你的位置:首页 > 操作系统

[操作系统]在 Xamarin.Forms 实现密码输入EntryCell


  在 Xamarin.Forms 中,我们通常使用 TableView 来构建输入表单。Xamarin 为我们提供了 EntryCell 用于输入文本,但是其并不支持密码输入,即密码掩码。这里要对 EntryCell 进行扩展,使其支持密码输入。

  首先,我们需要在共享项目(多平台项目)中增加控件定义,我们称之为:ExtendedEntryCell

 1   /// <summary> 2   /// An extended entry cell control that allows set IsPassword 3   /// </summary> 4   public class ExtendedEntryCell : EntryCell 5   { 6  7     /// <summary> 8     /// The IsPassword property 9     /// </summary>10     public static readonly BindableProperty IsPasswordProperty = BindableProperty.Create<ExtendedEntryCell, bool>(p => p.IsPassword, false);11 12     /// <summary>13     /// Gets or sets IsPassword 14     /// </summary>15     public bool IsPassword16     {17       get { return (bool)GetValue(IsPasswordProperty); }18       set { SetValue(IsPasswordProperty, value); }19     }20   }

我们需要在Android和iOS中加入各自的Render。

Android 平台的 Render:

 1 using Android.Content; 2 using Android.Text.Method; 3 using Android.Views; 4 using Android.Widget; 5 using WsLink.App.Controls; 6 using Xamarin.Forms; 7 using Xamarin.Forms.Platform.Android; 8 using View = Android.Views.View; 9 10 [assembly: ExportRenderer(typeof(ExtendedEntryCell), typeof(ExtendedEntryCellRenderer))]11 12 namespace App.Controls13 {14   public class ExtendedEntryCellRenderer : EntryCellRenderer15   {16     protected override View GetCellCore(Cell item, View convertView, ViewGroup parent, Context context)17     {18       var cell = base.GetCellCore(item, convertView, parent, context);19       var textField = (cell as EntryCellView)?.EditText as TextView;20 21       if (textField != null && textField.TransformationMethod != PasswordTransformationMethod.Instance)22       {23         textField.TransformationMethod = PasswordTransformationMethod.Instance;24       }25       return cell;26     }27   }28 }

iOS 平台的 Render 

 1 using UIKit; 2 using WsLink.App.Controls; 3 using Xamarin.Forms; 4 using Xamarin.Forms.Platform.iOS; 5  6 [assembly: ExportRenderer(typeof(ExtendedEntryCell), typeof(ExtendedEntryCellRenderer))] 7  8 namespace WsLink.App.Controls 9 {10   public class ExtendedEntryCellRenderer : EntryCellRenderer11   {12     public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv)13     {14       var entryCell = (ExtendedEntryCell) item;15       var cell = base.GetCell(item, reusableCell, tv);16       if (cell != null)17       {18         var textField = (UITextField) cell.ContentView.Subviews[0];19         textField.SecureTextEntry = entryCell.IsPassword;20       }21       return cell;22     }23   }24 }

使用方法

<??><ContentPage ="http://xamarin.com/schemas/2014/forms"       ="http://schemas.microsoft.com/winfx/2009/xaml"       ="clr-namespace:WsLink.App.Controls"       x:Class="App.Account.LoginPage" Title="登录"> <TableView Intent="Form">  <TableSection>   <EntryCell Label="账户" Placeholder="账户" Text="{Binding Username}"></EntryCell>   <controls:ExtendedEntryCell IsPassword="True" Label="密码" Placeholder="密码" Text="{Binding Password}"></controls:ExtendedEntryCell>  </TableSection> </TableView></ContentPage>