Plot a Graph with Real Time Data
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wrote on 26 Jun 2013, 06:46 last edited by
hi,
I want to draw (plot) a graph in Qt creator with the real time data
Is there any special procedure to draw a graph?
can any one help me.
Thanks in advance
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Hi,
For plotting, you need a 3rd-party library because Qt doesn't have its own plotting functions. Have a look at "Qwt":http://qwt.sourceforge.net/
Someone else talked about his experiences here: http://technofreak-robotics.blogspot.com.au/2011/07/real-time-graph-plotting-in-gui-with-qt.html
By the way, "Qt Creator" is the name of the "IDE":http://en.wikipedia.org/wiki/Integrated_development_environment; "Qt" is the name of the software library.
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wrote on 26 Jun 2013, 07:48 last edited by
thanks for the reply.
I found that QCustomPlot is also used to plot graphs. what is the difference between these two?
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QCustomPlot is also a 3rd party solution and not part of the official Qt release.
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[quote author="Swinetha" date="1372232893"]thanks for the reply.
I found that QCustomPlot is also used to plot graphs. what is the difference between these two?[/quote]You're welcome. You'll have to ask someone who has used both Qwt and QCustomPlot before though -- I have never used them.
Try reading their documentation to see what's different.
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wrote on 26 Jun 2013, 11:31 last edited by
At first Itried to install qwt in my system.
1st step
/usr/local/Qt-5.0.2/bin/qmake qwt.pro
its work fine.2nd step
makebut it's giving an error
bq. cd src/ && ( test -e Makefile || /usr/local/Qt-5.0.2/bin/qmake /usr/local/qwt-6.1.0/src/src.pro -o Makefile ) && gmake -f Makefile
Project ERROR: Unknown module(s) in QT: opengl
gmake: *** [sub-src-make_first-ordered] Error 3any body know about this error?
if knows please help me. -
wrote on 26 Jun 2013, 16:07 last edited by
Yout Qt version had been built without the opengl module. If you want to use an OpenGL plot canvas you need to rebuild Qt with this module - but usually you are not intersted in this feature and you can simply disable this feature for Qwt: edit qwtconfig.pri.
Uwe
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wrote on 27 Jun 2013, 04:59 last edited by
hi, thanks for the reply. opengl means?
to use this is there any procedure?
you said that,
bq. you can simply disable this feature for Qwt: edit qwtconfig.pri.
How can I disable it? could you explain me please
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wrote on 30 Jun 2013, 09:08 last edited by
QCustomPlot doesn't require installing. The simplest mode of operation is to just include the qcustomplot.h and qcustomplot.cpp file, that's it.
Of course, you can also compile a dynamic library from it, if you'd like.
Have a look at the "QCustomPlot webpage":http://www.workslikeclockwork.com/index.php/components/qt-plotting-widget/ It offers an introductory tutorial that should get you started quickly.
A new website is in progress with much more support material. -
wrote on 30 Jun 2013, 10:00 last edited by
DerManu said that
bq. The simplest mode of operation is to just include the qcustomplot.h and qcustomplot.cpp file, that’s it.
From where can I add these files?
Thanks in advance
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wrote on 30 Jun 2013, 10:49 last edited by
[quote author="Swinetha" date="1372586436"]DerManu said thatFrom where can I add these files?[/quote]
Just download the QCustomPlot.tar.gz package from the download section (at the bottom of the page). In there, you'll find the .h/.cpp files. Copy them to your local project directory, and add them to your project. In QtCreator, right click on the root project icon in the top left sidebar, select "Add Existing Files..." to do that.
Then just #include "qcustomplot.h" wherever you need it (e.g. in your mainwindow.h).
Have a look at the webpage, it's pretty well explained there. The examples project should also help alot in getting started (that's also in the download package). -
wrote on 15 Sept 2015, 07:21 last edited by
Compile Qwt :
Create visual studio project and copy only the header files and cpp files to the project and just compile. You can get the Qtw dll and libs.QCustomPlot : does not have that much performance when it comes to adding real time data.
graph will lag after adding 100k points and will lag even more when few series are overlapped.i think Qwt is much better choice than QCustomPlot,, but lack documentation is big issue. They have few doxygen generated documents, but they will be of little help.
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Hi and welcome
The mailing list is pretty good source for help combined with the samples. -
wrote on 15 Sept 2015, 21:20 last edited by
Although this post is rather old, here's my two cents:
http://stackoverflow.com/questions/32419897/drawing-simple-bar-charts-in-qml
With QQuickWidget, you basically get a javascript accessible canvas that acts sort of like webkit's canvas (with some exceptions), and the javascript borrows from Chromium, minus the bulk of Chromium. I think it's v8 engine? Anyway, someone figured out how to port the chartjs.org project code over to this on Github. That means you can draw charts in Javascript, which is a whole lot easier than drawing them in other ways.