如何在重绘时保存先前绘制到画布上的对象？

每次重绘 SurfaceView 时，之前绘制的内容都会被擦除。如何保存它们的状态，以便我的循环将新对象添加到屏幕上而不删除旧对象？

用一个画Bitmap:

Bitmap mDrawBitmap;
Canvas mBitmapCanvas;
Paint mDrawPaint = new Paint();

@Override
public void onDraw(Canvas canvas) {

    if (mDrawBitmap == null) {
        mDrawBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
        mBitmapCanvas = new Canvas(mDrawBitmap);
    }

    // draw on the btimapCanvas
    //... and more
    mBitmapCanvas.drawWhatever(...);

    // after drawing with the bitmapcanvas,
    //all drawn information is stored in the Bitmap       

    // draw everything to the screen
    canvas.drawBitmap(mDrawBitmap, 0, 0, mDrawPaint);
}

这样，“mDrawBitmap”将始终包含当前绘制的状态。如果您愿意，可以通过调用来清除它mBitmapCanvas.drawColor(Color.WHITE);