If a web page contains a chart with a zoom behavior, there's an inconvenience: when you scroll the page, as soon as your mouse is over the chart the scroll wheel stops scrolling the document and starts zooming that chart.
To avoid this, you might activate the chart zoom after a certain amount of time the mouse entered the chart and disable the chart zoom when the mouse leaves the chart.
I find this a nice solution as the user has to express the intention to use the chart by keeping the mouse over it for a bit.
On a mobile device:
- pinching outside of the rectangle zooms the page itself (not the viz);
- clicking inside the rectangle area enables the zoom, then you'll be able to pinch the viz to zoom the circle.
This block originated from this discussion.