From c8b00bb929b372e67ce5e77bda27bc6d92dd44a8 Mon Sep 17 00:00:00 2001
From: darshanr0107 <darshan@mermaidchart.com>
Date: Thu, 14 Aug 2025 13:13:48 +0530
Subject: [PATCH] fix: revert the curve setting for edges

on-behalf-of: @Mermaid-Chart <hello@mermaidchart.com>
---
 .../rendering-elements/edges.js               | 117 +++++++++++++-----
 1 file changed, 84 insertions(+), 33 deletions(-)

diff --git a/packages/mermaid/src/rendering-util/rendering-elements/edges.js b/packages/mermaid/src/rendering-util/rendering-elements/edges.js
index 84331aaf2..9833f65ac 100644
--- a/packages/mermaid/src/rendering-util/rendering-elements/edges.js
+++ b/packages/mermaid/src/rendering-util/rendering-elements/edges.js
@@ -352,41 +352,92 @@ const cutPathAtIntersect = (_points, boundaryNode) => {
   return points;
 };
 
-const adjustForArrowHeads = function (lineData, size = 5) {
-  if (!Array.isArray(lineData) || lineData.length < 2) {
-    return lineData;
+function extractCornerPoints(points) {
+  const cornerPoints = [];
+  const cornerPointPositions = [];
+  for (let i = 1; i < points.length - 1; i++) {
+    const prev = points[i - 1];
+    const curr = points[i];
+    const next = points[i + 1];
+    if (
+      prev.x === curr.x &&
+      curr.y === next.y &&
+      Math.abs(curr.x - next.x) > 5 &&
+      Math.abs(curr.y - prev.y) > 5
+    ) {
+      cornerPoints.push(curr);
+      cornerPointPositions.push(i);
+    } else if (
+      prev.y === curr.y &&
+      curr.x === next.x &&
+      Math.abs(curr.x - prev.x) > 5 &&
+      Math.abs(curr.y - next.y) > 5
+    ) {
+      cornerPoints.push(curr);
+      cornerPointPositions.push(i);
+    }
   }
-  const newLineData = [...lineData];
-  const lastPoint = lineData[lineData.length - 1];
-  const secondLastPoint = lineData[lineData.length - 2];
+  return { cornerPoints, cornerPointPositions };
+}
 
-  const distanceBetweenLastPoints = Math.sqrt(
-    (lastPoint.x - secondLastPoint.x) ** 2 + (lastPoint.y - secondLastPoint.y) ** 2
-  );
-
-  if (distanceBetweenLastPoints < size) {
-    // Calculate the direction vector from the last point to the second last point
-    const directionX = secondLastPoint.x - lastPoint.x;
-    const directionY = secondLastPoint.y - lastPoint.y;
-
-    // Normalize the direction vector
-    const magnitude = Math.sqrt(directionX ** 2 + directionY ** 2);
-    const normalizedX = directionX / magnitude;
-    const normalizedY = directionY / magnitude;
-
-    // Calculate the new position for the second last point
-    const adjustedSecondLastPoint = {
-      x: lastPoint.x + normalizedX * size,
-      y: lastPoint.y + normalizedY * size,
-    };
-
-    // Replace the second last point in the new line data
-    newLineData[newLineData.length - 2] = adjustedSecondLastPoint;
-  }
-
-  return newLineData;
+const findAdjacentPoint = function (pointA, pointB, distance) {
+  const xDiff = pointB.x - pointA.x;
+  const yDiff = pointB.y - pointA.y;
+  const length = Math.sqrt(xDiff * xDiff + yDiff * yDiff);
+  const ratio = distance / length;
+  return { x: pointB.x - ratio * xDiff, y: pointB.y - ratio * yDiff };
 };
 
+const fixCorners = function (lineData) {
+  const { cornerPointPositions } = extractCornerPoints(lineData);
+  const newLineData = [];
+  for (let i = 0; i < lineData.length; i++) {
+    if (cornerPointPositions.includes(i)) {
+      const prevPoint = lineData[i - 1];
+      const nextPoint = lineData[i + 1];
+      const cornerPoint = lineData[i];
+
+      const newPrevPoint = findAdjacentPoint(prevPoint, cornerPoint, 5);
+      const newNextPoint = findAdjacentPoint(nextPoint, cornerPoint, 5);
+
+      const xDiff = newNextPoint.x - newPrevPoint.x;
+      const yDiff = newNextPoint.y - newPrevPoint.y;
+      newLineData.push(newPrevPoint);
+
+      const a = Math.sqrt(2) * 2;
+      let newCornerPoint = { x: cornerPoint.x, y: cornerPoint.y };
+      if (Math.abs(nextPoint.x - prevPoint.x) > 10 && Math.abs(nextPoint.y - prevPoint.y) >= 10) {
+        log.debug(
+          'Corner point fixing',
+          Math.abs(nextPoint.x - prevPoint.x),
+          Math.abs(nextPoint.y - prevPoint.y)
+        );
+        const r = 5;
+        if (cornerPoint.x === newPrevPoint.x) {
+          newCornerPoint = {
+            x: xDiff < 0 ? newPrevPoint.x - r + a : newPrevPoint.x + r - a,
+            y: yDiff < 0 ? newPrevPoint.y - a : newPrevPoint.y + a,
+          };
+        } else {
+          newCornerPoint = {
+            x: xDiff < 0 ? newPrevPoint.x - a : newPrevPoint.x + a,
+            y: yDiff < 0 ? newPrevPoint.y - r + a : newPrevPoint.y + r - a,
+          };
+        }
+      } else {
+        log.debug(
+          'Corner point skipping fixing',
+          Math.abs(nextPoint.x - prevPoint.x),
+          Math.abs(nextPoint.y - prevPoint.y)
+        );
+      }
+      newLineData.push(newCornerPoint, newNextPoint);
+    } else {
+      newLineData.push(lineData[i]);
+    }
+  }
+  return newLineData;
+};
 export const insertEdge = function (elem, edge, clusterDb, diagramType, startNode, endNode, id) {
   const { handDrawnSeed } = getConfig();
   let points = edge.points;
@@ -434,8 +485,8 @@ export const insertEdge = function (elem, edge, clusterDb, diagramType, startNod
   }
 
   let lineData = points.filter((p) => !Number.isNaN(p.y));
-  lineData = adjustForArrowHeads(lineData);
-  // lineData = fixCorners(lineData);
+  //lineData = adjustForArrowHeads(lineData);
+  lineData = fixCorners(lineData);
   let curve = curveBasis;
   curve = curveLinear;
   switch (edge.curve) {