Loading XAML XML through runtime?

问题:

We are migrating to Winforms to WPF based solution. We have custom XML definition which are used to build the windows form at runtime.

Since XAML is XML based, can we define a HelloWorldWindow.xml file with XAML definition and can it be loaded into the WPF app without any code behind CSharp files? We will attach the code behind hook at runtime.

How to attach the code behind at runtime?

回答1:

Create an XML file Tempwin.xml using this XAML

<UserControl 
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Height="300" Width="300" Background="Transparent" >
<Border Background="Black" CornerRadius="10" BorderThickness="4" BorderBrush="RoyalBlue">
<Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
        </Grid.RowDefinitions>
        <TextBlock Text="Sample Text" Foreground="White" Margin="2"></TextBlock>
        <TextBox Grid.Row="1" Margin="5"> </TextBox>
        <TextBlock Text="Sample Text 1" Grid.Row="2" Foreground="White" Margin="2"></TextBlock>
        <TextBox Grid.Row="3" Margin="5"></TextBox>
        <Ellipse Fill="Red" Height="100" Width="100" Grid.Row="4" Margin="0,10,0,0"></Ellipse>
    </Grid>
    </Border>

Create a sample WPF Application with the below xaml

<Window x:Class="WpfApplication12.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="600" Width="600">
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition/>

    </Grid.RowDefinitions>

    <Button Height="25" Width="100" Margin="2" Click="Button_Click"> Show Content</Button>
    <Grid x:Name="content" Grid.Row="1" Margin="2">

    </Grid>
</Grid>

Paste the below C# code in codebehind the Button_Click

  StreamReader mysr = new StreamReader(@"D:\Tempwin.xml");
        FrameworkElement  rootObject = XamlReader.Load(mysr.BaseStream) as FrameworkElement;
        content.Children.Add(rootObject);

if you want to load xaml at runtime you cannot give any code behind your XAML file. So i have removed the x:Class attribute before creating the xml

Events Hooking....

<UserControl 
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Height="300" Width="300" Background="Transparent" >
<Border Background="Black" CornerRadius="10" BorderThickness="4" BorderBrush="RoyalBlue">
<Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
        </Grid.RowDefinitions>
        <TextBlock Text="Sample Text" Foreground="White" Margin="2"></TextBlock>
        <TextBox Grid.Row="1" Margin="5"> </TextBox>
        <TextBlock Text="Sample Text 1" Grid.Row="2" Foreground="White" Margin="2"></TextBlock>
        <TextBox Grid.Row="3" Margin="5"></TextBox>
        <Ellipse Fill="Red" Height="100" Width="100" Grid.Row="4" Margin="0,10,0,0"></Ellipse>
        <Button Grid.Row="5" Height="25" Content="Event added at Runtime" x:Name="btnTest"></Button>
    </Grid>
    </Border>

Button ButtoninXAML;

    private void Button_Click(object sender, RoutedEventArgs e)
    {

        StreamReader mysr = new StreamReader(@"D:\Tempwin.xml");
        FrameworkElement  rootObject = XamlReader.Load(mysr.BaseStream) as FrameworkElement;
        ButtoninXAML = LogicalTreeHelper.FindLogicalNode(rootObject, "btnTest") as Button;
        ButtoninXAML.Click += new RoutedEventHandler(Button_Click1); 

        content.Children.Add(rootObject);

    }
    private void Button_Click1(object sender, RoutedEventArgs e)
    {
        MessageBox.Show("Added At Runtime");
    }

回答2:

You can display Xaml dynamically like this:

    string text = @"<TextBlock Text='test' xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' />";

    // Convert to stream
    // You can also just stream the xaml from a file, using a FileStream
    MemoryStream stream = new MemoryStream(ASCIIEncoding.UTF8.GetBytes(text));

    // Convert to object
    TextBlock block = (TextBlock)System.Windows.Markup.XamlReader.Load(stream);

    //... now you can put that TextBlock somewhere, for example in your main Window

See the XamlReader class for further information: http://msdn.microsoft.com/en-us/library/ms613427%28v=VS.95%29.aspx

回答3:

I have done loading XAML at runtime, here is a short example

Grid grd = new Grid();
var grdEncoding = new ASCIIEncoding();
var grdBytes = grdEncoding.GetBytes(myXAML);
grd = (Grid)XamlReader.Load(new MemoryStream(grdBytes));
Grid.SetColumn(grd, 0);
Grid.SetRow(grd, 0);
parentGrid.Children.Add(grd);

private String myXAML = @" <Grid xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' Margin='30 10 30 65' VerticalAlignment='Bottom'>" +
                "<Label Content='Date: 1-Feb-2013' FontFamily='Arial' FontSize='12' Foreground='#666666' HorizontalAlignment='Left'/>" +
                "<Label Content='4'  FontFamily='Arial' FontSize='12' Foreground='#666666' HorizontalAlignment='Center'/>" +
                "<Label Content='Hello World'  FontFamily='Arial' FontSize='12' Foreground='#666666' HorizontalAlignment='Right'/>" +
            "</Grid>";