glsurfaceview.java

android 例子中的确良ApiDemos。很有代表意义

            /*
             * Always check for EGL_CONTEXT_LOST, which means the context
             * and all associated data were lost (For instance because
             * the device went to sleep). We need to sleep until we
             * get a new surface.
             */
            return mEgl.eglGetError() != EGL11.EGL_CONTEXT_LOST;
        }

        public void finish() {
            if (mEglSurface != null) {
                mEgl.eglMakeCurrent(mEglDisplay, EGL10.EGL_NO_SURFACE,
                        EGL10.EGL_NO_SURFACE,
                        EGL10.EGL_NO_CONTEXT);
                mEgl.eglDestroySurface(mEglDisplay, mEglSurface);
                mEglSurface = null;
            }
            if (mEglContext != null) {
                mEgl.eglDestroyContext(mEglDisplay, mEglContext);
                mEglContext = null;
            }
            if (mEglDisplay != null) {
                mEgl.eglTerminate(mEglDisplay);
                mEglDisplay = null;
            }
        }

        EGL10 mEgl;
        EGLDisplay mEglDisplay;
        EGLSurface mEglSurface;
        EGLConfig mEglConfig;
        EGLContext mEglContext;
    }

    /**
     * A generic GL Thread. Takes care of initializing EGL and GL. Delegates
     * to a Renderer instance to do the actual drawing.
     *
     */

    class GLThread extends Thread {
        GLThread(Renderer renderer) {
            super();
            mDone = false;
            mWidth = 0;
            mHeight = 0;
            mRenderer = renderer;
            setName("GLThread");
        }

        @Override
        public void run() {
            /*
             * When the android framework launches a second instance of
             * an activity, the new instance's onCreate() method may be
             * called before the first instance returns from onDestroy().
             *
             * This semaphore ensures that only one instance at a time
             * accesses EGL.
             */
            try {
                try {
                sEglSemaphore.acquire();
                } catch (InterruptedException e) {
                    return;
                }
                guardedRun();
            } catch (InterruptedException e) {
                // fall thru and exit normally
            } finally {
                sEglSemaphore.release();
            }
        }

        private void guardedRun() throws InterruptedException {
            mEglHelper = new EglHelper();
            /*
             * Specify a configuration for our opengl session
             * and grab the first configuration that matches is
             */
            int[] configSpec = mRenderer.getConfigSpec();
            mEglHelper.start(configSpec);

            GL10 gl = null;
            boolean tellRendererSurfaceCreated = true;
            boolean tellRendererSurfaceChanged = true;

            /*
             * This is our main activity thread's loop, we go until
             * asked to quit.
             */
            while (!mDone) {

                /*
                 *  Update the asynchronous state (window size)
                 */
                int w, h;
                boolean changed;
                boolean needStart = false;
                synchronized (this) {
                    Runnable r;
                    while ((r = getEvent()) != null) {
                        r.run();
                    }
                    if (mPaused) {
                        mEglHelper.finish();
                        needStart = true;
                    }
                    if(needToWait()) {
                        while (needToWait()) {
                            wait();
                        }
                    }
                    if (mDone) {
                        break;
                    }
                    changed = mSizeChanged;
                    w = mWidth;
                    h = mHeight;
                    mSizeChanged = false;
                }
                if (needStart) {
                    mEglHelper.start(configSpec);
                    tellRendererSurfaceCreated = true;
                    changed = true;
                }
                if (changed) {
                    gl = (GL10) mEglHelper.createSurface(mHolder);
                    tellRendererSurfaceChanged = true;
                }
                if (tellRendererSurfaceCreated) {
                    mRenderer.surfaceCreated(gl);
                    tellRendererSurfaceCreated = false;
                }
                if (tellRendererSurfaceChanged) {
                    mRenderer.sizeChanged(gl, w, h);
                    tellRendererSurfaceChanged = false;
                }
                if ((w > 0) && (h > 0)) {
                    /* draw a frame here */
                    mRenderer.drawFrame(gl);

                    /*
                     * Once we're done with GL, we need to call swapBuffers()
                     * to instruct the system to display the rendered frame
                     */
                    mEglHelper.swap();
                }
             }

            /*
             * clean-up everything...
             */
            mEglHelper.finish();
        }

        private boolean needToWait() {
            return (mPaused || (! mHasFocus) || (! mHasSurface) || mContextLost)
                && (! mDone);
        }

        public void surfaceCreated() {
            synchronized(this) {
                mHasSurface = true;
                mContextLost = false;
                notify();
            }
        }

        public void surfaceDestroyed() {
            synchronized(this) {
                mHasSurface = false;
                notify();
            }
        }

        public void onPause() {
            synchronized (this) {
                mPaused = true;
            }
        }

        public void onResume() {
            synchronized (this) {
                mPaused = false;
                notify();
            }
        }

        public void onWindowFocusChanged(boolean hasFocus) {
            synchronized (this) {
                mHasFocus = hasFocus;
                if (mHasFocus == true) {
                    notify();
                }
            }
        }
        public void onWindowResize(int w, int h) {
            synchronized (this) {
                mWidth = w;
                mHeight = h;
                mSizeChanged = true;
            }
        }

        public void requestExitAndWait() {
            // don't call this from GLThread thread or it is a guaranteed
            // deadlock!
            synchronized(this) {
                mDone = true;
                notify();
            }
            try {
                join();
            } catch (InterruptedException ex) {
                Thread.currentThread().interrupt();
            }
        }

        /**
         * Queue an "event" to be run on the GL rendering thread.
         * @param r the runnable to be run on the GL rendering thread.
         */
        public void queueEvent(Runnable r) {
            synchronized(this) {
                mEventQueue.add(r);
            }
        }

        private Runnable getEvent() {
            synchronized(this) {
                if (mEventQueue.size() > 0) {
                    return mEventQueue.remove(0);
                }

            }
            return null;
        }

        private boolean mDone;
        private boolean mPaused;
        private boolean mHasFocus;
        private boolean mHasSurface;
        private boolean mContextLost;
        private int mWidth;
        private int mHeight;
        private Renderer mRenderer;
        private ArrayList<Runnable> mEventQueue = new ArrayList<Runnable>();
        private EglHelper mEglHelper;
    }

    private static final Semaphore sEglSemaphore = new Semaphore(1);
    private boolean mSizeChanged = true;

    private SurfaceHolder mHolder;
    private GLThread mGLThread;
    private GLWrapper mGLWrapper;
}