Traditional graphs like this http://dygraphs.com/tests/range-selector.html or http://www.highcharts.com/products/highstock have tooltips to indicate the values at cursor position. Since there is no cursor in a touch based device.. that element of interactivity is not available.
Also the range selector has couple of hooks that are easy to latch onto with the mouse, but fairly difficult to use with touch.
Are there any interaction paradigms to follow for graphs on touch interfaces? I have used native iOS library like CorePlot earlier, but it was limited in capabilities. So started looking at the Web based plotting frameworks. Quite a few of them claim to have touch support but I think the graph interaction patterns need to change.
Even the common pinch and zoom.. though it can be used to zoom into a plot - very often conflicts with the rest of the page. It gets confusing - you don't know if you have zoomed the plot or the whole page.
I have been looking mainly at Canvas based Plotting libraries like dygraphs, jqPlot but I am assuming the same applies to SVG based ones as well.
If you could point me to some great examples of charting for touch based devices or best practices, that would help a lot.