Maximum custom window loses drop shadow effect

Question

I have a custom WPF window defined as:

<Window x:Class="MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" MinHeight="300" Height="350" MinWidth="600" Width="700" ResizeMode="CanResizeWithGrip" AllowsTransparency="True" WindowStyle="None">

I found a class online that creates drop shadows, shown below. This works well, even with a resize grip, until I maximise the window. Once I maximise the window or change the window state of another window (eg. Visual Studio), I loose the drop shadow and I cannot get it back. Any Ideas?

Drop Shadow Class:

Public Class DropShadow Private Shared _handler As EventHandler = New EventHandler(AddressOf window_SourceInitialized) <DllImport("dwmapi.dll", PreserveSig:=True)> _ Private Shared Function DwmSetWindowAttribute(hwnd As IntPtr, attr As Integer, ByRef attrValue As Integer, attrSize As Integer) As Integer End Function <DllImport("dwmapi.dll")> _ Private Shared Function DwmExtendFrameIntoClientArea(hWnd As IntPtr, ByRef pMarInset As Margins) As Integer End Function Public Shared Sub DropShadowToWindow(window As Window) If Not DropShadow(window) Then AddHandler window.SourceInitialized, _handler AddHandler window.SizeChanged, New SizeChangedEventHandler(AddressOf windowSizeChanged) End If End Sub Private Shared Sub window_SourceInitialized(sender As Object, e As EventArgs) Dim window As Window = DirectCast(sender, Window) DropShadow(window) RemoveHandler window.SourceInitialized, _handler End Sub Private Shared Function DropShadow(window As Window) As Boolean Try Dim helper As New WindowInteropHelper(window) Dim val As Integer = 2 Dim ret1 As Integer = DwmSetWindowAttribute(helper.Handle, 2, val, 4) If ret1 = 0 Then Dim m As New Margins() With { _ .Bottom = 0, _ .Left = 0, _ .Right = 0, _ .Top = 0 _ } Dim ret2 As Integer = DwmExtendFrameIntoClientArea(helper.Handle, m) Return ret2 = 0 Else Return False End If Catch ex As Exception ' Probably dwmapi.dll not found (incompatible OS) Return False End Try End Function Private Shared Sub windowSizeChanged(sender As Object, e As SizeChangedEventArgs) Dim window As Window = DirectCast(sender, Window) DropShadow(window) End Sub End Class

When you debug it, what is the first return value from DropShadow? If it is returning False, the event handler won't be hooked up and the DS will disappear when you resize it. — Chris Shain
– Chris Shain, Commented Sep 10, 2011 at 2:42
It was setting the handlers correctly. I have decided to remove it and try it a different way. I'll post the way I did it in a bit... — Stuart Blackler
– Stuart Blackler, Commented Sep 10, 2011 at 10:01

Alastair Pitts · Accepted Answer · 2011-12-31 06:30:19Z

So I found out a way to get this to work.

You need to use the WPF Shell Integration Library (here) to do the work for you. As it's been written by MS, they have fixed (it seems) any issues with doing to the P/Invoke code.

So it is easy to get a Window that has no Aero glass, is resizable on the edges, has a caption area that behaves with Aero snap, and has a drop shadow that reappears after min/maxing.

This is the code for my window (note, you need to have referenced Microsoft.Windows.Shell)

<Window x:Class="MyLibrary.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:shell="http://schemas.microsoft.com/winfx/2006/xaml/presentation/shell" Title="MainWindow" WindowStyle="SingleBorderWindow" ResizeMode="CanResizeWithGrip" mc:Ignorable="d" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" d:DesignHeight="449" d:DesignWidth="677" Foreground="White" Background="Black"> <shell:WindowChrome.WindowChrome> <shell:WindowChrome CaptionHeight="35" GlassFrameThickness="0,0,0,1" ResizeBorderThickness="5" /> </shell:WindowChrome.WindowChrome> <Grid x:Name="LayoutRoot"> </gGrid> </Window>

The <shell:WindowChrome> is where you set all the different variables for the interop.

CaptionHeight: This is the height of the caption area (headerbar) that allows for the Aero snap, double clicking behaviour as a normal title bar does.
GlassFrameThickness: Setting this to 0,0,0,1 for some reason removes the chrome (glass), keeps the square border, and adds a drop shadow.
ResizeBorderThickness: This is thickness at the edge of the window which is where you can resize the window.

Other things to note as that you keep the Window.WindowStyle property equal to SingleBorderWindow and let the Shell Library deal with removing the title, buttons and other chrome.

So I kinda wasted my bounty there, but it looks like a completely viable solution that works a treat!

EDIT:

Here is a picture of the result: Sample Metro WPF Application

I also put up a sample project on http://code.google.com/p/sample-metro-wpf-application/. It's an MIT license and people can use it however they want.

Thanks for the additional answer. Could you post a picture of the code to show what it will look like in the end. Will help anyone else that returns to this thread :)
@StuartBlackler: I added the image and a link to a sample project.
Note that you can use the CanResize option for ResizeMode if you don't want to see the grip.
Nowadays you don't need the Microsoft.Windows.Shell package. The class is in PresentationFramework.dll as System.Windows.Shell.WindowChrome.

Stuart Blackler · Accepted Answer · 2011-09-10 11:03:50Z

To create a drop shadow effect whilst having the ability to re-size the form try the following:

Set the following properties on the window:
- ResizeMode="CanResizeWithGrip"
- AllowsTransparency="True"
- WindowStyle="None"
- Background="Transparent"
- BorderThickness="3"
After the window declaration, add a Border element
Create a Border.Effect element inside of the border

For the border effect add the following:

<DropShadowEffect BlurRadius="5" Color="Black" Opacity="0.8" ShadowDepth="0.5" />

This will create the following (without the control box in the top right):

enter image description here

Full XAML:

<Window x:Class="MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" MinHeight="500" Height="350" MinWidth="300" Width="700" ResizeMode="CanResizeWithGrip" AllowsTransparency="True" WindowStyle="None" Background="White" BorderThickness="3"> <Border> <Border.Effect> <DropShadowEffect BlurRadius="5" Color="Black" Opacity="0.8" ShadowDepth="0.5" /> </Border.Effect> <!-- Put your content in here --> </Border> </Window>

These options didn't work for me... Stuart Blackler Can you please post the Entire XAML of the above picture?
I believe the only piece I didn't include was the buttons. I will see if I can find the project, but I can't guarantee anything, sorry.
I created a new project from scratch... and it worked... All that I want to see is the buttons... I created them using Webdings font... How did you created? By the way the idea of BorderThickness rocks!!! Thanks!!!!!! :)
This worked for me, with one caveat. My window is programatically opened from a tray icon click, and does not display the border until minimized then maximized once. To get around this in the code which displays the window, I did (pipes denote new lines): theWindow = New MainWindow() | theWindow.Show() | theWindow.Visibility = Visibility.Hidden | theWindow.Visibility = Visibility.Visible
This works, but you lose the window animation when minimizing to taskbar and restoring from taskbar. Any idea how to reimplement that.

Drew Noakes · Accepted Answer · 2016-10-08 11:58:03Z

Here's some minimal code that does what you're after.

<Window x:Class="WindowChromeSpike.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> <WindowChrome.WindowChrome> <WindowChrome GlassFrameThickness="0,0,0,1" CornerRadius="0" /> </WindowChrome.WindowChrome> <!-- window contents: just a blue rectangle for demo purposes --> <Border Background="#0093C0" /> </Window>

This window behaves like a usual window in that it can be:

resized via its edges
dragged within the title area
right-clicked the title area to show the system menu
maximised/restored by double clicking the title area
snapped to the sides of your screens by dragging or using hotkeys (Win 10)

It also has a drop shadow.

The end result looks like this:

How did you add the shadow effect to the window? Is this the only code you need to add a shadow or this is along with the code posted by OP?

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