侧滑菜单的实现（2.自定义属性）

接 侧滑菜单1.
自定义属性，允许用户自定义菜单离屏幕右边距。

步骤如下：1.书写xml文件 values/attr.xml
2.activity_main.xml增加一条
3.在SlidingMenu中写有自定义属性的对象

代码如下：
attr的xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <attr name="rightPadding" format="dimension" >
    </attr>
<declare-styleable name="SlidingMenu">
<attr name="rightPadding"></attr>
</declare-styleable>
    </resources>

activity_main中

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:chase="http://schemas.android.com/apk/res-auto" 
    <!--在原基础上 上面自定义了-->

    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <view.SlidingMenu
        android:layout_width="match_parent"
        android:layout_height="match_parent"

    <!--下面自定义修改属性 修改成了150dp-->
        chase:rightPadding="150dp"
        >

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:orientation="horizontal">
            <!--引入左菜单-->
            <include layout="@layout/leftmenu" />

            <!--内容区域-->
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="#34df45">

            </LinearLayout>
        </LinearLayout>

    </view.SlidingMenu>


</RelativeLayout>

SlidingMenu中 写进去一个参数的方法和三个参数的方法

package view;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.view.MotionEvent;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;

import com.chase.cn.demon.R;

/**
 * Created by Chase on 2016/11/7.
 */

public class SlidingMenu extends HorizontalScrollView {
    private LinearLayout mWapper;
    private ViewGroup mMenu;
    private ViewGroup mContent;
    private int mScreenWidth;

    private int mMenuWidth;
    // dp
    private int mMenuRightPadding = 50;

    private boolean once;

    private boolean isOpen;

    /**
     * 未使用自定义属性时，调用
     *
     * @param context
     * @param attrs
     */
    public SlidingMenu(Context context, AttributeSet attrs)
    {
        this(context, attrs, 0); //这里两个参数返回去三个
    }

    /**
     * 当使用了自定义属性时，会调用此构造方法
     *
     * @param context
     * @param attrs
     * @param defStyle
     */
    public SlidingMenu(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);

        // 获取我们定义的属性
        TypedArray a = context.getTheme().obtainStyledAttributes(attrs,
                R.styleable.SlidingMenu, defStyle, 0);

        int n = a.getIndexCount();
        for (int i = 0; i < n; i++)
        {
            int attr = a.getIndex(i);
            switch (attr)
            {
                case R.styleable.SlidingMenu_rightPadding:
                    mMenuRightPadding = a.getDimensionPixelSize(attr,
                            (int) TypedValue.applyDimension(
                                    TypedValue.COMPLEX_UNIT_DIP, 50, context
                                            .getResources().getDisplayMetrics()));//括号内的内容(attr,原来的默认值)

                    break;
            }
        }
        a.recycle(); //及时释放

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

    }

    public SlidingMenu(Context context)//一个参数的给他返回两个参数
    {
        this(context, null);
    }

    /**
     * 设置子View的宽和高 设置自己的宽和高
     */
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
    {
        if (!once)
        {
            mWapper = (LinearLayout) getChildAt(0);
            mMenu = (ViewGroup) mWapper.getChildAt(0);
            mContent = (ViewGroup) mWapper.getChildAt(1);
            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
     */
    @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:
                // 隐藏在左边的宽度
                int scrollX = getScrollX();
                if (scrollX >= mMenuWidth / 2)
                {
                    this.smoothScrollTo(mMenuWidth, 0);
                    isOpen = false;
                } else
                {
                    this.smoothScrollTo(0, 0);
                    isOpen = true;
                }
                return true;
        }
        return super.onTouchEvent(ev);
    }



}