在Xamarin Forms共享项目中将返回更改为next/done键

Question

是否可以将键盘上"return"键中的文本更改为"next"或"done"？我有一个包含用户名和密码的登录表单.我希望返回键在用户名字段上显示"下一步",然后在密码字段上显示"完成",但无论如何都没有看到这样做.这是一个共享项目,Android和iOS.

Answer 1

自定义EntryRenderer可以处理更改键盘返回键描述.

• iOS:UITextField具有ReturnKeyType可以设置为预分配列表的属性(请参阅UIReturnType枚举).

• Android:EntryEditText有一个ImeOptions属性可以控制键盘上的"Action"按钮的作用,以及一个SetImeActionLabel可以用来为它设置任何文本字符串的方法.

用法自定义Entry/EntryRenderer的示例:

new EntryExt {
    Text = "Next Key",
    ReturnKeyType = ReturnKeyTypes.Next
},
new EntryExt {
    Text = "Done Key",
    ReturnKeyType = ReturnKeyTypes.Done
}

一个Xamarin.Forms自定义的Entry类:

namespace YourNameSpaceHere
{
    public class EntryExt : Entry
    {
        public const string ReturnKeyPropertyName = "ReturnKeyType";

        public EntryExt() { }

        public static readonly BindableProperty ReturnKeyTypeProperty = BindableProperty.Create(
            propertyName: ReturnKeyPropertyName,
            returnType: typeof(ReturnKeyTypes),
            declaringType: typeof(EntryExt),
            defaultValue: ReturnKeyTypes.Done);

        public ReturnKeyTypes ReturnKeyType
        {
            get { return (ReturnKeyTypes)GetValue(ReturnKeyTypeProperty); }
            set { SetValue(ReturnKeyTypeProperty, value); }
        }
    }

    // Not all of these are support on Android, consult EntryEditText.ImeOptions
    public enum ReturnKeyTypes : int
    {
        Default,
        Go,
        Google,
        Join,
        Next,
        Route,
        Search,
        Send,
        Yahoo,
        Done,
        EmergencyCall,
        Continue
    }
}

iOS自定义EntryRenderer:

[assembly: ExportRenderer(typeof(Entry), typeof(EntryExtRenderer_iOS))]
namespace KeyboardDone.iOS
{
    public class EntryExtRenderer_iOS : EntryRenderer
    {
        public EntryExtRenderer_iOS() { }

        protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
        {
            base.OnElementChanged(e);
            if ((Control != null) && (e.NewElement != null))
                Control.ReturnKeyType = (e.NewElement as EntryExt).ReturnKeyType.GetValueFromDescription();
        }

        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);
            if (e.PropertyName == EntryExt.ReturnKeyPropertyName)
            {
                D.WriteLine($"{(sender as EntryExt).ReturnKeyType.ToString()}");
                Control.ReturnKeyType = (sender as EntryExt).ReturnKeyType.GetValueFromDescription();
            }
        }
    }

    public static class EnumExtensions
    {
        public static UIReturnKeyType GetValueFromDescription(this ReturnKeyTypes value)
        {
            var type = typeof(UIReturnKeyType);
            if (!type.IsEnum) throw new InvalidOperationException();
            foreach (var field in type.GetFields())
            {
                var attribute = Attribute.GetCustomAttribute(field,
                    typeof(DescriptionAttribute)) as DescriptionAttribute;
                if (attribute != null)
                {
                    if (attribute.Description == value.ToString())
                        return (UIReturnKeyType)field.GetValue(null);
                }
                else
                {
                    if (field.Name == value.ToString())
                        return (UIReturnKeyType)field.GetValue(null);
                }
            }
            throw new NotSupportedException($"Not supported on iOS: {value}");
        }
    }
}

Android自定义EntryRenderer:

[assembly: ExportRenderer(typeof(Entry), typeof(EntryExtRenderer_Droid))]
namespace KeyboardDone.Droid
{
    public class EntryExtRenderer_Droid : EntryRenderer
    {
        public EntryExtRenderer_Droid() { }

        protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
        {
            base.OnElementChanged(e);
            if ((Control != null) && (e.NewElement != null))
            {
                var entryExt = (e.NewElement as EntryExt);
                Control.ImeOptions = entryExt.ReturnKeyType.GetValueFromDescription();
                // This is hackie ;-) / A Android-only bindable property should be added to the EntryExt class 
                Control.SetImeActionLabel(entryExt.ReturnKeyType.ToString(), Control.ImeOptions);
            }
        }
        protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            base.OnElementPropertyChanged(sender, e);
            if (e.PropertyName == EntryExt.ReturnKeyPropertyName)
            {
                var entryExt = (sender as EntryExt);
                Control.ImeOptions = entryExt.ReturnKeyType.GetValueFromDescription();
                // This is hackie ;-) / A Android-only bindable property should be added to the EntryExt class 
                Control.SetImeActionLabel(entryExt.ReturnKeyType.ToString(), Control.ImeOptions);
            }
        }

    }
    public static class EnumExtensions
    {
        public static ImeAction GetValueFromDescription(this ReturnKeyTypes value)
        {
            var type = typeof(ImeAction);
            if (!type.IsEnum) throw new InvalidOperationException();
            foreach (var field in type.GetFields())
            {
                var attribute = Attribute.GetCustomAttribute(field,
                    typeof(DescriptionAttribute)) as DescriptionAttribute;
                if (attribute != null)
                {
                    if (attribute.Description == value.ToString())
                        return (ImeAction)field.GetValue(null);
                }
                else
                {
                    if (field.Name == value.ToString())
                        return (ImeAction)field.GetValue(null);
                }
            }
            throw new NotSupportedException($"Not supported on Android: {value}");
        }
    }
}

Answer 2

这是另一种方法,但类似于SushiHangover的解决方案.它包括UWP支持:

PCL中的ReturnType.cs

public enum ReturnType
{
    Go,
    Next,
    Done,
    Send,
    Search
}

PCL中的BaseEntry.cs

public class BaseEntry : Entry
{
    // Need to overwrite default handler because we cant Invoke otherwise
    public new event EventHandler Completed;

    public static readonly BindableProperty ReturnTypeProperty = BindableProperty.Create(
        nameof(ReturnType),
        typeof(ReturnType),
        typeof(BaseEntry),
        ReturnType.Done, 
        BindingMode.OneWay
    );

    public ReturnType ReturnType
    {
        get { return (ReturnType)GetValue(ReturnTypeProperty); }
        set { SetValue(ReturnTypeProperty, value); }
    }

    public void InvokeCompleted()
    {
        if (this.Completed != null)
            this.Completed.Invoke(this, null);
    }
}

适用于Android的BaseEntryRenderer.cs

public class BaseEntryRenderer : EntryRenderer
{
    protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
    {
        base.OnElementChanged(e);

        BaseEntry entry = (BaseEntry)this.Element;

        if(this.Control != null)
        {
            if(entry != null)
            {
                SetReturnType(entry);

                // Editor Action is called when the return button is pressed
                Control.EditorAction += (object sender, TextView.EditorActionEventArgs args) =>
                {
                    if (entry.ReturnType != ReturnType.Next)
                        entry.Unfocus();

                    // Call all the methods attached to base_entry event handler Completed
                    entry.InvokeCompleted();
                };
            }
        }
    }

    private void SetReturnType(BaseEntry entry)
    {
        ReturnType type = entry.ReturnType;

        switch (type)
        {
            case ReturnType.Go:
                Control.ImeOptions = ImeAction.Go;
                Control.SetImeActionLabel("Go", ImeAction.Go);
                break;
            case ReturnType.Next:
                Control.ImeOptions = ImeAction.Next;
                Control.SetImeActionLabel("Next", ImeAction.Next);
                break;
            case ReturnType.Send:
                Control.ImeOptions = ImeAction.Send;
                Control.SetImeActionLabel("Send", ImeAction.Send);
                break;
            case ReturnType.Search:
                Control.ImeOptions = ImeAction.Search;
                Control.SetImeActionLabel("Search", ImeAction.Search);
                break;
            default:
                Control.ImeOptions = ImeAction.Done;
                Control.SetImeActionLabel("Done", ImeAction.Done);
                break;
        }
    }
}

适用于iOS的BaseEntryRenderer.cs

public class BaseEntryRenderer : EntryRenderer
{
    protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
    {
        base.OnElementChanged(e);

        BaseEntry entry = (BaseEntry)this.Element;

        if (this.Control != null)
        {
            if(entry != null)
            {
                SetReturnType(entry);

                Control.ShouldReturn += (UITextField tf) =>
                {
                    entry.InvokeCompleted();
                    return true;
                };
            }
        }
    }

    private void SetReturnType(BaseEntry entry)
    {
        ReturnType type = entry.ReturnType;

        switch (type)
        {
            case ReturnType.Go:
                Control.ReturnKeyType = UIReturnKeyType.Go;
                break;
            case ReturnType.Next:
                Control.ReturnKeyType = UIReturnKeyType.Next;
                break;
            case ReturnType.Send:
                Control.ReturnKeyType = UIReturnKeyType.Send;
                break;
            case ReturnType.Search:
                Control.ReturnKeyType = UIReturnKeyType.Search;
                break;
            case ReturnType.Done:
                Control.ReturnKeyType = UIReturnKeyType.Done;
                break;
            default:
                Control.ReturnKeyType = UIReturnKeyType.Default;
                break;
        }
    }
}

UWP的BaseEntryRenderer.cs

public class BaseEntryRenderer : EntryRenderer
{
    protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
    {
        base.OnElementChanged(e);

        BaseEntry entry = (BaseEntry)this.Element;

        if(this.Control != null)
        {
            if(entry != null)
            {
                this.Control.KeyDown += (object sender, Windows.UI.Xaml.Input.KeyRoutedEventArgs eventArgs) =>
                {
                    if (eventArgs.Key == Windows.System.VirtualKey.Enter)
                    {
                        entry.InvokeCompleted();
                        // Make sure to set the Handled to true, otherwise the RoutedEvent might fire twice
                        eventArgs.Handled = true;
                    }
                };
            }
        }
    }
}

在UWP上似乎无法将返回键更改为next/done/...您需要ExportRenderer自己为所有自定义渲染器添加属性.

用法

XAML文件

<renderer:BaseEntry x:Name="username" Text="Username" ReturnType="Next" />
<renderer:BaseEntry x:Name="password" Text ="Password" IsPassword="true" ReturnType="Done" />

代码隐藏文件:

this.username.Completed += (object sender, EventArgs e) => this.password.Focus();

基于此来源.

Answer 3

最新的 Xamarin Forms 包为 Entry 元素添加了 ReturnType 属性。单击“完成”按钮时，它还将执行命令。现在都支持 Done、Next、Search、Go 和 Send 的 IMEAction 类型。

Answer 4

是的，最新的Xamarin表单直接允许ReturnType作为属性，只需要在Xaml中添加ReturnType

 <Entry x:Name="myEntry" ReturnType="Done"/>