I found two problems with zooming a line chart:
1) Clipping of data points
Let's say I have 5 points at x = 1..5. If I zoom to x = [1.5, 3.5] the line is only drawn for the points with x = 2,3,4. What i would expect is, that the line is interpolated from x = 1 to x = 2 and drawn starting with x = 1.5...
This is not only true for zooming but for drawing in general (e.g. manual axis).
If no data point is with the specified range, the line is not drawn at all. Instead i would expect the visible sector of the line is drawn.
I set the visibility of some series using
However, after zooming or scrolling, all series are visible again.
3) If at least one series has no data in a zoom range, zooming is not possible at all. (see 1)
Please fix this in an upcoming release.