Silverlight:用Enter键替换Tab键切换焦点

业务系统中，很多录入人员习惯于用Enter键来代替Tab键切换控件焦点（虽然我个人并不觉得这样录入速度会变得有多高效，呵呵），有需求了，自然就得想办法满足。

思路：为了更灵活的控件焦点顺序，我决定用TabIndex来做文章，每个输入控件按下回车时，找到下一个比当前控件TabIndex更大且最接近的控件，然后focus().

XAML界面部分：

<UserControl x:Class="tab_key_test.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300" d:DesignWidth="400">

    <StackPanel x:Name="LayoutRoot" Background="White">
        <TextBox Margin="5" TabIndex="0"></TextBox>
        <CheckBox Margin="5" TabIndex="1" Content="CheckBox Test"></CheckBox>
        <TextBox Margin="5" TabIndex="2"></TextBox>
        <ComboBox Margin="5" TabIndex="3">
            <ComboBox.Items>
                <ComboBoxItem Content="ComboBox Test 11"></ComboBoxItem>
                <ComboBoxItem Content="ComboBox Test 22"></ComboBoxItem>
            </ComboBox.Items>
        </ComboBox>
        <TextBox Margin="5" TabIndex="4"></TextBox>
        <RadioButton Margin="5" Content="Radio Test" TabIndex="5"></RadioButton>
        <TextBox Margin="5" TabIndex="6"></TextBox>
    </StackPanel>
</UserControl>

CS后端代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace tab_key_test
{
    public partial class MainPage : UserControl
    {
        List<Control> allInputControls = new List<Control>();

        public MainPage()
        {
            InitializeComponent();

            this.Loaded += MainPage_Loaded;
        }

        void MainPage_Loaded(object sender, RoutedEventArgs e)
        {
            //把界面上的TextBox,RadioButton,ComboBox,CheckBox都加入列表
            //注：一般业务录入界面上只有这4种类型的输入控件，如果还有其实类型，可自行扩展
            allInputControls.AddRange(FindChildren<TextBox>(LayoutRoot).Cast<Control>());
            allInputControls.AddRange(FindChildren<RadioButton>(LayoutRoot).Cast<Control>());
            allInputControls.AddRange(FindChildren<ComboBox>(LayoutRoot).Cast<Control>());
            allInputControls.AddRange(FindChildren<CheckBox>(LayoutRoot).Cast<Control>());
            //按TabIndex排序
            allInputControls = allInputControls.OrderBy(c => c.TabIndex).ToList();
            foreach (Control c in allInputControls)
            {
                c.KeyDown += EnterKeyDownToTab;
                if (c is ComboBox)
                {
                    //ComboBox要特殊处理
                    (c as ComboBox).DropDownClosed += DropDownClosedToNext;
                }
            }
        }

        void EnterKeyDownToTab(object sender, KeyEventArgs e)
        {
            if (e.Key == Key.Enter)
            {
                GoToNextControl(sender);
            }
        }

        void GoToNextControl(object sender)
        {
            var self = sender as Control;
            if (self == null)
            {
                return;
            }

            var selfTabIndex = self.TabIndex;
            //找出下一个控件
            var nextControl = allInputControls.FirstOrDefault(c => c.TabIndex > selfTabIndex);
            if (nextControl != null)
            {
                nextControl.Focus();
            }
            else
            {
                allInputControls[0].Focus();//最后一个控件时，再跳到第一个(可选处理)
            }
        }

        /// <summary>
        /// 查找所有子元素(递归)
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="parent"></param>
        /// <returns></returns>
        public static IEnumerable<T> FindChildren<T>(DependencyObject parent) where T : class
        {
            int count = VisualTreeHelper.GetChildrenCount(parent);
            if (count > 0)
            {
                for (int i = 0; i < count; i++)
                {
                    DependencyObject child = VisualTreeHelper.GetChild(parent, i);
                    var t = child as T;
                    if (t != null)
                        yield return t;

                    IEnumerable<T> children = FindChildren<T>(child);
                    foreach (T item in children)
                        yield return item;
                }
            }
        }

        private void DropDownClosedToNext(object sender, EventArgs e)
        {
            GoToNextControl(sender);
        }
    }
}

　这个思路还可以应用到html网页上：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
	<head>
		<title>Enter Key Replace Tab</title>
		<script type="text/javascript" src="http://lib.sinaapp.com/js/jquery/1.6/jquery.min.js"></script>
		<style type="text/css">
			input,select,textarea{
				padding:0;
				margin:5px;
				width:150px;
				display:block;
			}
		</style>

		<script type="text/javascript">			

			$(document).ready(function(){
				var inputs = $("input,textarea,select").sort(function(a,b){return a.tabIndex>b.tabIndex?1:-1});

				inputs.each(function(){
					$(this).keypress(function(e){
						if (e.keyCode==13||e.which==13){
							//修正textarea的多余回车问题(可选)
							//if ($(this).get(0).tagName == "TEXTAREA"){
							//	$(this).val($.trim($(this).val()));
							//};

							var selfTabIndex = parseInt($(this).attr("tabIndex"),10);
							var nextInput = null;

							//找出下一个元素
							for(var i=0; i<inputs.length; i++){
								if (inputs[i].tabIndex > selfTabIndex){
									nextInput = inputs[i];
									break;
								}
							}							

							if (nextInput != null){
								nextInput.focus();
							}
							else{
								inputs[0].focus();
							}
						}
					}).focus(function(){
						$(this).select();
					})
				})
			})

		</script>
	</head>
	<body>
		<input type="text" tabindex="0" value="000"/>
		<input type="text" tabindex="1" value="111"/>
		<textarea tabindex="2">222</textarea>
		<input type="radio" tabindex="3" id="r3" style="width:20px;display:inline"/><label for="r3">333</label>
		<input type="text" tabindex="4" value="444"/>
		<input type="checkbox" tabindex="5" id="c5" style="width:20px;display:inline"/><label for="c5">555</label>
		<input type="text" tabindex="6" value="666"/>
		<select tabindex="7">
			<option>777</option>
			<option>xxx</option>
		</select>
		<select size="2" tabindex="8">
			<option>888</option>
			<option>yyy</option>
		</select>

	</body>
</html>