|
downloader对象为Silverlight 插件提供了下载功能其通过HTTP(get)请求异步下载指定的内容 downloader所支持的event包括 Completed下载完成 (Downloader) DownloadFailed 下载失败 DownloadProgressChanged下载进度变化 (Downloader) 支持的方法包括 Abort Equals FindName (DependencyObject) GetHost GetResponseText GetValue Open Send SetValue 下面这个DEMO演示使用downloader从网上下载jpg图片以及xaml文件并完成数据加载的过程 其xaml代码如下所示 <Canvas CanvasLeft=> <TextBlock CanvasLeft= CanvasTop= Name=StartDownLoadImg>下载图片</TextBlock> <TextBlock CanvasLeft= CanvasTop= Name=StartDownLoadXaml>下载xaml</TextBlock> </Canvas> <! 下载进度条 > <Canvas CanvasTop=> <Rectangle Name=progressRectangle CanvasLeft= Height= Width= Fill=Maroon /> <Rectangle CanvasTop = CanvasLeft= Height= Width= StrokeThickness= Stroke=Black /> <TextBlock Name=progressText CanvasTop = CanvasLeft= Text=% FontSize= /> </Canvas> <Image Name=loadimg Height= Width= /> <Canvas CanvasTop= x:Name=loadxaml/> 接下来就是相应的js代码（详情见注释） Silverlight_JsWebDownloader = function() { } Silverlight_JsWebDownloaderprototype = { handleLoad: function(plugIn userContext sender) { thisplugIn = plugIn; // 附加事件处理程序 senderfindName(StartDownLoadImg)addEventListener(MouseLeftButtonDown SilverlightcreateDelegate(this thishandleMouseLeftButtonDown)); senderfindName(StartDownLoadXaml)addEventListener(MouseLeftButtonDown SilverlightcreateDelegate(this thishandleMouseLeftButtonDown)); progressText = senderfindName(progressText); progressRectangle = senderfindName(progressRectangle); } //开始下载 handleMouseLeftButtonDown:function (sender eventArgs) { var slPlugin = sendergetHost(); //创建downloader对象 var downloader = slPlugincreateObject(downloader); //下载进度变化事件绑定 downloaderaddEventListener(downloadProgressChanged SilverlightcreateDelegate(this thishandleDownloadProgressChanged)); //下载结束事件绑定 downloaderaddEventListener(completed SilverlightcreateDelegate(this thishandleCompleted)); //下载失败事件绑定 downloaderaddEventListener(downloadFailed SilverlightcreateDelegate(this thishandleDownloadFailed)); //初始化下载请求 if(sendername == StartDownLoadImg) { downloaderopen(GET ClientBin/tangjpg); } else { downloaderopen(GET xaml/PathScenexaml); } //downloaderopen(GET contosoTTF);字体下载 //执行下载请求 downloadersend(); } //下载进度改变 handleDownloadProgressChanged:function (sender eventArgs) { var percentage = Mathfloor(senderdownloadProgress * ); progressTexttext = percentage + %; progressRectanglewidth = percentage * ; } //下载完成 handleCompleted:function (sender eventArgs) { var plugin = sendergetHost(); if (senderuri == ClientBin/tangjpg) { //绑定图片信息 senderfindName(loadimg)setSource(sender); //清除 loadxaml 下的内容 senderfindName(loadxaml)childrenclear(); //var pathCanvas = senderfindName(pathCanvas); //if (pathCanvas != null) //{ // senderfindName(loadxaml)childrenremove(pathCanvas); //} //senderfindName(loadxaml)childrenremoveAt(); } if (senderuri == xaml/PathScenexaml) { // 获取下载内容 var xamlFragment = senderResponseText; // 创建内容 var xamlPath = ntentcreateFromXaml(xamlFragment); senderfindName(loadxaml)childrenadd(xamlPath); // 清除图片绑定 senderfindName(loadimg)Source = ; } // 下面为下载字体并进行加载的测试 // var myTextBlock = senderfindName(myTextBlock); //myTextBlocksetFontSource(sender); // 设置字体 Contoso Font //myTextBlockfontFamily = Contoso Font; //myTextBlocktext = This is my new font!; } //下载失败处理事件 handleDownloadFailed:function (sender errorArgs) { var errorMsg = Silverlight Error: \n\n; errorMsg += Error Type: + errorArgserrorType + \n; errorMsg += Error Message: + errorArgserrorMessage + \n; errorMsg += Error Code: + errorArgserrorCode + \n; switch(errorArgserrorType) { case RuntimeError: if (errorArgslineNumber != ) { errorMsg += Line: + errorArgslineNumber + \n; errorMsg += Position: + errorArgscharPosition + \n; } errorMsg += MethodName: + thodName + \n; break; case ParserError: errorMsg += Xaml File: + errorArgsxamlFile + \n; errorMsg += Xml Element: + errorArgsxmlElement + \n; errorMsg += Xml Attribute: + errorArgsxmlAttribute + \n; errorMsg += Line: + errorArgslineNumber + \n; errorMsg += Position: + errorArgscharPosition + \n; break; default: break; } alert(errorMsg); } } 好了今天的内容就到这里了 |
