How to set the source ID for a connector while using a user handle draw in Angular Diagram

The Syncfusion® Angular Diagram nodes and connectors are treated as diagram objects, while user handles are not. This distinction can cause unexpected behavior when a user handle is placed above a node. Specifically, when hovering over a user handle, the node beneath the handle is often detected as the target. As a result, the source of the connector being drawn may be incorrectly set to the node below the handle, even though the user intends to draw the connector from the selected node.

To ensure that the connector is correctly associated with the intended node, you can explicitly set the source ID of the connector in the elementDraw event. This article explains how to achieve this.

In the elementDraw event, the source node ID is set dynamically during the drawing process. The event gives you the opportunity to change properties, such as the source ID, as the user drags the connector.

In the sample code below, we first capture the selected node during the Start state. Then, during the Progress state, we dynamically set the source ID of the connector being drawn to the node ID of the selected node

public elementDraw(event: any): void {
   if (event.state === 'Start') {
     // Select the node where the drawing starts
     this.targetNode = this.diagram.selectedItems.nodes[0];
   }
   if (event.state === 'Progress') {
     // Ensure that the connector's source ID is always set to the selected node's ID
     if (this.diagram.nameTable[event.source.id].sourceID !== this.targetNode.id) {
       this.diagram.nameTable[event.source.id].sourceID = this.targetNode.id;
     }
   }
 } 

elementDraw: The elementDraw event is triggered when a user begins drawing a connector. This event provides the current state of the drawing operation, which can be Start or Progress.

Start: This state is triggered when the drawing starts, and you can capture the selected node that will be the source of the connector.
Progress: This state occurs as the user drags the connector. During this state, we dynamically set the sourceID of the connector to ensure that it always originates from the correct node.

When the drawing process starts, the targetNode is assigned the selected node ID.
As the user drags the connector (during the Progress state), the source ID of the connector is updated to match the targetNode.id.

Sample:
You can try this code example in the following StackBlitz

Conclusion

I hope you enjoyed learning how to set the source ID for a connector while using a user handle draw using Angular Diagram. You can refer to our Angular Diagram feature tour page to know about its other groundbreaking feature representations and documentation and how to quickly get started for configuration specifications. You can also explore our Angular Diagram example to understand how to create and manipulate data. For current customers, you can check out our components from the License and Downloads page. If you are new to Syncfusion®, you can try our 30-day free trial to check out our other controls. If you have any queries or require clarifications, please let us know in the comments section below. You can also contact us through our support forums, Direct-Trac, or feedback portal. We are always happy to assist you!