topic Re: Selection Limitation by Category in Revit API Forum

Selection Limitation by Category

Anonymous — Sun, 30 Aug 2015 06:27:06 GMT

Hi Revit API community,

I am a newbie in Revit API and on my way to create a simple command which can “limit user selection by category” with the code snippet shown below.

My purpose:

While the command is active: only wall category is selectable
After command is ended: the selected elements become current select element set

Step 1 is now working fine since only wall category is selectable while the command is active (refer to the attached screenshot for detail)

Please show me how to continue with step 2 to set selected reference as current select element set after ending the command.

Any help would be appreciated

Thanks

Code snippet:

namespace CategorySelector
{
    [Autodesk.Revit.Attributes.Transaction(Autodesk.Revit.Attributes.TransactionMode.Manual)]
    public class Command : IExternalCommand
    {
        public Autodesk.Revit.UI.Result Execute(ExternalCommandData commandData, ref string message, ElementSet element)
        {
            UIApplication uiApp = commandData.Application;
            Document doc = uiApp.ActiveUIDocument.Document;
            Selection sel = uiApp.ActiveUIDocument.Selection;

            // Limit element selection => works fine
            ISelectionFilter selFilter = new wallSelectionFilter(doc);
            IList<Reference> refWalls = sel.PickObjects(ObjectType.Element, selFilter, "Please select wall");

            // How to convert selected reference list to elements?
            // How to set converted elements as current select element set?
            
            return Autodesk.Revit.UI.Result.Succeeded;
        }
      
        public class wallSelectionFilter : ISelectionFilter
        {
            Document doc = null;
            public wallSelectionFilter(Document document)
            {
                doc = document;
            }
                        
            public bool AllowElement(Element element)
            {
                return (element.Category.Id.IntegerValue.Equals((int)BuiltInCategory.OST_Walls));
            }
            public bool AllowReference(Reference refer, XYZ point)
            {
                return false;
            }
        }
    }
}

Re: Selection Limitation by Category

jeremytammik — Mon, 31 Aug 2015 11:56:13 GMT

Dear Mr. Hoa,

Congratulations on solving the first part of your task.

If you are new to the Revit API, make sure you have worked through and understood the basics before going any further, e.g. by studying the hand-on DevTV and My first Revit plugin tutorials provided with the getting started material:

http://thebuildingcoder.typepad.com/blog/about-the-author.html#2

The more you understand Revit from an end user point of view, the better you will be equipped to find optimal solutions for you programming and automation tasks.

Also make sure you have installed the help file and Revit SDK programming samples.

Your question is fully answered by one of the latter, in steps 3, 5, 7 and 9 of the DirectionCalculation SDK sample, cf. its readme file SDK/Samples/DirectionCalculation/CS/ReadMe_DirectionCalculation.rtf:

Instructions:

1. Open FindSouthFacing.rvt

2. Run external command “South Facing Walls Without ProjectLocation”

3. The walls that face south (without regard to the project’s location) are selected

4. Run external command “South Facing Walls With ProjectLocation”

5. The walls that face south (with regard to the project’s location) are selected

6. Run external command “South Facing Windows Without ProjectLocation”

7. The windows that face south (without regard to the project’s location) are selected

8. Run external command “South Facing Windows With ProjectLocation”

9. The windows that face south (with regard to the project’s location) are selected

More details on this sample are discussed by The Building Coder:

http://thebuildingcoder.typepad.com/blog/2010/06/highlight-elements.html

This kind of selection is also demonstrated by the Lab1_2_CommandArguments of the ADN Xtra labs:

https://github.com/jeremytammik/AdnRevitApiLabsXtra/blob/master/XtraCs/Labs1.cs

I hope this helps.

Best regards,

Jeremy

Re: Selection Limitation by Category

Anonymous — Tue, 01 Sep 2015 09:56:43 GMT

Dear Mr. Jeremy,

Thank you for spending time on providing me such useful information and detail instruction.

Your site (The Building Coder) covers plenty of such information which is out of my knowledge frame since I am not from programing discipline. I believe I will find much information for my coming questions from there.

Regarding my question, I finally found a suitable answer (of course from your information) for the second step. Although I am not sure this is the best and the only answer but anyway now the command works smoothly.

Cheer!

Sincerely

The answer found:

// Set the selected element set as current select element set
                ICollection<ElementId> wallIds = sel.GetElementIds();
                foreach (Reference r in refWalls)
                {
                    Element e = doc.GetElement(r);
                    wallIds.Add(e.Id);
                }
                UIDoc.Selection.SetElementIds(wallIds);