摘要:
先介紹一下System.Windows.Browser命名空間下的幾個類, 接著介紹Silverlight如何操縱Html元素, 最後介紹如何從Javascript調用Silverlight的方法, 以及Silverlight調用Javascript方法.
1.System.Windows.Browser
Silverlight提供了一組對象來描述Html文件物件模型(DOM), 包括HtmlPage, HtmlDocument, HemlElement, HtmlElementCollection, 等等. 我們可以通過這些對象從Silverlight訪問Html頁面的內容, 如擷取某個Html元素, 導航到新的URL等.(ps:Silverlight 1.1 Complete API List )
首先看HtmlPage類, 其提供了瀏覽器資訊的靜態屬性BrowserInformation;提供的靜態方法Navigate, 可以方便的跳轉到其他的web頁.提供了Document屬性訪問Html Dom, 有了它就可以幹很多事了
HtmlDocument/HemlElement類用來訪問DOM, 有了DOM就可以像Javascript一樣做任何事了.
注意: 如果需要Silverlight可以訪問Html頁面的內容, 在建立Silverlight控制項的時候必須將enableHtmlAccess設為true.
2.Silverlight操縱Html
想象Javascript是怎麼訪問Html元素的, Silverlight也同樣可以.
修改頁面屬性:如修改頁面標題, HtmlPage.Document.SetProperty("title", "new title");
操縱html元素:
HtmlElement elem = HtmlPage.Document.GetElementByID("btn");
elem.SetAttribute("value", "haha");
elem.GetAttribute("value");
elem.AttachEvent("onclick", delegate(object sender, HtmlEventArgs he){
// ...
});
3.Javascript調用Silverlight方法
Javascript要想調用Silverlight, Silverlight必須通過DOM提供給Javascript一個可操作的對象.
建立一個silverlight項目, 修改Page.xaml.cs如下:
using System;
using System.Windows;
using System.Windows.Browser;
using System.Windows.Controls;
namespace SilverlightProject1
{
[Scriptable]
public partial class Page : Canvas
{
public void Page_Loaded(object o, EventArgs e)
{
// Required to initialize variables
InitializeComponent();
WebApplication.Current.RegisterScriptableObject("js", this);
}
[Scriptable]
public string CalledByJs(string name)
{
return "i'm silverlight, called by " + name;
}
}
}
修改TestPage.html如下:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Silverlight Project Test Page </title>
<script type="text/javascript" src="Silverlight.js"></script>
<script type="text/javascript" src="TestPage.html.js"></script>
<style type="text/css">
.silverlightHost { width: 640px; height: 480px; }
</style>
<script type="text/javascript">
function callSL()
{
var control = document.getElementById("SilverlightControl");
var manager = control.Content.js;
alert( manager.CalledByJs('js') );
}
</script>
</head>
<body>
<div id="SilverlightControlHost" class="silverlightHost" >
<script type="text/javascript">
createSilverlight();
</script>
</div>
<input id="btn" type="button" value="call silverlight method" onclick="callSL()" />
</body>
</html>
好像還不支援Silverlight方法返回一個複雜類型, 不過還好Silverlight內建了json的支援, 使用System.Windows.Browser.Serialization命名空間下JavaScriptSerializer序列化一下就ok了.
4.Silverlight調用Javascript方法
Silverlight無法直接調用javascript方法, 不過可以利用事件, 在Silverlight裡拋出事件, 在javascript響應該事件.
修改Page.xaml如下:
<Canvas x:Name="parentCanvas"
xmlns="http://schemas.microsoft.com/client/2007"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Loaded="Page_Loaded"
x:Class="SilverlightProject1.Page;assembly=ClientBin/SilverlightProject1.dll"
Width="640"
Height="480"
Background="White"
>
<TextBlock Text="call js method" MouseLeftButtonDown="OnClick"/>
</Canvas>
修改Page.xaml.cs如下:
using System;
using System.Windows;
using System.Windows.Browser;
using System.Windows.Controls;
using System.Windows.Input;
namespace SilverlightProject1
{
[Scriptable]
public partial class Page : Canvas
{
public void Page_Loaded(object o, EventArgs e)
{
// Required to initialize variables
InitializeComponent();
WebApplication.Current.RegisterScriptableObject("js", this);
}
protected void OnClick(object sender, MouseEventArgs e)
{
if (this.CallJs != null )
{
EventHandler temp = this.CallJs;
temp(this, EventArgs.Empty);
}
}
[Scriptable]
public event EventHandler CallJs;
}
}
修改TestPage.html.js:在onLoad事件裡添加了對Silverlight拋出的CallJs 事件的響應.
// JScript source code
//contains calls to silverlight.js, example below loads Page.xaml
function createSilverlight()
{
Silverlight.createObjectEx({
source: "Page.xaml",
parentElement: document.getElementById("SilverlightControlHost"),
id: "SilverlightControl",
properties: {
width: "100%",
height: "100%",
version: "1.1",
enableHtmlAccess: "true"
},
events: { onLoad : OnLoaded}
});
// Give the keyboard focus to the Silverlight control by default
document.body.onload = function() {
var silverlightControl = document.getElementById('SilverlightControl');
if (silverlightControl)
{
silverlightControl.focus();
}
}
}
function OnLoaded(sender, args)
{
sender.Content.js.CallJs = calledBySL;
}
function calledBySL(sender, args)
{
alert("i'm js, called by silverlight");
}
done!
我嘗試了在Silverlight事件裡加了自訂的參數, javascript這邊好像接收不到??不知道是什麼原因.
總結:
Silverlight與Javascript的互操作的方式和Flex類似, 不過個人還是喜歡Silverlight的方式, C#的文法簡單清晰.