Android中SlidingDrawer利用透明动画提示效果

效果图如下：

SlidingDrawer在xml布局中的使用：
android:handle="" ------->把手
android:content=""------->内容

本Demo布局代码（drawer_bg为那张大的图片，drawer_arrow_up为向上的箭头图片，drawer_arrow_down为向下的箭头图片）

  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".activity.MyDemo">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"></RelativeLayout>
    <SlidingDrawer
        android:layout_weight="1"
        android:id="@+id/demo_sd"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:handle="@id/demo_ll_handle"
        android:content="@id/demo_ll_content"
        >
        <!--抽屉的把手-->
        <LinearLayout
            android:id="@+id/demo_ll_handle"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:gravity="center"
            android:background="@mipmap/drawer_bg">
            <ImageView
                android:id="@+id/demo_lv_up1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:src="@mipmap/drawer_arrow_up"/>
            <ImageView
                android:id="@+id/demo_lv_up2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:src="@mipmap/drawer_arrow_up"/>
        </LinearLayout>
        <!--抽屉的内容-->
        <RelativeLayout
            android:background="#ffffff"
            android:id="@+id/demo_ll_content"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">
            <TextView
                android:layout_centerInParent="true"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textSize="26sp"
                android:text="抽屉的内容"/>
        </RelativeLayout>
    </SlidingDrawer>
    <Button

        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="我是打酱油的"
        android:background="#ff00ff"
        />
</LinearLayout>

Activity中的实现效果的代码：（透明动画）

Activity代码如下：

public class MyDemo extends AppCompatActivity {

    private ImageView demo_lv_up1;
    private ImageView demo_lv_up2;
    private LinearLayout demo_ll_handle;
    private RelativeLayout demo_ll_content;
    private SlidingDrawer demo_sd;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my_demo);
        initView();
        //动画的实现
        initAnimation();
        //抽屉的点击事件
        setOnDrawerListener();

    }
    private void initView() {
        demo_lv_up1 = (ImageView) findViewById(R.id.demo_lv_up1);
        demo_lv_up2 = (ImageView) findViewById(R.id.demo_lv_up2);
        demo_ll_handle = (LinearLayout) findViewById(R.id.demo_ll_handle);
        demo_ll_content = (RelativeLayout) findViewById(R.id.demo_ll_content);
        demo_sd = (SlidingDrawer) findViewById(R.id.demo_sd);
    }

    //动画的实现
    private void initAnimation() {
        demo_lv_up1.setImageResource(R.mipmap.drawer_arrow_up);
        demo_lv_up2.setImageResource(R.mipmap.drawer_arrow_up);
        //半透明-不透明
        AlphaAnimation animation = new AlphaAnimation(0.2f, 1.0f);
        animation.setDuration(500);
        animation.setRepeatCount(Animation.INFINITE);
        animation.setRepeatMode(Animation.REVERSE);
        demo_lv_up1.startAnimation(animation);
        //不透明-半透明
        AlphaAnimation animation1 = new AlphaAnimation(1.0f, 0.2f);
        animation1.setDuration(500);
        animation1.setRepeatCount(Animation.INFINITE);
        animation1.setRepeatMode(Animation.REVERSE);
        demo_lv_up2.startAnimation(animation1);
    }

    //抽屉的点击事件
    private void setOnDrawerListener() {
        //打开抽屉
        demo_sd.setOnDrawerOpenListener(new SlidingDrawer.OnDrawerOpenListener() {
            @Override
            public void onDrawerOpened() {
                //关闭动画，改变箭头方向
                closeAnimation();

            }
        });
        demo_sd.setOnDrawerCloseListener(new SlidingDrawer.OnDrawerCloseListener() {
            @Override
            public void onDrawerClosed() {
                //改变箭头方向,开启动画
                initAnimation();
            }
        });
    }

    //关闭动画且改变箭头方向
    private void closeAnimation() {
        demo_lv_up1.clearAnimation();
        demo_lv_up2.clearAnimation();
        //改变箭头方向
        demo_lv_up1.setImageResource(R.mipmap.drawer_arrow_down);
        demo_lv_up2.setImageResource(R.mipmap.drawer_arrow_down);
    }
}