[C#] WPF Window with transparency makes WindowsFormsHost disappear

[ProclaimDragon]

Hi,

I have a WPF window without border and with Allow Transparency set to true but this makes any WindowsFormsHost component inside the WPF window disappear.

Is there any workaround to solve this?

[SimpleJack]

Hi,

I have a WPF window without border and with Allow Transparency set to true but this makes any WindowsFormsHost component inside the WPF window disappear.

Is there any workaround to solve this?

You'll have to go old school.

I've seen in a few spots on the web where people are asking about using the WebBrowser control with a borderless window. I wondered the same thing. Using straight WPF you can not. However, being the old man that I am, I remember how to use the Win API. Below is the code to not only do it but I threw in some dragging code for good measure.

#region The Classic Window API

//The SendMessage function sends a message to a window or windows.

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)]

static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);

//ReleaseCapture releases a mouse capture

[DllImportAttribute("user32.dll", CharSet = CharSet.Auto, SetLastError = false)]

public static extern bool ReleaseCapture();

//SetWindowLong lets you set a window style

[system.Runtime.InteropServices.DllImport("user32.dll")]

static extern int SetWindowLong(IntPtr hWnd, int nIndex, long dwNewLong);

#endregion

/* Borderless - The window which contains the WebBrowser control* /

Window win = new Window();

const int GWL_STYLE = -16;

const long WS_POPUP = 2147483648;

IntPtr hWnd = new System.Windows.Interop.WindowInteropHelper(win).Handle;

SetWindowLong(hWnd, GWL_STYLE, WS_POPUP);

/* Drag Window - Capture this on the mouse down of a control in the window*/

ReleaseCapture();

SendMessage(hWnd, 0xa1, 0x2, 0);

[dotnetukguru]

You'll have to go old school.

I've seen in a few spots on the web where people are asking about using the WebBrowser control with a borderless window. I wondered the same thing. Using straight WPF you can not. However, being the old man that I am, I remember how to use the Win API. Below is the code to not only do it but I threw in some dragging code for good measure.

#region The Classic Window API

//The SendMessage function sends a message to a window or windows.

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)]

static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);

//ReleaseCapture releases a mouse capture

[DllImportAttribute("user32.dll", CharSet = CharSet.Auto, SetLastError = false)]

public static extern bool ReleaseCapture();

//SetWindowLong lets you set a window style

[system.Runtime.InteropServices.DllImport("user32.dll")]

static extern int SetWindowLong(IntPtr hWnd, int nIndex, long dwNewLong);

#endregion

/* Borderless - The window which contains the WebBrowser control* /

Window win = new Window();

const int GWL_STYLE = -16;

const long WS_POPUP = 2147483648;

IntPtr hWnd = new System.Windows.Interop.WindowInteropHelper(win).Handle;

SetWindowLong(hWnd, GWL_STYLE, WS_POPUP);

/* Drag Window - Capture this on the mouse down of a control in the window*/

ReleaseCapture();

SendMessage(hWnd, 0xa1, 0x2, 0);

Are we sure this works?

[SimpleJack]

Are we sure this works?

Works like a champ. Also, lets say you have the WebBrowser control in a grid and you want to set margins to provide transparency around the browser. Just extend the glass to the entire window and set your win.Background to Transparent and you are good to go.

In Summary:

IntPtr hWnd = new System.Windows.Interop.WindowInteropHelper(win).Handle;

const int GWL_STYLE = -16;

int style = GetWindowLong(hWnd, GWL_STYLE)

SetWindowLong(hWnd, GWL_STYLE, style );

Extend the glass - Adam Nathan - Extend Glass

Off you go

[SimpleJack]

Are we sure this works?

Also, I had a WS_POPUP constant in the original code. I found it wasn't needed.

[SimpleJack]

Also, I had a WS_POPUP constant in the original code. I found it wasn't needed.

Man, I feel like a moron! Yes, you do need the WS_POPUP constant. Sorry about that!

This is the only code you need once you extend the glass and make the background transparent

IntPtr hWnd = new System.Windows.Interop.WindowInteropHelper(win).Handle;

SetWindowLong(hWnd, GWL_STYLE, WS_POPUP);