From 91d2ff35734fd1ab3ce90c4c5ef25ea2b801a3f2 Mon Sep 17 00:00:00 2001
From: DJP <DJP>
Date: Mon, 20 Oct 2025 16:33:47 -0400
Subject: [PATCH] Fix coordinate origin - remove Y-axis flipping
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Issue: Markers still misaligned after DPI scaling
Cause: pdfplumber uses top-left origin, I was flipping Y incorrectly
Fix: Remove Y-flip - both pdfplumber and SVG use top-left (0,0)

Coordinate Systems:
- pdfplumber: (0,0) = top-left, y increases DOWN
- SVG: (0,0) = top-left, y increases DOWN
- Standard PDF: (0,0) = bottom-left, y increases UP

Since pdfplumber already gives us top-left coords, just scale, don't flip!

Now: x_pixel = x_pdf × scale, y_pixel = y_pdf × scale

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 index.html | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/index.html b/index.html
index cc30d8d..b061ebf 100644
--- a/index.html
+++ b/index.html
@@ -1344,17 +1344,18 @@
             pageIssues.forEach((issue, index) => {
                 const coords = issue.coordinates;
 
-                // Scale PDF coordinates to image pixels
-                // PDF coordinates are bottom-left origin, need to flip Y and scale
+                // Scale coordinates from PDF points to image pixels
+                // pdfplumber uses top-left origin (0,0 = top-left), same as SVG
+                // So NO Y-flipping needed, just scale!
                 const x0 = coords.x0 * scaleFactor;
+                const y0 = coords.y0 * scaleFactor;  // coords.y0 is 'top' from pdfplumber
                 const x1 = coords.x1 * scaleFactor;
-                const y0 = imgHeight - (coords.y1 * scaleFactor); // Flip Y
-                const y1 = imgHeight - (coords.y0 * scaleFactor); // Flip Y
+                const y1 = coords.y1 * scaleFactor;  // coords.y1 is 'bottom' from pdfplumber
 
                 const width = x1 - x0;
                 const height = y1 - y0;
 
-                console.log(`Issue ${index + 1}: PDF coords (${coords.x0}, ${coords.y0}) → Screen (${x0.toFixed(0)}, ${y0.toFixed(0)}), size: ${width.toFixed(0)}x${height.toFixed(0)}`);
+                console.log(`Issue ${index + 1}: PDF (${coords.x0}, ${coords.y0}, ${coords.x1}, ${coords.y1}) → Pixels (${x0.toFixed(0)}, ${y0.toFixed(0)}, ${x1.toFixed(0)}, ${y1.toFixed(0)}), size: ${width.toFixed(0)}x${height.toFixed(0)}`);
 
                 // Color based on severity
                 let strokeColor, fillColor;