Can trackbar data being updated by the realtime data that passing by?

[Zhu]

Hi,

TrackBar is a good way to show multiple data, I like it.

Though, in a realtime chart, it only show the data at the time you touch the screen, and don't change until next touch, it would be  better if it can be updated by the data passing by.

Is this possible?

[Lokesh Palani]

Hi Zhu,

We have analyzed your requirement and suspect that you meant to display the Trackball in a fixed position by continuously updating the values in the tooltip label, while updating new data or deleting existing data. If this is your requirement, we can provide a viable solution. Please let us know if you require any further assistance.

Regards,

Lokesh.

[Zhu]

Hi, Lokesh,

What I mean is:

The position of the trackbar is decided by where user touch, set shouldAlwaysShow: true to keep it showing, then, when data stream passing by it, it shows the updated data.

People can touch somewhere else to change it's position, no matter where it is, the time at this position are keep changing( the x axis is supposed to be a DateTimeAxis), the data it shows is the data of the time at this position.

Regards,

Zhu

[Lokesh Palani]

Hi Zhu,

You can achieve your requirement by using show method and showByIndex method in the TrackballBehavior. By using this, you can display the trackball at the specified location. We have shared a user guide documentation for your reference. Please let us know if you need any further assistance.

UG,

https://help.syncfusion.com/flutter/cartesian-charts/methods#show-method-in-trackballbehavior

https://help.syncfusion.com/flutter/cartesian-charts/methods#showbyindex--method-in-trackballbehavior

Regards,

Lokesh.

[Zhu]

Hi, Lokesh,

I tried to add this line:

_trackballBehavior.showByIndex(pmData.length - 1);

in _updateDataSource, nothing happens, seems it don't work?

Regards,

Zhu

[Lokesh Palani]

Hi Zhu,

You can achieve your requirement by using the show method in the TrackballBehavior. We called the trackball after the updateDataSource method and passed the pixel value to show the trackball in a fixed position when the data points are updated dynamically. We have provided a sample for your reference. Please let us know if you require any further assistance.

Regards,

Lokesh.

Attachment: chart_182773_(2)_fa0a2fd7.zip

[Zhu]

Hi, Lokesh,

Yeah, it do work in this example.

But when I try it in streambuilder way, it even can't pass the compile.

Can you provide an example that works in  streambuilder way?

Attached is my test code.

Regards,

Zhu

Attachment: main_ce82b7b2.zip

[Lokesh Palani]

Hi Zhu,

We have created a ticket for your query. Please check the ticket from the below site for further updates.

https://support.syncfusion.com/support/tickets

Regards,

Lokesh.

[Zhu]

Hi, Lokesh,

Thank you, but there's only one ticket for my another question?

Regards,

Zhu

[Lokesh Palani]

Hi Zhu,

Most Welcome. The response has been posted for another question also in the same ticket. Please check the below ticket link.

Ticket link - https://support.syncfusion.com/support/tickets

Regards,

Lokesh.