java - 框架布局 : How to add other Views on top of GLSurfaceView?

Question

我是 Andriod 的新手，很难在我的 GLSurfaceView 上添加控件( View )。我希望将其添加到角落。 (说右下角)最初我想添加像小部件一样的操纵杆，但起初我想添加“左”、“右”、“上”、“下”按钮。我创建了一个布局 XML 文件，如下所示:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <View
        android:id="@+id/viewControls"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/relativeLayout1"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" />

    <RelativeLayout
        android:id="@+id/relativeLayout1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_centerVertical="true"
        android:layout_marginLeft="140dp" >
    </RelativeLayout>

    <Button
        android:id="@+id/buttonR"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/relativeLayout1"
        android:text="R" />

    <Button
        android:id="@+id/buttonL"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:text="L" />

</RelativeLayout>

在我的 Activity 中，我尝试如下:

public class MyOpenGL2Activity extends Activity {

    private GLSurfaceView mGLview;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

        mGLview=new MyOpenGL2SurfaceView(this);

        FrameLayout flayout=new FrameLayout(this);     
        flayout.addView(mGLview);

        View controller=findViewById(R.id.viewControls);

        flayout.addView(controller);       


        setContentView(flayout);
}
...

但是应用程序崩溃说

05-05 14:40:08.015: W/dalvikvm(2258): threadid=1: thread exiting with uncaught exception (group=0x40a841f8) 05-05 14:40:08.023: E/AndroidRuntime(2258): FATAL EXCEPTION: main 05-05 14:40:08.023: E/AndroidRuntime(2258): java.lang.RuntimeException: Unable to start activity ComponentInfo{ausoft.opengl/ausoft.opengl.MyOpenGL2Activity}: java.lang.NullPointerException 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955) 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980) 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.app.ActivityThread.access$600(ActivityThread.java:122) 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146) 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.os.Handler.dispatchMessage(Handler.java:99) 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.os.Looper.loop(Looper.java:137) 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.app.ActivityThread.main(ActivityThread.java:4340) 05-05 14:40:08.023: E/AndroidRuntime(2258): at java.lang.reflect.Method.invokeNative(Native Method) 05-05 14:40:08.023: E/AndroidRuntime(2258): at java.lang.reflect.Method.invoke(Method.java:511) 05-05 14:40:08.023: E/AndroidRuntime(2258): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 05-05 14:40:08.023: E/AndroidRuntime(2258): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 05-05 14:40:08.023: E/AndroidRuntime(2258): at dalvik.system.NativeStart.main(Native Method) 05-05 14:40:08.023: E/AndroidRuntime(2258): Caused by: java.lang.NullPointerException 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.view.ViewGroup.addView(ViewGroup.java:3165) 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.view.ViewGroup.addView(ViewGroup.java:3152) 05-05 14:40:08.023: E/AndroidRuntime(2258): at ausoft.opengl.MyOpenGL2Activity.onCreate(MyOpenGL2Activity.java:35) 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.app.Activity.performCreate(Activity.java:4465) 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 05-05 14:40:08.023: E/AndroidRuntime(2258): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919) 05-05 14:40:08.023: E/AndroidRuntime(2258): ... 11 more

有什么建议吗？

Answer 1

您正在尝试 findViewById(R.id.viewControls); 但您之前没有调用过 setContentView()... View viewControls 在哪里 ?

---

如果你愿意，你可以像这样创建 View

View controller = new View(this.getApplicationContext());

或者其他...