Borderless window Drop shadow Opacity elements issue - wpf

Question

I am trying to create a borderless window in WPF. I am using the class mentioned in the link.
This works fine as long as all elements are all enabled (Opacity = 1). if i set opacity to 0.5, it is almost invisible.
The opacity works fine if i remove the code for the drop shadow. I am not sure what is the cause of this.
The class is the same one i am using as explained in link above. The rest of my code is below.
Any help is appreciated :
Girija
XAML:
<Window x:Class="Sample.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:Sample">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="70"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<TextBox Margin="2" Text="Something" Grid.Row="0"/>
<Button Grid.Row="1" Content="Something" IsEnabled="False" Opacity="0.7"/>
</Grid>
Code behind :
/// <summary>
/// Interaction logic for Window1.xaml
/// </summary>
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
}
/// <summary>
/// Raises the <see cref="E:System.Windows.FrameworkElement.Initialized"/> event.
/// This method is invoked whenever
/// <see cref="P:System.Windows.FrameworkElement.IsInitialized"/> is set to true internally.
/// </summary>
/// <param name="e">The <see cref="T:System.Windows.RoutedEventArgs"/>
/// that contains the event data.</param>
protected override void OnInitialized(EventArgs e)
{
//AllowsTransparency = false;
ResizeMode = ResizeMode.NoResize;
WindowStartupLocation = WindowStartupLocation.CenterScreen;
WindowStyle = WindowStyle.None;
DwmDropShadow.DropShadowToWindow(this);
base.OnInitialized(e);
}
}
helper Class taken from above link :
class DwmDropShadow
{
[DllImport("dwmapi.dll", PreserveSig = true)]
private static extern int DwmSetWindowAttribute(IntPtr hwnd, int attr, ref int attrValue, int attrSize);
[DllImport("dwmapi.dll")]
private static extern int DwmExtendFrameIntoClientArea(IntPtr hWnd, ref Margins pMarInset);
/// <summary>
/// Drops a standard shadow to a WPF Window, even if the window isborderless. Only works with DWM (Vista and Seven).
/// This method is much more efficient than setting AllowsTransparency to true and using the DropShadow effect,
/// as AllowsTransparency involves a huge permormance issue (hardware acceleration is turned off for all the window).
/// </summary>
/// <param name="window">Window to which the shadow will be applied</param>
public static void DropShadowToWindow(Window window)
{
if (!DropShadow(window))
{
window.SourceInitialized += new EventHandler(window_SourceInitialized);
}
}
private static void window_SourceInitialized(object sender, EventArgs e)
{
Window window = (Window)sender;
DropShadow(window);
window.SourceInitialized -= new EventHandler(window_SourceInitialized);
}
/// <summary>
/// The actual method that makes API calls to drop the shadow to the window
/// </summary>
/// <param name="window">Window to which the shadow will be applied</param>
/// <returns>True if the method succeeded, false if not</returns>
private static bool DropShadow(Window window)
{
try
{
WindowInteropHelper helper = new WindowInteropHelper(window);
int val = 2;
int ret1 = DwmSetWindowAttribute(helper.Handle, 2, ref val, 4);
if (ret1 == 0)
{
Margins m = new Margins { Bottom = 0, Left = 0, Right = 0, Top = 0 };
int ret2 = DwmExtendFrameIntoClientArea(helper.Handle, ref m);
return ret2 == 0;
}
else
{
return false;
}
}
catch (Exception ex)
{
// Probably dwmapi.dll not found (incompatible OS)
return false;
}
}
}

Answer 1

I dont know why are you using shadow effect by using dwmapi.dll. Why arent you using the hardware accelerated drop shadow effects from WPF Extended toolkit or from presentationframework.Aero (referred from .NET assemblies in visual studio)?
<ResourceDictionary Source="/presentationframework.Aero;V3.0.0.0;31bf3856ad364e35;component/themes/aero.normalcolor.xaml"/>
<DropShadowEffect ShadowDepth="2"></DropShadowEffect>

Answer 2

Here you go :)
<Window x:Class="Test.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
AllowsTransparency="True"
Title="MainWindow"
Background="Transparent"
WindowStyle="None"
Height="350"
Width="500">
<Border Background="#ffFEFEFE" CornerRadius="5" BorderThickness="2" Margin="10" BorderBrush="#ffaaaaaa">
<Border.Effect>
<DropShadowEffect Direction="270"
ShadowDepth="5"
Opacity="0.8"
BlurRadius="7" />
</Border.Effect>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="70" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<TextBox Margin="2"
Text="Something"
Grid.Row="0" />
<Button Grid.Row="1"
Content="Something"
IsEnabled="False"
Opacity="0.5" />
</Grid>
</Border>
</Window>

Answer 3

Use nonzero value for one of the margins, eg. 1, 0, 0, 0; or 1, 1, 1, 1; and use your own Margins:
[StructLayout(LayoutKind.Sequential)]
public struct Margins
{
public int Left;
public int Right;
public int Top;
public int Bottom;
}