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 IsPassword 16 { 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.Controls 13 { 14 public class ExtendedEntryCellRenderer : EntryCellRenderer 15 { 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 : EntryCellRenderer 11 { 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
<?xml version="1.0" encoding="utf-8" ?> <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:controls="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>
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