[Qt-interest] Qt Charting Component - Feedback Request

[Markus Franke]

Dear all,

Syam Krishnan wrote:

> I'm very much interested in a good charting component. We've been trying 

> out Qwt, but it seems to have some performance problems when used with 
> larger changing datasets.
> Our requirement often is plotting of continuous data. i.e. a new data 
> point is available every 100 or 200 ms. Adding these points to the plot 
> should be as light-weight an operation as possible. As far as I can see, 

> the current Qwt implementation requires copying the entire point list 
> again and re-plotting from the beginning. This consumes a lot of CPU. 
> I'd love to see an implementation where incremental plotting is 
super-fast.

same with us. We're looking for a charting class which is able to 
efficiently plot data which continously changes over time. Cycle times are 
also around 50 to 100 milliseconds. Right now we do everything by 
ourselves based on QWidget. However for a graph like a sinus wave which 
amplitude continuously changes over time it's always needed to repaint the 
whole waveform once a new data point is appended to the end. The whole 
graphic needs to be shifted to the left as we only print the values of the 
last few seconds. 

Is there a way to efficiently plot this kind of data with your charting 
class?

Best regards,
Markus Franke


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