Android ScrollView褪色边缘

Question

默认情况下,只有可以在该方向上滚动时,scrollview的渐变边缘才可见.我怎样才能让它随时可见？

我不想把任何抽签放在上面或类似的东西.我想使用内置的淡化边缘来完成它,可能是通过覆盖一些scrollview函数.

提前致谢

Answer 1

是的,扩展ScrollView并覆盖这些方法(基于Donut-release2):

@Override
protected float getTopFadingEdgeStrength() {
    if (getChildCount() == 0) {
        return 0.0f;
    }
    return 1.0f;
}

@Override
protected float getBottomFadingEdgeStrength() {
    if (getChildCount() == 0) {
        return 0.0f;
    }
    return 1.0f;
}

为了比较,这是原始代码,当你接近列表的末尾时缩短了衰落边缘:

@Override
protected float getTopFadingEdgeStrength() {
    if (getChildCount() == 0) {
        return 0.0f;
    }

    final int length = getVerticalFadingEdgeLength();
    if (mScrollY < length) {
        return mScrollY / (float) length;
    }

    return 1.0f;
}

@Override
protected float getBottomFadingEdgeStrength() {
    if (getChildCount() == 0) {
        return 0.0f;
    }

    final int length = getVerticalFadingEdgeLength();
    final int bottomEdge = getHeight() - mPaddingBottom;
    final int span = getChildAt(0).getBottom() - mScrollY - bottomEdge;
    if (span < length) {
        return span / (float) length;
    }

    return 1.0f;
}