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！