XML中定义的扩展LinearLayout的子代不显示 [英] Children of extended LinearLayout defined in XML do not show

问题描述

在我的项目中，我的屏幕上重复了很多相同的图案-它基本上是一个视图容器，其中包含标题，图像和特定背景的线性布局.为避免多次复制和粘贴相同的序列，我认为我可以创建一个复合视图，扩展LinearLayout并在那里定义所有样式"，然后在布局中使用该组件. 我遵循了howto的示例，并使我的复合视图起作用.但是，我见过的所有示例都使用结果视图，如下所示:

In my project I have screens where the same pattern is repeated a lot - it's basically a container for views consisting of a linear layout with the heading, image and specific background. To avoid copying and pasting the same sequence multiple times I thought I could create a compound view, extend LinearLayout and define all the "styling" there, and then just use that component in my layouts. I followed howto's and examples and got my compound view to work. However, all examples I've seen use the resulting view as follows:

<com.myproject.compound.myview
    ...some attrs...
/>

即没有通过XML添加任何子级.我需要这样使用它:

I.e. no children are added via XML. I need to use it like this:

<com.myproject.compound.myview
    ...some attrs...>
    <TextView 
        ..../>
    ...other views...

</com.myproject.compound.myview>

由于我正在扩展LinearLayout，因此我期望"myview"标签也可以像LinearLayout一样工作，但是由于某些原因，放置在我内部的项不会被绘制.为了绘制内部视图，我需要做些特别的事情吗?

Since I'm extending LinearLayout I was expecting "myview" tag to work like LinearLayout too, but for some reason items I put inside do not get drawn. Is there something I need to do specially to get the inner views to draw?

我扩展的LinearLayout非常简单，我没有重写任何方法，只是在构造函数中调用super并像这样夸大了布局:

My extended LinearLayout is very simple, I am not overriding any methods and just calling super in constructor and inflating the layout like this:

    LayoutInflater inflater = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        inflater.inflate(R.layout.my_compound_view, this, true);

更新:我想我将添加XML作为参考点:

UPDATE: I thought I'd add an XML as a point of reference:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" 
android:background="@drawable/bg"
android:padding="12dp">
<TextView 
    android:id="@+id/section_title"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textColor="#FF0000AA"        />
<ImageView
    android:layout_width="match_parent"
    android:layout_height="2dp"
        android:src="@drawable/line"        />
</LinearLayout>

推荐答案

实际上找到了一个更优雅的解决方案.只需在复合视图中使用合并标记而不是LinearLayout.全部归结为:

Actually found a more elegant solution. Just need to use merge tag instead of LinearLayout in the compound view. All boils down to:

<merge xmlns:android="http://schemas.android.com/apk/res/android"
    <TextView 
        android:id="@+id/section_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="HEADING"
        android:textColor="#FF0000AA"        />
    <ImageView
        android:layout_width="match_parent"
        android:layout_height="2dp"
        android:src="@drawable/line"        />
</merge>

和

public class CompoundLayout extends LinearLayout{
    public CompoundLayout(Context context, AttributeSet attrs) {
        super(context, attrs);

        LayoutInflater inflater = (LayoutInflater) context
           .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        inflater.inflate(R.layout.compound_layout, this, true);
    }
}

主要布局:

<com.testbench.CompoundLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="#FFFFDDEE"
    android:orientation="vertical">
    <TextView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Inner text"
            android:layout_gravity="center_horizontal"/>        
</com.testbench.CompoundLayout>

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