Through the Interface

Merging AutoCAD blocks using .NET

I decided to dust off Visual Studio and write a quick AutoCAD app, this morning. It tackles a question received via a blog comment from Pankaj Potdar, over the weekend. I have two blocks with different attributes I want to merge them in single block, and I don't want to create any nested blocks. I haven’t had much time to spend on AutoCAD, of late. Part of the reason has been work-related: I’m heads-down getting the VR/AR track in shape for the upcoming Forge DevCon, as well as spending time on new duties in Autodesk Research. The other part... Read more →

Creating AutoCAD Xrefs as overlays with relative paths using .NET

After showing how to automatically attach xrefs at the origin inside AutoCAD, and then redoing the approach to take care of different unit systems, I then had the request from a couple of places to look at making the xrefs overlays and adjusting their paths to be relative rather than absolute. Looking around, I found some code on the AutoCAD DevBlog that changes an attachment to an overlay, after the fact. Henrik Ericson found the code didn’t work for him, but did spot the db.OverlayXref() method which did. So I went ahead and made use of that for overlays.... Read more →

Converting units between different AutoCAD drawings using .NET

This is actually a redo of last week’s post, just with a different title: while the approach shown worked well when creating external references to drawings using the same units, when bringing in (for instance) metric xrefs into an imperial master drawing the scale was all messed up. Thanks to Hans Lammerts for reporting the issue. The scaling ended up being straightforward to implement: the hard work was done by UnitsConverter.GetConversionFactor(), which established the scale factor to use, converting between the Units property of the new block table record and the Insunits property of the target database. Then it... Read more →

Attaching AutoCAD Xrefs and inserting them at the origin using .NET

I just received this interesting (and quick to solve) question from Henrik Ericson, this morning: I’m looking for a new xref command (or perhaps overriding the internal xref command) that always insert the selected xref at 0,0,0 coordinates and in World coordinate system. I’m often inserting an xref and ’nothing happens’ and then I realize that I’m in a UCS. I created a simple command called XAO – for XrefAttach[At]Origin – that does just this. As a helper function I implemented a simple extension method to both attach and insert an external reference in the current space of the... Read more →

Launching AutoCAD’s REFEDIT command with an entity selected using .NET

A really interesting problem came up during an internal discussion, this week: someone wanted to launch the REFEDIT command on a selected xref and pre-select the entity found at the picked point. The entity that’s part of the selected xref, of course. This turned out to be quite a tricky problem and yet one that could be solved with relatively few lines of code. The tricky parts were finding the right entity in the nested selection and then the corresponding entity in the xref. Here’s the approach I ended up taking: Ask the user to selected a nested entity... Read more →

Adjusting the size of multiple AutoCAD text and block attribute objects to fit their containers using .NET

This is a follow-up to the post where we modified the size of selected text in a drawing, to make it fit its container. I received this comment last week: instead of selecting the nested entities one by one, is it possible to make a "selectall" selection ? It turns out that the question was related to a completely different post, but by the time I realised I’d already completed most of the work. It seems a very valid question for this topic, so that’s fine. :-) Looping through all the text – some of which may be nested... Read more →

Adjusting the size of AutoCAD text and block attributes to fit their containers using .NET

We started this series by looking at how to get the centroid of a region, and then how to create text that fits an arbitrary space. In this post we’re going to wrap up by looking at the original question of how to resize block attributes to fit their container. The core algorithm is actually very similar to the code we saw in “space labelling” application: it’s simply been refactored to be more general and forms the basis for both the previous and the new commands. Here’s the C# code: using Autodesk.AutoCAD.ApplicationServices; using Autodesk.AutoCAD.BoundaryRepresentation; using Autodesk.AutoCAD.DatabaseServices; using Autodesk.AutoCAD.EditorInput; using... Read more →

Preventing AutoCAD objects from being purged using .NET – Part 2

In the last post we introduced a static C# class containing extension methods for the ObjectId and Transaction classes. The new Transaction methods allow you to more easily “lock” objects, whether because they’re “system” objects you want to keep around in every drawing or because they’re objects that shouldn’t be purged at whim by users. Under the hood, the implementation uses Xrecords stored in the Named Objects Dictionary that contain hard-pointer references to the various locked objects. This stops the PURGE command from removing them, but also allows us to check via Database.Purge() – or our new ObjectId.IsErasable() shortcut... Read more →

Preventing AutoCAD objects from being purged using .NET – Part 1

This is one of those topics that has been at the back of my mind for a number of years. Here’s a question I received via a blog comment back in 2009: I was wondering if there's an easy way to modify the objects to purge. For example, if a particular text style was included in the drawing that I did not want to be purged. Can this easily be done? Here’s how I responded, at the time: There are a couple of ways: You can maintain your own list of objects "to keep" and remove any items that... Read more →

Checking for built-in AutoCAD objects using .NET

This interesting question came in by email from Igor, over the weekend: Let say I want to delete a layer by it's name. I can get ObjectId or LayerTabelRecord from the name, like LayerTable tLayers = (LayerTable) Transaction.GetObject(Database.LayerTableId,OpenMode.ForRead,false) LayerTableRecord ltRecord = (LayerTableRecord) Transaction.GetObject(tLayers.Item[Name],OpenMode.ForWrite,false); Now having LayerTableRecord how can I found out that this DBObject is not the built-in one? Like names '0' or 'DEFPOINTS'. Same goes for TextStyle (STANDARD) or layout (MODEL)….? I can't found any property regarding this, like IsBuiltIn. The IsPersistent property is no help. It’s true that there isn’t an IsBuiltIn property on AutoCAD objects… for... Read more →

Adding a symbol overlay to an AutoCAD table cell using .NET

While my last post on tables was apparently interesting, it turns out it didn’t actually address the question that inspired it. Oh well. Here’s a recent comment that gave greater clarity on the requirement: Do you know those no smoking signs commonly seen in public places: a cigarette with a red cross struck through it. Can a similar thing be done programmatically in a table with the strike through happening through a number. A picture is worth a 1000 words: http://imgur.com/gallery/qPzEm... In other words, can a block be inserted into a particular cell which already contains a number value?... Read more →

Adding a new column to an existing AutoCAD table using .NET

After the last post, where we saw some code that creates an AutoCAD table based on the blocks in a drawing, in this post we’re going to modify our table, adding a new, initial column that numbers the contents. Here’s what we want to create using our new MBT command: Here’s the way the command looks when it runs: And, finally, here’s the updated C# code with our new MBT command: using Autodesk.AutoCAD.ApplicationServices; using Autodesk.AutoCAD.DatabaseServices; using Autodesk.AutoCAD.EditorInput; using Autodesk.AutoCAD.Runtime; namespace TableCreationAndModification { public class Commands { const double rowHeight = 3.0, colWidth = 5.0; const double textHeight = rowHeight... Read more →

Creating a table of AutoCAD blocks using .NET

This post – and the one to follow it – were inspired by a comment on this old post (which in many ways is quite similar to this one, just using an older syntax and starting with a static array of table data). We’re creating a table with information about the various blocks in the block table of the current drawing: in this post we create the basic table containing the table name and its thumbnail, while in the next post we’re going add some additional (and as-yet-to-be-determined) information. The basic point is to show how to manipulate an... Read more →

Replacing AutoCAD blocks with Xrefs using .NET

I mentioned in a recent post about some code I put together to replace a drawing’s internal block structure with external references. The code determines the blocks used in the modelspace and then works through, saving each to a file via the wblock mechanism and then attaching them back in as Xrefs. The code was surprisingly easy to put together. It’s a bit on the destructive side – it rips out blocks and creates equivalent drawings in the temp folder – so I do suggest running this on a copy of your drawings. But as part of a process... Read more →

Preventing an AutoCAD block from being exploded using .NET (redux)

When I was a boy, I used to love going to play with toys at my grandmother’s house. My absolute favourite was a die-cast Batmobile made by Corgi in the UK. What I particularly liked about this toy was its hidden features: the cars apparently came with secret instructions, although these were nowhere to be seen by the time I started playing with it. The Batmobile had plastic flames that came out of the exhaust when the rear wheels turned and spring-loadable, vertical rocket launchers. The biggest surprise was when I discovered the cutting blade that popped out of... Read more →

Jigging an AutoCAD block with attributes using .NET (redux)

Our old friend Roland Feletic emailed me last week. He’d been having some trouble with this previous post when jigging blocks with multiline attributes. Roland had also identified some code in this post on another blog which worked properly for him. I spent some time looking into what was wrong with the original post. It certainly didn’t deal with the appropriate placement of multiline text, and didn’t take proper care of annotation scaling and UCS. Time for a do-over. :-) The following C# code is a combination of the code from the previous post and the approach spiderinnet1 took... Read more →

Exploding nested AutoCAD blocks using .NET

Some time ago I posted about how to use Entity.Explode() to do something similar to AutoCAD’s EXPLODE command. At the time it was mentioned in the comments that BlockReference.ExplodeToOwnerSpace() had some relative benefits, but it’s taken me some time to code up a simple sample to show how you might use it (Patrick’s recent comment reminded me I ought to, though). Anyway, to end the week I thought I’d throw together a quick sample. BlockReference.ExplodeToOwnerSpace() doesn’t return a list of created objects, so I opted to capture this using a Database.ObjectAppended event handler and then recursively call our custom... Read more →

Moving text in an AutoCAD block using .NET – Part 3

I wasn’t expecting to write a third part in this series of posts, but then Samir Bittar went and asked a follow-up question that I felt obliged to look into. Thanks for the suggestion, Samir! :-) Samir basically wanted to provide the user with more feedback as they’re selecting the nested entity – so that the sub-entity gets highlighted, rather than the full block reference. This turned out to be quite a tricky scenario to address. The overall approach I used was to use a PointMonitor to perform a non-interactive, nested selection of the geometry beneath the cursor and... Read more →

Moving text in an AutoCAD block using .NET – Part 2

I was planning to post about Autodesk University 2013 today, but things have just been too hectic. I have a 3-hour layover in Heathrow on the journey home – which starts this evening – so I’ll try to use that to post a summary of this year’s AU as experienced by yours truly. In the last post we saw some code to move an entity – any entity, with text as the primary requirement – in a block. Here’s a version of the C# code that shows the entity as it’s being jigged across the screen to its new... Read more →

Moving text in an AutoCAD block using .NET – Part 1

I had this question come in from Bruce Gordon by email a couple of weeks ago, and it seemed like a fun one to look at: Is it possible to write a utility to pick a text entity in a block reference and move it to a new location? As a first step, I put together some code that launches a nested entity selection and then performs a translation of the selected entity by a specified displacement from the picked point. Given the requirement in the original request, the code works “first time” for text entities (DBText and MText),... Read more →