OpenGL ES EGL環境搭建

一、EGL使用
1、創建EglHelper

public class EglHelper {

    private EGL10 mEgl;
    private EGLDisplay mEglDisplay;
    private EGLContext mEglContext;
    private EGLSurface mEglSurface;

    public void initEgl(Surface surface, EGLContext eglContext)
    {

        //1、得到Egl實例
        mEgl = (EGL10) EGLContext.getEGL();

        //2、得到默認的顯示設備（就是窗口）
        mEglDisplay = mEgl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);
        if (mEglDisplay == EGL10.EGL_NO_DISPLAY) {
            throw new RuntimeException("eglGetDisplay failed");
        }

        //3、初始化默認顯示設備
        int[] version = new int[2];
        if(!mEgl.eglInitialize(mEglDisplay, version)) {
            throw new RuntimeException("eglInitialize failed");
        }

        //4、設置顯示設備的屬性
        int [] attrbutes = new int[]{
                EGL10.EGL_RED_SIZE, 8,
                EGL10.EGL_GREEN_SIZE, 8,
                EGL10.EGL_BLUE_SIZE, 8,
                EGL10.EGL_ALPHA_SIZE, 8,
                EGL10.EGL_DEPTH_SIZE, 8,
                EGL10.EGL_STENCIL_SIZE, 8,
                EGL10.EGL_RENDERABLE_TYPE, 4,
                EGL10.EGL_NONE};

        int[] num_config = new int[1];
        if(!mEgl.eglChooseConfig(mEglDisplay, attrbutes, null, 1, num_config))
        {
            throw new IllegalArgumentException("eglChooseConfig failed");
        }

        int numConfigs = num_config[0];
        if (numConfigs <= 0) {
            throw new IllegalArgumentException(
                    "No configs match configSpec");
        }

        //5、從系統中獲取對應屬性的配置
        EGLConfig[] configs = new EGLConfig[numConfigs];
        if (!mEgl.eglChooseConfig(mEglDisplay, attrbutes, configs, numConfigs,
                num_config)) {
            throw new IllegalArgumentException("eglChooseConfig#2 failed");
        }

        //6、創建EglContext
        if(eglContext != null)
        {
            mEglContext = mEgl.eglCreateContext(mEglDisplay, configs[0], eglContext, null);
        }
        else
        {
            mEglContext = mEgl.eglCreateContext(mEglDisplay, configs[0], EGL10.EGL_NO_CONTEXT, null);
        }

        //7、創建渲染的Surface
        mEglSurface = mEgl.eglCreateWindowSurface(mEglDisplay, configs[0], surface, null);

        //8、綁定EglContext和Surface到顯示設備中
        if(!mEgl.eglMakeCurrent(mEglDisplay, mEglSurface, mEglSurface, mEglContext))
        {
            throw new RuntimeException("eglMakeCurrent fail");
        }
    }

    public boolean swapBuffers()
    {
        if(mEgl != null)
        {
            return mEgl.eglSwapBuffers(mEglDisplay, mEglSurface);
        }
        else
        {
            throw new RuntimeException("egl is null");
        }
    }

    public EGLContext getmEglContext() {
         return mEglContext;
    }

    public void destoryEgl()
    {
        if(mEgl != null)
        {
            mEgl.eglMakeCurrent(mEglDisplay, EGL10.EGL_NO_SURFACE,
                    EGL10.EGL_NO_SURFACE,
                    EGL10.EGL_NO_CONTEXT);

            mEgl.eglDestroySurface(mEglDisplay, mEglSurface);
            mEglSurface = null;

            mEgl.eglDestroyContext(mEglDisplay, mEglContext);
            mEglContext = null;

            mEgl.eglTerminate(mEglDisplay);
            mEglDisplay = null;
            mEgl = null;
        }
    }

}

2、使用EglHelper

public class MainActivity extends AppCompatActivity {
    private static String TAG = "MainActivity";
    private SurfaceView surfaceView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        surfaceView = findViewById(R.id.surfaceview);
        surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                Log.i(TAG, "surfaceCreated()");
            }

            @Override
            public void surfaceChanged(final SurfaceHolder holder, int format, final int width, final int height) {
                Log.i(TAG, "surfaceChanged()"+"=width="+width+"==height="+height);
                new Thread(){
                    @Override
                    public void run() {
                        super.run();
                        EglHelper eglHelper = new EglHelper();
                        eglHelper.initEgl(holder.getSurface(), null);

                        while(true)
                        {
                            GLES20.glViewport(0, 0, width, height);

                            GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
                            GLES20.glClearColor(1.0f, 1.0f, 0.0f, 1.0f);
                            eglHelper.swapBuffers();

                            try {
                                Thread.sleep(16);
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }.start();


            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                //egl.destroy
            }
        });
    }
}

3、代碼執行流程

2019-12-05 20:33:15.864 4926-4926/? I/MainActivity: surfaceCreated()
2019-12-05 20:33:15.864 4926-4926/? I/MainActivity: surfaceChanged()=width=1080==height=1792