Android数据绑定layout_width和layout_height

Question

我需要能够动态设置EditText的height属性.我在我的应用程序中使用数据绑定其他属性,所以我希望能够使用数据绑定来控制我的元素的高度.这是我的xml的精简版:

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">

<data>
    <variable name="loginVM" type="com.testing.stuff.ViewModels.LoginViewModel" />
</data>

<EditText android:inputType="number"
            android:id="@+id/txtVerificationCode"
            android:layout_height="@{loginVM.compact ? @dimen/verificationHeightCompact : @dimen/verificationHeightFull}"
            android:layout_width="match_parent"
            android:paddingRight="16dp"
            android:paddingLeft="16dp"
            android:focusable="true"
            android:focusableInTouchMode="true"
            android:layout_marginLeft="10dp"
            android:alpha="@{loginVM.verificationOpacity}"
            android:layout_marginStart="10dp"
            android:textAlignment="center"
            android:visibility="visible"
            android:hint="Enter verificationCode"
            android:text="@{loginVM.verificationCode}" />
</layout> 

这是我的View模型的精简版:

public class LoginViewModel extends BaseObservable {
public final ObservableField<String> verificationCode; 
public final ObservableField<Boolean> compact;

@Bindable
public String getVerificationCode() {
    if (this.verificationCode == null) {
        return "";
    } else {
        return this.verificationCode.get();
    }
}

public void setVerificationCode(String verificationCode) {
    this.verificationCode.set(verificationCode);
    invalidateProperties();
}

@Bindable
public Boolean getCompact(){return this.compact.get();}

public void setCompact(Boolean value)
{
    this.compact.set(value);
    this.invalidateProperties();
}

@BindingAdapter("android:layout_height")
public static void setLayoutHeight(EditText view, float height)
{
    ViewGroup.LayoutParams layoutParams = view.getLayoutParams();
    layoutParams.height = (int)height;
    view.setLayoutParams(layoutParams);
}

public LoginViewModel(Context ctx) {
    verificationCode = new ObservableField();
    compact = new ObservableField();
}

维度位于dimens.xml文件中.我正在修改视图模型中的属性.但是,当我启动应用程序时,我在启动后立即收到以下错误(bindingadapter未在调试时触发).我在屏幕上还有其他几个元素,但是这个特殊的元素是我需要在特定动作发生时改变高度的元素:

FATAL EXCEPTION: main

Process: com.testing.stuff, PID: 32752

java.lang.RuntimeException: Unable to start activity  
ComponentInfo{com.testing.stuff/com.testing.stuff.Login}: 
java.lang.RuntimeException: Binary XML file line #69: You must supply 
a layout_height attribute.

Caused by: java.lang.RuntimeException: Binary XML file line #69: You 
must supply a layout_height attribute.

有关此问题的SO上有一些帖子,但没有确定的答案或方法不起作用.当然,这是一种常见的实施方式.在此先感谢您的帮助.

Answer 1

在Java中

@BindingAdapter("layout_height")
public static void setLayoutHeight(View view, float height) {
    LayoutParams layoutParams = view.getLayoutParams();
    layoutParams.height = height;
    view.setLayoutParams(layoutParams);
}

并在您的XML中

app:layout_height="@{ viewModel.isBig ? @dimen/dp_20 : @dimen/dp_5 }"

像这样导入应用程序

xmlns:app="http://schemas.android.com/apk/res-auto"

Answer 2

使用数据绑定时,我们从XML中删除值.您可以添加在剥离时使用的默认值以避免出现问题.

请参阅:http://developer.android.com/tools/data-binding/guide.html(页面底部).

android:layout_height="@{loginVM.compact ? @dimen/verificationHeightCompact : @dimen/verificationHeightFull, default=wrap_content}"

Answer 3

我在Kotlin而不是Java 中解决了这个问题。

制作一个名为

MyBindings.kt

并输入：

@BindingAdapter("bind:customHeight")
fun setLayoutHeight(view: View, height: Float) {
    view.layoutParams = view.layoutParams.apply { this.height = height.toInt() }
}

然后你可以在你的布局中使用它：

<EditText 
android:id="@+id/internalTopDisplay"
android:layout_width="match_parent"
bind:customHeight="@{loginVM.compact ? @dimen/verificationHeightCompact : @dimen/verificationHeightFull}"
android:layout_height="wrap_content"/>

Answer 4

根据Android问题跟踪器的讨论,如果不创建自定义绑定适配器,则无法使用数据绑定设置布局高度或宽度:

https://code.google.com/p/android/issues/detail?id=180666

设置视图高度所需的绑定适配器将如下所示:

@BindingAdapter("android:layout_height")
public static void setLayoutHeight(View view, int height) {
    LayoutParams layoutParams = view.getLayoutParams();
    layoutParams.height = height;
    view.setLayoutParams(layoutParams);
}

Answer 5

对我来说，这个技巧是这样的：

    @BindingAdapter("android:layout_height")
    public static void setLayoutHeight(View view, final Number height) {
        final ViewGroup.LayoutParams layoutParams = view.getLayoutParams();
        layoutParams.height =  height.intValue();
        view.setLayoutParams(layoutParams);
    }

和 XML：

android:layout_height="@{item.isItemCollapsed ? @dimen/radar_item_first_background_height  : item.textMaxLines, default=@dimen/radar_item_first_background_height}"