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

Question

我尝试用 EGL 初始化 GLES(因为我想从主线程中绘制而不是使用渲染器并从 onDrawFrame 内部绘图)。我收到错误消息:“确保 SurfaceView 或关联的 SurfaceHolder 具有有效的 Surface”。显然 mEgl.eglCreateWindowSurface 失败了，因为 surfaceHolder 没有有效的表面。如何获得具有有效 Surface 的 SurfaceHolder 才能继续？

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 得到的日志输出是:

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)

感谢任何帮助。

Answer 1

surface 的有效性检查应该在创建 surface 时进行。所以，surface.isValid()应该在onSurfaceCreated或onSurfaceChanged中调用，显然，你应该添加surfaceholder.callback.