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ImageGear ASP.NET FAQ

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Q1: Why am I not seeing my image on the Web Form?
Q2: I have configured the config.web file for logging. Where is the log file?
Q3: Why am I seeing the following error in design mode with Microsoft .NET Framework 3.5 Service Pack 1 (SP1) installed: Error Creating Control - ImageView1 ....'<your image>' could not be set on property 'ImageIdentifier'?
Q4: Why am I not able to see the image that was loaded, but I do see an image with the text ImageGear17.Web.dll license is invalid?
Q5: Why do my config.web edits for licensing not seem to properly license my deployed Asp.Net application?
Q6: Why do I see the following error in my log file and how do I correct it: Error: Cannot find required ImageDataProcessor DLL?
Q7: Why do I see the image appear to load 2 times in ASP.NET?
Q8: Why do my annotations look different on different browsers?
Q9: Why do mouse tools behave differently on different browsers?
Q10: Why do my images look wrong when printed?
Q11: Why does it appear that a user can edit text for text marks?
Q12: Why does changing the scrollBars property of the client-side PageView control cause the scroll position of the image to reset?
Q13: Why does CTRL-MouseWheel resize the entire page instead of the image in the viewer?
Q14: Why does dragging a mark in Internet Explorer cause the mark handles to move and the mark itself to lag behind?
Q15: Why do rotated images sometimes display unrotated in Internet Explorer?
Q16: Why does the selection rectangle sometimes appear opaque in Internet Explorer?
Q17: Why does ImageGear ASP.NET not update the image when I change the size of the viewer’s window?

Q1: Why am I not seeing my image on the Web Form?
There are numerous reasons why an image may not appear. Besides using a common web debugger, the Asp.Net controls are designed to generate logs. See the Error Logging Configuration Settings found in the Using ImageGear.Web.UI Namespace section of the ImageGear help file for setting up logging. Please contact Accusoft Pegasus for assistance in analyzing the log.

Q2: I have configured the config.web file for logging. Where is the log file?
If one is using Microsoft Visual Studio, watch the output tab from the Debug view and see if any ImageGear.Web messages appear. If not, reconfigure the web.config file as outlined in the Using ImageGear.Web.UI Namespace section of the ImageGear help file for error logging. Try bumping the <switches> element <add name="imageGearSwitch" value="Error" /> value from Error to Verbose. The IIS emulation package, Cassini, should have started the ASP.NET Development Server and one should see the icon on the right side of the toolbar at the bottom of the screen. Sometimes it is necessary to stop that server and then restart the debugging process again. Be sure that the element is configured similarly to the description in the ImageGear help file. The initializeData parameter must be set to a proper file name as outlined by windows specification and not have any illegal characters. The path is relative to the config.web file and the directory must have writable permissions and have the appropriate security permissions for the user debugging their application. Again, the path is already relative so please do not use the tilde ‘~’ symbol as it has no meaning. Paths may be fully qualified specified locations if they begin with a hard drive location.

If the log file can be generated using Visual Studio debugging but fails to show when the application is deployed under ISS, it is most likely a security issue. Be sure that the directory picked has NETWORK SERVICE user name Read and Write permissions set.

Q3: Why am I seeing the following error in design mode with Microsoft .NET Framework 3.5 Service Pack 1 (SP1) installed: Error Creating Control - ImageView1 ....'<your image>' could not be set on property 'ImageIdentifier'?
The issue has been addressed by Microsoft support article 961847 and depending on the Operating System platform, the solution is provided by the articles in the Microsoft Knowledge Base : 969612 (Windows XP and Windows Server 2003) or 967535 (Windows Vista and Windows Server 2008).

Q4: Why am I not able to see the image that was loaded, but I do see an image with the text ImageGear17.Web.dll license is invalid?
The described scenario can be occurring under any of the following situations:

1) I have installed the ImageGear Developer’s kit for 32 bit or 64 bit.
2) I see images under Visual Studio but not IIS.
3) I see images under IIS but not Visual Studio.

While different scenarios, these may be symptomatic of a mismatch of the toolkit to the hosting environment. The installed kit must match the testing environment bit depth or the ImageGear license will not be satisfactorily registered. Visual Studio 2008 or earlier can only be used for 32 bit testing if using the built in ASP.NET Development Server, Cassini. The IIS server on a 64 bit Windows OS platform can work with either a 32 bit or 64 bit Asp.Net server but typically requires enablement for 32 bit services. If the ImageGear Asp.Net product is not explicitly assigned a license in the web.config file, it will try to use one in the registry. However, it will pick the appropriate license for the bit depth it detects while running under IIS which would be normally matched to the OS bit depth (which is either 32 bit or 64 bit). Again, the kit installed must match the same bit depth so a 32 bit kit on a 64 bit Windows Operating System must have the IIS server enabled for 32 bit support.

Q5: Why do my config.web edits for licensing not seem to properly license my deployed Asp.Net application?
Please be sure to copy the license strings exactly. Even trailing spaces in quoted strings must be applied. Please note that the Asp.Net SolutionKey can only take the four signed decimal values and will not work with the alternate four unsigned hexadecimal values supplied when one receives the ImageGear license. Also, with IIS services, it sometimes is necessary to restart or recycle the Application Pool for which the hosted Asp.Net application resides and not just the IIS service itself.

Q6: Why do I see the following error in my log file and how do I correct it: Error: Cannot find required ImageDataProcessor DLL?

Error: Cannot find required ImageDataProcessor DLL.

Control type : Component

Critical: -1: value cannot be null

The error is seen when the value property that is passed into the igComponent property is either Null or not valid. Make sure the value property of the igComponent has a valid value passed into it. For example, if the path listed below were Null or not valid then the error would be generated.

<add key="igComponent" value="~/bin/ImageGear17.Web.ImageDataProcessor.dll" />

Please refer to the section in the help file entitled,  “Web.config Settings for ImageView and ThumbnailView Controls”  as this contains additional information regarding using these settings.


Q7: Why do I see the image appear to load 2 times in ASP.NET?
This is done to give the web browser user a more responsive feel. A low resolution full sized image is first loaded which is fairly quick and responsive. Then, a higher resolution image will typically follow for the portion of the image being viewed in the client viewer. This higher quality image can be the one showing a full image at better resolution or one or more tiles showing a portion of the image depending on how far zoomed in the image may be. When you scrolls around or zooms into the client viewer, you may see the previously loaded low resolution view for a moment while a better quality image gets requested and then subsequently displayed.

Q8: Why do my annotations look different on different browsers?
These differences are due to bugs, limitations and differences in the browsers themselves. The following list highlights the known differences between browsers:
  • Opera does not display text for text marks.
  • Internet Explorer shows a faint black halo around marks that are not fully opaque.
  • In some cases, FireFox will display text for text marks outside of the bounds of the viewer or magnifier.
  • Different browsers apply the lineStyle and calloutLineStyle properties differently to the rendered mark.

Q9: Why do mouse tools behave differently on different browsers?
Browsers, other than Internet Explorer, have poor support for tracking the mouse across multiple parts of an HTML page. The ImageGear ASP.NET client viewer will cancel any mouse tool whenever the mouse moves outside of the viewer’s area. Accusoft Pegasus is preparing a workaround for this issue and it will be part of a future release.

Q10: Why do my images look wrong when printed?
Web browsers were designed to print documents, not interactive applications. As browsers improve their ability to print application-generated content, Accusoft Pegasus will expand the printing support in ImageGear ASP.NET.

Q11: Why does it appear that a user can edit text for text marks?
In some cases, especially in Internet Explorer, the browser’s default handling of text cannot be suppressed. This results in undesired behavior, such as the text editing cursor appearing over text marks in some cases, or users having the ability to select the text of a text mark. As browsers expose ways to disable this default behavior, Accusoft Pegasus will improve ImageGear ASP.NET to deliver a more consistent user experience.

Q12: Why does changing the scrollBars property of the client-side PageView control cause the scroll position of the image to reset?
This is due to a bug in Chrome Version 4 and Safari Version 4.

Q13: Why does CTRL-MouseWheel resize the entire page instead of the image in the viewer?
Chrome Version 4 and Safari Version 4 do not pass the mouse wheel event to the viewer if the control key is pressed. Instead, those browsers use that action to zoom the entire page.

Q14: Why does dragging a mark in Internet Explorer cause the mark handles to move and the mark itself to lag behind?
Internet Explorer is slower than other browsers and one of the shortcuts it takes while it is busy is to redraw only part of the page. Other browsers are able to display the entire page more frequently.

Q15: Why do rotated images sometimes display unrotated in Internet Explorer?
This is a bug in Internet Explorer that causes it to display all or part of an image unrotated, even though ImageGear ASP.NET has instructed it to rotate the image.

Q16: Why does the selection rectangle sometimes appear opaque in Internet Explorer?
This is a bug in Internet Explorer that causes it to ignore the opacity setting of the selection rectangle. This should only occur when an area is selected and then the image is zoomed in so that the selected area is very large. Once it occurs, the behavior will persist until a new image is loaded into the viewer.

Q17: Why does ImageGear ASP.NET not update the image when I change the size of the viewer’s window?
Other than Internet Explorer, browsers do not raise an event when a portion of the HTML document changes size. Whenever you change the size of the viewer, you should call the PageView.display() function to instruct ImageGear.ASP.NET to recognize and account for the size change.