left = right;
        }
        Log.d(TAG, "left  " + left);
        //LinearLayout第一个子view左边等于内容部分的右边
        int childLeft = mContentView.getMeasuredWidth();
        for (int i = 0; i < mLinearLayout.getChildCount(); i++) {
            View childAt = mLinearLayout.getChildAt(i);
            int childRight = childLeft + childAt.getMeasuredWidth();
            Log.d(TAG, "childLeft  " + childLeft);
            Log.d(TAG, "childRight  " + childRight);
            childAt.layout(childLeft, 0, childRight, bottom);
            childLeft = childRight;
        }

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);
        mWidthSize = MeasureSpec.getSize(widthMeasureSpec);
        Log.d(TAG, "widthMeasureSpec  " + widthMeasureSpec);
        Log.d(TAG, "widthSize  " + mWidthSize);
        //测量第一个孩子，内容部分
        //宽度跟父控件一样，高度有3种情况
        //getMeasuredWidth测量不了我们提前放进去的TextView大小，getLayoutParams可以,要先测量一下
        int measuredWidth = mContentView.getMeasuredWidth();
        int measuredHeight = mContentView.getMeasuredHeight();
        Log.d(TAG, "mContentView-Width  " + measuredWidth);
        Log.d(TAG, "mContentView-Height  " + measuredHeight);
        LayoutParams layoutParams = mContentView.getLayoutParams();
        int height = layoutParams.height;
        int width = layoutParams.width;
        Log.d(TAG, "height " + height);
        Log.d(TAG, "width  " + width);
        int contentHeightMeasureSpec;
        if (height == LayoutParams.MATCH_PARENT) {
            contentHeightMeasureSpec = MeasureSpec.makeMeasureSpec(heightSize, MeasureSpec.EXACTLY);
        } else if (height == LayoutParams.WRAP_CONTENT) {
            contentHeightMeasureSpec = MeasureSpec.makeMeasureSpec(heightSize, MeasureSpec.AT_MOST);
        } else {
            //指定大小
            contentHeightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
        }
        //如果最外面布局不是LinearLayout view会越界，居中显示能看出,但是活动的时候还是宽度会越界，应该是测量问题，与父控件布局无关
        Log.d(TAG, "measure widthMeasureSpec  " + widthMeasureSpec);
        mContentView.measure(widthMeasureSpec, contentHeightMeasureSpec);
        //拿到内容部分，测量高度
        int contentMeasureHeight = mContentView.getMeasuredHeight();
        //测量编辑部分，宽度3/4，高度跟内容部分一样，就是提前添加的TextView,要设置模式
        mLinearLayout.measure(MeasureSpec.makeMeasureSpec(mWidthSize * 3 / 4, MeasureSpec.EXACTLY),
                contentHeightMeasureSpec);
        Log.d(TAG, "mLinearLayout.getMeasuredWidth() * 1 / 3  " + mLinearLayout.getMeasuredWidth() * 1 / 3);
        for (int i = 0; i < mLinearLayout.getChildCount(); i++) {
            View childAt = mLinearLayout.getChildAt(i);
            childAt.measure(MeasureSpec.makeMeasureSpec(mLinearLayout.getMeasuredWidth() * 1 / 3, MeasureSpec.EXACTLY),
                    MeasureSpec.makeMeasureSpec(mContentView.getMeasuredHeight(), MeasureSpec.EXACTLY));
        }
       /* mRead.measure(MeasureSpec.makeMeasureSpec(mWidthSize * 1 / 4, MeasureSpec.EXACTLY),
                MeasureSpec.makeMeasureSpec(contentMeasureHeight, MeasureSpec.EXACTLY));
        mTop.measure(MeasureSpec.makeMeasureSpec(mWidthSize * 1 / 4, MeasureSpec.EXACTLY),
                MeasureSpec.makeMeasureSpec(contentMeasureHeight, MeasureSpec.EXACTLY));
        mDelete.measure(MeasureSpec.makeMeasureSpec(mWidthSize * 1 / 4, MeasureSpec.EXACTLY),
                MeasureSpec.makeMeasureSpec(contentMeasureHeight, MeasureSpec.EXACTLY));*/
        //测量自己
        //宽度是前面的总和，高度和内容一样
        //测量自己不需要模式
        setMeasuredDimension(mWidthSize + mWidthSize * 3 / 4, contentMeasureHeight);
    }
}