问题
I am trying to update the dygraph title according to the current visible window. Such information can be retrieved using graph.xAxisRange(), however checking the documentation shows that there is only a callback for zoom.
The zoom callback works fine but won't get called after a pan is made. Also tried to use draw callback with lack of success.
Is there any possible solutions for this?
回答1:
drawCallback is what you want. You have to be careful to avoid loops with it, though — calling updateOptions inside of a drawCallback can invoke the drawCallback again. Take a look at synchronizer.js to see a workaround.
An alternative would be to throttle your calls to updateOptions within the drawCallback, e.g. to one update every 500ms.
来源：https://stackoverflow.com/questions/32764367/updating-chart-title-according-to-zoom-pan