Xamarin.Forms:单击后按钮文本对齐错误(Android) [英] Xamarin.Forms: wrong button text alignment after click (Android)

问题描述

我在 Android (Nexus 5) 上使用 Xamarin.Forms(版本 1.2.2)有问题.Button.Text 的对齐方式在执行点击后通常不会居中.

在一个简短的项目中，我发现更新 UI 会导致问题.

公共类应用{公共静态页面 GetMainPage(){var 标签 = 新标签 {文字 = "标签",};var buttonBad = 新按钮 {Text = "buttonBad",Command = new Command(() => label.Text += "1"),};var buttonGood = 新按钮 {Text = "buttonGood",};返回新的 ContentPage {内容 = 新的 StackLayout {儿童 = {按钮坏，按钮好，标签，}}};}}

单击buttonBad"(更新label.Text)会导致此按钮的文本对齐不再居中.单击buttonGood"不会导致问题.

有没有好的解决方法来解决这个问题?

这个解决方法似乎太复杂了:当 StackLayout 被 AbsolutLayout 替换时，对齐是正确的，但我需要 StackLayout 才能正常工作.

解决方案

好的，在处理这个愚蠢的错误数小时后，我通过实现自定义渲染器并覆盖 ChildDrawableStateChanged 来解决它:

public override void ChildDrawableStateChanged(Android.Views.View child){base.ChildDrawableStateChanged(child);Control.Text = Control.Text;}

I have a problem with Xamarin.Forms (version 1.2.2) on Android (Nexus 5). The alignment of Button.Text is often not centered after performing a click.

In a short project, I figured out, that updating the UI causes the problem.

public class App
{
    public static Page GetMainPage()
    {   
        var label = new Label {
            Text = "label",
        };
        var buttonBad = new Button {
            Text = "buttonBad",
            Command = new Command(() => label.Text += "1"),
        };
        var buttonGood = new Button {
            Text = "buttonGood",
        };

        return new ContentPage { 
            Content = new StackLayout {
                Children = {
                    buttonBad,
                    buttonGood,
                    label,
                }
            }
        };
    }
}

A click on "buttonBad" (updating the label.Text) causes the text-alignment of this button to not be centered anymore. A click on "buttonGood" does not cause the problem.

Is there a good workaround to solve this problem?

This workaround seems to be too complicated: http://forums.xamarin.com/discussion/20608/fix-for-button-layout-bug-on-android

edit: A programatically edit of the UI also cases the bug. Changing the label.Text in an async method after a short waiting leads the "buttonGood" to align its text wrong after a click.

edit2: I created an example / test project on GitHub: https://github.com/perpetual-mobile/ButtonTextAlignmentBug.git The alignment is correct, when the StackLayout is replaced by an AbsolutLayout, but i need the StackLayout to work well.

解决方案

Ok, after hours of dealing with this silly bug, I resolved it by implementing a custom renderer and overriding ChildDrawableStateChanged:

public override void ChildDrawableStateChanged(Android.Views.View child) 
{
    base.ChildDrawableStateChanged(child); 
    Control.Text = Control.Text; 
}

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