Exporting particular entities from CAD files using Aspose.CAD for .NET

Sometimes need arise to export only some particular entities from a CAD file. It may not be obvious how to do this. However, in reality it is a very simple thing to do with Aspose.CAD for .NET. The method described in this article works for DWG, DXF and STL files.

For these files, a loaded file Image is actually a descendant or an instance of CadImage class, which has Entities property. This property is an array containing all entities from a file in form of CadBaseEntity class instances. Exporting particular entities is as simple as retrieving this array, picking any entities you need, putting them into another array and setting Entities property back with this array.

Here is an example where only TEXT entities are left to display:

using System;
using System.Collections.Generic;
using Aspose.CAD;
using Aspose.CAD.FileFormats.Cad;
using Aspose.CAD.FileFormats.Cad.CadConsts;
using Aspose.CAD.FileFormats.Cad.CadObjects;
using Aspose.CAD.ImageOptions;

namespace LineCapDemo
{
    class Program
    {
        static void Main()
        {
            string fileName = "TestFile.dwg"; 
            try 
            { 
                //Casting loaded Image to CadImage
                //as plain Image doesn't have Entities property
                CadImage cadImage = (CadImage)Image.Load(fileName); 

                CadRasterizationOptions rasterizationOptions = new CadRasterizationOptions(); 
                rasterizationOptions.PageWidth = cadImage.Width * 100; 
                rasterizationOptions.PageHeight = cadImage.Height * 100; 

                PdfOptions pdfOptions = new PdfOptions();

                //Retrieving all entities
                CadBaseEntity[] entities = cadImage.Entities;
                List<CadBaseEntity> filteredEntities = new List<CadBaseEntity>();

                foreach (CadBaseEntity entity in entities)
                {
                    //selecting only entities of TEXT type
                    if(entity.TypeName == CadEntityTypeName.TEXT)
                        filteredEntities.Add(entity);
                }

                //Making array of filtered entities
                entities = filteredEntities.ToArray();
                //Now only filtered entities are left in image
                cadImage.Entities = entities;

                pdfOptions.VectorRasterizationOptions = rasterizationOptions; 
                string outPath1 = fileName + "_flat" + ".pdf"; 
                Console.WriteLine("output path: " + outPath1); 
                cadImage.Save(outPath1, pdfOptions); 
            } 
            catch (Exception ex) 
            { 
                Console.WriteLine(ex.Message); 
            } 
        }
    }
}

As you see, you can filter the entities whatever way you want, just assign whatever you selected back to Entities property and it's done.