如何获得具有有效Surface的SurfaceHolder（EGL.eglCreateWindowSurface所需）？

Question

我试图使用EGL初始化GLES（因为我想要从主线程绘制而不是使用Renderer并在onDrawFrame内部绘制）。 我遇到了错误：“确保SurfaceView或相关的SurfaceHolder具有有效的Surface”。很明显mEgl.eglCreateWindowSurface失败，因为surfaceHolder没有有效的表面。如何获得一个具有有效表面的SurfaceHolder以继续进行？

我的Activity.onCreate方法是：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    GLSurfaceView surfaceView = new GLSurfaceView(this);
    setContentView(surfaceView);
    SurfaceHolder surfaceHolder = surfaceView.getHolder();
    Surface surface = surfaceHolder.getSurface();
    Log.v("HelloAndroid", "surface.isValid()= " + Boolean.toString(surface.isValid()));

    EGL10 mEgl = (EGL10) EGLContext.getEGL();
    EGLDisplay mEglDisplay = mEgl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);
    int[] version = new int[2];
    mEgl.eglInitialize(mEglDisplay, version);
    EGLConfig[] configs = new EGLConfig[1];
    int[] num_config = new int[1];
    int[] configSpec = {
            EGL10.EGL_NONE
    };
    mEgl.eglChooseConfig(mEglDisplay, configSpec, configs, 1, num_config);
    EGLConfig mEglConfig = configs[0];
    EGLContext mEglContext = mEgl.eglCreateContext(mEglDisplay, mEglConfig,
            EGL10.EGL_NO_CONTEXT, null);
    EGLSurface mEglSurface = null;
    Log.v("HelloAndroid", "M");
    mEglSurface = mEgl.eglCreateWindowSurface(mEglDisplay,
            mEglConfig, surfaceHolder, null);
    Log.v("HelloAndroid", "N");
    mEgl.eglMakeCurrent(mEglDisplay, mEglSurface, mEglSurface,
            mEglContext);
    Log.v("HelloAndroid", "O");
}

我使用platform-tools/adb logcat获取的日志输出是：

V/HelloAndroid( 1861): surface.isValid()= false
D/libEGL  ( 1861): egl.cfg not found, using default config
D/libEGL  ( 1861): loaded /system/lib/egl/libGLES_android.so
V/HelloAndroid( 1861): M
D/AndroidRuntime( 1861): Shutting down VM
W/dalvikvm( 1861): threadid=3: thread exiting with uncaught exception (group=0x4001b188)
E/AndroidRuntime( 1861): Uncaught handler: thread main exiting due to uncaught exception
E/AndroidRuntime( 1861): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.helloandroid/com.example.helloandroid.HelloAndroid}: java.lang.IllegalArgumentException: Make sure the SurfaceView or associated SurfaceHolder has a valid Surface
E/AndroidRuntime( 1861):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496)

非常感谢您的帮助。

- Thomas Mertes

Answer 1

在创建surface时应该进行surface的有效性检查。因此，应该在onSurfaceCreated或onSurfaceChanged中调用surface.isValid()，显然，你需要添加surfaceholder.callback。

- Lee

Answer 2

实现SurfaceHolder.Callback，等待直到告诉您表面已创建。同时注意它何时被销毁。在匹配的创建和销毁调用之间，您应仅依赖于表面有效。

- Laurence Gonsalves

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在应用程序启动后，持有者需要花费很长时间才能给出表面读数，这是否正常？此时，is Valid()=true吗？ - Ashwin