Android example source code file (GLView.java)

This example Android source code file (GLView.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, arraylist, content, egl10, eglconfig, egldisplay, eglhelper, gl, glthread, glview, glwrapper, interruptedexception, override, renderer, runnable, semaphore, ui, util, utilities, view

The GLView.java Android example source code

/*
 * Copyright (C) 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.opengles.triangle;

import android.content.Context;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

import java.util.ArrayList;
import java.util.concurrent.Semaphore;

import javax.microedition.khronos.egl.EGL10;
import javax.microedition.khronos.egl.EGL11;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.egl.EGLContext;
import javax.microedition.khronos.egl.EGLDisplay;
import javax.microedition.khronos.egl.EGLSurface;
import javax.microedition.khronos.opengles.GL;
import javax.microedition.khronos.opengles.GL10;

/**
 * An implementation of SurfaceView that uses the dedicated surface for
 * displaying an OpenGL animation.  This allows the animation to run in a
 * separate thread, without requiring that it be driven by the update mechanism
 * of the view hierarchy.
 *
 * The application-specific rendering code is delegated to a GLView.Renderer
 * instance.
 */
class GLView extends SurfaceView implements SurfaceHolder.Callback {
    GLView(Context context) {
        super(context);
        init();
    }

    public GLView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed
        mHolder = getHolder();
        mHolder.addCallback(this);
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_GPU);
    }

    public void setGLWrapper(GLWrapper glWrapper) {
        mGLWrapper = glWrapper;
    }

    public void setRenderer(Renderer renderer) {
        mGLThread = new GLThread(renderer);
        mGLThread.start();
    }

    public void surfaceCreated(SurfaceHolder holder) {
        mGLThread.surfaceCreated();
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // Surface will be destroyed when we return
        mGLThread.surfaceDestroyed();
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // Surface size or format has changed. This should not happen in this
        // example.
        mGLThread.onWindowResize(w, h);
    }

    /**
     * Inform the view that the activity is paused.
     */
    public void onPause() {
        mGLThread.onPause();
    }

    /**
     * Inform the view that the activity is resumed.
     */
    public void onResume() {
        mGLThread.onResume();
    }

    /**
     * Inform the view that the window focus has changed.
     */
    @Override public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        mGLThread.onWindowFocusChanged(hasFocus);
    }

    /**
     * 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) {
        mGLThread.queueEvent(r);
    }

    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        mGLThread.requestExitAndWait();
    }

    // ----------------------------------------------------------------------

    public interface GLWrapper {
      GL wrap(GL gl);
    }

    // ----------------------------------------------------------------------

    /**
     * A generic renderer interface.
     */
    public interface Renderer {
        /**
         * @return the EGL configuration specification desired by the renderer.
         */
        int[] getConfigSpec();

        /**
         * Surface created.
         * Called when the surface is created. Called when the application
         * starts, and whenever the GPU is reinitialized. This will
         * typically happen when the device awakes after going to sleep.
         * Set your textures here.
         */
        void surfaceCreated(GL10 gl);
        /**
         * Surface changed size.
         * Called after the surface is created and whenever
         * the OpenGL ES surface size changes. Set your viewport here.
         * @param gl
         * @param width
         * @param height
         */
        void sizeChanged(GL10 gl, int width, int height);
        /**
         * Draw the current frame.
         * @param gl
         */
        void drawFrame(GL10 gl);
    }

    /**
     * An EGL helper class.
     */

    private class EglHelper {
        public EglHelper() {

        }

        /**
         * Initialize EGL for a given configuration spec.
         * @param configSpec
         */
        public void start(int[] configSpec){
            /*
             * Get an EGL instance
             */
            mEgl = (EGL10) EGLContext.getEGL();

            /*
             * Get to the default display.
             */
            mEglDisplay = mEgl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);

            /*
             * We can now initialize EGL for that display
             */
            int[] version = new int[2];
            mEgl.eglInitialize(mEglDisplay, version);

            EGLConfig[] configs = new EGLConfig[1];
            int[] num_config = new int[1];
            mEgl.eglChooseConfig(mEglDisplay, configSpec, configs, 1,
                    num_config);
            mEglConfig = configs[0];

            /*
            * Create an OpenGL ES context. This must be done only once, an
            * OpenGL context is a somewhat heavy object.
            */
            mEglContext = mEgl.eglCreateContext(mEglDisplay, mEglConfig,
                    EGL10.EGL_NO_CONTEXT, null);

            mEglSurface = null;
        }

        /*
         * Create and return an OpenGL surface
         */
        public GL createSurface(SurfaceHolder holder) {
            /*
             *  The window size has changed, so we need to create a new
             *  surface.
             */
            if (mEglSurface != null) {

                /*
                 * Unbind and destroy the old EGL surface, if
                 * there is one.
                 */
                mEgl.eglMakeCurrent(mEglDisplay, EGL10.EGL_NO_SURFACE,
                        EGL10.EGL_NO_SURFACE, EGL10.EGL_NO_CONTEXT);
                mEgl.eglDestroySurface(mEglDisplay, mEglSurface);
            }

            /*
             * Create an EGL surface we can render into.
             */
            mEglSurface = mEgl.eglCreateWindowSurface(mEglDisplay,
                    mEglConfig, holder, null);

            /*
             * Before we can issue GL commands, we need to make sure
             * the context is current and bound to a surface.
             */
            mEgl.eglMakeCurrent(mEglDisplay, mEglSurface, mEglSurface,
                    mEglContext);


            GL gl = mEglContext.getGL();
            if (mGLWrapper != null) {
                gl = mGLWrapper.wrap(gl);
            }
            return gl;
        }

        /**
         * Display the current render surface.
         * @return false if the context has been lost.
         */
        public boolean swap() {
            mEgl.eglSwapBuffers(mEglDisplay, mEglSurface);

            /*
             * 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();
        private EglHelper mEglHelper;
    }

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

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