在SurfaceView中画图，怎么在里面加网格，心电图

Question

我想在一个SurfaceView中画图，每当SurfaceHolder变化时就重新绘制网格，但是老实现不了

Answer 1

public class RTMonitorActivity extends Activity{
    // private String dataStr = new String();
    private boolean enRead = false;
    public TextView tvDeviceName;
    public static TextView tvDeviceStatus;    private SurfaceHolder holder;    private BTReadThread mReadThread = new BTReadThread(0);
    private Handler msgHandler;
    private DrawECGWaveForm mECGWF;    private String revTmpStr = new String();    public List<Integer> ECGDataList = new ArrayList<Integer>();
    public boolean ECGDLIsAvailable = true;    private int ECGData = 0;    private int WIDTH;    private int HEIGHT;
    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);// 隐藏标题
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.rtmonitor);
        // Init Resources
        tvDeviceName = (TextView)findViewById(R.id.tvDeviceName);
        tvDeviceStatus = (TextView)findViewById(R.id.tvDeviceStatus);
        final SurfaceView sfvECG = (SurfaceView)findViewById(R.id.sfvECG);
        holder = sfvECG.getHolder();        WIDTH = sfvECG.getWidth();
        HEIGHT = sfvECG.getHeight();
        mECGWF = new DrawECGWaveForm(sfvECG);        tvDeviceStatus.setText("Standby");
        holder.addCallback(new Callback() {
            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                Canvas canvas = holder.lockCanvas(new Rect(0, 80, 260, 530));
                // 绘制白色背景
                canvas.drawColor(Color.BLACK);
                Paint p = new Paint();                p.setStrokeWidth(2);
                p.setColor(Color.YELLOW);
                // 绘制坐标轴
                int length = WIDTH / 10;// 画多少条竖线，竖线之间宽度为
                int bound = HEIGHT / 10;// 竖长
                for (int i = 0; i < bound; i++) {
                    for (int j = 0; j < length; j++) {
                        /*
                         * 画竖线
                         */
                        canvas.drawLine(j * length, 0, j * length, HEIGHT, p);
                        /*
                         * 画横线
                         */
                        canvas.drawLine(0, i * bound, WIDTH, i * bound, p);
                    }
                }
                // canvas.drawLine(X_OFFSET , centerY , WIDTH , centerY , p);
                // canvas.drawLine(X_OFFSET , 40 , X_OFFSET , HEIGHT , p);
                holder.unlockCanvasAndPost(canvas);
                holder.lockCanvas(new Rect(0, 0, 0, 0));
                holder.unlockCanvasAndPost(canvas);
            }            @Override
            public void surfaceCreated(final SurfaceHolder myHolder) {
            }            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {            }
        });        try {
            if (BTConnectActivity.mBTSocket.getInputStream() != null) {
                enRead = true;
                mReadThread.start();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
这个是部分代码，但是holder添加的callback老是不能回调 不知道为什么