一个关于android touch事件的问题。。

Question

效果图如上。。是一个类似画笔的程序，多触控画线的时候，当一根手指up时，这个点以为是move到其他还在down的触控点。。实在是不知道怎么解决。。求大牛指点
代码如下：
public boolean onTouchEvent(MotionEvent event) {
float[] xs = new float[10];
float[] ys = new float[10];
touchPoint = event.getPointerCount();
for (int i = 0; i < touchPoint; i++) {
xs[i] =event.getX(i);
ys[i] = event.getY(i);
}
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
for (int i = 0; i < touchPoint; i++) {
lastXs[i] = xs[i];
lastYs[i] = ys[i];
showCoordinate(lastXs[i],lastYs[i]);
mPaths[i].moveTo(lastXs[i],lastYs[i]);
mCanvas.drawPoint(lastXs[i],lastYs[i],mPaints[i]);
}
break;
case MotionEvent.ACTION_POINTER_DOWN:
for (int i = 0; i < touchPoint; i++) {
lastXs[i] = xs[i];
lastYs[i] = ys[i];
showCoordinate(lastXs[i],lastYs[i]);
mPaths[i].moveTo(lastXs[i],lastYs[i]);
mCanvas.drawPoint(lastXs[i],lastYs[i],mPaints[i]);
}
break;

        case MotionEvent.ACTION_MOVE:

            for (int i = 0; i < touchPoint; i ++) {
                int xx = (int) Math.abs(lastXs[i] - xs[i]);
                int yy = (int) Math.abs(lastYs[i] - ys[i]);
                if (xx > 3 || yy > 3) {
                    mPaths[i].lineTo(xs[i], ys[i]);
                }
                lastXs[i] = xs[i];
                lastYs[i] = ys[i];
                showCoordinate(lastXs[i],lastYs[i]);
            }
            break;
    }
    invalidate();
    return true;

Answer 1

http://blog.csdn.net/zhenjing0824/article/details/50494082