在VS2008上运行时更改窗口样式，在VS2010上不运行

Question

Something that was working on VS2008 (framework 3.5) seems to not work on VS2010 (framework 4).

I need to change the style of a window at runtime (user preference). In VS2008 this code was working:

Window1.xaml

<Window x:Class="StyleTest.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow"
        ResizeMode="CanResizeWithGrip">

  <Window.Style>
    <Style TargetType="{x:Type Window}">
      <Setter Property="MinWidth" Value="400" />
      <Setter Property="Width" Value="500" />
      <Setter Property="MinHeight" Value="400" />
      <Setter Property="SizeToContent" Value="Height" />
    </Style>
  </Window.Style>

  <Grid>

  </Grid>
</Window>

Window1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Xml;
using System.Windows.Markup;
using System.IO;

namespace StyleTest
{
  /// <summary>
  /// Interaction logic for Window1.xaml
  /// </summary>
  public partial class Window1 : Window
  {
    public Window1()
    {
      InitializeComponent();

      Loaded += new RoutedEventHandler(ObjDialog_Loaded);
    }

    void ObjDialog_Loaded(object sender, RoutedEventArgs e)
    {
      XmlDocumentFragment frag = new XmlDocument().CreateDocumentFragment();
      frag.InnerXml = "<Style TargetType=\"{x:Type Window}\" xmlns=\"http://schemas.microsoft.com/winfx/2006/xaml/presentation\"> " +
                      "  <Setter Property=\"Height\" Value=\"200\" />" +
                      "  <Setter Property=\"Width\" Value=\"200\" />" +
                      "</Style>";
      XmlNode node = frag.FirstChild as XmlElement;

      Style style = LoadXaml(node.OuterXml) as Style;
      if (style != null)
        Style = style;

      UpdateLayout();
    }

    private object LoadXaml(string xaml)
    {
      Exception ex = null;
      object o = LoadXaml(xaml, out ex);

      if (ex != null)
        throw ex;

      return o;
    }

    public static object LoadXaml(string xaml, out Exception exception)
    {
      try {
        ParserContext pc = new ParserContext();
        pc.XmlnsDictionary.Add("", "http://schemas.microsoft.com/winfx/2006/xaml/presentation");
        pc.XmlnsDictionary.Add("x", "http://schemas.microsoft.com/winfx/2006/xaml");
        pc.XmlnsDictionary.Add("l", "http://www.teradp.com/schemas/GN4/1/WinUI");
        pc.XmlnsDictionary.Add("c", "clr-namespace:TeraDP.GN4.Common;assembly=Common");

        exception = null;
        return XamlReader.Load(new MemoryStream(Encoding.UTF8.GetBytes(xaml)), pc);
      }
      catch (Exception ex) {
        exception = ex;
      }

      return null;
    }

  }
}

When I run this code on Framework 3.5 the window is displayed with a size of 200x200. When I run this code on Framework 4 thw window is displayed with a size of 500x400

The strangest thing is that if I add MinWidth and MinHeight to the style applied at runtime those attributes works correctly also in VS2010, while Width and Height seems to be ignored.

Do someone has a solution for this problem?

Answer 1

AFAIK to change how the window is shown and/or its size you should just implement ArrangeOverride OR set Height and Width directly (for example in the Loaded event handlet)...

EDIT - as per comment:

Applying XAML at runtime can open up several security problems so I would recommend not doing so or at least implement some security measures to prevent the dynamically loaded XAML from messing with the application... that said:

• http://blogs.msdn.com/b/ashish/archive/2007/08/14/dynamically-loading-xaml.aspx
• WPF: Changing Resources (colors) from the App.xaml during runtime
• http://blog.xamltemplates.net/?p=20
• http://www.mostlydevelopers.com/blog/post/2009/01/15/load-xaml-at-runtime.aspx
• http://dotnetslackers.com/XAML/re-205412_Load_XAML_Resource_Dictionaries_at_Runtime.aspx
• http://www.codeproject.com/KB/WPF/wpfskins.aspx

This MS Connect entry is not exactly the same issue but somehow related and suggests that there could be a bug in WPF 4.