The Building Coder

API Context, Background Process, PostCommand

More aspects of the Revit API from a modeless context – Background process and Revit API – Revit background processor – Effective Revit API context predicate – PostCommand context and view focus – Protect creativity with no AI – European Union AI Act – The Sakana AI Scientist – Plasma in high school nuclear fusion reactor... Read more →

Can You Avoid Chaining Idling?

AU 2022 classes are available online now, as well as a new Dynamo book and resources project. I also present some ongoing nitty-gritty discussions on external events and Idling – Modern add-in deployment and testing – Parametric curvature in families – Awesome Dynamo online book project – Launching command after closing form – Chaining Idling events and other solutions... Read more →

Another Async Await, REX + Structural Analysis SDK

Here are two important utilities, one eagerly awaited, the other a nice surprise: the updated REX and Structural analysis SDKs and a powerful async and await wrapper for the Revit API external event – REX SDK and Structural Analysis SDK 2020 – Revit.Async – Background – Standard approach – Revit.Async approach... Read more →

Ten Years Anniversary, MVVM, WPF and WinForm

Today is The Building Coder's tenth birthday! The first post was a warm welcome on August 22, 2008. Very many thanks to the entire community for all your support, interest, comments and above all numerous contributions over the years! Today, let's pick up the recurring topic of accessing the Revit API from a modeless context... Read more →

Parameters, Walls and Driving Revit via WCF Service

Exciting news from Russia and some mundane updates on other repetitive topics – Driving Revit from a modeless context via a WCF service – Room walls' directions – Retrieving all exterior walls – Getting and setting a shared parameter value... Read more →

External Access to the Revit API

We are currently being flooded with questions about a topic that has already been discussed repeatedly and in depth in the past, external access to the Revit API. Possibly, the cause is the growing interest in implementing web driven solutions to generate RFA and RVT files. It is in fact possible to implement a web server driving Revit in the background to execute such tasks, as demonstrated by the old sample showing how to drive Revit through a WCF service and other examples listed in the topic group on Idling and external events for modeless access and driving Revit from outside – Revit I/O and Forge – Question – Answer... Read more →

RvtFader, AVF, Ray Tracing and Signal Attenuation

I implemented a neat new little sample add-in, RvtFader, that calculates and displays signal attenuation caused by distance and obstacles, specifically walls. It uses two very interesting pieces of Revit API functionality – AVF, the Analysis Visualisation Framework, for displaying graphical data in a transient manner directly in the BIM – The ReferenceIntersector ray tracing functionality to detect walls and other obstacles between two points. In the course of implementing the AVF part of things, I also resuscitated my trusty old RevitWebcam add-in – RevitWebcam – RvtFader – Task – Implementation – Further Reading... Read more →

Setting Active View During Idling

Here is a summary of the discussion and solution for setting ActiveView during the Idling event from the Revit API discussion forum raised and solved by Rudi 'Revitalizer' and Kinjal Desai; As per API documentation, this operation should not be invalid: no open transactions; IsModifiable is ok; IsReadOnly is ok; No pre-action events around. However, trying to do so throws an InvalidOperationException with the message "Setting active view is temporarily disabled"... Read more →

UIView Windows Coordinate Ray Casting Tooltip

I revisited the custom tooltip implementation that I prepared to demonstrate the Revit 2013 API features including the View API and its UIView class. It class still provides the only possibility to convert back and forth between Revit model coordinates and Windows device screen points. That functionality can be combined with the ReferenceIntersector to shoot a ray through the model to determine what Revit database element is located under the current cursor position and display a custom tooltip presenting information about it or anything else you please... Read more →

FireRatingCloud Context and Architecture

A picture says more than a thousand words. I find a compelling and clear picture takes a lot of work, though. I created the image below to explain the context and architecture of the FireRatingCloud and other samples connecting BIM and the cloud like RoomEditorApp, followed by some musings on using Revit as a server – FireRatingCloud context and architecture – You cannot use Revit as a server... Read more →

Vipassana and Idling versus External Events

I am leaving for a ten-day Vipassana meditation retreat next week, so I'll cram in this quick Saturday post on the meditation retreat and mindfulness before I have too much to do getting prepared next week. It includes yet another discussion of Idling versus external events for modeless dialogues and dockable panels. Vipassana means 'seeing'. In this case, seeing is enhanced by concentration on my own self, my body, my mind, my thoughts. No talking, no communication whatsoever, no Internet, no mobile devices, no pen and paper, no reading. No input, no output. Sitting... Read more →

Idling, DMU, DocumentChanged and Need for Regen

Today we have two ever-recurring topics to revisit: a discussion on how to react to a document modification and yet another example of the need for regeneration – Idling and external events, DMU and DocumentChanged – Need for regen in an updater... Read more →

External Events and 10 Year Forum Anniversary

Ten years ago today, on December 9, 2005, Jim Quanci posted the first thread on the Revit API discussion forum. This was pointed out by Revitalizer, one of the forum's chief contributors. Thank you very much for this, Revitalizer, and thank you even more for all the good advice and numerous solutions you have provided to the community! – Use of the Revit API Requires a Valid Context – Driving Revit from Outside through an External Event... Read more →

PostCommand causes Internal Exceptions, a Break

For the past few years now, the development team has been adding various checks to prevent illegal use of Revit API entry points from outside a valid Revit API context. Read all about the valid Revit API context and how to access it – Idling and External Events for modeless access and driving Revit from outside – New checks were just added in the Revit 2016 service pack 2 which uncovered more long-standing illegal API calls – CompHound connects desktop and cloud – Do not call `PostCommand` from a modeless context – Do Not Call `PostCommand` from an `Idling` Event Handler – Vacation time... Read more →

Batch Processing, DWFx Links and Future-Proofing

The never-ending stream of Revit API topics continues. Today, let's look at: Unrestricted VendorId. Retrieving DWFx links. Batch processing Revit documents. Future-proofing The Building Coder samples. Recent Revit API AEC DevBlog posts: Delete custom family parameter. JoinGeometryUtils.JoinGeometry for walls and columns. Reading gross and rentable area elements. Unrestricted VendorId In the past, we recommended using an Autodesk registered developer symbol or RDS as your vendor id, stored in the add-in manifest VendorId tag (starting from the Revit 2012 extensible storage... Read more →

Revit API Context and Form Creation Errors

I am back from my vacation. I had a wonderful time. Now, let's look at two important recurring topics that came up while I was away: Revit API Context Summary. Detailed Form Creation Error Information. Before getting to those, let me mention some of the nice places and mountain tours I was blessed with in the past few weeks: Pallanza and the Lago Maggiore: Mont Blanc, mountaneering and climbing around the Cabane d'Orny: Monte Leone above Locarno (photo album): Pizzo... Read more →

Clicks, DMU, Surfaces, FireRating Feedback, Vacation

Let me list some of the topics we discussed today in the Revit API discussion forum before I head off for vacation: Reacting to Windows mouse clicks in Revit. Reacting to changes and setting parameters using DMU or DocumentChanged. Creating a surface in Revit. FireRating in the Cloud feedback. Vacation Time Now. Summer has seriously arrived in Europe, and the weather is really good as well, for a change. I took advantage of it this weekend and climbed the Alphubel... Read more →

Element Selection Changed Event

Many add-in developers are interested in being notified when the current selection changes in the Revit user interface. Among other things, it led to the implementation of the selection watcher using the Idling event and was one aspect of the discussion of element level events. Checking for Selection Changes in Idling Event Handler Ken Goulding submitted a comment on that, saying: When you mentioned "Element Level", I was hoping that included element selection events, but that does not seem to... Read more →

Opening and Activating Document in an Event Handler

I have been a busy beaver with the Revit API on the discussion forum in the past few days, and on GitHub as well. I want to take a closer look at two related issues that date back a little bit further: Switching active documents is not allowed during API event handling Loading a RVT project file automatically on start-up Let's discuss the first today and save the second for later. Before getting to that, I also want to mention... Read more →

AU Ends and Batch Rendering Across Several Projects

Let me share a couple of thoughts and a batch of links to discussions of topics related to batch processing that came up answering a case today in between all the hectic activity at Autodesk University. For my part, AU is over now, and I am already sitting in the airport waiting for the flight back to Europe and the series of West European DevDays conferences starting in Paris on Monday. The batch-processing topic was raised by this query: Question:... Read more →

The Revit API is Never Ever Thread Safe

Let us summarise and preserve this interesting Revit API forum discussion between Erik Eriksson, Ollikat and Arnošt Löbel on why the Revit API cannot safely be used from multiple threads under any circumstances whatsoever, even for read-only operations: Question: I've been using the Revit API for some years now, but I have never tried multithreaded requests. Basically because Autodesk told me that it will never work. I've now grown a little more confident and started testing a bit. So I... Read more →

Room Editor Live and Unofficial Custom Ribbon Button

I spent a wonderful weekend and yesterday's Whit Monday holiday enjoying high summer in Swiss nature with no electricity and a Chäschessi, the Swiss variant of a Jacuzzi or hot tub. Today I am leaving for a ten-day camping vacation in nature in Sweden. Here are two topics I would like to address before leaving that will hopefully keep you occupied and entertained during my absence: Room Editor Live Adding a custom button to the Modify tab Vacation time Room... Read more →

Revit as a Service and Sheet-View-Element Transforms

Several people recently brought up the question of running Revit as a service, e.g. in this Revit API forum discussion thread, so let us take a closer look at that. I also finally got around to making some seriously overdue progress on the RoomEditorApp, which I should really rename to SimplifiedBimEditorApp. It now displays a Windows preview form showing the sheets, the views, and the elements they contain in preparation to uploading them to a cloud database. While I'm at... Read more →

Determining the Quiescent State

I am still going through my emails after returning from the desert. Here is a summary of an interesting discussion between Katsuaki Takamizawa, Arnošt Löbel, Partha Sarkar, Joe Ye and Miroslav Schonauer on how to determine the quiescent state of Revit for accessing the API from a modeless context, and some recommendations to simply avoid that entirely, since other more efficient and stream-lined interaction models end up being easier to implement and more reliable to use. Question: I am using... Read more →

Wrangling Revisions with Ruby

Here is a write-up by Andy Holmes, Integration Specialist at OPX design consultancy on a Ruby project that uses a lot of different Revit API features, e.g., revisions on sheet, DMU updaters, Idling and document events, and creating a Ruby 'add-in' by using an application-level macro that has no macros in it. This write-up will soon be made available on the redesigned OPX website, and the code is already freely available on GitHub. Andy adds that Mat is colleague who... Read more →

Triggering Immediate External Event Execution

We held our first West European Devday in Paris on Monday and I am now sitting in the airport headed for Milano. En route to Milano, I worked at testing Joe Ye's trick to trigger the Idling event (potential SetRaiseWithoutDelay workaround) to force an immediate execution of my external event. I also added a comment from Guy Robinson on Revit requiring focus that had me worried for a moment. However, the solution is easy! Before we get to that, here... Read more →

Replacing an Idling Event Handler by an External Event

I arrived back in Europe safe and sound from America. Healthy, as well, in spite of air conditioning and the freezing temperatures in some of the Autodesk University conference rooms. Thank God, I went well prepared with long-sleeved woollen underwear and thick heavy sweaters to face the arctic challenges of the desert town. As I hinted at when describing my last day at AU, I realised that I can significantly improve the implementation of the RoomEditorApp subscription to real-time database... Read more →

AU Day 3, ReCap & Cloud-based Round-trip Model Editing

When you get to read this, I will be sitting in a plane at 30'000 feet over the middle of the Atlantic Ocean... or somewhere over Greenland, whatever. Thursday was the third and last day of Autodesk University. I went out for a quick beer with some of my ex-Autodesk-colleagues from decades ago on Wednesday evening, and a very nice time was had by all. It turned out to be not quite so quick, however, and not just one beer,... Read more →

RoomEditorApp Idling and Benchmarking Timer

I solved my two RoomEditorApp Idling issues! They were especially worrying due to the fact that I am planning to present this application in my Autodesk university class DV1736 on Cloud-Based, Real-Time, Round-Trip, 2D Revit Model Editing on Any Mobile Device. By the way, you should now enrol in the AU classes you are interested in – unless you already did :-) Go to the AU class catalogue, sign in, click 'View All Classes', use the filters or keyword search... Read more →

Singleton Application versus Multiple Command Instances

I recently discussed the RoomEditorApp external application, the Revit add-in part of my cloud-based real-time round-trip 2D Revit model editing application, while creating the RoomEditorApp GitHub repository and migrating it to Revit 2014. I also mentioned that I was mysteriously unable to unsubscribe from the Idling event. I raised this mystifying question with the development team and received a very satisfying answer, which includes some important information on how external applications and commands are handled and instantiated by the Revit... Read more →

RoomEditorApp Architecture and External Application

A couple of days ago, I wrote about creating the RoomEditorApp GitHub repository for the Revit add-in part of my cloud-based real-time round-trip 2D Revit model editing application on any mobile device and promised to discuss its implementation details anon. Well, the obvious place to start that is by providing an architectural overview, followed by a look at its external application implementation. I'll also mention an issue with unresponsive Idling that I am currently experiencing and hope to resolve, and... Read more →

No Command Launching from Dockable Panel

Here is an issue that has come up a few times now and is worthwhile clarifying: how to operate on a Revit document from a dockable panel. The dockable panel UI API framework was introduced in Revit 2014. Its use is demonstrated by the DockableDialogs SDK sample, including modeless dialog design and external events, and also by the simpler dockable panel sample. The fact that a dockable panel lives in a modeless context is apparently confusing for some. Since the... Read more →

The Revit Server REST API

Let's take a look at the material available for programmatic access to the Revit Server. This came up in a developer query on automatically extracting data from a Revit model housed there. The automatic extraction of data requires batch mode opening of a Revit model and launching of a command, for which there is no direct Revit API support. However, this can be easily worked around using normal batch files to start Revit with a given project file, an add-in... Read more →

Animation and the DisplacementElement Class

A recent developer query asks about animating elements in the Revit model and updating the display within a loop in the external command to show the step-by-step displacements. This provides a welcome opportunity to highlight another one of the Revit 2014 SDK Samples: The DisplacementElementAnimation SDK Sample One of the very visually impressive Revit 2014 API samples is the DisplacementElementAnimation application. It automatically animates groups of structural building members in any Revit BIM, proceeding sequentially from bottom level to top.... Read more →

Curve Length, Idling, Units and RevitPythonShell

Here are a couple of recent interesting questions that came up: Curve Length versus ApproximateLength Potential SetRaiseWithoutDelay workaround Unit handling improvements Self-contained RevitPythonShell deployment Curve Length versus ApproximateLength Question: What is the difference between the Curve Length and ApproximateLength properties, please? I am using them to obtain an arc wall length. As far as I can tell, the result is exactly the same, so which one should I normally use? Answer: All Revit geometry curves are parameterised. A curve is... Read more →

Behind the Scenes of the NBS Revit Add-in

Here is a guest post by Stephen Hamil of RIBA Enterprises, director of NBS, the national standard specification company in the UK, owned by the Royal Institute of British Architects. They just released the new version of their Revit plug-in that integrates the Revit design model with the NBS specification model, technical guidance and National BIM Library objects. Below, Chris and Calum from the NBS software development team give a little insight into some of the API functionality they used... Read more →

Tech Summit and More AutoExport Considerations

Today is the day I have been working towards with my cloud-based round-trip 2D Revit model editing project, which I am presenting this afternoon (cf. the 30-minute pre-recorded video). Before I get to that, I would like to pass on the following thoughts and suggestions on yesterday's auto PDF batch printing system from Constantin Gherasim of Genivar Inc. on a similar project of his own, up in use and running for over a year already, expanding on what he already... Read more →

Auto PDF Print from Revit 2014

Below, we will take a look at a Revit multi-project batch PDF printer project driven by the Windows task scheduler and the Revit Idling event. Before getting to that, though, let me share some of my Sunday activities. Contact Impro Jam and Tech Summit Arrival From the Fells, I continued along the Mystic Valley Parkway and stopped to enjoy the beautiful Mystic Lakes on my way to the weekly Sunday contact improvisation jam in the Arlington Center, followed by a... Read more →

Copy and Paste API Applications and Modeless Assertion

Here is a detailed description of one of the most exciting Revit 2014 API features that you should have heard about by now and promises numerous uses, prompted by a question from a developer on duplicating views from one document to another. Another couple of uses of it cropped up in the past, so it seems like an overview is called for: Duplicating a view from one document to another Solving the non-unique unique id problem Managing materials in adsklib... Read more →

What I Do, Wall Layers and Open Transactions

One of my tasks today and tonight will be a minimal little contribution to an in... Read more →

AU Classes on Python, UI, Server and Framework APIs

Thursday was another very full and fruitful day at AU. I gave my third and last class, the most exciting one in my eyes, on some UI and integration aspects. I was unable to attend Iffat May's class introducing Python and using it in Revit and Vasari via RevitPythonShell, but I love her material so much I am including it anyway. Adam Nagy presented a class addressing cloud and mobile development and the Revit Server API. Finally, Arnošt Löbel provided... Read more →

Updater Queues Multi-Transaction Operation for Idling

I recently pointed out that certain operations require multiple transactions to complete. The dynamic model updater framework DMU, on the other hand, takes complete control over the transaction handling, making it impossible to incorporate such a multi-transaction operation. The updater framework is designed to enable an add-in to incorporate its own additional behaviour into a running transaction to react to changes in the model. The advantage is that the entire operation including the custom add-in behaviour is encapsulated in one... Read more →

Drive Revit through a WCF Service

Today, a special titbit for you: How can I access Revit functionality from an external process? As we have underlined many times in the past, the Revit API does not support any kind of asynchronous access. The Idling event, however, provides a possibility to work around this limitation. Daren Thomas, the author or RevitPythonShell, even presented a neat and clean pattern for semi asynchronous Idling API access. Now Victor Chekalin, aka Виктор Чекалин, presents another very neat sample providing such... Read more →

UIView, Windows Coordinates, ReferenceIntersector and My Own Tooltip

Here is my well-meant contribution to making this the most exciting Wednesday of your entire week. For the first time in history, the Revit 2013 UIView class provides a possibility to convert back and forth between Revit model coordinates and Windows device screen points. I imagined making use of that right away when I read about the UIView class, and mentioned it when discussing UIView and Windows device coordinates. I am still a bit surprised that I have not yet... Read more →

DevCamp Day Two

This morning I presented my second session, on some of the Revit 2013 UI API enhancements, in the Revit API beginner track. After that, I returned back to the Revit API expert one to attend the presentations on modeless interaction and IFC before presenting my final session on the Revit MEP API. Here then are my sessions of today, in chronological order: 1-4 Revit 2013 UI API enhancements 2-3 Asynchronous interactions 2-2 IFC export open source 2-7 Revit MEP API... Read more →

Prompt User to Avoid Modeless Interaction

Once again on the topic of asynchronous interaction with Revit, which is not supported by the Revit API, and often worked around using the Idling and external events... As I recently pointed out, no Revit API methods at all can be called outside a valid Revit API context, not even the new DoDragDrop method or Application.IsQuiescent property. I already presented two convincing examples in the past of how you could work around a lack of direct API access by interacting... Read more →

Drag and Drop API

We already looked at what can be done using drag and drop in Revit 2012. At that point, an external Windows application could be used to initiate a standard Revit drag and drop sequence, but we had no control over Revit's behaviour on receiving the dropped files. This has changed in the Revit 2013 API, which provides a drag and drop API as part of the add-in integration features and includes the UIAPI sample in the Revit SDK to demonstrate... Read more →

Idling Enhancements and External Events

Revit 2013 has been released, and I presented an overview of the Revit 2013 API and the new SDK samples last week. One of the areas of enhancement is the Idling event and interaction with modeless dialogues, which also was the subject of Arnošt Löbel's Autodesk University 2011 class CP5381 on asynchronous interactions and managing modeless UI. As I mentioned, the enhancements and new functionality are demonstrated by the new ModelessForm_ExternalEvent and ModelessForm_IdlingEvent SDK samples. Here is an overview of... Read more →

New Revit 2013 SDK Samples

Revit 2013 has been released, and I presented an overview of the Revit 2013 API two days ago. As always, the use of most of the API features is demonstrated by various SDK samples. For a better understanding of the use and contents of the Revit SDK in general, please refer to the getting started and self-preparation guides. Here is an overview of the new samples: ModelessForm_ExternalEvent and ModelessForm_IdlingEvent (ModelessDialog) ProgressNotifier (Events) RoutingPreferenceTools UIAPI WorkThread (MultiThreading) These samples are all... Read more →

Revit Webcam 2012

I recently discussed the elimination of warnings about use of deprecated API methods from The Building Coder samples. In a similar vein, and for similar reasons, I also decided to migrate to Revit 2012 and clean up the RevitWebcam sample that I implemented to demonstrate the use of the Idling event when it was first introduced in the Revit 2011 API. Please note that this sample is intentionally not related to any BIM specific workflow. A webcam just provides an... Read more →