Added per link styling

Edited flowDB.ts which already had interpolate for styling links
individually. Added the ability to modify this parameter using the
newer @ syntax using the curve property.

packages/mermaid/src/diagrams/flowchart/flowDb.ts

@@ -139,6 +139,9 @@ export class FlowDB implements DiagramDB {
       if (edgeDoc?.animation !== undefined) {
         edge.animation = edgeDoc.animation;
       }
+      if (edgeDoc?.curve !== undefined) {
+        edge.interpolate = edgeDoc.curve;
+      }
       return;
     }
 

packages/mermaid/src/types.ts

@@ -16,6 +16,19 @@ export interface NodeMetaData {
 export interface EdgeMetaData {
   animation?: 'fast' | 'slow';
   animate?: boolean;
+  curve?:
+    | 'basis'
+    | 'bumpX'
+    | 'bumpY'
+    | 'cardinal'
+    | 'catmullRom'
+    | 'linear'
+    | 'monotoneX'
+    | 'monotoneY'
+    | 'natural'
+    | 'step'
+    | 'stepAfter'
+    | 'stepBefore';
 }
 import type { MermaidConfig } from './config.type.js';