Silverlight IFrame control position relative to browser window

I am working on making a very simple IFrame control for silverlight.

Goal: Control the placement of an IFrame overlayed on a silverlight application

The silverlight IFrame control is being used inside a silverlight application that allows the user to build a search query, then a url is formed from the search query and set to be the source of the IFrame. It's a basic search application.

I want the IFrame to change size and position based on the size and position of the silverlight control.

I found code here: http://www.kirupa.com/blend_silverlight/absolute_position_transformtovisual.htm, that I put in the constructor of the silverlight control to get the position of the control relative to the silverlight application. I then use that position to set the IFrameLeft and IFrameTop dependency properties of the silverlight control.

        this.LayoutUpdated += (obj, args) =>
            {
                GeneralTransform gt = HtmlViewerStackPanel.TransformToVisual(null);
                Point point = gt.Transform(new Point());

                IFrameLeft = (int)point.X;
                IFrameTop = (int)point.Y;

            };

Then in the SizeChanged event I have the following which makes the changes to the IFrame. In the constructor I set FrameID to be a new Guid. Then create an IFrame with that Guid as the id.

    private void UserControl_SizeChanged(object sender, SizeChangedEventArgs e)
    {

        IFrameHeight = (int)this.ActualHeight;
        IFrameWidth = (int)this.ActualWidth;

        var iframeElement = System.Windows.Browser.HtmlPage.Document.GetElementById(this.IFrameID);
        iframeElement.SetStyleAttribute("width", string.Format("{0}px", IFrameWidth));
        iframeElement.SetStyleAttribute("height", string.Format("{0}px", IFrameHeight));

    }

It only works as desired if the silverlight application takes up the whole browser window. However that is not how I most commonly use it.

From reading this question: Getting absolute position of an element relative to browser, it appears that if I could get a reference to the object tag HtmlElement that the silverlight application is hosted in I could read the offsetleft and offsettop properties. If I had the position of the object tag relative to the browser it seems like I could very easily calculate the silverlight control's offset from the browser. Since I can determine the silverlight control's offset from the silverlight application.

In the past I have just given the object, or a wrapping div tag an id and then used the HtmlPage.Document.GetElementById to get a reference to the element. I'd like to avoid that if possible.

I tried this in the LayoutUpdated event after getting the GeneralTransform and setting the IFrame Left and Top. It gets the object tag and uses the offset properties I talked about before.

                var objectElements = System.Windows.Browser.HtmlPage.Document.GetElementsByTagName("object");

                if (objectElements.Count == 1)
                {
                    var objElement = objectElements.Single();

                    do
                    {
                        IFrameLeft += Convert.ToInt32(objElement.GetProperty("offsetLeft"));
                        IFrameTop += Convert.ToInt32(objElement.GetProperty("offsetTop"));

                    } while ((objElement=(System.Windows.Browser.ScriptObject)objElement.GetProperty("offsetParent")) != null);
                }

Using the object tag to get the offset from the browser window works, I was having some problems with one of the pages I tested it on then I learned that the offsets are from offsetparent instead of always from the browser window. I added the code to loop untill the offsetparent is null. The code now basicly works.

I want to be able to put the开发者_运维问答 silverlight control anywhere, and the IFrame be contained to the area of the control, and be at the position of the control.

I'm wide open to any ideas on a better approach to positioning the IFrame to match the silverlight control.

Here are a few more examples of what I'm trying to do:

• http://www.wintellect.com/cs/blogs/jlikness/archive/2010/09/19/hosting-html-in-silverlight-not-out-of-browser.aspx
• http://www.davidezordan.net/blog/?p=700
• http://csharp-snippets.blogspot.com/2009/03/html-host-control-in-silverlight.html
• http://www.codeproject.com/KB/silverlight/BlendPDFwithSilverlight.aspx