manual_wpf/NoteDetectionRefactor.md

Project: Refactor the NOTE Content Box Detection Algorithm

1. High-Level Goal: The primary objective is to replace the current, fragile “horizontal search line” algorithm in Models/DwgDataExtractor.cs with a more robust and accurate method that reliably finds the content box for any “NOTE” text, regardless of its position or the composition of its bounding box.

2. Core Strategy: “Vertical Ray-Casting” We will implement a new algorithm that emulates how a human would visually locate the content. This involves a “gradual downward scan” (or vertical ray-cast) from the NOTE’s position.

3. Implementation Plan (TODO List):

• Step 1: Unify All Geometry into Line Segments

  • Create a single helper method, GetAllLineSegments, that processes all Line and Polyline entities from the drawing.
  • This method will decompose every Polyline into its constituent Line segments.
  • It will return a single, unified List containing every potential boundary segment in the drawing.
  • Crucially: This method must ensure all temporary Line objects created during the process are properly disposed of to prevent memory leaks.

• Step 2: Implement the Ray-Casting Logic in FindNoteBox

  • The FindNoteBox method will be completely rewritten.
  • It will first call GetAllLineSegments to get the unified geometry list.
  • It will then perform the vertical ray-cast starting from the NOTE’s X-coordinate and scanning downwards.
  • It will find all horizontal lines that intersect the ray and sort them by their Y-coordinate (from top to bottom).
  • It will identify the second line in this sorted list as the top edge of the content box (the first is assumed to be the NOTE’s own bounding box).

• Step 3: Implement Smart Box Tracing

  • Create a new helper method, TraceBoxFromTopLine.
  • This method will take the identified top line segment as its starting point.
  • It will intelligently trace the remaining three sides of the rectangle by searching the unified list of line segments for the nearest connecting corners.
  • This tracing logic must be tolerant of small gaps between the endpoints of the lines forming the box.

• Step 4: Final Cleanup

  • Once the new ray-casting algorithm is fully implemented and validated, all of the old, obsolete methods related to the previous search-line approach must be deleted to keep the code clean. This includes:
    • FindIntersectingLineSegments
    • TraceRectangleFromLineSegments
    • FindNextConnectedLineSegment
    • DoesLineIntersectPolyline
    • GetPolylineBounds