@ng-draw-flow/core

NgDrawFlow

NgDrawFlow is a library for creating interfaces based on displaying data as nodes. A node is a div container into which you can place any Angular component. The library takes care of all the state management of the node on the canvas. Thanks to this, it allows you to create both simple diagrams and complex editors for building customised charts and graphs.

Documentation

taiga-family.github.io/ng-draw-flow

Installation

To get started locally you should have a few things:

• Node.js installed.
• A working knowledge of Angular. You don't need to be an expert, but you should be comfortable with the basics.

First, spin up a new Angular project

ng new my-app

NgDrawFlow is published on npm as ng-draw-flow, so go ahead and add it next.

npm i @ng-draw-flow/core --save

Lastly, spin up the dev server and we're good to go!

ng serve

Import Dependencies and Register Node Components

To get started with the ng-draw-flow library, begin by setting up your module with the necessary imports and component registrations.

Add the NgDrawFlowComponent and ReactiveFormsModule to your module's imports array:

imports: [
  // ... (other necessary imports)
  NgDrawFlowComponent,
  ReactiveFormsModule,
];

Then, within the providers section, register the components that you want to be available for use as nodes within the graph editor and optionally configure connection arrowheads:

app.module.ts

providers: [
  provideNgDrawFlowConfigs({
    nodes: {
      yourNode: YourNodeComponent,
    },
    connection: {
      arrowhead: {type: DfArrowhead.Arrow},
    },
  }),
];

The connection.arrowhead option accepts a DfArrowhead value (Arrow, ArrowClosed, or None) and optional width and height settings.

Set Up Data Model and Control for Graph Structure

In the component where you intend to construct your graph, you need to create a data structure that defines the nodes and connections.

app.component.ts

data: DfDataModel = {
  nodes: [],
  connections: [],
};
form = new FormControl(this.data);

Next, link this data structure to your ng-draw-flow component using a FormControl. This will allow for reactive updates and interactions within your graph editor:

app.component.html

<ng-draw-flow [formControl]="form"></ng-draw-flow>

This setup ensures that your ng-draw-flow component is fully integrated with the Angular forms system, enabling seamless data flow and state management for your graph.

Populate Example DfDataModel

To illustrate how to set up the DfDataModel with actual data, the following example lays out a scenario with a collection of nodes and their connections:

app.component.ts

data: DfDataModel = {
  nodes: [
    {
      id: 'node-1',
      data: {type: 'yourNode', text: 'This base node'},
      position: {x: 0, y: 0},
      startNode: true,
    },
    {id: 'node-2', data: {type: 'yourNode', text: 'This child node 1'}, position: {x: 250, y: 50}},
    {id: 'node-3', data: {type: 'yourNode', text: 'This child node 2'}, position: {x: 250, y: -50}},
    {
      id: 'node-4',
      data: {type: 'yourNode', text: 'This child node 3'},
      position: {x: 500, y: 0},
      endNode: true,
    },
  ],
  connections: [
    {
      source: {nodeId: 'node-1', connectorType: DfConnectionPoint.Output, connectorId: 'node-1-output-1'},
      target: {nodeId: 'node-2', connectorType: DfConnectionPoint.Input, connectorId: 'node-2-input-1'},
    },
    {
      source: {nodeId: 'node-1', connectorType: DfConnectionPoint.Output, connectorId: 'node-1-output-1'},
      target: {nodeId: 'node-3', connectorType: DfConnectionPoint.Input, connectorId: 'node-3-input-1'},
    },
    {
      source: {nodeId: 'node-2', connectorType: DfConnectionPoint.Output, connectorId: 'node-2-output-1'},
      target: {nodeId: 'node-4', connectorType: DfConnectionPoint.Input, connectorId: 'node-4-input-1'},
    },
    {
      source: {nodeId: 'node-3', connectorType: DfConnectionPoint.Output, connectorId: 'node-3-output-1'},
      target: {nodeId: 'node-4', connectorType: DfConnectionPoint.Input, connectorId: 'node-4-input-1'},
    },
  ],
};

Each node mainly consists of an id, a position, and a data field. Inside the data field, you need to specify the node type that was previously registered and all the data you want to provide to the node.

The connections array contains objects that describe the start and end points of each connection. The source and target holds information about which node and specific connector are used for each connection.

Creating Custom Nodes

In ng-draw-flow, nodes can be customized to look and function just how you want them to. To create your own node, you should develop a component that extends from the NgDrawFlowBaseNode class. This component will incorporate directives such as DrawFlowInputDirective and DrawFlowOutputDirective.

import {NgIf} from '@angular/common';
import {ChangeDetectionStrategy, Component} from '@angular/core';
import {DfInputComponent, DfOutputComponent, DrawFlowBaseNode} from '@ng-draw-flow/core';

@Component({
  standalone: true,
  selector: 'app-your-node',
  imports: [NgIf, DfInputComponent, DfOutputComponent],
  templateUrl: './your-node.component.html',
  styleUrls: ['./your-node.component.less'],
  changeDetection: ChangeDetectionStrategy.OnPush,
})
export class YourNodeComponent extends DrawFlowBaseNode {}

:host {
  background: var(--tui-base-09);
  width: 10rem;
  box-shadow: var(--tui-shadow);
  border-radius: 0.5rem;
  padding: 0.5rem;
  border: 0.0625rem solid transparent;
  transition: border-color 0.2s ease-in-out;
  color: var(--tui-base-01);

  &.df-selected {
    border-color: var(--tui-text-action);
  }
}

.input,
.output {
  position: absolute;
  z-index: 1;
}

.input {
  left: -0.5rem;
  top: 0.25rem;
}

.output-wrapper {
  position: relative;
}

.output {
  right: -0.5rem;
  top: 0;
}

<df-input
  class="input"
  *ngIf="!startNode"
  [connectorData]="{nodeId, connectorId: nodeId + '-input-1', single: false}"
/>

<p class="tui-text_body-xs">{{ model.text }}</p>

<df-output
  class="output"
  *ngIf="!endNode"
  [connectorData]="{nodeId, connectorId: nodeId + '-output-1', single: false}"
/>

Changelog

0.17.1 (2025-10-21)

🐞 Bug Fixes

• ng-draw-flow: update selection rendering and emit nodeMoved only on real move (0d430aa)