android 自定义粘性View，可寄生于其他控件给予其添加半透明spinner的效果

转载请注明出处:王亟亟的大牛之路

git上看到一个不错的“自定义寄生View”，个人觉得还是很有拓展性的，写篇博文介绍下

目录结构+运行效果

AS的项目，内容不多，就2个类，想整合进自己项目的话也不难

MainActivity

public class MainActivity extends ActionBarActivity
    implements OverMenuView.OnSelectionChangeListener, OverMenuView.OnMenuVisibilityChangeListener {
    private static final String TAG = "MainActivity";
    private ImageView mImageView;
    private OverMenuView overMenuView;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mImageView = (ImageView) findViewById(R.id.image);

        textView = (TextView) findViewById(R.id.text);

        overMenuView = (OverMenuView) findViewById(R.id.overmenu);
        overMenuView.setOnSelectionChangedListener(this);
        overMenuView.setOnMenuVisibilityChangeListener(this);

        try {
            loadImage("image.jpg");
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    private void loadImage(@NonNull final String file) throws IOException {
        final InputStream input = getAssets().open(file);
        Bitmap bitmap = BitmapFactory.decodeStream(input);
        mImageView.setImageBitmap(bitmap);
        input.close();
    }

    @Override
    public void onSelectionChanged(final int position) {
        Log.d(TAG, "onSelectionChanged: " + position);
        textView.setText(overMenuView.getEntries()[position]);
    }

    @Override
    public void onVisibilityChanged(final View view, final boolean visible) {
        Log.d(TAG, "onVisibilityChanged: " + view + ", " + visible);
    }
}

分析：
没有参杂什么逻辑，只是把assets目录下的图片set到imageview中并且把选择的结果放入textView呈现而已。

布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dip"
        android:layout_weight="1">

        <ImageView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/image" />

        <it.sephiroth.android.library.overlaymenu.OverMenuView
            app:overmenu_centerInView="@+id/image"
            android:entries="@array/overmenuEntries"
            android:id="@+id/overmenu"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </RelativeLayout>

    <LinearLayout
        android:layout_marginTop="@dimen/activity_vertical_margin"
        android:paddingLeft="16dip"
        android:paddingRight="16dip"
        android:gravity="center"
        android:background="?attr/colorPrimary"
        android:layout_width="match_parent"
        android:layout_height="90dip">

        <TextView
            android:text="@string/waiting_for_selection"
            android:id="@+id/text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textAppearance="@style/TextAppearance.AppCompat.Title"
            android:gravity="center" />

    </LinearLayout>

</LinearLayout>

分析：
这里有一个自定义的标签xmlns:app="http://schemas.android.com/apk/res-auto"
也就是将我们的时间“绑定到”ImageView上去了而已！

下拉列表的数据源：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="overmenuEntries">
        <item>First Item</item>
        <item>Second Item</item>
        <item>Third Item</item>
        <item>Fourth Item</item>
        <item>Fifth Item</item>
        <item>Sixth Item</item>
        <item>Seventh Item</item>
    </string-array>
</resources>

具体代码可以看源码，源码地址：http://yunpan.cn/cmxaWSzZH3mqQ 访问密码 f898