silverlight 生成二维码

MainPage.xaml

 <Grid x:Name="LayoutRoot" Background="White">
        <Border BorderThickness="2" BorderBrush="Black" />
        <Grid ShowGridLines="True">
            <Grid.RowDefinitions>
                <RowDefinition/>
                <RowDefinition Height="50"/>
                <RowDefinition Height="50"/>
                <RowDefinition Height="50"/>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="100"/>
                <ColumnDefinition/>
            </Grid.ColumnDefinitions>
            <TextBlock Text="二维码" Grid.Column="0" Grid.Row="0" TextAlignment="Center" Margin="10,50" />
            <Image x:Name="imgCode" Grid.Column="1" Grid.Row="0" Margin="2"/>
            <TextBlock Text="图片大小" Grid.Column="0" Grid.Row="1" Margin="10" TextAlignment="Center" />
            <ComboBox x:Name="cmbSize" Grid.Column="1" Grid.Row="1" Width="100" Height="30" HorizontalAlignment="Right" Margin="0,10,100,10">
                <ComboBoxItem Content="100" IsSelected="True" />
                <ComboBoxItem Content="150" />
            </ComboBox>
            <TextBlock Text="二维码内容" Grid.Column="0" Grid.Row="2" TextAlignment="Center" Margin="10"/>
            <TextBox x:Name="txtContent" Height="30" Margin="5" Grid.Column="1" Grid.Row="2" />
            <Button x:Name="btnAdd" Content="生成" Width="100"  Grid.Row="3" Grid.Column="1" Click="btnAdd_Click" Margin="5"/>
        </Grid>
    </Grid>

MainPage.xaml.cs

 public partial class MainPage : UserControl
    {
        StringBuilder sb = null;
        Uri uri = null;
        public MainPage()
        {
            InitializeComponent();
            sb = new StringBuilder();
        }
        private void btnAdd_Click(object sender, RoutedEventArgs e)
        {
            sb.Append("http://chart.apis.google.com/chart?cht=qr&chs=");
            sb.Append(((ComboBoxItem)cmbSize.SelectedItem).Content.ToString());
            sb.Append("x");
            sb.Append(((ComboBoxItem)cmbSize.SelectedItem).Content.ToString());
            sb.Append("&chl=");
            sb.Append(txtContent.Text);
            uri = new Uri(sb.ToString());
            imgCode.Source = new BitmapImage(uri);
            sb.Clear();
        }
    }