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C3D-PARCELLBL · Label 19 PARCEL lines: bearing + distance done

MText bearing+distance at each PARCEL line midpoint (rotated, upright) on C-PROP-LINE-TEXT. Idempotent. C3D-22.

C# payload

// Label the 19 Line entities on layer "PARCEL" with bearing + distance.
// MText at each line midpoint, rotated to the line, on layer C-PROP-LINE-TEXT.
// Idempotent: skip a line if an MText already sits within 1' of its midpoint on the label layer.
using System;
using System.Collections.Generic;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;

var db = Db;
const string SRC_LAYER = "PARCEL";
const string LBL_LAYER = "C-PROP-LINE-TEXT";
const double TXT_HT = 5.0;   // model units (survey feet); tune later, it's a draft

EnsureLayer(LBL_LAYER, 2);

string Bearing(Point3d a, Point3d b)
{
    double dx=b.X-a.X, dy=b.Y-a.Y;
    string ns = dy>=0 ? "N" : "S";
    string ew = dx>=0 ? "E" : "W";
    double q = Math.Atan2(Math.Abs(dx), Math.Abs(dy)) * 180.0/Math.PI; // angle off the N-S axis
    int deg=(int)q; double mf=(q-deg)*60; int min=(int)mf; int sec=(int)Math.Round((mf-min)*60);
    if(sec==60){sec=0;min++;} if(min==60){min=0;deg++;}
    return $"{ns}{deg:00}°{min:00}'{sec:00}\"{ew}";
}

int labeled=0, skipped=0;
using (var tr = db.TransactionManager.StartTransaction())
{
    var ms = (BlockTableRecord)tr.GetObject(SymbolUtilityServices.GetBlockModelSpaceId(db), OpenMode.ForWrite);

    // gather existing label midpoints (idempotency)
    var existing = new List<Point3d>();
    foreach (ObjectId id in ms)
    {
        var e = tr.GetObject(id, OpenMode.ForRead);
        if (e is MText m && string.Equals(m.Layer, LBL_LAYER, StringComparison.OrdinalIgnoreCase))
            existing.Add(m.Location);
    }

    // collect the PARCEL lines first (don't add while iterating the same btr open-for-read set)
    var lines = new List<Line>();
    foreach (ObjectId id in ms)
    {
        var e = tr.GetObject(id, OpenMode.ForRead) as Autodesk.AutoCAD.DatabaseServices.Entity;
        if (e is Line ln && string.Equals(e.Layer, SRC_LAYER, StringComparison.OrdinalIgnoreCase))
            lines.Add(ln);
    }
    Log($"PARCEL lines found: {lines.Count}");

    foreach (var ln in lines)
    {
        var mid = new Point3d((ln.StartPoint.X+ln.EndPoint.X)/2, (ln.StartPoint.Y+ln.EndPoint.Y)/2, 0);
        bool dupe=false;
        foreach (var p in existing) if (p.DistanceTo(mid) < 1.0) { dupe=true; break; }
        if (dupe) { skipped++; continue; }

        double ang = Math.Atan2(ln.EndPoint.Y-ln.StartPoint.Y, ln.EndPoint.X-ln.StartPoint.X);
        if (ang > Math.PI/2 || ang < -Math.PI/2) ang += Math.PI; // keep text upright

        string txt = $"{Bearing(ln.StartPoint, ln.EndPoint)}  {ln.Length:0.00}'";

        var mt = new MText();
        mt.SetDatabaseDefaults();
        mt.Layer = LBL_LAYER;
        mt.Location = mid;
        mt.TextHeight = TXT_HT;
        mt.Rotation = ang;
        mt.Attachment = AttachmentPoint.MiddleCenter;
        mt.Contents = txt;

        ms.AppendEntity(mt);
        tr.AddNewlyCreatedDBObject(mt, true);
        existing.Add(mid);
        labeled++;
    }
    tr.Commit();
}
Log($"DONE. labeled={labeled}, skipped(existing)={skipped}. Layer '{LBL_LAYER}'. Re-run is idempotent.");

Result

PARCEL lines found: 19
DONE. labeled=19, skipped(existing)=0. Layer 'C-PROP-LINE-TEXT'. Re-run is idempotent.