Google charts: is it possible to display tooltips when hovering areas in stacked area chart?

Question

I have a stacked area chart using google charts. An example is here: https://code.google.com/apis/ajax/playground/?type=visualization#area_chart

The problem is, when I hover the cursor over an area, no tooltip is displayed. I need to hover the boundary of two neighboring areas to display the tooltip.

Is it possible to display tooltips when hovering areas? If not, do you know of some workaround?

Answer 1

You can use a SteppedAreaChart for this. Set isStacked to true, and by default the tooltips will be shown on hovering over an area.

Answer 2

No, you can't spawn the tooltips by hovering over the area. There is no way easy way to work around this, as the Visualization API does not trigger mouse events on the areas.

If you want to put the effort into this, you can create custom mouse event handlers on the chart's SVG/VML code. It might be possible to extrapolate which area the mouse is in, and given that, you can extrapolate the x-axis position from the mouse coordinates using the ChartLayoutInterface, and spawn a custom tooltip based on that information. Be aware that any solution involving the chart's SVG/VML code could break at any time, as the internal structure of the charts is not guaranteed to be stable from version to version.