Android:将带有剪辑的图片绘制到 ScrollView 中会导致一致的 ANR？

Question

我的应用程序遇到了一个神秘的 ANR，它使用图片记录绘图命令(路径、剪辑、文本等)，然后将这些图片绘制到 ScrollView 持有的 View 中。我能够通过以下 Activity 重现该问题。在此 Activity 中，向下滚动 ScrollView 将在到达正方形底部时立即产生 ANR。还有其他人遇到过这个吗？关于如何避免它的任何建议？

public class AnrTest extends Activity
{
    public void onCreate(Bundle saveInstBundle)
    {
        super.onCreate(saveInstBundle);

        ScrollView sc = new ScrollView(this);
        MyView view = new MyView(this);
        sc.addView(view);
        setContentView(sc);
    }

    class MyView extends View
    {
        Picture mPic;

        public MyView(Context context)
        {
            super(context);
            mPic = new Picture();
            Canvas picCanvas = mPic.beginRecording(300, 900);

            Paint p = new Paint();
            p.setColor(Color.RED);
            picCanvas.drawRect(20, 20, 100, 100, p);

            picCanvas.clipRect(0, 0, 100, 100);

            mPic.endRecording();
        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) 
        {
            //set a height larger than the screen, so that we can scroll.
            setMeasuredDimension(300, 900);
        }

        protected void onDraw(Canvas canvas)
        {
            canvas.drawPicture(mPic);
        }
    }
}

Answer 1

@Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) 
    {
        //set a height larger than the screen, so that we can scroll.
        setMeasuredDimension(300, 900);
        requestLayout();
    }

你让 child 比它的 parent 大。 requestLayout() 将解决您的问题。