Android SurfaceView 只绘制两次

Question

我试图在surfaceView上简单地绘制一些东西，即使我使用它也只会渲染两次

setWillNotDraw(假)

我怎样才能让我的 onDraw 方法每次都被调用，而不仅仅是两次？

screen of log

代码：

public class MainActivity extends Activity implements SurfaceHolder.Callback {

private static final String TAG = "SurfaceView";
private SurfaceView surfaceView;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    surfaceView = new SurfaceView(this);
    surfaceView.setWillNotDraw(false);

    setContentView(surfaceView);
    surfaceView.getHolder().addCallback(this);
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
    tryDrawing(holder);
    surfaceView.setWillNotDraw(false);
}

@Override
public void surfaceChanged(SurfaceHolder holder, int frmt, int w, int h) {
    tryDrawing(holder);
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {}

private void tryDrawing(SurfaceHolder holder) {
    Log.i(TAG, "Trying to draw...");
    Canvas canvas = holder.lockCanvas();
    if (canvas == null) {
        Log.e(TAG, "Cannot draw onto the canvas as it's null");
    } else {
        drawMyStuff(canvas);
        holder.unlockCanvasAndPost(canvas);
    }
}

private void drawMyStuff(final Canvas canvas) {
    Log.i(TAG, "Drawing...");
    Random random = new Random();
    canvas.drawRGB(random.nextInt(255), random.nextInt(255), random.nextInt(255));
}

}

Answer 1

尝试像这样从 View 扩展您自己的类，并在 onDraw() 方法中无效：

public class ScreenView extends View {

    private Context context;
    private Paint paintLine = new Paint(Paint.ANTI_ALIAS_FLAG);

    public ViewStats(Context context) {
        super(context);
        this.context = context;
        init();
    }

    public ViewStats(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        init();
    }

    public ViewStats(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        this.context = context;
        init();
    }

    private void init() {
        paintLine.setStyle(Paint.Style.FILL_AND_STROKE);
        paintLine.setColor(0xFFE4455B);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.getSize(heightMeasureSpec));
    }

    @Override
    protected void onDraw(Canvas canvas) {
        Random random = new Random();
        canvas.drawRGB(random.nextInt(255), random.nextInt(255), random.nextInt(255));
        invalidate();
    }
}