WPF学习小结

今天开始WPF的学习，分析了一下Windows SDK 里面的Sample——DataBindingLab
        该解决方案示意图为：

这个Sample是个在线拍卖的实例，其中DataBindingLabApp.xaml是该应用程序的入口，为什么呢？
一、DataBindingLabApp类继承于Application类，而Application类在.NET 3.0后整合了WPF应用程序类。
二、请看DataBindingLabApp.xaml开始的一段代码

< Application  x:Class ="DataBindingLab.DataBindingLabApp"
  xmlns ="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x ="http://schemas.microsoft.com/winfx/2006/xaml"
    Startup ="AppStartup"
    xmlns:src ="clr-namespace:DataBindingLab"  
    xmlns:System ="clr-namespace:System;assembly=Mscorlib"
     >
<!-- 省略 -->
</ Application >

其中Startup="AppStartup"这句，说明它作为程序入口，相应后台代码有：

         void  AppStartup( object  sender, StartupEventArgs args)
         {
            LoadAuctionData();
            MainWindow mainWindow = new MainWindow();
            mainWindow.Show();
            //AddProductWindow addProductWindow = new AddProductWindow();
            //addProductWindow.Show();
        }

其中LoadAuctionData()加载拍卖数据，mainWindow.Show()将打开MainWindow窗口，MainWindow窗口是个MainWindow类，文件为MainWindow.xaml.cs

       现在来具体看看DataBindingLabApp.xaml在做些什么。
1、首先是个Application.Resources的标识，它是用来获取和设置应用程序范围资源的集合，比如Styles或者Brushes；
2、各种style定义，其实功能相当与Web使用的CSS/Skin等，比如

< Style  x:Key ="titleStyle"  TargetType ="TextBlock" >
         < Setter  Property ="FontWeight"  Value ="Bold" />
         < Setter  Property ="Foreground"  Value ="DodgerBlue" />
         < Setter  Property ="FontSize"  Value ="18" />
       </ Style >

titleStyle作为该Style关键字，针对的控件类型为TextBlock，相当于Label
<Setter>就是设置各种属性了，这里就不多说了。
3、<DataTemplate> 数据模版

< DataTemplate  DataType ="{x:Type src:AuctionItem}" >
             < Border  BorderThickness ="1"  BorderBrush ="Gray"
                    Padding ="7"  Name ="border"  Margin ="3"  Width ="500" >
                 < Grid >
                   < Grid .RowDefinitions >
                     < RowDefinition />
                     < RowDefinition />
                     < RowDefinition />
                     < RowDefinition />
                   </ Grid.RowDefinitions >
                   < Grid .ColumnDefinitions >
                     < ColumnDefinition  Width ="20" />
                     < ColumnDefinition  Width ="86" />
                     < ColumnDefinition  Width ="*" />
                   </ Grid.ColumnDefinitions >
                      
                     < Polygon  Grid.Row ="0"  Grid.Column ="0"  Grid.RowSpan ="4"
                             Fill ="Yellow"  Stroke ="Black"  StrokeThickness ="1"
                             StrokeLineJoin ="Round"  Width ="20"  Height ="20"
                             Stretch ="Fill"
                             Points ="9,2 11,7 17,7 12,10 14,15 9,12 4,15 6,10 1,7 7,7"
                             Visibility ="Hidden"  Name ="star" />

                     < TextBlock  Grid.Row ="0"  Grid.Column ="1"  Margin ="0,0,8,0"
                               Name ="descriptionTitle"
                               Style ="{StaticResource smallTitleStyle}" > Description: </ TextBlock >
                     < TextBlock  Name ="DescriptionDTDataType"  Grid.Row ="0"  Grid.Column ="2"  
                        Text ="{Binding Path=Description}"  
                        Style ="{StaticResource textStyleTextBlock}" />

                     < TextBlock  Grid.Row ="1"  Grid.Column ="1"  Margin ="0,0,8,0"
                               Name ="currentPriceTitle"
                               Style ="{StaticResource smallTitleStyle}" > Current Price: </ TextBlock >
                     < StackPanel  Grid.Row ="1"  Grid.Column ="2"  Orientation ="Horizontal" >
                         < TextBlock  Text ="$"  Style ="{StaticResource textStyleTextBlock}" />
                         < TextBlock  Name ="CurrentPriceDTDataType"  
                            Text ="{Binding Path=CurrentPrice}"  
                            Style ="{StaticResource textStyleTextBlock}" />
                     </ StackPanel >
                 </ Grid >
             </ Border >
             < DataTemplate .Triggers >
                 < DataTrigger  Binding ="{Binding Path=SpecialFeatures}" >
                     < DataTrigger .Value >
                         < src:SpecialFeatures > Color </ src:SpecialFeatures >
                     </ DataTrigger.Value >
                   < DataTrigger .Setters >
                     < Setter  Property ="BorderBrush"  Value ="DodgerBlue"  TargetName ="border"   />
                     < Setter  Property ="Foreground"  Value ="Navy"  TargetName ="descriptionTitle"   />
                     < Setter  Property ="Foreground"  Value ="Navy"  TargetName ="currentPriceTitle"   />
                     < Setter  Property ="BorderThickness"  Value ="3"  TargetName ="border"   />
                     < Setter  Property ="Padding"  Value ="5"  TargetName ="border"   />
                   </ DataTrigger.Setters >
                 </ DataTrigger >
                 < DataTrigger  Binding ="{Binding Path=SpecialFeatures}" >
                     < DataTrigger .Value >
                         < src:SpecialFeatures > Highlight </ src:SpecialFeatures >
                     </ DataTrigger.Value >
                     < Setter  Property ="BorderBrush"  Value ="Orange"  TargetName ="border"   />
                     < Setter  Property ="Foreground"  Value ="Navy"  TargetName ="descriptionTitle"   />
                     < Setter  Property ="Foreground"  Value ="Navy"  TargetName ="currentPriceTitle"   />
                     < Setter  Property ="Visibility"  Value ="Visible"  TargetName ="star"   />
                     < Setter  Property ="BorderThickness"  Value ="3"  TargetName ="border"   />
                     < Setter  Property ="Padding"  Value ="5"  TargetName ="border"   />
                 </ DataTrigger >
             </ DataTemplate.Triggers >
         </ DataTemplate >

DataType是数据类型，就是该模版要与AuctionItem类绑定，文件为AuctionItem.cs。
-------------------------------------
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="20"/>
<ColumnDefinition Width="86"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
说明该网格分布为4行3列，其中第0列为20px,第1列为86px,第2列为*
<Polygon>多边形控件，这里是个星状体;<TextBlock>文本控件；可以看到每个控件都有属性Grid.Row和Grid.Column
Grid.Row是该网格分布第几行，Grid.Column是该网格分布第几列，如Grid.Row="0" Grid.Column="1"表示该控件属于第0行第1列;
-----------------------------------------
并且控件的属性Style，用到前面谈到的Style，如Style="{StaticResource textStyleTextBlock}"，用到了关键字为textStyleTextBlock的Style;
-----------------------------------------
属性Text，表示显示的文本内容，如Text="{Binding Path=CurrentPrice}"，绑定了前面说的AuctionItem.cs中的属性CurrentPrice
-----------------------------------------
<DataTemplate.Triggers>数据触发

< DataTemplate .Triggers >
                 < DataTrigger  Binding ="{Binding Path=SpecialFeatures}" >
                     < DataTrigger .Value >
                         < src:SpecialFeatures > Color </ src:SpecialFeatures >
                     </ DataTrigger.Value >
                   < DataTrigger .Setters >
                     < Setter  Property ="BorderBrush"  Value ="DodgerBlue"  TargetName ="border"   />
                     < Setter  Property ="Foreground"  Value ="Navy"  TargetName ="descriptionTitle"   />
                     < Setter  Property ="Foreground"  Value ="Navy"  TargetName ="currentPriceTitle"   />
                     < Setter  Property ="BorderThickness"  Value ="3"  TargetName ="border"   />
                     < Setter  Property ="Padding"  Value ="5"  TargetName ="border"   />
                   </ DataTrigger.Setters >
                 </ DataTrigger >
                 < DataTrigger  Binding ="{Binding Path=SpecialFeatures}" >
                     < DataTrigger .Value >
                         < src:SpecialFeatures > Highlight </ src:SpecialFeatures >
                     </ DataTrigger.Value >
                     < Setter  Property ="BorderBrush"  Value ="Orange"  TargetName ="border"   />
                     < Setter  Property ="Foreground"  Value ="Navy"  TargetName ="descriptionTitle"   />
                     < Setter  Property ="Foreground"  Value ="Navy"  TargetName ="currentPriceTitle"   />
                     < Setter  Property ="Visibility"  Value ="Visible"  TargetName ="star"   />
                     < Setter  Property ="BorderThickness"  Value ="3"  TargetName ="border"   />
                     < Setter  Property ="Padding"  Value ="5"  TargetName ="border"   />
                 </ DataTrigger >
             </ DataTemplate.Triggers >

它的意思是绑定了AuctionItem.cs中的属性SpecialFeatures，实际上SpecialFeatures是个枚举类型，它包括None,Color,Highlight,上面代码得出，当SpecialFeatures为Color时，设置边框属性；当SpecialFeatures为Highlight时，设置边框属性并且加颗星星，这么做的目的是来区分拍卖级别。

        再来看看MainWindows.xaml做些什么
总的来说，其实真正用来呈现窗体给我们的就是这个类。
1 有这么一句代码

<CollectionViewSource 
              Source = " {Binding Source={x:Static Application.Current}, Path=AuctionItems} "    
              x:Key = " listingDataView "  />

它是绑定了当前应用程序入口的数据源，换句话说，就是它把DataBindingLabApp.xaml.cs中的的属性队列AuctionItems数据攘入其中，也就是各种拍卖信息了。
2

<ListBox Name = " Master "  Grid.Row = " 2 "  Grid.ColumnSpan = " 3 "  Margin = " 8 "
            ItemsSource = " {Binding Source={StaticResource listingDataView}} " >
            <ListBox.GroupStyle>
                <GroupStyle 
                  HeaderTemplate = " {StaticResource groupingHeaderTemplate} "
                  />
            </ListBox.GroupStyle>
        </ListBox>

绑定源就是上面定义的关键字listingDataView的数据源。至此，该ListBox就把各种拍卖信息显示出来了，如下图所示

3、其他问题

<CheckBox Name = " Grouping "  Grid.Row = " 1 "  Grid.Column = " 0 "  
            Checked = " AddGrouping "  Unchecked = " RemoveGrouping "  
            Margin = " 8 "  Style = " {StaticResource checkBoxStyle} " >Group by category</CheckBox>

 <Button Name = " OpenAddProduct "  Grid.Row = " 4 "  Grid.Column = " 1 "  Content = " Add Product "  HorizontalAlignment = " Center "  Margin = " 8 "  
            Click = " OpenAddProductWindow "  />

其中属性Checked,Unchecked,Click都一一对应的是一个方法AddGrouping,RemoveGrouping,OpenAddProductWindow，它在MainWindow.xaml.cs后台代码展出，这里就不一一叙述了。
整个运行界面为：


下载代码

结束语：对于xaml的评价，有这么几点：

灵活的平台级控件开发体系
更方便的控件布局能力
利用了图形加速能力的图像处理管道
灵活丰富的样式功能和样式模板
强大的声明式数据绑定

而对于XAML的使用将会使得windows应用程序很像现在的web开发。

以上是我今天学习WPF的心得，觉得有什么不对的地方请多多指教，小弟初入门，呵呵！