feat(lib): export edge utils #418

README.md

@@ -15,6 +15,7 @@ React Flow is a library for building node-based graphs. You can easily implement
 - [Edges](#edges)
   - [Options](#options)
   - [Edge Types & Custom Edges](#edge-types--custom-edges)
+  - [Edge Utils](#edge-utils)
 - [Components](#components)
   - [Background](#background)
   - [Minimap](#minimap)
@@ -289,7 +290,7 @@ If you wanted to display this edge, you would need a node with id = 1 (source no
 
 You can find an example with different edges in the [edges example](https://reactflow.dev/edges).
 
-### Edge Types & Custom Edges
+## Edge Types & Custom Edges
 
 The basic edge types are `default` (bezier), `straight`, `step` and `smoothedge`. The default `edgeTypes` object looks like this:
 
@@ -315,6 +316,49 @@ Now you could use the new type `special` for an edge.
 The `straight`, `default` and `step` types would still be available unless you overwrote one of them.
 There is an implementation of a custom edge in the [edges example](/example/src/Edges/index.js).
 
+## Edge Utils
+
+There are several utils that help you to create a custom edge. They are used in the [custom edge](/example/src/Edges/CustomEdge.js) example.
+
+### getBezierPath
+
+Returns the path of a bezier edge.
+
+`getBezierPath({
+  sourceX,
+  sourceY,
+  sourcePosition = Position.Bottom,
+  targetX,
+  targetY,
+  targetPosition = Position.Top,
+}: GetBezierPathParams): string`
+
+### getSmoothStepPath
+
+Returns the path of a smooth step edge. You can set `borderRadius` = `0` to get a step edge path.
+
+`getSmoothStepPath({
+  sourceX,
+  sourceY,
+  sourcePosition = Position.Bottom,
+  targetX,
+  targetY,
+  targetPosition = Position.Top,
+  borderRadius = 5,
+}: GetSmoothStepPathParams): string`
+
+### getEdgeCenter
+
+Returns the center poostion `[centerX, centerY]` of the edge.
+
+`getEdgeCenter({ sourceX, sourceY, targetX, targetY }: GetCenterParams): [number, number, number, number]`
+
+### getMarkerEnd
+
+Returns the marker end url for displaying the arrow head.
+
+`getMarkerEnd(arrowHeadType?: ArrowHeadType, markerEndId?: string): string`
+
 # Components
 
 ## Background

example/src/Edges/CustomEdge.js

@@ -1,14 +1,25 @@
 import React from 'react';
+import { getBezierPath, getMarkerEnd } from 'react-flow-renderer';
+
+export default function CustomEdge({
+  id,
+  sourceX,
+  sourceY,
+  targetX,
+  targetY,
+  sourcePosition,
+  targetPosition,
+  style = {},
+  data,
+  arrowHeadType,
+  markerEndId,
+}) {
+  const edgePath = getBezierPath({ sourceX, sourceY, sourcePosition, targetX, targetY, targetPosition });
+  const markerEnd = getMarkerEnd(arrowHeadType, markerEndId);
 
-export default function CustomEdge({ id, sourceX, sourceY, targetX, targetY, style = {}, data }) {
   return (
     <>
-      <path
-        id={id}
-        style={style}
-        className="react-flow__edge-path"
-        d={`M ${sourceX},${sourceY}L ${targetX},${targetY}`}
-      />
+      <path id={id} style={style} className="react-flow__edge-path" d={edgePath} markerEnd={markerEnd} />
       <text>
         <textPath href={`#${id}`} style={{ fontSize: '12px' }} startOffset="50%" textAnchor="middle">
           {data.text}

example/src/Edges/index.js

@@ -41,7 +41,7 @@ const initialElements = [
     labelBgStyle: { fill: '#eee', fillOpacity: 0.7 },
     arrowHeadType: 'arrowclosed',
   },
-  { id: 'e5-8', source: '5', target: '8', type: 'custom', data: { text: 'custom edge' } },
+  { id: 'e5-8', source: '5', target: '8', type: 'custom', data: { text: 'custom edge' }, arrowHeadType: 'arrowclosed' },
 ];
 
 const edgeTypes = {

src/components/ConnectionLine/index.tsx

@@ -59,18 +59,12 @@ export default ({
   const targetY = (connectionPositionY - transform[1]) * (1 / transform[2]);
 
   let dAttr: string = '';
-  const xOffset = Math.abs(targetX - sourceX) / 2;
-  const centerX = targetX < sourceX ? targetX + xOffset : targetX - xOffset;
 
-  const yOffset = Math.abs(targetY - sourceY) / 2;
-  const centerY = targetY < sourceY ? targetY + yOffset : targetY - yOffset;
   const isRightOrLeft = sourceHandle?.position === Position.Left || sourceHandle?.position === Position.Right;
   const targetPosition = isRightOrLeft ? Position.Left : Position.Top;
 
   if (connectionLineType === ConnectionLineType.Bezier) {
     dAttr = getBezierPath({
-      centerX,
-      centerY,
       sourceX,
       sourceY,
       sourcePosition: sourceHandle?.position,
@@ -80,10 +74,6 @@ export default ({
     });
   } else if (connectionLineType === ConnectionLineType.Step) {
     dAttr = getSmoothStepPath({
-      xOffset,
-      yOffset,
-      centerX,
-      centerY,
       sourceX,
       sourceY,
       sourcePosition: sourceHandle?.position,
@@ -94,10 +84,6 @@ export default ({
     });
   } else if (connectionLineType === ConnectionLineType.SmoothStep) {
     dAttr = getSmoothStepPath({
-      xOffset,
-      yOffset,
-      centerX,
-      centerY,
       sourceX,
       sourceY,
       sourcePosition: sourceHandle?.position,

src/components/Edges/BezierEdge.tsx

@@ -1,12 +1,11 @@
 import React, { memo } from 'react';
 
 import EdgeText from './EdgeText';
-import { getMarkerEnd } from './utils';
+
+import { getMarkerEnd, getCenter } from './utils';
 import { EdgeBezierProps, Position } from '../../types';
 
 interface GetBezierPathParams {
-  centerX: number;
-  centerY: number;
   sourceX: number;
   sourceY: number;
   sourcePosition?: Position;
@@ -16,8 +15,6 @@ interface GetBezierPathParams {
 }
 
 export function getBezierPath({
-  centerX,
-  centerY,
   sourceX,
   sourceY,
   sourcePosition = Position.Bottom,
@@ -25,10 +22,11 @@ export function getBezierPath({
   targetY,
   targetPosition = Position.Top,
 }: GetBezierPathParams): string {
-  let path = `M${sourceX},${sourceY} C${sourceX},${centerY} ${targetX},${centerY} ${targetX},${targetY}`;
-
+  const [centerX, centerY] = getCenter({ sourceX, sourceY, targetX, targetY });
   const leftAndRight = [Position.Left, Position.Right];
 
+  let path = `M${sourceX},${sourceY} C${sourceX},${centerY} ${targetX},${centerY} ${targetX},${targetY}`;
+
   if (leftAndRight.includes(sourcePosition) && leftAndRight.includes(targetPosition)) {
     path = `M${sourceX},${sourceY} C${centerX},${sourceY} ${centerX},${targetY} ${targetX},${targetY}`;
   } else if (leftAndRight.includes(targetPosition)) {
@@ -56,15 +54,8 @@ export default memo(
     arrowHeadType,
     markerEndId,
   }: EdgeBezierProps) => {
-    const yOffset = Math.abs(targetY - sourceY) / 2;
-    const centerY = targetY < sourceY ? targetY + yOffset : targetY - yOffset;
-
-    const xOffset = Math.abs(targetX - sourceX) / 2;
-    const centerX = targetX < sourceX ? targetX + xOffset : targetX - xOffset;
-
+    const [centerX, centerY] = getCenter({ sourceX, sourceY, targetX, targetY });
     const path = getBezierPath({
-      centerX,
-      centerY,
       sourceX,
       sourceY,
       sourcePosition,

src/components/Edges/EdgeText.tsx

@@ -11,6 +11,9 @@ export default memo(({ x, y, label, labelStyle = {}, labelShowBg = true, labelBg
   useEffect(() => {
     if (edgeRef.current) {
       const textBbox = edgeRef.current.getBBox();
+
+      console.log(textBbox);
+
       setEdgeTextBbox({
         x: textBbox.x,
         y: textBbox.y,

src/components/Edges/SmoothStepEdge.tsx

@@ -1,7 +1,7 @@
 import React, { memo } from 'react';
 
 import EdgeText from './EdgeText';
-import { getMarkerEnd } from './utils';
+import { getMarkerEnd, getCenter } from './utils';
 import { EdgeSmoothStepProps, Position } from '../../types';
 
 // These are some helper methods for drawing the round corners
@@ -34,10 +34,6 @@ const rightTopCorner = (cornerX: number, cornerY: number, cornerSize: number): s
   `L ${cornerX - cornerSize},${cornerY}Q ${cornerX},${cornerY} ${cornerX},${cornerY + cornerSize}`;
 
 interface GetSmoothStepPathParams {
-  xOffset: number;
-  yOffset: number;
-  centerX: number;
-  centerY: number;
   sourceX: number;
   sourceY: number;
   sourcePosition?: Position;
@@ -48,10 +44,6 @@ interface GetSmoothStepPathParams {
 }
 
 export function getSmoothStepPath({
-  xOffset,
-  yOffset,
-  centerX,
-  centerY,
   sourceX,
   sourceY,
   sourcePosition = Position.Bottom,
@@ -60,9 +52,10 @@ export function getSmoothStepPath({
   targetPosition = Position.Top,
   borderRadius = 5,
 }: GetSmoothStepPathParams): string {
+  const [centerX, centerY, offsetX, offsetY] = getCenter({ sourceX, sourceY, targetX, targetY });
   const cornerWidth = Math.min(borderRadius, Math.abs(targetX - sourceX));
   const cornerHeight = Math.min(borderRadius, Math.abs(targetY - sourceY));
-  const cornerSize = Math.min(cornerWidth, cornerHeight, xOffset, yOffset);
+  const cornerSize = Math.min(cornerWidth, cornerHeight, offsetX, offsetY);
 
   const leftAndRight = [Position.Left, Position.Right];
 
@@ -145,17 +138,9 @@ export default memo(
     markerEndId,
     borderRadius = 5,
   }: EdgeSmoothStepProps) => {
-    const yOffset = Math.abs(targetY - sourceY) / 2;
-    const centerY = targetY < sourceY ? targetY + yOffset : targetY - yOffset;
-
-    const xOffset = Math.abs(targetX - sourceX) / 2;
-    const centerX = targetX < sourceX ? targetX + xOffset : targetX - xOffset;
+    const [centerX, centerY] = getCenter({ sourceX, sourceY, targetX, targetY });
 
     const path = getSmoothStepPath({
-      xOffset,
-      yOffset,
-      centerX,
-      centerY,
       sourceX,
       sourceY,
       sourcePosition,

src/components/Edges/utils.ts

@@ -7,3 +7,25 @@ export const getMarkerEnd = (arrowHeadType?: ArrowHeadType, markerEndId?: string
 
   return typeof arrowHeadType !== 'undefined' ? `url(#react-flow__${arrowHeadType})` : 'none';
 };
+
+export interface GetCenterParams {
+  sourceX: number;
+  sourceY: number;
+  targetX: number;
+  targetY: number;
+}
+
+export const getCenter = ({
+  sourceX,
+  sourceY,
+  targetX,
+  targetY,
+}: GetCenterParams): [number, number, number, number] => {
+  const xOffset = Math.abs(targetX - sourceX) / 2;
+  const centerX = targetX < sourceX ? targetX + xOffset : targetX - xOffset;
+
+  const yOffset = Math.abs(targetY - sourceY) / 2;
+  const centerY = targetY < sourceY ? targetY + yOffset : targetY - yOffset;
+
+  return [centerX, centerY, xOffset, yOffset];
+};

src/index.ts

@@ -4,6 +4,9 @@ export default ReactFlow;
 
 export { default as Handle } from './components/Handle';
 export { default as EdgeText } from './components/Edges/EdgeText';
+export { getBezierPath } from './components/Edges/BezierEdge';
+export { getSmoothStepPath } from './components/Edges/SmoothStepEdge';
+export { getMarkerEnd, getCenter as getEdgeCenter } from './components/Edges/utils';
 
 export { isNode, isEdge, removeElements, addEdge, getOutgoers } from './utils/graph';