自动 select 聚焦 Xamarin 上的所有文本

Question

如何自动select Entry、Editor、Label 中的所有文本都成为焦点？使用跨平台。

Quantity.IsFocused = true;

没有工作:(

Answer 1

在MainActivity中添加

public class MyEntryRenderer : EntryRenderer
{
    public MyEntryRenderer(Context ctx) : base(ctx) {}
    protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
    {
        base.OnElementChanged(e);
        if (e.OldElement == null)
        {
            var nativeEditText = (EditText)Control;
            nativeEditText.SetSelectAllOnFocus(true);
        }
    }
}

并在顶部添加：

[assembly: ExportRenderer (typeof (Entry), typeof (MyEntryRenderer))]

Answer 2

UWP 自定义条目渲染器可以是...

using System.ComponentModel;

using Xamarin.Forms;
using Xamarin.Forms.Platform.UWP;

[assembly: ExportRenderer(typeof(Entry), typeof(myApp.UWP.ExtendedEntryRenderer))]
namespace myApp.UWP
{
    public class ExtendedEntryRenderer : EntryRenderer
    {
        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);

            if (e.PropertyName == nameof(Entry.IsFocused)
                && Control != null && Control.FocusState != Windows.UI.Xaml.FocusState.Unfocused)
                Control.SelectAll();
        }
    }
}

Answer 3

1.Add 专注 Event.Cs

protected  void Txt_Focussed(object sender, FocusEventArgs e)
{
    txt.CursorPosition = 0;
    txt.SelectionLength = txt.Text.Length;
}

设置焦点

protected override void OnAppearing()
{
    base.OnAppearing();
    txt.Focus();
}

XAML代码

<Entry x:Name="txt" Text="155134343" Focused="Txt_Focussed" />

Answer 4

在我的例子中，为了让@SAIJAN KP 回答有效，我制作了 Focused 处理程序 async 并等待一小段延迟以等待光标出现在 Entry 上：

    private async void Entry_Focused(object sender, FocusEventArgs e)
    {
        await Task.Delay(100);
        entryTest.CursorPosition = x;
        entryTest.SelectionLength = y;
    }

XAML

<Entry x:Name="entryTest" Text="155134343" Focused="Entry_Focused"  />

Answer 5

如其他答案中所述，如果您使用的是 Xamarin Forms 4.2+，则可以使用 CursorPosition 和 SelectionLength 属性。但是，您需要确保在 Main/UI 线程上调用，因为必须在那里完成对 UI 元素的所有直接操作。如果不这样做，应用程序很可能会在部署到设备时崩溃，即使它在模拟器中看起来运行正常。

XAML

<Entry x:Name="MyEntry" Focused="MyEntry_Focused"  />

C#

private void MyEntry_Focused(object sender, FocusEventArgs e)
{
    Dispatcher.BeginInvokeOnMainThread(() =>
    {
        MyEntry.CursorPosition = 0;
        MyEntry.SelectionLength = MyEntry.Text != null ? MyEntry.Text.Length : 0
    });
}

对于 Xamarin.Forms，您还可以使用 Device.BeginInvokeOnMainThread() rather than Dispatcher. If you're using Xamarin Essentials, there is also MainThread.BeginInvokeOnMainThread()（与 Device.BeginInvokeOnMainThread() 的作用相同）。

Xamarin.Forms has a method called Device.BeginInvokeOnMainThread(Action) that does the same thing as MainThread.BeginInvokeOnMainThread(Action). While you can use either method in a Xamarin.Forms app, consider whether or not the calling code has any other need for a dependency on Xamarin.Forms. If not, MainThread.BeginInvokeOnMainThread(Action) is likely a better option.

Answer 6

@kiddailey posted ，这是一个基于此的可重用解决方案：

在代码隐藏中创建行为

public class SelectContentWhenFocusedBehavior : Behavior<Entry>
{
    protected override void OnAttachedTo(Entry entry)
    {
        entry.Focused += OnFocused;
        base.OnAttachedTo(entry);
    }

    protected override void OnDetachingFrom(Entry entry)
    {
        entry.Focused -= OnFocused;
        base.OnDetachingFrom(entry);
    }

    private static void OnFocused(object sender, FocusEventArgs args)
    {
        Device.BeginInvokeOnMainThread(() =>
        {
            Entry myEntry = sender as Entry;
            myEntry.CursorPosition = 0;
            myEntry.SelectionLength = myEntry.Text != null ? myEntry.Text.Length : 0;
        });
    }
}

在您的视图中将 link 添加到行为命名空间

 xmlns:behav="clr-namespace:MyApp.Resources.Behaviors"

在视图中为您的条目添加行为

        <Entry Text="{Binding something, Mode=TwoWay}" Keyboard="Numeric">
            <Entry.Behaviors>
                <behav:SelectContentWhenFocusedBehavior/>
            </Entry.Behaviors>
        </Entry>

自动 select 聚焦 Xamarin 上的所有文本

Automatically select all text on focus Xamarin

c#

xaml

onfocus

xamarin.forms