WifiDisplay中Preference使用

1) WifiDispaly对应文件WifiDisplaySettings.java

2) 里面采用Preference来实现

3) 对Preference的点击调用到onPreferenceTreeClick中，连接或者断开WifiDisplay，summary和title,icon的设置具体追溯到PreferenceActivity.java的preference_header_item.xml

4) Option点击dialog对话框，对应R.layout.wifi_display_option，在createWifiDisplayPreference中创建， p.setWidgetLayoutResource(R.layout.wifi_display_preference);点击事件在WifiDisplayPreference的onBindView中设置，在onClick中响应，wifi_display_preference.xml在Preference中为什么会靠右显示，问题未知？

1. Preference.java   onCreateView  关联文件preference.xml

    protected View onCreateView(ViewGroup parent) {
        final LayoutInflater layoutInflater =
            (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        
        final View layout = layoutInflater.inflate(mLayoutResId, parent, false); 
        
        final ViewGroup widgetFrame = (ViewGroup) layout
                .findViewById(com.android.internal.R.id.widget_frame);
        if (widgetFrame != null) {
            if (mWidgetLayoutResId != 0) {
                layoutInflater.inflate(mWidgetLayoutResId, widgetFrame);
            } else {
                widgetFrame.setVisibility(View.GONE);
            }
        }
        return layout;
    }

2.  对setWidgetLayoutResource赋值

    public void setWidgetLayoutResource(int widgetLayoutResId) {
        if (widgetLayoutResId != mWidgetLayoutResId) {
            // Layout changed
            mHasSpecifiedLayout = true;
        }
        mWidgetLayoutResId = widgetLayoutResId;
    }

3. 如何靠右显示，其实和android:layout_weight="1"相关

     type in the "widget_frame" layout. -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:minHeight="?android:attr/listPreferredItemHeight"
    android:gravity="center_vertical"
    android:paddingEnd="?android:attr/scrollbarSize"
    android:background="?android:attr/selectableItemBackground" >

    <ImageView
        android:id="@+android:id/icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        />

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="15dip"
        android:layout_marginEnd="6dip"
        android:layout_marginTop="6dip"
        android:layout_marginBottom="6dip"
        android:layout_weight="1">

        <TextView android:id="@+android:id/title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:singleLine="true"
            android:textAppearance="?android:attr/textAppearanceLarge"
            android:ellipsize="marquee"
            android:fadingEdge="horizontal" />

        <TextView android:id="@+android:id/summary"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@android:id/title"
            android:layout_alignStart="@android:id/title"
            android:textAppearance="?android:attr/textAppearanceSmall"
            android:textColor="?android:attr/textColorSecondary"
            android:maxLines="4" />

    </RelativeLayout>

    <!-- Preference should place its actual preference widget here. -->
    <LinearLayout android:id="@+android:id/widget_frame"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:gravity="center_vertical"
        android:orientation="vertical" />

</LinearLayout>