Add tooltip on legend labels

[Anthony]

Is there any ability to provide a tooltip on hover over a series label in the legend? Since the label itself is drawn on the canvas and is not an html element we can’t just set the ‘title’ attribute. Looks like there are some events that could be used to simulate it though:

itemmouseover
itemmouseout

Any tips on how that might work? Set title of canvas on itemmouseover and clear it on itemmouseout?

[Anthony]

The following works for adding tooltip:

                itemmouseover: function (e) {
                    $(e.chart._canvasJSContainer).attr("title", "My custom toolip");
                    console.log('mouseover');
                    e.chart.legend.fontColor = 'orange';
                    e.chart.legend.backgroundColor = 'blue';
                    e.chart.legend.borderColor = 'red';
                    e.chart.legend.borderThickness = 3;
                    e.chart.legend.fontStyle = 'italic';
                    e.chart.legend.fontWeight = 'bold';
                    e.chart.render();
                },
                itemmouseout: function (e) {
                    $(e.chart._canvasJSContainer).removeAttr("title");                    
                    console.log('mouseout');
                    e.chart.legend.fontColor = 'black';
                    e.chart.legend.backgroundColor = 'transparent';
                    e.chart.legend.borderColor = 'transparent';
                    e.chart.legend.borderThickness = 0;
                    e.chart.legend.fontStyle = 'normal';
                    e.chart.legend.fontWeight = 'normal'; 
                    e.chart.render();
                }

But, doesn’t work for changing the color/style/border/whatever of the series label. Any tips on how to get that to work?

• This reply was modified 7 years, 5 months ago by Anthony.

[Anthony]

Figured it out. Gotta use setter methods:

                itemmouseover: function (e) {
                    $(e.chart._canvasJSContainer).attr("title", "My custom tooltip");
                    console.log('mouseover');
                    e.chart.legend.set("fontColor", 'orange');
                    e.chart.legend.set("backgroundColor", 'blue');
                    e.chart.legend.set("borderColor", 'red');
                    e.chart.legend.set("borderThickness", 3);
                    e.chart.legend.set("fontStyle", 'italic');
                    e.chart.legend.set("fontWeight", 'bold');
                    e.chart.render();
                },
                itemmouseout: function (e) {
                    $(e.chart._canvasJSContainer).removeAttr("title");                    
                    console.log('mouseout');
                    e.chart.legend.set("fontColor", 'black');
                    e.chart.legend.set("backgroundColor", 'transparent');
                    e.chart.legend.set("borderColor", 'transparent');
                    e.chart.legend.set("borderThickness", 0);
                    e.chart.legend.set("fontStyle", 'normal');
                    e.chart.legend.set("fontWeight", 'normal'); 
                    e.chart.render();
                }

[Anthony]

This is unusable performance-wise with large charts though. Is there a way to trigger just the legend to re-render. Drawing the entire unchanged graph over again takes way too long.

[Bivek Singh]

Anthony,

By default, chart will render each time on calling set method. You need to pass false as third parameter in the set method which would prevent the re-render of chart and set it to true on last call to set method which might improve the performance as there won’t be repeated chart rendering.

Bivek Singh,
Team CanvasJS