Android ListView扩展动画跳跃

Question

我正在尝试根据按钮点击扩展listView项目。

到目前为止一切正常，没有错误。问题是，第一次动画跳转时，listItem跳转到扩展高度，而不是平滑滑动。但在那之后动画效果很好。

此外，只有在绘图之前将expandView设置为适配器类中的View.GONE时，动画才有效。

这是动画类，它取自here

public class ExpandAnimation extends Animation {
private View mAnimatedView;
private LayoutParams mViewLayoutParams;
private int mMarginStart, mMarginEnd;
private boolean mIsVisibleAfter = false;
private boolean mWasEndedAlready = false;

/**
 * Initialize the animation
 * @param view The layout we want to animate
 * @param duration The duration of the animation, in ms
 */
public ExpandAnimation(View view, int duration) {

    setDuration(duration);
    mAnimatedView = view;
    mViewLayoutParams = (LayoutParams) view.getLayoutParams();

    // decide to show or hide the view
    mIsVisibleAfter = (view.getVisibility() == View.VISIBLE);

    mMarginStart = mViewLayoutParams.bottomMargin;
    mMarginEnd = (mMarginStart == 0 ? (0 - view.getHeight()) : 0);

    view.setVisibility(View.VISIBLE);
}

@Override
public boolean willChangeBounds() {
    return true;
}


@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
    super.applyTransformation(interpolatedTime, t);

    if (interpolatedTime < 1.0f) {

        // Calculating the new bottom margin, and setting it
        mViewLayoutParams.bottomMargin = mMarginStart
                + (int) ((mMarginEnd - mMarginStart) * interpolatedTime);

        // Invalidating the layout, making us seeing the changes we made
        mAnimatedView.requestLayout();

        // Making sure we didn't run the ending before (it happens!)
    } else if (!mWasEndedAlready) {
        mViewLayoutParams.bottomMargin = mMarginEnd;
        mAnimatedView.requestLayout();

        if (mIsVisibleAfter) {
            mAnimatedView.setVisibility(View.GONE);
        }
        mWasEndedAlready = true;
    }
}