The Building Coder

Modeless Form and Shared Parameter Disappearance

I am still acclimatising to Europe after four weeks in Thailand and Cambodia. So many differences: time zone, temperature, food, health, people...

Yesterday I was able to join some colleagues in Neuchâtel for a game of hockey, which is generally the most exhausting sportive event I participate in on a regular basis. I managed to keep up in spite of feeling a bit weak, and was saved by the rain which stopped us from going for the full customary hour and a half. Great fun!

Here is a question from before my holidays which starts out discussing a shared parameter visibility issue seemingly arising from a port of an application from a previous API version to Revit 2011. However, it ends up as a completely different issue, showing the importance of proper handling of asynchronous access to the Revit API, for instance the special care that needs to be taken when trying to interact with Revit from a modeless dialogue.

This just goes to show how much confusion an attempt to access the Revit from an invalid context can cause. It also shows how useful it can be to create a really minimal sample project to reproduce an issue, because that very often narrows down the question so significantly, almost automatically producing the answer. Finally, it also shows that a completely different approach can vastly reduce complexity and avoid certain errors completey, in this case the use of the new PickObjects method instead of a modeless dialogue.

Question 1: We have to add some instance parameters through the API to elements within our Revit model. I used the code on page 270 of the 2011 developer's guide. This code works fine until I hit the save button. After save the newly added parameters are 'lost'. They are no longer visible within the element properties. Though, they are still visible in the shared parameter window within Revit.

In 2010 we use the 2010 version of the same code without any problems. The difference we see is that after the parameters are added, in 2010 they show up as project parameters. In 2011 they do not show up as project parameters.

Is there a fix or workaround so that my parameters are not getting lost in 2011?

Answer 1: I had a look at the sample code you mention, and I see that it uses the line

  // create an instance definition in 
  // definition group MyParameters

  Definition myDefinition_ProductDate 
    = myGroup.Definitions.Create( 
      "Instance_ProductDate", 
      ParameterType.Text );

Looking at the Definitions.Create method in the Revit API help file RevitAPI.chm, I see the following two overloads listed:

• Create(String, ParameterType) Creates a new parameter definition using name, type and visibility.
• Create(String, ParameterType, Boolean) Creates a new user visible parameter definition using name and type.

Note that the second version taking three parameters mentions 'user visible', whereas the first overload with only two arguments does not. The name of the Boolean argument is 'visible'. I assume that you need to set that to true to ensure that the shared parameter appears in the user interface.

I looked at the Revit 2010 and 2009 API help files as well, and the overloads there are identical and described in a similar fashion, so I do not actually see how that should affect the behaviour of your code. Anyway, I would suggest using the overload taking the 'visible' argument and setting it to true and seeing whether that helps.

Some categories do not allow visible shared parameters to be added to them at all. This is indicated by the AllowsBoundParameters property on the corresponding category instance.

For an example of checking that property and setting the shared parameter to be visible whenever that is permitted, please refer to the CmdCreateSharedParams command in The Building Coder sample code that I touched on most recently when discussing the creation of a shared type parameter. It is also described in previous posts to highlight various topics in the area of the creation of shared parameters that may also be of interest to you.

Here is the code snippet that checks the property and sets the visibility accordingly:

  // set visibility of the new parameter:
 
  // Category.AllowsBoundParameters property 
  // indicates if a category can have shared 
  // or project parameters. If it is false, 
  // it may not be bound to shared parameters 
  // using the BindingMap. Please note that 
  // non-user-visible parameters can still be 
  // bound to these categories.
 
  bool visible = cat.AllowsBoundParameters;
 
  // get or create the shared params definition:
 
  string defname = _defname + nameSuffix.ToString();
 
  Definition definition = group.Definitions.get_Item(
    defname );
 
  if( null == definition )
  {
    definition = group.Definitions.Create(
      defname, _deftype, visible );
  }

Question 2: I created a sample project to illustrate the problem and now I know exactly where the problem is. The problem seems not to be related to the method of adding parameters after all.

I add parameters from within a Windows form. When I display this form with MyForm.ShowDialog it all works fine and the parameters do not disappear. The problem occurs when I want to keep my form open. For that I use MyForm.Show.

I want to keep the form open while users set different parameter values to different Revit elements. To close and open the tool each time for every new set of elements is annoying, so I need to keep the form open.

Is there another way to keep the form open so that users can select one or more elements while the form is open?

Answer 2: Thank you for your update, and I am very glad that you were able to nail down the exact problem.

That clarifies everything completely for me. Now let's see if I can explain it to you.

The problem you are encountering is the fact that the Revit API is only available and accessible to your add-in as long as you remain within a valid Revit API context. One such context is during the execution of your external command Execute method. Other valid Revit API contexts are provided by all of the various notification methods called by the Revit API events.

I provided a detailed discussion of this issue in the presentation of my modeless loose connectors navigator, which points to more detailed previous posts on the topic as well.

In short, you can solve the problem by subscribing to the Idling event. Your modeless form has no valid Revit API context. When some user action in your modeless form requires access to the Revit API, you can notify you Idling event handler, which does have Revit API access. The next time it fires, it can pick up the request from the modeless form and execute it.

The Idling event is called so frequently that the user will not necessarily notice that the modeless form is actually running in a separate thread, as demonstrated by my modeless loose connector navigator form.

Response: Thank you for your reply. I understand why it loses the API context and how I can implement a work around through the idle event, but maybe I have another easier solution. If I remember well, from 2011 onwards the API provides a PickObjects method. The reason to keep the window open is to let the user select elements. Maybe I can alter the user interface a little to make use of this method.

Answer: Yes, making use of the Selection.PickObjects method instead will definitely be much simpler and more stable. If you can avoid the modeless interaction, you definitely should. For samples of using PickObjects, please refer to the Revit SDK Selections sample and my pipe to conduit converter sample.

Network Access to Add-In Manifest and Icons

We already discussed quite a few aspects of the add-in manifest files, including:

• A simple example of creating one for my first Revit 2011 plug-in, the pipe to conduit converter.
• The RevitAddInUtility which can be used to read and write add-in manifest files.
• My Guidize utility which can populate the add-in manifest ClientId GUID.
• A Guidize update which also handles the AddInId tag.
• The visibility mode which controls which in which Revit editor contexts an external command add-in appears.
• How to handle external applications for multiple flavours of Revit.

Here is a new question on the location of the add-in manifest files:

Question: Is there a way to make Revit look for add-in manifest files in any other locations than the All Users and current user's AppData folders? I have a client that would like to place them on a server rather than distribute them across many machines.

Answer: As you say, add-in manifest files are automatically picked up and processed by Revit simply by placing them in specific folders in the local file system. Placing these files elsewhere on a network may be difficult due to .NET permissions and security issues. Here are some considerations which may apply:

Due to inherent security settings in the Microsoft .NET Framework, .NET applications cannot access registry settings or the file system without permission when applications (.dlls) are loaded from a network location. To grant permission to run such applications from a network (to simplify distribution/update of .dll files), .NET Framework policies must be set on the users' machines. The following statements (1) enable such permissions, (2) list the permissions to verify the setting, and (3) remove the permissions. Refer to Microsoft .NET Framework documentation for further information:

1. C:\Windows\Microsoft.NET\Framework\v2.0.50727\caspol.exe -addgroup 1.2 -url \\someserver\someshare\somefolder\* FullTrust
2. C:\Windows\Microsoft.NET\Framework\v2.0.50727\caspol.exe -listgroups
3. C:\Windows\Microsoft.NET\Framework\v2.0.50727\caspol.exe -remgroup 1.2.3

Revit itself does not provide any option in Revit to modify the add-in manifest location. You don't mention which OS the customer is using, but I would expect that the most likely route for a solution would be some sort of network drive mapping or file copying approach to copy/link the files from the server to the standard location on each machine.

Here is another issue concerning ribbon image resources that may have a related cause, which also includes a pointer to more up-to-date information on the .NET framework security settings:

Loading Ribbon Images from a Network Drive

Question: Is the creation of a ribbon panel with some UI widgets on it by an external application stored on a network drive possible? We would like to also store the associated DLLs and icon images on the network. That would make the application easier to maintain and update. Even though all the necessary permissions have been set, as far as we can tell, Revit throws a SecurityException when we try to load the application. We have confirmed that the permissions to the folder and files are open to everyone. The same application works fine when it is all installed on the local hard drive.

Is there a limitation when using network shares?

It seems the error is associated with making the .PNG file into a bitmap for the ribbon panel. Even with this error being raised the rest of the code still works as expected, one just does not have the icon in the ribbon panel. Is there a way to easily deploy this application companywide?

Answer: I suspect this is not a Revit issue, but rather related to the .NET framework, similarly to above. Likely a .NET Framework security policy issue not related to user/file/folder read/write access settings. When trying to load an AutoCAD.NET application from a network drive, I ran into a similar issue and found that the .NET framework considerations listed above were causing it.

Here is some more recent information on the code access security policy (caspol.exe) GUI utility, which includes the following note on when one might need to modify the policy: 'I want to run some .NET apps off a network share, and the machine I'm using doesn't have .NET 3.5 SP1.'

From that statement, one might possibly also infer that a simple upgrade of the .NET framework may help?

Setting a Locked Parameter

I arrived back in Europe and am still working through my pile of email. Here is another interesting tidbit that arose in the course of some correspondence with Anthony Forlong, Associate and CAD Manager at Clendon Burns & Park Ltd over the past few days:

Question: I've written an application that lets our users search our network and insert Revit families and load types from type catalogues. To help increase performance I have been using the duplicate method if the family exists, and then setting the parameters to their values from the type catalogue.

I am facing the following problem: there doesn't seem to be a method for setting locked parameters in the document. Is that correct? The call to the Set method fails.

The following user interface dialogue provides access to the parameter locking:

If I manually clear the check box, my function works fine. Is there away to set the parameter when it is ticked?

Answer: The following Revit 2011 API FamilyManager methods should work for this case. The documentation states that they work for Conceptual Mass and Curtain Panel families. My colleague Phil Xia tried other families and found that they worked there as well:

• IsParameterLockable: For Conceptual Mass and Curtain Panel families, indicate whether the specified parameter can be locked.
• IsParameterLocked: For Conceptual Mass and Curtain Panel families, indicate whether the specified dimension-driving parameter is locked.
• SetParameterLocked: For Conceptual Mass and Curtain Panel families, lock or unlock a dimension-driving parameter.

Thanks to Anthony and Phil for raising and clarifying this issue!

Slope is Slope, Not Radians

I am still in Thailand, flying home tonight. Still, I had time to go through some email today, and picked up lots of interesting tidbits. Let me start with this one:

Question: When I use the sample code from the Revit API help file RevitAPI.chm to create a NewFootPrintRoof, the slope is set to 0.5 radians. This results in a slope of 26.57 degrees for the newly created roof. This value is incorrect, however, since 0.5 radian equals about 28.65 degrees.

Using the Revit Lookup tool, I can see that the value has indeed been set to 26.57, which is also what we get to see in the UI, and the internal value in radians is 0.5. What is wrong here, and where does this inconsistency come from?

Answer: The value is not in radians. It is really a 'slope', e.g. 0.5 means half a foot = 6” / 12”, 0.75 means three quarters of a foot = 9” / 12”, etc., and

atan (0.5) ≈ 26.57°

Thanks to Saikat and Scott for raising and clarifying this issue!

Add New Materials from List

I am happily back from Siem Reap in Cambodia and the ruins of Angkor Wat (more photos):

Yesterday I visited the Grand Palace and the reclining Buddha in Wat Pho in Bangkok (more photos):

Angkor Wat and Cambodia was absolutely wonderful, and I am really glad that I went there. The places I visited in Thailand were rather touristy, whereas in Cambodia I had the feeling of getting much more in touch with real people and life:

Before going there I was thinking that I am not really all that interested in this kind of travelling, but the connection that I experienced there really motivated me to return again, and possibly visit Laos as well. One nice idea would be to go for a walk from northern Thailand along the western border of Laos all the way up to China.

Now I am staying with my brother Marcus in Pattaya again, picking up my computer before returning to Switzerland.

So, returning to Revit programming topics after this wonderful break from computers and the heart-warming dive into loving friendliness of Cambodian people...

Importing and Creating New Materials from a List

Quite a while back, I discussed programmatically adding a new material to the Revit project. I would like to present a useful real-world application that takes this much further, created by Jinsol Kim of RCMS GROUP to add an entire list of materials read from an Excel spreadsheet to a Revit project. Here is part of the discussions we had during the development and Jinsol's detailed description of the final process:

Question: I am trying to add some material lists programmatically and running into some problems here. The materials are defined in Excel spreadsheets used as input and containing data such as

• Material Name
  • Code
  • Title
  • Strength
• Graphics
  • RGB colour
  • Rendering data
• Identity
  • Filter criteria
  • Descriptive information
  • Custom parameters

I found a way to add materials like this:

  string newName = "03 15 00";
 
  MaterialOther myMaterial
    = doc.Settings.Materials.AddOther(
      newName );
 
  myMaterial.Color = new Color( 127, 127, 127 );
  myMaterial.Transparency = 0;

However, I cannot find out any parameters related to 'Identity'. In order to classify the material lists, I need to put values on 'Material Class'. How can I access that value, i.e. Materials > Identity > Material Class (Filter Criteria)?

Answer: As said, we did discuss adding a new material quite a while back.

For the identity fields, you could simply add your own shared parameters to the model.

Using shared parameters, you can add arbitrary data to all elements of any category.

Question: One more thing: If I create a shared parameter named 'Material Class' for example under the Materials and finishes group, then there seems to be no way for users to use the Material Class filter. Using the API, I will add up to about 2000 materials at once to avoid typing in every material in each project. Users might want to see only specific materials which belong to specific material class by filtering them out with material class. If the material class doesn't support filter by material class, then do you think I need to create a custom filter separately for it?

Here are the expected results, although created manually in this case:

Answer: That looks a bit similar to the view filter, for which there is full API access as demonstrated by the ElementFilter/ViewFilters sample. Unfortunately, it looks to me as if the materials filter is not accessible in the same way.

Question: I chose another way to solve how to maintain the material class name in the identity data of Materials.

First, I created a set of root materials manually with the proper Material Class and then duplicated them accordingly to appropriate master format division.

Here is a more detailed description:

Step 1: Set up the basic materials manually within the project file to duplicate with 'Material Class'.

Note: The Material Class name should follow this format: 'CSI XX'.

Step 2: Check all the material information in defined in the right format.

The input spreadsheet is read from C:\RevitAPI\MaterialList.xlsx.

Note 1: Graphics section doesn't allow an empty space. It should be filled with '0' or N/A.

Note 2: Material Class values should be equivalent to basic material class that will be used for duplication.

Step 3: Run the add-in and check that the materials were added successfully.

Here is Jinsol's original Powerpoint version of the detailed description, and here is AddMaterials01.zip containing the complete Visual Studio solution and source code of the AddMaterials Revit add-in.

Thank you very much, Jinsol, for creating this solution and documenting and sharing it with us!

Suppress Unwanted Dialogue

I am posting this in advance from Pattaya before leaving laptop-less for Cambodia, so that you have a little something for the duration of my absence.

Before I left on vacation, we had several queries on suppressing unwanted dialogues, and we also looked at this issue in some depth discussing editing elements inside groups. Here are some further examples of the questions and solutions we found:

Question: I am importing a DWG containing AutoCAD solids into a Revit document. The DWG imports just fine but we always get a dialogue stating that "Some ACIS objects could not be imported. To import them, use AutoCAD to convert them into polymesh objects and reimport." Oddly, when launching the same process manually in the Revit user interface, we get the same successful end result without any dialogue. Is there a way to suppress the unwanted dialogue?

Answer: As mentioned in the last post, there are several different possible ways to suppress unwanted dialogues in Revit 2011.

1. The old method that was already available in Revit 2010 was to use the DialogBoxShowing event, which can be used to dismiss a dialogue programmatically.
2. The Revit 2011 API also includes a comprehensive failure processing API, which can be do much more than the DialogBoxShowing event.
3. If all else fails and you just want to get rid of the dialogue box by any means, you can also use the Windows API to detect when it is displayed and dismiss it using my dialogue clicker application to suppress it.

Question: I used the following code to suppress a dialogue box that appears when reloading modified families:

void myDialogBoxShowing(
  object sender,
  DialogBoxShowingEventArgs e )
{
  TaskDialogShowingEventArgs e1
    = e as TaskDialogShowingEventArgs;
 
  if( e1 != null )
  {
    if( e1.DialogId.Equals(
      "TaskDialog_Family_Already_Exists" ) )
    {
      e1.OverrideResult(
        ( int ) TaskDialogResult.CommandLink1 ); // 1001
    }
  }
}

How can I suppress this dialogue box that is displayed when I delete a linked RVT file?

Answer: I would suggest using the Failure API to suppress that dialogue.

Response: Thanks you for your quick reply. It works fine and is easier to control.

I still have to figure out how to override with another option instead of the default one, in case of a warning dialogue box with more than one button. In my case, I want to pick "Remove Link" instead of "OK". Here is the code:

public class WarningSwallower 
  : IFailuresPreprocessor
{
  public FailureProcessingResult 
    PreprocessFailures( FailuresAccessor a )
  {
    IList<FailureMessageAccessor> failures 
      = a.GetFailureMessages();
 
    foreach( FailureMessageAccessor f in failures )
    {
      //if (f.GetSeverity().ToString() == "Warning")
      //a.DeleteWarning(f);
 
      FailureDefinitionId id 
        = f.GetFailureDefinitionId();
 
      if( id == BuiltInFailures.LinkFailures
        .DeleteLinkSymbolPrompt )
      {
        // only default option being choosen, 
        // not good enough!
        a.DeleteWarning( f ); 
      }
    }
    return FailureProcessingResult.Continue;
  }
}

Is there a way within the Failure API to suppress the warning and specifying a non-default option?

The closest possibility I see is to set the FailureResolutionType. I tried that, but it does not work.

Answer: Could you please try to use the ResolveFailure method to mimic clicking the 'Remove Link' button? Here is a code snippet showing how to resolve a failure, excerpted from the Revit 2011 SDK ErrorHandling sample:

public FailureProcessingResult ProcessFailures( 
  FailuresAccessor failuresAccessor )
{
  IList<FailureMessageAccessor> fmas 
    = failuresAccessor.GetFailureMessages();
 
  if( fmas.Count == 0 )
  {
    return FailureProcessingResult.Continue;
  }
 
  String transactionName 
    = failuresAccessor.GetTransactionName();
 
  if( transactionName.Equals( 
    "Error_FailuresProcessor" ) )
  {
    foreach( FailureMessageAccessor fma in fmas )
    {
      FailureDefinitionId id 
        = fma.GetFailureDefinitionId();
 
      if( id == Command.m_idError )
      {
        failuresAccessor.ResolveFailure( fma );
      }
    }
    return FailureProcessingResult
      .ProceedWithCommit;
  }
  else
  {
    return FailureProcessingResult.Continue;
  }
}

Response: I just tested using the ResolveFailure method, and it still seems not to be working, i.e. the dialogue box is still showing up using this code:

public FailureProcessingResult PreprocessFailures( 
  FailuresAccessor a )
{
  IList<FailureMessageAccessor> failures 
    = a.GetFailureMessages();
 
  foreach( FailureMessageAccessor f in failures )
  {
    FailureDefinitionId id 
      = f.GetFailureDefinitionId();
 
    if( id == BuiltInFailures.LinkFailures
      .DeleteLinkSymbolPrompt )
    {
      // only default option being choosen, 
      // not good enough!
      //a.DeleteWarning(f); 
 
      // cannot suppress dialogue box
      a.ResolveFailure( f ); 
    }
  }
  return FailureProcessingResult.Continue;
}

DeleteWarning is working, the only problem is that it only uses the default OK option. Certainly there must be a way to specify another option when deleting a warning?

Answer: Please try to use a class derived from IFailureProcessor, and implement its ResolveFailure method appropriately.

If all else fails, a workaround would be to delete the remaining RVT model link via the API after you dismiss the warning using the default option.

Correction: Aleksey Moiseyev very friendlily pointed out that the ResolveFailure method shown above is still not working, i.e. the dialogue box is still showing up using the code shown.

The method should be returning the FailureProcessingResult ProceedWithCommit, not Continue. The latter allows the error dialog to appear as usual, whereas the former suppresses it.

Thank you very much, Aleksey, for pointing this out, and sorry for the erroneous original post!

Editing Elements inside Groups

Today is the last day here with my brother Marcus in Pattaya. We had a look at the Sanctuary of Truth yesterday and I posted some photos from the beach in front of it, which was surprisingly quiet and lonely:

Early tomorrow morning I will be heading off towards Cambodia and Angkor Wat, then spend a day or two in Bangkok, and return back here again to pick up my parked things before heading back to the airport.

I am a bit leery of taking any valuables with me to Cambodia, so the computer will be staying behind and I will remain offline for a week or so. So this is the last post you will see for a couple of days, and I will not be answering comments either for a while.

Returning to the Revit API, I discussed some aspects of Revit element groups in the past, such as how to create and rename a group. Here is another question on the topic of groups that came up repeatedly:

Question: I am having trouble changing parameters of an element inside of a group that occurs in multiple locations in a project. Revit is displays the following error message:

If I were doing this operation outside of the API I would first select the group, click "Edit Group", make the changes, and then click Finish. I'm not sure how to access the "edit group" functionality programmatically. I could ungroup the group, make changes, and then regroup it using the API but that would create new duplicate groups with different names.

Answer: Unfortunately, the workaround you describe is the only way to achieve this at the moment. You have to ungroup a group before being able to modify elements in it. The document 'Getting Started with the Revit API.doc' in the Revit SDK provides the following information on this in the Question and Answer section:

Q: When exporting a model containing groups to an external program, the user receives an error at the end of the export:

"Changes to group "Group 1" are allowed only in group edit mode. Use the Edit Group command to make the change to all instances of the group. You may use the "Ungroup" option to proceed with this change by ungrouping the changed group instances."

A: Currently the API does not permit changes to members of groups. You can programmatically ungroup, make the change, regroup and then swap the other instances of the old group to the new group to get the same effect.

By the way, there are a number of other interesting questions addressed in that section as well, so it is well worth having a look at them.

Here is another version of the same question that I discussed in more depth with Henrik Bengtsson of Lindab. This discussion highlights some additional points:

Question: I am trying to move and rotate items inside a group but I cannot get it to work.

The actual problem is not so much to move or rotate the elements within the group as to get rid of the warning dialogue that pops up when something is changed inside an already existing group.

Can you provide a solution for moving and rotating elements within groups and avoiding this dialogue?

Answer: I am sorry to say that you cannot change an element as long as it resides in a group, not even modify their parameters. In a previous case, a customer tried to edit parameter value of many elements included in a group. This failed, especially in large models. The workaround is ungroup the group first, edit the parameters, and then regroup the elements again.

Actually, an element parameter can indeed be edited and its parameter value changed when the element is contained in a group. However, a warning dialog is displayed saying 'A group has been changed outside group edit mode. The change is being allowed because there is only one instance of the type'. If one clicks 'OK', then the elements in group are changed. The only bother is the warning dialog. If you really insist on going this way, the dialogue can probably be suppressed by various means. There are several different possible ways to suppress unwanted dialogues in Revit 2011:

• The old method using the DialogBoxShowing event that was already available in Revit 2010, which can be used to dismiss a dialogue programmatically.
• The comprehensive failure processing API added to the Revit 2011 API, which can be do much more than that.
• If all else fails and you just want to get rid of the dialogue box by any means, you can also use the Windows API to detect when it is displayed and dismiss it using my dialogue clicker application.

However, the situation described above is only true and the suppression of the warning message will only work for one single instance of the group. If there are multiple instances, the whole editing operations fails. With large models and lots of groups, one can reportedly crash Revit by attempting to modify parameters of grouped element without ungrouping them first.

So I would suggest trying the same workaround in your case as well: ungroup the group, make the required modifications to the elements, and create a new group of them again.

Response: Excellent work, as always...

The solution using the dialogue event did not work out for me. First of all, the group element selected when the command was executed was left in the model with a yellow colour when the command was finished. Secondly, the dialog pops up before it is closed down by the override method. It isn't completely pretty if that solution is included in an application for customers. If it has been an internal routine it wouldn't have mattered...

The second solution that you mentioned covering the Failure API worked like a rocket. I cannot see any problems with that at all, it just works perfectly. I took me some time to find the right BuiltInFailureID though ;-)

The third option is of course always a possibility but the Failure API wins this match by far!

When it comes to editing groups, there are two types of scenarios for me.

1. Change of parameter values in a group which is present in the model only once. This is possible to achieve using the API, but the problem has been the warning dialog. This is now handled with the Failure API.
2. Change of parameter values in a group which is present in the model more than once. Since this cannot be committed no matter what, I have handled this scenario before it can occur using our application. If the user tries to edit a group like that, I display a warning dialog if the group.grouptype.size is larger than one.

In my application, I will never encounter a case were the geometry content has to be changed in a group, because any changes in one of the groups causes the group to be deleted, re-created and placed in the model

If the need arises in the future, I can go for the solution you suggested and explode and regroup the items in the element set.

Here is the warning message I get:

It is not exactly the same as the one above, which is a sort of dead end, since the continue button is missing.

Here is some code from my project demonstrating the use of the Failure API and my IFailuresPreprocessor implementation. I have removed unnecessary bits to make it as clear and simple as possible:

Public Function Execute( _
  ByVal commandData As ExternalCommandData, _
  ByRef message As String, _
  ByVal elements As ElementSet) _
  As Result Implements IExternalCommand.Execute
 
  Dim trans As Transaction = Nothing
  Dim ebRes As Boolean
 
  Try
    Dim ret As Result = Nothing
 
    Dim app As Application _
      = commandData.Application.Application
 
    Dim uidoc As UIDocument = app.ActiveUIDocument
    Dim doc As Document = uidoc.Document
 
    Dim es As ElementSet = uidoc.Selection.Elements
 
    trans = New Transaction(doc, "MyCommand")
    trans.Start()
 
    Dim fhOpt As FailureHandlingOptions _
      = trans.GetFailureHandlingOptions()
 
    fhOpt.SetFailuresPreprocessor(New clsWallInfoFailure)
 
    trans.SetFailureHandlingOptions(fhOpt)
 
    ebRes = ChangeParametersAndSoOn(app, uidoc, doc, es)
 
    If ebRes = True Then
      trans.Commit()
    Else
      trans.RollBack()
    End If
 
  Catch ex As Exception
    trans.RollBack()
  Finally
    trans.Dispose()
  End Try
End Function
 
Public Class clsWallInfoFailure
  Implements IFailuresPreprocessor
 
  Public Function PreprocessFailures( _
    ByVal failuresAccessor As FailuresAccessor) _
    As FailureProcessingResult _
    Implements IFailuresPreprocessor.PreprocessFailures
 
    Dim deleteWarning As Boolean
 
    Try
      Dim flist As List(Of FailureMessageAccessor) _
        = failuresAccessor.GetFailureMessages
 
      For Each f As FailureMessageAccessor In flist
 
        Dim fDefId As FailureDefinitionId = f.GetFailureDefinitionId
 
        Select Case fDefId
          Case BuiltInFailures.GroupFailures.AtomViolationWhenOnePlaceInstance
            deleteWarning = True
        End Select
 
        If deleteWarning = True Then
          failuresAccessor.DeleteWarning(f)
        End If
      Next
 
    Catch ex As Exception
 
    End Try
  End Function
End Class

Comment: One final little comment from Jeremy regarding the coding style using statements such as this:

    If ebRes = True Then

I find the following statement more succinct and readable, and actually more correct:

    If ebRes Then

Please refer to Kean's post on testing truth for a more in-depth discussion and further comments on this topic.

Flex Duct Start Tangent

Still zipping around in Pattaya with my brother Marcus, and still blogging a bit now and then as well ...

Here is a suggestion for a workaround to specify the start and end tangents of a flex duct or pipe that evolved through a recent exchange of comments with Zhu XiaoMeng:

Question: In the Revit application UI, I can create a FlexDuct properly with the start tangent of the Hermite curve in a reasonable direction. But when I create a flex duct in the API, the start tangent is always horizontal. How can I do the same thing in API as in the UI?

The initial code is as follows:

  FlexDuct flexDuct = doc.Create.NewFlexDuct( 
    points, flexducttype );

Answer: One thing to note regarding this is that it does not seem to be related to the Hermite spline issue that we recently discussed.

Here is a suggestion for a possible workaround:

1. Place a fitting with a connector temporarily where the direction of the connector matches the desired tangent.
2. Place the flex duct or pipe and attach it to the connector.
3. Delete the fitting.

Response: I did as what you say, but I get confused with the second step. I placed a fitting with two side connectors in the right place, and then placed the flex duct in the right position, but they did not join. So the tangent did not change. So the point is: how can I get them joined?

Here is my current code:

  Family fittingFamily 
    = lstElem.Where( e => e.Name == "M_xyz" )
    .Select( e => e as Family )
    .FirstOrDefault();
 
  FamilySymbol fittingType = fittingFamily
    .Symbols
    .ToList()
    .First();
 
  const double fitLen = 1.5;
 
  var vectDown 
    = ( samplePoints[1] - samplePoints[0] )
      .Normalize();
 
  var fittPos = ptA - vectDown * fitLen;
 
  // vectAb is the vector pointing from 
  // ptA(samplePoints[First]) to 
  // ptB(samplePoints[Last])
 
  //  remove the z values (as the 
  // flexDuct first tangent do)
 
  var vectAbHoriz = new XYZ( vectAb.X, vectAb.Y, 0 );
 
  FamilyInstance fittingInstance 
    = _doc.Create.NewFamilyInstance( 
      fittPos, fittingType, 
      StructuralType.NonStructural );
 
  Line axis2 = _app.Create.NewLine( 
    fittPos, vectDown.CrossProduct( XYZ.BasisZ ), 
    false );
 
  // rotate the fitting to the desired angle
 
  bool success = _doc.Rotate( fittingInstance, 
    axis2, -vectDown.AngleTo( vectAbHoriz ) );
 
  SortedList valuePairs = new SortedList();
 
  valuePairs["xyz 01"] = fitLen;
 
  ChangeParametersValue( fittingInstance, valuePairs );
 
  FlexDuct flexDuct2 = CreateDuct( 
    samplePoints, flexDuctType );

Answer: You probably have to explicitly connect them with each other as demonstrated in the AutoRoute and AvoidObstruction SDK samples.

Response: Thank you, it's solved!

Here is my way in case some one else encounters the same problem:

Find the right connector of the fitting as well as the right connector of flexDuct, and call the connector ConnectTo method to join them.

Before deleting the temporary fitting, call the document Regenerate method, otherwise the tangent will not change!

Very many thanks to Zhu XiaoMeng for this discussion and sharing the successful result!

Queen's Birthday Fireworks in Pattaya

After an afternoon and a night on boats and buses, I arrived at my brother Marcus' place in Pattaya. We had a nice breakfast on the beach and discovered by chance that the Queen's birthday was being celebrated with a fireworks competition on the same beach in the evening [1. 2, 3], What a lucky coincidence! We went and had a look together with tens of thousands (or hundreds of thousands?) of other people. It was very pleasant, with the sand and the water and palm trees, and very impressive as well:

Here are some more photos from last night. Another interesting aspect of life here is riding a motorbike around through the dense traffic of this interminable city...

Filtering for a Non-Native Class

I left Ko Tao by boat and night bus to Bangkok and am now heading towards Pattaya, where my brother Marcus currently lives. Mentioning this to a resident of Ko Tao I learned that Pattaya is renowned for foreign old age pensioners and prostitutes, and a saying says that "good boys go to heaven – bad boys go to Pattaya". Marcus has friends there, enjoys the local bridge club, great transport links, a nice apartment at a good price and the best Internet connection he has ever had in Thailand. I am looking forward to seeing him and it.

I just arrived in Kao San Road in Bangkok at three am in the morning after a good sleep on the bus and now need to find out how to get to Ekamai to catch a bus for the three hour ride over there.

Before continuing, and before returning to the Revit API, here are a few more memorable items from my stay on Ko Tao:

• Maurizio's cocoanut.
• My cocoanut.
• Ripe mangoes.
• A beautiful sunset and new moon.

Maurizio's cocoanut almost fell on and killed him as he sat in a deckchair on the veranda of a bar. It landed less than a foot away from him and splashed him soaking wet with its juice. The owners came out, laughed, and said 'Oh yes, that is the second one today'. They didn't even move the deck chair in case another one might come down and smash it to smithereens.

My cocoanut was a much more pleasurable affair. I have always wanted to experience step by step how a cocoanut can be opened and consumed. One morning at breakfast, one fell down ten metres away. I went and picked it up and asked the workmen next to us how to open it. They were building a little hut to house a new beach bar, and I thought that their tools might come in useful. Instead they took me over to a pole stuck firmly in the earth with a sharp long metal blade attached. You need both hands to hold and twist the nut against the blade to cut and lever off its husk. Once the husk is off, the point of the same blade can be used to poke out a hole in one of the three weak spots at one end of the nut to stick in a straw to drink the juice.

After I had drunk the juice, I took the empty nut over to the workmen again. One good whack with a hammer split it cleanly in two, and then I was able to cut out the cocoanut flesh strip by strip all day long. I didn't finish it until breakfast next morning.

The mangoes are ripe here! I love ripe mangoes!

I climbed hill and went and sat on a promontory to watch the one sunset that halfway made it through the last days' cloudy skies. It was a beautiful viewpoint and gave an impressive panorama of several beautiful cloudscapes and storms of all shapes and sizes in all directions. The sun was obscured before actually setting, but the exquisite thin crescent of the new moon waxing appeared sharp and clear further up soon after.

Anyway, back to the Revit API again, and another episode in the interminable saga of the filtered element collectors, the latest of which were on parameter filters, a correction to that, and filtering for shared parameters. The first of these includes a list of pointers to many previous filtered element collector examples.

Here is another filtering query that has cropped up repeatedly, in spite of the API documentation explaining the situation pretty clearly:

Question: Please advise me on how to access AnnotationSymbols in the API. There is not enough documentation, and no code samples provided in the SDK.

I want to get a collection of annotation symbols in a family document (but this should work on any document)

I first tried to create a filtered element collector

ElementClassFilter filter1 
  = new ElementClassFilter(
    typeof( AnnotationSymbol ) ); 

This throws the following exception: "Input type is of an element type that exists in the API, but not in Revit's native object model. Try using Autodesk.Revit.DB.FamilyInstance instead, and then post-processing the results to find the elements of interest."

After that I tried the following:

List ann 
  = new List();

ElementClassFilter filter1 
  = new ElementClassFilter(
    typeof( FamilyInstance ) );

FilteredElementCollector coll1 
  = new FilteredElementCollector( doc );

coll1.WherePasses( filter1 );

foreach( Element el in coll1 )
{
  AnnotationSymbol anns 
    = el as AnnotationSymbol;

  if( anns != null )
  {
    ann.Add( el as AnnotationSymbol );
  }
}

This returns nothing.

I found the post on imports in families, but the following code provided there does not work in the Revit 2011 API:

List annotations = new List();
  doc.get_Elements( typeof( AnnotationSymbol ),
    annotations );

Answer: The message that you received is actually pretty self explanatory: the AnnotationSymbol class is available in the Revit API, but does not correspond to a "real" internal Revit class, so the internal Revit filtering mechanisms cannot search for it. Instead, you can specify a base class of AnnotationSymbol in the filter, such as the FamilyInstance class.

The code that you found in the blog post calling the get_Elements method is making use of the document Elements property which returned an iterator over all the database elements in the Revit 2010 API. That property was removed, because it is much less efficient than the filtered element collector access introduced in the Revit 2011 API.

The Revit API help file RevitAPI.chm lists the AnnotationSymbol base classes:

System.Object
  Autodesk.Revit.DB.Element
    Autodesk.Revit.DB.Instance
      Autodesk.Revit.DB.FamilyInstance
        Autodesk.Revit.DB.AnnotationSymbol

Here is an example of a helper method that retrieves Revit MEP spaces and runs into the same issue:

/// <summary>
/// Retrieve all spaces in given document.
/// </summary>
public static List<Space> GetSpaces( Document doc )
{
  FilteredElementCollector collector 
    = new FilteredElementCollector( doc );
 
  // trying to collect all spaces directly causes 
  // the following error:
  //
  // Input type is of an element type that exists 
  // in the API, but not in Revit's native object 
  // model. Try using Autodesk.Revit.DB.Enclosure 
  // instead, and then postprocessing the results 
  // to find the elements of interest.
  //
  //collector.OfClass( typeof( Space ) );
 
  collector.OfClass( typeof( Enclosure ) );
 
  return (from e in collector.ToElements() 
          where e is Space select e as Space)
    .ToList<Space>();
}

The same issue also occurs with rooms, represented by the Room class, also derived from the Enclosure base class. For rooms, another solution is also possible using the dedicated RoomFilter filter class:

  FilteredElementCollector rooms
    = new FilteredElementCollector( doc );
 
  RoomFilter filter = new RoomFilter();
  rooms.WherePasses( filter );

I beg to differ from your opinion that "There is not enough documentation". If you look at the description of the ElementClassFilter class that you are using in the sample code you provided, it clearly states:

This filter is a quick filter. Quick filters operate only on the ElementRecord, a low-memory class which has a limited interface to read element properties. Elements which are rejected by a quick filter will not be expanded in memory. This filter will match elements whose class is an exact match to the input class, or elements whose class is derived from the input class.

There is a small subset of Element subclasses in the API which are not supported by this filter. These types exist in the API, but not in Revit's native object model, which means that this filter doesn't support them. In order to use a class filter to find elements of these types, it is necessary to use a higher level class and then process the results further to find elements matching only the subtype. The following types are affected by this restriction:

• Subclasses of Autodesk.Revit.DB.Material
• Subclasses of Autodesk.Revit.DB.CurveElement
• Subclasses of Autodesk.Revit.DB.ConnectorElement
• Subclasses of Autodesk.Revit.DB.HostedSweep
• Autodesk.Revit.DB.Architecture.Room
• Autodesk.Revit.DB.Mechanical.Space
• Autodesk.Revit.DB.Area
• Autodesk.Revit.DB.Architecture.RoomTag
• Autodesk.Revit.DB.Mechanical.SpaceTag
• Autodesk.Revit.DB.AreaTag
• Autodesk.Revit.DB.CombinableElement
• Autodesk.Revit.DB.Mullion
• Autodesk.Revit.DB.Panel
• Autodesk.Revit.DB.AnnotationSymbol
• Autodesk.Revit.DB.Structure.AreaReinforcementType
• Autodesk.Revit.DB.Structure.PathReinforcementType
• Autodesk.Revit.DB.AnnotationSymbolType
• Autodesk.Revit.DB.Architecture.RoomTagType
• Autodesk.Revit.DB.Mechanical.SpaceTagType
• Autodesk.Revit.DB.AreaTagType
• Autodesk.Revit.DB.Structure.TrussType

The sample code that you provided looks perfectly correct to me, though. I do not see why it should not return any annotation symbols if there are any present in the model.

One idea for retrieving annotation symbols is to debug what goes on in RevitLookup. I created a new project and looked at the database contents using Add-Ins > Revit Lookup > Snoop DB... In the empty project, there was no entry for the AnnotationSymbol class.

I added an annotation symbol to the model using Annotate > Symbol and looked at the updated database contents in RevitLookup again, at which point the annotation symbol appears as expected: