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另類的Silverlight中文解法

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@H_404_0@   @H_404_0@ 另類的 Silverlight 中文解法
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@H_404_0@ / 黃忠成
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@H_404_0@     如你所知,由於字型的關係, Silverlight 目前對於雙位元文字顯示可說是困難重重,大概可歸類出兩種解法,一種是下載字型到客戶端,一種是利用 Blend2 文字變成圖形,下載字型目前有法律問題的隱憂,而且一個中文字型檔大小約 5MB ,仍嫌過大。在上次嘗試實作 DataBinding 功能後,心中就有一種想法,假如於 Server 端將文字轉成圖形後下載到客戶端,那麼因為不是直接下載字型,所以應無法律問題 ( 這我不確定! ) ,也不會因下載整個字型檔而導致網頁開啟速度過慢,這樣是否就能讓前次的 Data Bindigns 例子支援中文的顯示呢?可惜前幾天因陪老婆考試,一直沒時間來實現心中的構想,這幾天終於有時間來實現這個架構了。基本上,實現這個架構有兩個問題必須先行解決,第一個問題是 Server 端如何將文字變成圖形?這不難,下列的程式便可辦到。
@H_404_0@ protected void Page_Load(object sender,EventArgs e) @H_404_0@ { @H_404_0@         if (Request.QueryString["ID"] != null && @H_404_0@            Request.QueryString["ID"].Length > 0) @H_404_0@         { @H_404_0@           .................. @H_404_0@         } @H_404_0@         else if (Request.QueryString["Transform"] != null) @H_404_0@         { @H_404_0@             int index; @H_404_0@             string column; @H_404_0@             ResolveParams(Request.QueryString["Transform"],
out index,out column);
@H_404_0@             if (index != -1) @H_404_0@             { @H_404_0@                 Employee data = GetData(index); @H_404_0@                 MemoryStream ms = ResolveTransform(data,column); @H_404_0@                 if (ms != null) @H_404_0@                 { @H_404_0@                     Response.Clear(); @H_404_0@                     Response.BufferOutput = true; @H_404_0@                     Response.ContentType = "image/bmp"; @H_404_0@                     Response.OutputStream.Write(ms.GetBuffer(),(int)ms.Length); @H_404_0@                     ms.dispose(); @H_404_0@                     Response.Flush(); @H_404_0@                     Response.End(); @H_404_0@                 } @H_404_0@                 else @H_404_0@                     Response.End(); @H_404_0@             } @H_404_0@         } @H_404_0@     } @H_404_0@   @H_404_0@     private void ResolveParams(string transformParams,out int index,out string column) @H_404_0@     { @H_404_0@         string[] p = Request.QueryString["Transform"].Split('*'); @H_404_0@         index = -1; @H_404_0@         column = string.Empty; @H_404_0@         if (p.Length == 2) @H_404_0@         { @H_404_0@             index = int.Parse(p[0]); @H_404_0@             column = p[1]; @H_404_0@         }        @H_404_0@     } @H_404_0@   @H_404_0@     private MemoryStream ResolveTransform(object data,string column) @H_404_0@     {        @H_404_0@         PropertyInfo pi = data.GetType().GetProperty(column); @H_404_0@         if (pi != null) @H_404_0@             return GetDBCSJpestream(pi.GetValue(data,null).ToString(),
new Font("PMingLiU",11,FontStyle.Bold),Color.Black,Color.White,280,24);
@H_404_0@         return null; @H_404_0@     } @H_404_0@   @H_404_0@     private MemoryStream GetDBCSJpestream(string str,Font font,Color foreColor,
Color background,int width,int height)
@H_404_0@     { @H_404_0@         Bitmap bmp = new Bitmap(width,height);        @H_404_0@         Graphics g = Graphics.FromImage(bmp); @H_404_0@         Brush bFore = new SolidBrush(foreColor); @H_404_0@         Brush bBack = new SolidBrush(background); @H_404_0@         g.Clear(Color.Transparent); @H_404_0@         g.DrawString(str,font,bFore,2,2); @H_404_0@         bFore.dispose(); @H_404_0@         bBack.dispose(); @H_404_0@         MemoryStream ms = new MemoryStream(); @H_404_0@         bmp.Save(ms,System.Drawing.Imaging.ImageFormat.Png); @H_404_0@         bmp.dispose(); @H_404_0@         ms.Position = 0; @H_404_0@         return ms; @H_404_0@     }
@H_404_0@ 如果你仔細看上面的程式,會發覺其中有字體預設的問題,若要以此觀念實作一個完整的架構,關於字型的資訊應於 XAML 中指定才好,不過目前我只是展示這個想法的可行性,就先放著這部份不理了。第二個要解決的問題是如何於 XAML 中指定 Data Bindings 資訊,這點不難,依據前版以 TAG 來指定 Binding Expression 的概念,只需加油添醋一番,即可套用。
@H_404_0@ < Canvas xmlns = "http://schemas.microsoft.com/client/2007" @H_404_0@ ................... @H_404_0@ < Image Name = "imgLastName"Tag="BindingField:LastName;BindingProperty:Source;Format:Default.aspx?Transform={INDEX}*{BindingField}"Width="300"Height="24"Canvas.Left="500"Canvas.Top="23" /> @H_404_0@ </ Canvas >
@H_404_0@ 請注意,由於採圖形方式的緣故,這裡已不再使用 TextBlock ,而是使用 Image 控制項來顯示, SLDH.js 也需稍做修改
@H_404_0@ ///////////////////////////////////////////////////////////////////////// @H_404_0@ // Silverlight Data Binding Helper 0.1 @H_404_0@ ///////////////////////////////////////////////////////////////////////// @H_404_0@   @H_404_0@ if (!window.SilverlightBinding) @H_404_0@            window.SilverlightBinding = {}; @H_404_0@   @H_404_0@ SilverlightBinding.BindingData = function(ctrl,bindingExpression,context) @H_404_0@ { @H_404_0@    var bindings = bindingExpression.split(';'); @H_404_0@    this.bindingComplete = false; @H_404_0@    this.ctrl = ctrl; @H_404_0@    this.context = context; @H_404_0@    for(var i = 0; i < bindings.length; i++) @H_404_0@    { @H_404_0@       var temp = bindings[i].split(':'); @H_404_0@       if(temp.length != 2) @H_404_0@       { @H_404_0@          this.bindingComplete = false; @H_404_0@          return; @H_404_0@       } @H_404_0@       if(temp[0] == 'BindingField') @H_404_0@          this.bindingField = temp[1]; @H_404_0@       else if(temp[0] == 'BindingProperty') @H_404_0@          this.bindingProperty = temp[1]; @H_404_0@       else if(temp[0] == 'Format') @H_404_0@          this.format = temp[1];   @H_404_0@    } @H_404_0@    this.bindingComplete = true; @H_404_0@ } @H_404_0@   @H_404_0@ SilverlightBinding.BindingData.prototype = @H_404_0@ { @H_404_0@    updateValue : function(dataItem) @H_404_0@    { @H_404_0@       if(this.bindingComplete) @H_404_0@       { @H_404_0@         if(this.format) @H_404_0@         { @H_404_0@            var str = eval("this.format.replace('{0}',dataItem."+this.bindingField+');');                                 @H_404_0@            if(this.format.indexOf("INDEX") != -1) @H_404_0@               str = str.replace("{INDEX}",this.context.currentDataIndex); @H_404_0@            if(this.format.indexOf("BindingField") != -1) @H_404_0@               str = str.replace("{BindingField}",this.bindingField); @H_404_0@            eval('this.ctrl.'+this.bindingProperty+" = str;"); @H_404_0@         } @H_404_0@         else @H_404_0@            eval('this.ctrl.'+this.bindingProperty+' = dataItem.'+this.bindingField+';'); @H_404_0@       } @H_404_0@    } @H_404_0@ } @H_404_0@   @H_404_0@ SilverlightBinding.BindingContext = function(bindingContainer) @H_404_0@ { @H_404_0@    var parseBindings = bindingContainer.tag.split(';'); @H_404_0@    this.bindingComplete = false; @H_404_0@    this.bindingContainer = bindingContainer; @H_404_0@    this.bindingControls = new Array(); @H_404_0@    this.currentDataIndex = 0; @H_404_0@    this.recordCount = 0; @H_404_0@    for(var i = 0; i < parseBindings.length; i++) @H_404_0@    { @H_404_0@      var parseBinding = parseBindings[i].split(':'); @H_404_0@      if(parseBinding[0] == "BindingContext") @H_404_0@      { @H_404_0@         var bindingMethods = parseBinding[1].split(','); @H_404_0@         if(bindingMethods.length == 2) @H_404_0@         { @H_404_0@            this.bindingMethod = bindingMethods[0]; @H_404_0@            this.bindingCountMethod = bindingMethods[1]; @H_404_0@            this.bindingComplete = true; @H_404_0@         } @H_404_0@      } @H_404_0@      @H_404_0@    } @H_404_0@    if(!this.bindingComplete) alert('ERROR,Binding Failed.'); @H_404_0@ } @H_404_0@   @H_404_0@   @H_404_0@ SilverlightBinding.BindingContext.prototype = @H_404_0@ { @H_404_0@    _childWorker : function(parent,parseParent) @H_404_0@    { @H_404_0@      if(parent.tag && parent.tag != '') @H_404_0@      { @H_404_0@         if(parseParent) @H_404_0@         { @H_404_0@           var bindingData = new SilverlightBinding.BindingData(parent,parent.tag,this); @H_404_0@           if(bindingData.bindingComplete) @H_404_0@           { @H_404_0@              this.bindingControls.length++; @H_404_0@              this.bindingControls[this.bindingControls.length-1] = bindingData; @H_404_0@           } @H_404_0@           else @H_404_0@             delete bindingData; @H_404_0@         } @H_404_0@         try @H_404_0@         { @H_404_0@            var temp = parent.children; @H_404_0@         } @H_404_0@         catch(err) @H_404_0@         { @H_404_0@            return; @H_404_0@         } @H_404_0@         for(var i = 0; i < parent.children.count; i++) @H_404_0@             this._childWorker(parent.children.getItem(i),true); @H_404_0@      }   @H_404_0@    }, @H_404_0@    initialize:function() @H_404_0@    { @H_404_0@      this._childWorker(this.bindingContainer,false);  @H_404_0@      this._receiveCount();   @H_404_0@      this._receiveData(0);               @H_404_0@    }, @H_404_0@    OnSucceeded: function(result,userContext,methodName) @H_404_0@     { @H_404_0@        if (methodName == userContext.bindingMethod) @H_404_0@        {              @H_404_0@            for(var i = 0; i < userContext.bindingControls.length; i++) @H_404_0@                userContext.bindingControls[i].updateValue(result); @H_404_0@        } @H_404_0@        else if(methodName == userContext.bindingCountMethod) @H_404_0@            userContext.recordCount = result; @H_404_0@     },          @H_404_0@     OnFailed:function(error,methodName) @H_404_0@     { @H_404_0@        if(error !== null) @H_404_0@        { @H_404_0@           alert(error.get_message()); @H_404_0@        } @H_404_0@     }, @H_404_0@     _receiveData: function(index) @H_404_0@     { @H_404_0@         eval('PageMethods.'+this.bindingMethod+'(index,this.OnSucceeded,this.OnFailed,this);'); @H_404_0@     }, @H_404_0@     _receiveCount: function() @H_404_0@     { @H_404_0@         eval('PageMethods.'+this.bindingCountMethod+'(this.OnSucceeded, @H_404_0@     next:function() @H_404_0@     { @H_404_0@         if(this.currentDataIndex+1 >= this.recordCount) @H_404_0@            return; @H_404_0@         this._receiveData(++this.currentDataIndex); @H_404_0@     }, @H_404_0@     prev:function() @H_404_0@     { @H_404_0@         if(this.currentDataIndex -1 < 0) @H_404_0@            return; @H_404_0@         this._receiveData(--this.currentDataIndex); @H_404_0@     } @H_404_0@ }
@H_404_0@ 下圖為執行例。 @H_404_0@

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後記
@H_404_0@   @H_404_0@   這種方式僅是一個應急的解法,畢竟傳輸圖形也是需要時間的,自然不比直接使用位於客戶端的字型來的有效率。 @H_404_0@   @H_404_0@ 示例下載: @H_404_0@ http://www.dreams.idv.tw/~code6421/files/SLDataDemo2.zip  
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