Axis values mismatch tips values in ExtJs

Question

I had created using ExtJS a form where I filter values according to time periods in order to get a chart. I have noticed that when the selected time period is small my values are displayed correctly. That means that the values of the y axis fit the values of the tooltips, like in the first figure.

The problem starts when I filter data for a bigger period of time. In this case for some reason the values of the label don't fit with the values on the tooltips (figure 2). Do you have any idea what is causing this???

EDIT: I found out that if I stretch/resize the chart of figure 2 then the data are displayed correctly and the values of the axis match the values of the tooltips. Any idea why this is happening? Can it be because I have put my chart inside a popup window???

Thanks Dimitris

Answer 1

After more research I found out in sencha forum the following information regarding the performance as the number of points increase: There's not a technical limit from the ExtJs framework as to how many points you can render in a chart / series. The performance of an ExtJs Chart is given by the points to draw by the engine. As the number of points increase, the performance will decrease. This is because the client (web browser) has to render the data locally. When the number of points is extremely high (e.g. 10000 points) most of the browsers will have problems in handle it, even just in memory. Moreover, in the above case, the chart should be around 3000px wide to actually display all the lines from point to point (wider than almost any monitor on the market).

In some cases a solution would be to thin out the data by applying some filter on the store. In my case, the number of points even applying time/date filters are so many that I don't get correct charts for ranges more than 15 days.