【发布时间】：2015-02-13 00:36:56
【问题描述】：
我有一个DialogFragment，其中包含一个RecyclerView（卡片列表）。
在这个RecyclerView 中有一个或多个CardViews，可以有任何高度。
我想根据其中包含的CardViews 为这个DialogFragment 提供正确的高度。
通常这很简单，我会像这样在RecyclerView 上设置wrap_content。
<android.support.v7.widget.RecyclerView ...
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:clickable="true"
android:scrollbars="vertical" >
</android.support.v7.widget.RecyclerView>
因为我使用的是RecyclerView，所以这不起作用：
https://issuetracker.google.com/issues/37001674
和
Nested Recycler view height doesn't wrap its content
在这两个页面上，人们建议扩展 LinearLayoutManager 并覆盖 onMeasure()
我首先使用了某人在第一个链接中提供的 LayoutManager：
public static class WrappingLayoutManager extends LinearLayoutManager {
public WrappingLayoutManager(Context context) {
super(context);
}
private int[] mMeasuredDimension = new int[2];
@Override
public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
int widthSpec, int heightSpec) {
final int widthMode = View.MeasureSpec.getMode(widthSpec);
final int heightMode = View.MeasureSpec.getMode(heightSpec);
final int widthSize = View.MeasureSpec.getSize(widthSpec);
final int heightSize = View.MeasureSpec.getSize(heightSpec);
measureScrapChild(recycler, 0,
View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
mMeasuredDimension);
int width = mMeasuredDimension[0];
int height = mMeasuredDimension[1];
switch (widthMode) {
case View.MeasureSpec.EXACTLY:
case View.MeasureSpec.AT_MOST:
width = widthSize;
break;
case View.MeasureSpec.UNSPECIFIED:
}
switch (heightMode) {
case View.MeasureSpec.EXACTLY:
case View.MeasureSpec.AT_MOST:
height = heightSize;
break;
case View.MeasureSpec.UNSPECIFIED:
}
setMeasuredDimension(width, height);
}
private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
int heightSpec, int[] measuredDimension) {
View view = recycler.getViewForPosition(position);
if (view != null) {
RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
getPaddingLeft() + getPaddingRight(), p.width);
int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
getPaddingTop() + getPaddingBottom(), p.height);
view.measure(childWidthSpec, childHeightSpec);
measuredDimension[0] = view.getMeasuredWidth();
measuredDimension[1] = view.getMeasuredHeight();
recycler.recycleView(view);
}
}
}
但是这不起作用因为
heightSize = View.MeasureSpec.getSize(heightSpec);
返回一个似乎与match_parent 相关的非常大的值。
通过评论 height = heightSize;（在第二个 switch 案例中）我设法使高度起作用，但前提是 CardView 内的 TextView 子级不换行自己的文本（长句）。
一旦TextView 包装它自己的文本，高度应该增加，但它不会。它将长句子的高度计算为单行，而不是换行（2 行或更多行）。
关于我应该如何改进LayoutManager 以便我的RecyclerView 与WRAP_CONTENT 一起使用的任何建议？
编辑：这个布局管理器可能适用于大多数人，但它仍然存在滚动和计算包装文本视图高度的问题
public class MyLinearLayoutManager extends LinearLayoutManager {
public MyLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
super(context, orientation, reverseLayout);
}
private int[] mMeasuredDimension = new int[2];
@Override
public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
int widthSpec, int heightSpec) {
final int widthMode = View.MeasureSpec.getMode(widthSpec);
final int heightMode = View.MeasureSpec.getMode(heightSpec);
final int widthSize = View.MeasureSpec.getSize(widthSpec);
final int heightSize = View.MeasureSpec.getSize(heightSpec);
int width = 0;
int height = 0;
for (int i = 0; i < getItemCount(); i++) {
measureScrapChild(recycler, i,
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
mMeasuredDimension);
if (getOrientation() == HORIZONTAL) {
width = width + mMeasuredDimension[0];
if (i == 0) {
height = mMeasuredDimension[1];
}
} else {
height = height + mMeasuredDimension[1];
if (i == 0) {
width = mMeasuredDimension[0];
}
}
}
switch (widthMode) {
case View.MeasureSpec.EXACTLY:
width = widthSize;
case View.MeasureSpec.AT_MOST:
case View.MeasureSpec.UNSPECIFIED:
}
switch (heightMode) {
case View.MeasureSpec.EXACTLY:
height = heightSize;
case View.MeasureSpec.AT_MOST:
case View.MeasureSpec.UNSPECIFIED:
}
setMeasuredDimension(width, height);
}
private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
int heightSpec, int[] measuredDimension) {
View view = recycler.getViewForPosition(position);
if (view != null) {
RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
getPaddingLeft() + getPaddingRight(), p.width);
int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
getPaddingTop() + getPaddingBottom(), p.height);
view.measure(childWidthSpec, childHeightSpec);
measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
recycler.recycleView(view);
}
}
}
【问题讨论】：
-
好像谷歌finally managed to fix that:
Jan 22, 2016: This has been merged into the internal tree, should be available with the next version of support library.
标签： android android-layout android-fragments android-recyclerview