Real time chart
lazarus / 55-TAChart

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Johan Holstein · 2021-01-22 16:45

Hi group,

I search on the forum for a realtime chart with on X axis the time in
hh:mm but without luck,  this is for my temperature recorder.

I like to use one channel.

Can someone help with an example?

Best regards,
Johan

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MarkMLl · 2021-01-22 17:10

Have you investigated https://wiki.freepascal.org/TAChart ?

I've used it a little, and my recollection is that it's OK if your
sample times are evenly-spaced but rather less so if they're erratic
(e.g. you log the precise instants something changes but nothing
between).

MarkMLl

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wp · 2021-01-22 17:36

Please search the forum for "TAChart" and myself as a poster. There
are lots of posts about creating time-series charts.

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Johan Holstein · 2021-01-22 19:53

Hi WP,
 Sure but not a good example can you point me in a good direction?
Thanks,
Johan

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wp · 2021-01-22 21:15

It took me 20 seconds to find this one: https://forum.lazarus.freepasc
al.org/index.php/topic,49251.msg356477.html#msg356477

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Johan Holstein · 2021-01-26 19:56

Hi WP, group,

This is a bad example and not what I need .... I need a X time axis in
hh:mm but the example is far from that.

Is there someone who can help me with that or point to a example....

Thanks in advance,

Best regards,
Johan

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wp · 2021-01-26 21:24

It is a good example. If you had not given up immediately after
running the sample and had studied the code you would have seen that
time and value are passed to the series in the order x=value and y =
time (there's even a comment in the code pointing to this). So you
only have to exchange the order of value and time in the AddXY method
of the series:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.AddDataPoint(t: TDateTime; value: Double);begin//  
Chart1LineSeries1.AddXY(Value, t);   // value on x, time on y axis! 
 Chart1LineSeries1.AddXY(t, Value);end;
The remaining change is less straightforward. There is a
TDataTimeIntervalChartSource which is responsible for formatting
floating point numbers as date/time. The example had the time axis
pointing upward, therefore the DateTimeIntervalChartSource is hooked
to the Marks.Source property of the left axis. In order to format the
x axis as date/time remove the DateTimeIntervalChartSource from the
left axis and attach it to the bottom axis. And set
Chart.BottomAxis.Marks.Style to smsLabel (to display the time labels)
and reset Chart.LeftAxis.Marks.Style to smsValue (to restore the
original values on the y axis).

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MarkMLl · 2021-01-29 14:45

Quote from: j.g.holstein@rug.nl on January 26, 2021, 08:56:20 pmThis
is a bad example and not what I need .... I need a X time axis in
hh:mm but the example is far from that.

Is there someone who can help me with that or point to a example....

I've just been looking at https://forum.lazarus.freepascal.org/index.p
hp?action=dlattach;topic=49251.0;attach=36220 (data_arriving.zip)
which I believe was the example cited and found it perfectly adequate.

However (@j.g.holstein@rug.nl, this is for you): I think the important
point is that this sort of thing is not going to be very much use if
you simply type the files, since you don't get to see the hints that
the IDE is trying to give you about the design-time configuration of
the various components. You /did/ take the trouble to open the files
using the IDE didn't you? What did you find difficult to follow?

Responding "this is a bad example ... is there someone who can help"
when somebody /is/ trying to help you isn't going to make you any
friends.

MarkMLl

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trev · 2021-01-29 22:24

Quote from: j.g.holstein@rug.nl on January 26, 2021, 08:56:20 pmThis
is a bad example and not what I need

Of course it's not precisely what you need - it is, after all, an
example which demonstrates the principle. You will need to adapt it to
your own specific requirements. If you are unwilling to do that, then
you'll need to find someone else to do it for you and compensate them
appropriately.