Question

我有简单的LinearLayout和2个按钮。视图看起来不错，显示中间和末端分隔线。当我以编程方式将第二个按钮的可见性设置为View.GONE时，第一个按钮下方的分隔符丢失。如何改变？

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:divider="?android:attr/listDivider"
    android:orientation="vertical"
    android:showDividers="middle|end"
    android:animateLayoutChanges="true">

    <Button
        android:id="@+id/1_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="1"
        android:layout_marginLeft="@dimen/big_margin"
        android:layout_marginTop="@dimen/normal_margin"
        android:layout_marginRight="@dimen/big_margin"
        android:layout_marginBottom="@dimen/normal_margin"/>

    <Button
        android:id="@+id/2_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="2"
        android:layout_marginLeft="@dimen/big_margin"
        android:layout_marginTop="@dimen/normal_margin"
        android:layout_marginRight="@dimen/big_margin"
        android:layout_marginBottom="@dimen/normal_margin"/>
</LinearLayout>

Answer 1

我认为这是LinearLayout实施中的一个错误，因为它应该在end按钮消失后为1_id ID设置2_id分隔符。但是，这不是这种情况，因此可能的解决方法是从end中省略LinearLayout分频器设置，并在末尾添加一个虚拟View，以便它的中间分频器将模拟最后一个分隔线。

看看这个例子：

<!-- No 'end' divider in 'android:showDividers' attribute -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:showDividers="middle"
    android:divider="?android:attr/listDivider"
    android:orientation="vertical">

    <TextView
        android:text="Line 1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:text="Line 2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:text="Last line"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <!-- Dummy view to simulate last divider -->
    <View
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</LinearLayout>

Answer 2

我通过复制支持库类LinearLayoutCompat并修改以下两种方法来解决这个问题：

void drawDividersVertical(Canvas canvas) {
    final int count = getVirtualChildCount();
    View lastVisibleChild = null;

    for (int i = 0; i < count; i++) {
        final View child = getVirtualChildAt(i);
        if (child != null && child.getVisibility() != GONE) {
            lastVisibleChild = child;
            if (hasDividerBeforeChildAt(i)) {
                final LayoutParams lp = (LayoutParams) child.getLayoutParams();
                final int top = child.getTop() - lp.topMargin - mDividerHeight;
                drawHorizontalDivider(canvas, top);
            }
        }
    }

    if (hasDividerBeforeChildAt(count)) {
        final View child = lastVisibleChild;
        int bottom = 0;
        if (child == null) {
            bottom = getHeight() - getPaddingBottom() - mDividerHeight;
        } else {
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            bottom = child.getBottom() + lp.bottomMargin;
        }
        drawHorizontalDivider(canvas, bottom);
    }
}

protected boolean hasDividerBeforeChildAt(int childIndex) {
    if (childIndex == 0) {
        return (mShowDividers & SHOW_DIVIDER_BEGINNING) != 0;
    } else if (childIndex == getChildCount()) {
        return (mShowDividers & SHOW_DIVIDER_END) != 0;
    } else if ((mShowDividers & SHOW_DIVIDER_MIDDLE) != 0) {
        boolean hasVisibleViewBefore = false;
        for (int i = childIndex - 1; i >= 0; i--) {
            if (getChildAt(i).getVisibility() != GONE) {
                hasVisibleViewBefore = true;
                break;
            }
        }
        return hasVisibleViewBefore || (mShowDividers & SHOW_DIVIDER_BEGINNING) != 0;
    }
    return false;
}

https://code.google.com/p/android/issues/detail?id=200396&thanks=200396&ts=1454685515

当LinearLayout中最后一个视图的可见性设置为GONE时，底部分隔符丢失

2 个答案: