How to show the tooltip for annotation in Angular Charts?

Description

This article shows how to show a tooltip for the annotation in Angular Charts using the chartMouseLeave event.

Solution

The annotation is used to add explanatory text or graphical elements to a chart to provide additional information or context. The tooltip can be shown while hovering over an annotation by using the chartMouseLeave event in the chart.

The mouseMove event should be bound to the div element that contains the content of the annotation. While hovering on the annotation, this event gets triggered to show the tooltip in the appropriate position relative to the annotation.

Code Snippet

In the following example, the process above described is carried out using the mouseMove and chartMouseLeave methods. The following example shows how to render the tooltip for the annotation.

app.component.ts

   public mouseMove(args): void {
       this.annotationEle = document.getElementById('container_Annotation_0');
       this.tooltipEle = document.getElementsByClassName("tooltip")[0];
       this.tooltipEle.style.display = "block";
       this.tooltipEle.style.left = parseFloat(this.annotationEle.style.left.split('px')[0]) + 35 + "px";
       this.tooltipEle.style.top = this.annotationEle.style.top;
       this.tooltipEle.innerHTML = "Custom Text";
   }
   public chartMouseLeave(args: IMouseEventArgs): void {
       if(this.tooltipEle !=null)
       this.tooltipEle.style.display = "none";
   }
};

The following screenshot illustrates the output of the above code snippet

View Sample in Stackblitz

Conclusion

I hope you enjoyed learning how to show the tooltip for annotation in Angular Chart.

You can refer to our Angular Charts feature tour page to learn about its other features and documentation, and how to quickly get started for configuration specifications. You can also explore our Angular Charts example to understand how to create and visualize data.

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