Xamarin 表单标签 - 证明? [英] Xamarin Forms Label - Justify?

问题描述

我只是想问问是否有任何方法可以在 标签 中对齐文本.我正在使用 Xamarin Forms Xaml.

I just wanted to ask if there is any way to justify text in a Label. I am using Xamarin Forms Xaml.

谢谢.

更新:就目前而言，无法对齐文本.大多数答案都是关于将文本居中，但这不是我问的.一种方法是使用 Timothy 的 Renderer.

UPDATE: As for now, it is not possible to justify text. Most of the answers were about centering the text, but it is not what I asked. One way could be to use Renderer as by Timothy.

推荐答案

虽然您无法使用 Xamarin.Forms 功能将标签的文本拉伸到全宽，但可以使用平台渲染器轻松实现.

Though you can't stretch label's text to a full width using Xamarin.Forms features, it's easily achieved with a platform renderer.

大多数 Xamarin 平台都在相应的本机元素中提供了文本对齐功能，这只是设置本机元素的单个属性的问题.我想不将此功能添加到标准 Xamarin.Forms 标签的原因是该功能的平台滞后，例如Android 仅在 8.1 版中添加了 Android.Text.JustificationMode.InterWord 标志

Most Xamarin platforms have the text justification feature available in corresponding native elements, and it's just a matter of setting a single attribute of a native element. I suppose the reason for not adding this feature to standard Xamarin.Forms label is lagging of platforms in that capability, e.g. Android had Android.Text.JustificationMode.InterWord flag added only in version 8.1

下面你可以看到Android渲染器的实现:

Below you can see Android renderer implementation:

using Android.Content;
using Saplin.CPDT.UICore.Controls;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

[assembly: ExportRenderer(typeof(Saplin.CPDT.UICore.Controls.ExtendedLabel), typeof(Saplin.CPDT.Droid.ExtnededLabelRenderer))]
namespace Saplin.CPDT.Droid
{
    public class ExtnededLabelRenderer : Xamarin.Forms.Platform.Android.LabelRenderer
    {
        public ExtnededLabelRenderer(Context context) : base(context)
        {
        }

        protected override void OnElementChanged(ElementChangedEventArgs<Label> e)
        {
            base.OnElementChanged(e);

            var el = (Element as ExtendedLabel);

            if (el != null && el.JustifyText)
            {
                if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.O)
                {
                    Control.JustificationMode = Android.Text.JustificationMode.InterWord;
                }

            }
        }
    }
}

1. 您在本机项目中创建渲染器类
2. 您添加程序集:ExportRenderer 属性
3. 您设置了 TextView 的 JustificationMode

在我的示例中，我使用了 Xamarin.Forms.Label 的 ExtenedLabel 子类和额外的属性 JustifyText 来设置文本的对齐方式.这就是子类控件的声明方式:

In my example I used ExtenedLabel subclass of Xamarin.Forms.Label with extra property JustifyText to let setting the justification of the text. That's how the subclassed control can be declared:

using System;
using Xamarin.Forms;

namespace Saplin.CPDT.UICore.Controls
{
    public class ExtendedLabel : Label
    {
        public static readonly BindableProperty JustifyTextProperty =
            BindableProperty.Create(
                propertyName: nameof(JustifyText),
                returnType: typeof(Boolean),
                declaringType: typeof(ExtendedLabel),
                defaultValue: false,
                defaultBindingMode: BindingMode.OneWay
         );

        public bool JustifyText
        {
            get { return (Boolean)GetValue(JustifyTextProperty); }
            set { SetValue(JustifyTextProperty, value); }
        }
    }
}

• WPF 和 macOS.莉>

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