HTMLPlaceHolder and ActiveX

[Rainer]

Dear Telerik Team,

we are envisioning a silverlight application with the HTMLPlaceholder to host a HTMLWebpage containing a quite complex 3d cad visualisation activeX application. As an activeX the application (~40MB) the application should run on the client so that 3d interaction for zooming rotation of the 3D models can run efficiently. In fact, the tesselation of the model and the rendering of the mesh is done on the client.

The question is, if this is possible with your control and where will the activeX run?
As far as we know, Silverlight cannot host an activeX control directy and so your control might be the only  solution to make it run indirectly within the silverlight application...

Thanks a lot for a quick answer.
Rainer

[Kiril Stanoev]

Hello Rainer,

Thank you for your interest in our controls. In its core, RadHtmlPlaceholder is an IFrame that is rendered on top of the Silverlight plugin. Therefore, if you are able to show your ActiveX application in a simple IFrame you will encounter no problems doing the same in RadHtmlPlaceholder. You are correct that the Silverlight environment does not allow embedding ActiveX controls. Therefore, your only viable option is to host the ActiveX control on some external page and show that page using RadHtmlPlaceholder. Give it a try and let me know if you encounter any issues along the way. I'd be glad to assist you.

Best wishes,
Kiril Stanoev
the Telerik team

[Rainer]

Dear Kiril Stanoev,

this sould very good. Is it correct, that the activeX runs finally on the client, where the silverlight application runs? So the first time a user accesses the page, the control willl be automatically downloaded and installed on the client?

Thanks
Rainer

[Kiril Stanoev]

Hi Rainer,

The ActiveX control does not run within the Silverlight application itself but in an IFrame which is put above the Silverlight plugin. As I previously explained, RadHtmlPlaceholder is essentially an IFrame which is rendered on top of the Silverlight plugin. I am not sure whether the ActiveX control will automatically be downloaded and installed since this depends on the browser settings. If you browser has disabled the ActiveX controls, then it will not be installed.

Kind regards,
Kiril Stanoev
the Telerik team

[Oded Zadok]

Hi,

In my application I've a HtmlPlaceHolder to host WPF browser application (XBAP), and the XBAP host the ActiveX.
The reason for that is to use Full trust option of the XBAP, and avoid from security issues that can related to ActiveX of 3rd parties.

One open issue that i have is to display a silverlight overlay layer on top of the HtmlPlaceHolder.

Thanks,
Oded.

[Kiril Stanoev]

Hello Oded Zadok,

Unfortunately displaying anything above the HtmlPlaceholder is not possible, since in its core RadHtmlPlaceholder is an IFrame that sits on top of the Silverlight plugin.

http://www.telerik.com/help/silverlight/radhtmlplaceholder-getting-started.html
 

Greetings,
Kiril Stanoev
the Telerik team

[Daniel Kassell]

I've encountered an issue in viewing a ActiveX control in a HTMLPlaceholder.

It seem to make the browser (IE8 in this case) very unstable when hiding and showing this control and when disposing the control.

In my case I'm using an ActiveX control to view TIFF- and PDF-files and the Silverlight application is built with MVVM. When I'm unloading a module and removing the view from the region manager the browser crashes. If I keep switching tabs in the RadTabControl that is containing HTMLPlaceHolder I get the same crash. 

Worst of all is that this application has to handle this HTMLPlaceHolers Visibility alot since I have BusyIndicators and ChildWindows that needs to be shown and therefore I need to turn the Visibility of the HTMLPlacerHolder on and off alot.

My HTMLPlaceHolder is configured like below, is there any tips or tricks you can give me that might solve these issues? 

<telerik:RadHtmlPlaceholder x:Name="DocView" KeepContentInMemory="True" SourceUrl="{Binding Url}" UrlLoaded="DocumentViewer_UrlLoaded" RespectSilverlightLayoutMeasure="True" Visibility="{Binding Visible}" Grid.Row="1" />

[Petar Mladenov]

Hi Daniel Kassell,

 We are aware that ArgumentException: "Value does not fall within the expected range" occurs when RadHTMLplaceholder is placed in RadTabItem or RadPane or RadWindow and they are closed. This was introduced in Q2 2011 SP (0920) version of RadControls. The good news is that this is fixed in the internal builds after the SP. As for the "Visibility turning on and off" issue at your side, could you please elaborate more on it, do you encounter an exception when you make this Visibility changes ? 

Best wishes,
Petar Mladenov
the Telerik team

[Daniel Kassell]

Does this mean there is a fix for this to download now or will be released soon?

I managed to crash the whole browser by switchning tabs fast or by turning visibility on and off before the page was able to finish its load though I fixed this issue by using KeepContentInMemory = True.

I've stumbled accross numerous problems with using this ActiveX control in RadHtmlPlaceHolder. Last problem I came across is that the javascript events was running "too fast" for the browser so the ActiveX control wasn't loaded when the actual onload event was running. Though what's really wierd is that this error doesn't occur the first time the RadHtmlPlaceHolder is loaded but everytime after that even though it's the same code running.

Even the UrlLoaded event on the RadHtmlPlaceHolder fires before the ActiveX control is initialized and that is, as explained above, not the first time but everytime after that.

I've tried going both ways, using UrlSource and point out an ASP-page with the ActiveX control in it and using HtmlSource to present the ActiveX control directly in the webbrowser without making that fetch for a page somewhere. Same problems either way.

Perhaps you guys have a solution to viewing PDF and TIF in Silverlight? We tried DeepZoom and TIF/PDF to PNG tiles conversion but we needed to setup a whole new server to make that work properly since it took alot of CPU usage to convert and the tiles database size went through the roof in a day.

[Petar Mladenov]

Hello Daniel Kassell,

 The "ArgumentException" issue is resolved and the fix is available in every internal build from 3 October till now and will be available in the future internal builds and official releases.
As for the PDF viewing in Silverlight. We are currently working on PDF Viewer control and we plan to release its Beta version in the Official Q3 2011 (second part of November). So please stay tuned.  

Greetings,
Petar Mladenov
the Telerik team

[Daniel Kassell]

Sounds good, thanks for the information.

Regarding the PDF viewer, could you make it for TIFF-files as well? ;-)

[Iva Toteva]

Hello Daniel Kassell,

Thank you for this feature request.
We do not have TIFF import on our to-do list and are currently not considering implementing it for now. However, the PDF viewer will be extensible when it comes to the file formats it supports, following the approach adopted with RadRichTextBox. Therefore, you would be able to develop and plug-in custom format providers in order to show your documents.
I hope this answers your question.

Kind regards,
Iva Toteva
the Telerik team