WPF/E 技术解析-优快云博客

作为系列的开篇,写的也许简单了些,笼统了些,如果大家有意见或者建议,请通过kennethbyron@gmail.com与我联系.另外考虑到更多人阅读方便,所以这次直接写中文版的,英文版的等系列全部出完,打包提供下载.下面”眼”归正传.

    正如WPF/E项目经理Joe Stegman说的那样,WPF/E是WPF Everywhere.那么究竟WPF/E是什么呢?它又是如何工作的呢?让我们现在就看看它.
    这有几个WPF/E的页面效果演示,如果无法正常显示,请下载并安装WPF/E客户端运行库(1.1M)

  演示地址:
Page Turner
Sprawl Game
Film Strip Slide-Show
Media Library
Simple Video Playback

概要:

WPF/E开发背景及开发目标
WPF/E的实质和前景
WPF/E的实现原理及工作机制基础
WPF/E参考资源

1.WPF/E开发背景及开发目标

随着.NET框架3.0的正式发布,Windows Presentation Foundation(WPF)即Windows表现层基础,Windows Communication Foundation(WCF)即Windows通信层基础和Windows Workflow Foundation(WWF)即Windows工作流基础,三大基础成为开发组织方式新的实现,为开发分工协作提供了更好的模型和支持,并大幅度的完善了微软.NET类库.WPF作为表现层基础开发库,提供了对DirectX更好的支持,优化了2D和3D表现层引擎,与WinForm开发紧密结合,实现了传统的Win32和WinForm对XAML(拓展应用程序标记语言)程序的支持和装载功能.然而WPF却未能实现ASP.NET WebForm装载XAML程序,而且在非3.0运行库支持平台上WPF无法正常工作.
出于WPF的局限性,WPF/E应需而生,WPF/E对Web应用开发ASP.NET 2.0作出拓展,实现

更轻松,更自由的网络应用程序开发
提高网络应用程序对媒体文件的表现效果和支持性
应用最新的标准
采用友好的AJAX和XAML表现

当然.WPF/E并非仅仅定义在网络应用上,它的跨平台性,可拓展性及优越的兼容性势必使WPF/E在实际应用上得到更多层面的拓展.

2.WPF/E的前景和实质

    WPF/E是对图形界面,动画效果,媒体文件及XAML程序支持性的拓展,相信大家对WPF的展示效果也有所了解,在VISTA下,WPF将界面效果展示得淋漓尽致,玻璃,半透明,圆角,多边不规则图形,倒影等等.当然WPF的展示效果还不仅于此,WPF的动画效果也令人叹为观止,倒映,水波纹,滚动,浮动等等.试想下,如果我们将这些效果应用在网页上,那么动画页面便不再仅仅是FLASH的天地了.
    说了这么多.WPF/E到底是什么呢?
    WPF/E实际是通过JavaScript在普通的HTML页面上,将一个XAML程序以对象的方式呈现.
    而仅仅是呈现么?
    当然不是,在呈现之后.NET Framework会讲传统的HTML DOM树与XAML程序生成的XAML DOM树结合.这样我们可通过JavaScript同时将两个DOM树联系起来,形成HTML,ASP.NET和XAML的交互.这样整个Web应用程序形成了一个可以相互通信的有机体系.
    同时,WPF/E仅仅是小型的客户端运行库,所以它可以轻松实现跨平台安装,并且对媒体文件的支持非常好,其内建的WMV,WMA,MP3解码器摆脱了以往需要安装Windows Media Player才可以播放Windows媒体文件的烦恼.
    WPF/E将于明年被集成到ASP.NET,.NET FxCL及CLR Managed Code中.

3.WPF/E的实现原理及工作机制基础

首先来看一下下面这幅简单的WPF/E页面结构图

Simple WPF/E Structure

    如上图,在一个普通的HTML文档中,WPF/E通过object或embed对象元素,以ActiveX控件的形式,将XAML程序的一个实例插入页面中,参数以object或embed的param属性传入XAML程序.然后WPF/E建立XAML DOM树,通过HTML DOM树和XAML DOM树,我们可以轻松的取得页面中任何对象的ID属性,并可以随意在JavaScript中引用其对象.
    现在我们来模拟一下上面的过程.

    1.建立XAML元素并指定ID

< script type = " text/xaml " id = " agControlXaml " >
2

< Canvas xmlns = http://schemas.microsoft.com/winfx/2006/xaml/presentation
4

xmlns:x = http://schemas.microsoft.com/winfx/2006/xaml >
5

< Rectangle x:Name = " myRect " Fill = " Orange " Width = " 100 " Height = " 100 " Canvas.Top = " 10 " Canvas.Left = " 10 " />
6

</ Canvas >
7

</ script >

2.在HTML页面中插入一个DIV做为XAML程序的容器

< div class ="agHost" id ="agControlHost" >
2

</ div >

3.在页面中插入一个object/embed元素.用来承载ActiveX控件.并由该ActiveX控件负责调用XAML程序

< object id ="AgCtrl1" height ="312px" width ="354px" codebase ="xcpctrl.cab#version=0,0,3,0"
2

classid ="CLSID:32C73088-76AE-40F7-AC40-81F62CB2C1DA" >
3

< param name ="SourceElement" value ="agControlXaml" />
4

< param name ="BackgroundColor" value ="White" />
5

</ object >

这样就可以生成一个简单的WPF/E页面了.完整代码如下:

IE6+

< html xmlns ="http://www.w3.org/1999/xhtml" >
2

< head >
3

</ head >
4

< body >
5

< script type ="text/xaml" id ="agControlXaml" >
6

<Canvas xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
7

xmlns:x=http://schemas.microsoft.com/winfx/2006/xaml >
8

<Rectangle x:Name="myRect" Fill="Orange" Width="100" Height="100" Canvas.Top="10" Canvas.Left="10"/>
9

</Canvas>
10

</ script >
12

< div >
13

    < object id ="AgCtrl1" height ="312px" width ="354px"
                          codebase ="xcpctrl.cab#version=0,0,3,0"
                          classid ="CLSID:32C73088-76AE-40F7-AC40-81F62CB2C1DA" >
14

< param name ="SourceElement" value ="agControlXaml" />
15

< param name ="BackgroundColor" value ="White" />
16

</ object >
17

</ div >
18

</ body >
19

</ html >

< html xmlns ="http://www.w3.org/1999/xhtml" >
2

< head >
3

</ head >
4

< body >
5

< script type ="text/xaml" id ="agControlXaml" >
6

<Canvas xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
7

<Rectangle x:Name="myRect" Fill="Orange" Width="100" Height="100" Canvas.Top="10" Canvas.Left="10"/>
8

</Canvas>
9

</ script >
10

< div >
11

< embed id ="AgCtrl1" height ="312px" width ="354px" SourceElement ="agControlXaml" BackgroundColor ="White" type ="application/xcp-plugin" />
12

</ div >
13

</ body >
14

</ html >

效果:
IE Sample FF Sample

随着CTP的发布,通常该加载过程会被封装在一个JavaScript方法中, 当页面被加载时,浏览器通过object的classid属性或embed的pluginspage来找到特定类型的ActiveX控件,创建控件实例,并指定该ActiveX控件的ID,由该ActiveX控件寻找param中name为SourceElement的script XAML元素,或param中name为Source的XAML程序地址参数,ActiveX控件在容器元素中创建XAML程序的一个实例.

具体如下:
调用方法:

new agHost("wpfeControl1Host",// 容器元素ID
2

//(用来放置WPF/E ActiveX控件的HTML元素常用<div>)
3

"wpfobj", // 我们创建的WPF/E ActiveX控件的ID
4

"900", // 宽度
5

"710", // 高度
6

"#ffB42600", // 背景色
7 null, // SourceElement (Scrpt标记名,包含XAML)
8

"mainPage.xaml", // Source XAML源文件地址
9

"false", // 是否无窗口
10

"24", // 最大祯率
11

null); // OnError事件 (方法名--无括号)

封装的源代码(aghost.js):

var hosts = new Object();
2

function agHost(hostElementID, id, width, height, backgroundcolor, sourceelement, source, windowlessmode, framerate, errorhandler) {
3

var hostElement = document.getElementById(hostElementID);
4

var innerHTML;
5

//assign error handler
6

if(errorhandler == null) {
7

errorhandler = "aghost_errorhandler";
8

}
9

//IE detection
11

if((navigator.appVersion.indexOf('MSIE') != -1)) {
12

try {
13

var WPFE = new ActiveXObject("AgControl.AgControl.0.8");
14

innerHTML = '<object id="'+id+'" width="'+width+'" height="'+height+'" classid="CLSID:32C73088-76AE-40F7-AC40-81F62CB2C1DA">';
15

if (sourceelement != null) {
16

innerHTML += ' <param name="SourceElement" value="'+sourceelement+'" />';
17

}
18

if (source != null) {
19

innerHTML += ' <param name="Source" value="'+source+'" />';
20

}
21

if (framerate != null) {
22

innerHTML += ' <param name="MaxFrameRate" value="'+framerate+'" />';
23

}
24

if (errorhandler != null) {
25

innerHTML += ' <param name="OnError" value="'+errorhandler+'" />';
26

}
27

if (backgroundcolor != null) {
28

innerHTML += ' <param name="BackgroundColor" value="'+backgroundcolor+'" />';
29

}
30

if (windowlessmode != null) {
31

innerHTML += ' <param name="WindowlessMode" value="'+windowlessmode+'" />';
32

}
33

innerHTML += '<//object>';
34

}
35

catch(e) {
36

innerHTML = '<div width="'+width+'" height="'+height+'" >';
37

innerHTML += 'You must install "WPF/E" (codename) December 2006 CTP to view this page: ';
38

innerHTML += '<A href="http://go.microsoft.com/fwlink/?LinkID=77792&clcid=0x409">Get "WPF/E!"</A>';
39

innerHTML += '</div>'
40

}
41

}
42

//FF/Windows detection
44

else if((window.GeckoActiveXObject && navigator.userAgent.indexOf('Windows') != -1)) {
45

innerHTML = '<embed id="'+id+'" width="'+width+'" height="'+height+'" pluginspage="http://go.microsoft.com/fwlink/?LinkID=77792&clcid=0x409';
46

if (source != null) {
47

innerHTML += '" Source="'+source;
48

}
49

if (sourceelement != null) {
50

innerHTML += '" SourceElement="'+sourceelement;
51

}
52

if (framerate != null) {
53

innerHTML += '" MaxFrameRate="'+framerate;
54

}
55

if (errorhandler != null) {
56

innerHTML +='" OnError="'+errorhandler;
57

}
58

if (backgroundcolor != null) {
59

innerHTML += '" BackgroundColor="'+backgroundcolor;
60

}
61

if (windowlessmode != null) {
62

innerHTML += '" WindowlessMode="'+windowlessmode;
63

}
64

innerHTML += '" type="application/ag-plugin"/>';
65

}
66

//MAC detection
68

else if(navigator.userAgent.indexOf("Macintosh") != -1){
69

if(navigator.userAgent.indexOf("Firefox/1.5.0.8") != -1 || navigator.userAgent.indexOf("Safari") != -1){
70

innerHTML = '<embed id="'+id+'" width="'+width+'" height="'+height+'" pluginspage="http://go.microsoft.com/fwlink/?LinkID=77793&clcid=0x409';
71

if (source != null) {
72

innerHTML += '" Source="'+source;
73

}
74

if (sourceelement != null) {
75

innerHTML += '" SourceElement="'+sourceelement;
76

}
77

if (framerate != null) {
78

innerHTML += '" MaxFrameRate="'+framerate;
79

}
80

if (errorhandler != null) {
81

innerHTML +='" OnError="'+errorhandler;
82

}
83

if (backgroundcolor != null) {
84

innerHTML += '" BackgroundColor="'+backgroundcolor;
85

}
86

if (windowlessmode != null) {
87

innerHTML += '" WindowlessMode="'+windowlessmode;
88

}
89

innerHTML += '" type="application/ag-plugin"/>';
90

//Disable Safari caching
92

// For more information, see http://developer.apple.com/internet/safari/faq.html#anchor5
93

innerHTML += "<iframe style='visibility:hidden'/>";
94

}
95

else {
96

innerHTML = '<div width="'+width+'" height="'+height+'" >';
97

innerHTML += 'You must be running Firefox 1.5.0.8 to view "WPF/E" content on this page. ';
98

innerHTML += '<A href="http://go.microsoft.com/fwlink/?LinkID=78984&clcid=0x409">Visit the "WPF/E" product site for more details.</A>';
99

innerHTML += '</div>'
100

}
101

}
102

hostElement.innerHTML = innerHTML;
103

}
104

function aghost_errorhandler(line, col, hr, string) {
105

if(line !=0 && col !=0)
106

{
107

var str = "("+line+","+col+"): "+string+"/n";
108

str += "HRESULT: "+hr;
109

alert(str);
110

}
111

}

通过封装,简化了页面调用XAML的过程,使得页面代码更加清晰,分离了设计和实现代码.所以,我们看到的WPF/E页面的源代码通常是下面这样的:

<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
2

< HTML >< HEAD >< TITLE > "WPF/E" CTP(December 2006 < TITLE >
3

< script type ="text/javascript" src ="js/aghost.js
4

</HEAD>
5

<BODY>
6

<DIV id=" wpfeControl1Host" style ="width:900; height:710; background:White" >
7

<SCRIPT type="text/javascript">
8

new agHost("wpfeControl1Host", // hostElementID (HTML element to put WPF/E
9

// ActiveX control inside of -- usually a <div>)
10

"wpfobj", // ID of the WPF/E ActiveX control we create
11

"900", // Width
12

"710", // Height
13

"#ffB42600", // Background color
14

null, // SourceElement (name of script tag containing xaml)
15

"mainPage.xaml", // Source file
16

"false", // IsWindowless
17

"24", // MaxFrameRate
18

null); // OnError handler (method name -- no quotes)
19

</ SCRIPT >
20

</ DIV >
21

</ BODY ></ HTML >

同时WPF/E支持事件模型,该模型通过JavaScript实现.事件的声明在XAML元素中.当声明某事件时,预定义的事件以属性的方式写在XAML元素的属性集中,并将一个JavaScript函数作为事件处理方法赋值给事件.

< Canvas xmlns ="http://schemas.microsoft.com/client/2007"
2

xmlns:x ="http://schemas.microsoft.com/winfx/2006/xaml"
3

Loaded ="javascript:onLoaded" >
4

< TextBlock x:Name ="myTextBlock" />
5

</ Canvas >

当事件被触发时,窗体会自动调用JavaScript函数

function onLoaded(sender) {
2

// 设置文本内容为当前日期
3

sender.FindName("myTextBlock").Text = Date();
4

}

CTP中的预定义时间包括如下几个:

下面是几个简单的事件:

/* XAML */
2

< Canvas
3

xmlns ="http://schemas.microsoft.com/client/2007"
4

xmlns:x ="http://schemas.microsoft.com/winfx/2006/xaml" >
5

< Ellipse x:Name ="e1" MouseMove ="javascript:e1Move"
6

MouseEnter ="javascript:e1Enter" MouseLeave ="javascript:e1Leave"
7

MouseLeftButtonDown ="javascript:e1Down" MouseLeftButtonUp ="javascript:e1Up"
8

Height ="100" Width ="100" Canvas.Left ="80" Canvas.Top ="30"
9

Stroke ="Black" StrokeThickness ="2" Fill ="LightBlue" />
10 </ Canvas >
11

/* JavaScript */
2

function e1Enter(sender, args) {
3

sender.stroke = "red";
4

}
5

function e1Leave(sender, args) {
7

sender.stroke = "black";
8

}
9

function e1Down(sender, args) {
11

sender.fill = "Green";
12

}
13

function e1Up(sender, args) {
15

sender.fill = "LightBlue";
16

}
17

function e1Move(sender, args) {
19

sender.fill = "yellow";
20

}

从程序员的角度来说,如何取得HTML及XAML文件中的对象是很关键的.HTML DOM树和XAML DOM树可以使我们方便的取得页面中的任何一个对象.

上图显示了一个WPF/E页面的DOM结构.当XAML文件被加载到页面时.我们可以获取标准的DOM树取得XAML对象的ID.
通过JavaScript取得XAML中对象实例引用的具体实现方法如下:

< script type = " text/javascript " >
2

// 先创建一个WPF/E ActiveX控件.
3

new agHost( " agControl1Host " , // HostElementID
4

" ag6 " , // WPF/E ActiveX control ID
5

" 300px " , // Width
6

" 300px " , // Height
7

" #D6D6D6 " , // BackgroundColor
8

null , // SourceElementID
9

" myxaml.xaml " , // The XAML uri
10

" false " , // IsWindowless
11

" 30 " , // MaxFrameRate
12

null // OnError handler.
13

);
14

</ script >

通过下面的JavaScript.我们可以取得XAML对象

var ag6 = document.getElementById( " ag6 " );

接下来.试一下取得XAML内的子对象

想取得XAML内的子对象需要用到XAML元素的FindName(“strName”)方法,如:

function onLoaded(sender) {
2

// 取得XAML根元素
3

var control = document.getElementById("WpfeControl1");
4

// 获得特定子对象的引用
5

var object = control.findName("myTextBlock");
6

if (object != null) {
7

alert(object.ToString() + " found");
8

}
9

}
10

同样,我们也可以动态的通过JavaScript在XAML中创建子对象,具体方法如下:

/* XAML */
2

< Canvas Width ="300" Height ="300"
3

xmlns ="http://schemas.microsoft.com/client/2007"
4

xmlns:x ="http://schemas.microsoft.com/winfx/2006/xaml"
5

Background ="Transparent"
6

MouseLeftButtonDown ="javascript:createEllipse" >
7

< TextBlock Text ="click for circle" ? FontSize ="40" />
8

</ Canvas >
9

/* JavaScript */
2

function createEllipse(sender, args) {
3

var agControl = document.getElementById("ag7");
4

var e = agControl.createFromXaml('<Ellipse Height="200" Width="200" Fill="Blue"/>');
5

var canvas = sender;
6

canvas.children.Add(e);
7

}

4.WPF/E参考资源

SDK文档
http://msdn2.microsoft.com/en-us/library/bb188266.aspx

Channel9对WPF/E项目经理的采访视频
http://channel9.msdn.com/showpost.aspx?postid=263358

WPF/E开发中心
http://msdn2.microsoft.com/en-us/asp.net/bb187358.aspx

开发工具

VS2005 Express
http://msdn.microsoft.com/vstudio/express/
Expression
http://www.microsoft.com/products/expression/en/default.mspx

PS: 系列内容简介

Chapter I The history background, aim, nature and mechnism basic of WPF/E
Chapter II Focusd on XAML and animation presetation of WPF/E
Chapter III Hosting a XAML App in a HTML page
Chapter IV Encapsulated Java Script in WPF/E
Chapter V Understanding work behind pages
Chapter VI Develop and implemented WPF/E projects on VS2005
Chapter VII Demo projects and Questions review
12.07.2006
KennethByron

WPF/E解读系列(一)

1.WPF/E开发背景及开发目标

2.WPF/E的前景和实质

3.WPF/E的实现原理及工作机制基础

4.WPF/E参考资源