CODEWITHSUNDEEP
wpfcomwebbrowser-controlhwndadorner
Anderson Imes
Anderson Imes

Reputation: 25650

Display an Adorner over a WebBrowser control

I'm using the System.Windows.Controls.WebBrowser for various things in my app and I've noticed that adorners are cut off when they are supposed to appear over a WebBrowser. I realize that the WebBrowser control is really a wrapper around a COM component and probably renders differently, but I wondered if anyone figured out how to solve this.

This is the problem I'm seeing. Here I have just a sample adorner that is supposed to draw a big red circle in the top corner of something (as a sample).

When I adorn the WebBrowser with this, I get this result:

I expect to see the full circle.

Here's the code for this worthless adorner, in case that is helpful:

public class SillyAdorner : Adorner
{
    public SillyAdorner(UIElement element) : base(element)
    {

    }
    protected override void OnRender(DrawingContext drawingContext)
    {
        drawingContext.DrawEllipse(new SolidColorBrush(Colors.Red), new Pen(), new Point(7, 7), 30, 30);
        base.OnRender(drawingContext);
    }
}

And here is how I apply it to the browser in the OnRender method of the host control:

    protected override void OnRender(DrawingContext drawingContext)
    {
        base.OnRender(drawingContext);            
        var layer = AdornerLayer.GetAdornerLayer(browser);
        layer.Add(new SillyAdorner(browser));
    }

Anyone have any hacks or workarounds for this?

Edit: I'm using .NET 4.0, if that makes a difference.

Edit #2: WebBrowser appears to inherit from HwndHost, which I've seen another question or two regarding adorners and hwndsources, but I'm not seeing anything that looks like I could implement it for the WebControl, but hopefully this is useful information for someone.

Upvotes: 7

Views: 2478

Answers (4)

Michael Sutton
Michael Sutton

Reputation: 428

Here's my blog post introducing a library I wrote for layering a WPF adorner over any hwnd. A simple web browser demo looks like this: snapshot

Upvotes: 3

Reed Copsey
Reed Copsey

Reputation: 564413

This is caused by airspace issues. Since a WebBrowser is a native, non-WPF control, there is no way to directly render adorners (or other WPF content) on top of it.

In order to do this, you need to use a separate window of some sort, and put the content into that separate window. This typically means using a transparent WPF window layered over the top of your main window. Unfortunately, this will not be as integrated of a solution as a true native WPF control would provide.

Upvotes: 2

Sheng Jiang 蒋晟
Sheng Jiang 蒋晟

Reputation: 15261

Try use another transparent TOP LEVEL overlay window. Only supported on Windows 2000 or higher of course, Win9x does not have layered windows.

Upvotes: 1

John Myczek
John Myczek

Reputation: 12256

I don't think that will work with an Adroner, but you can float content over a WebBroswer control using a transparent Popup control. More details and a code sample can be found here.

Upvotes: 5

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