@suslucoder There is no scrollBar by default but you can increase the space for your QLegend https://doc.qt.io/qt-5/qtcharts-legend-example.html#detaching-and-attaching-legends Or you put a custom legend in a QScrollArea

@Pl45m4 thank you

Found this https://github.com/milosolutions/mcharts it might be what i need as chart.js seems to be very customizable.

@suslucoder There is no scrollbar. If you want one, you have to make one on your own, but it wouldn't make any sense. You have your data and you have your series. Now you can decide which parts you want to show in your chart (this is the "scrolling")

@tague Are you currently updating every time a point is added? If so, I wondered if you could buffer the incoming data so that you do not update so frequently? Perhaps use a QTimer to control update frequency.

@suslucoder said in QtCharts::QLineSeries(0x2ea7560, There is no data on chart: error says QtCharts::QLineSeries(0x2ea7560) What "error"? qDebug()<< series; Maybe QtCharts::QLineSeries(0x2ea7560) is what that prints when you ask it to print a QLineSeries *? Since it is a pointer, maybe you intended to go qDebug()<< *series;?

@suslucoder

@suslucoder said in Assign specific value to axis: I want to assign axis Y the 3rd column. How can i do it? The axis does not know anything about that file and columns inside it. You simply need to read your file and put data from that third column as data for Y axis. See https://doc.qt.io/qt-5/qxyseries.html If you read documentation https://doc.qt.io/qt-5/qxyseries.html#append you will see that you have to provide X AND Y...

@fcarney I put the QAbstractItemModelTester in both my model, and my proxy model, and... no errors. I also swapped it to FailureReportingMode::Fatal to double check, and nothing. The endless calls to data from VXYModelMapper continue.

@Kent-Dorfman thanx for reply. Actually I saw few java script programs for pointing accurate pixel values on image by using Mercator projection and it's formula. I checked it works fine in Java script. But in qt I want to display whole lat long trace so wanted to plot chart with image as it's background. But not able to correctly det the background image as per chart x and y axis values.

seen https://doc.qt.io/qt-5/qxyseries.html#replace-5 ? even if you are doing it just for one point - by destroying and creating a series over and over you do this anyhow. has to be quicker/better. I belive that also invokes https://doc.qt.io/qt-5/qxyseries.html#pointsReplaced ChartView should handle redraw and everything for you.

I'd recommend using https://doc.qt.io/qt-5.10/qxyseries.html#replace-5 Replacing points one by one destroys a cpu. The metrics for me was just not even worth measuring - it was just an immediate hell no - forget that - I need faster updates. I like declarative QML for gui as a preference but calling replace on a single point fires way too many signals and takes way too long. I throw my QML LineSeries to a QXYSeries and call replace in c++ In the future I'll probably just declare my series in C++. I wish I could have a better supported hybrid of c++ and QML charts but I have this working very fast using useOpenGL : true; (you can also c++ setUseOpenGL(true) )

When using line series, we've had severe performance problems. We end up with thousands of series to handle all of the gaps and have to create parallel scatter series because we want icons for each point that aren't part of the standard icon set. We pay a huge cost both constructing and destructing the series. Seems like it may be refreshing on each add series, but even removeAllSeries is slow. Have tried many things to suspend the painting, but with no timing effect. Any ideas on how to have many gaps without destroying performance?

I found a solution and post it here: link

Super :) oh it must have "()" on. The syntax is pretty funky via the automation server. Good work.

@KRHC hi and welcome to devnet, You need QApplication if you use anything that relies on the widgets module. Otherwise, there's no need for it and you would just bloat your deployment for no good reason.

@corianderop Hi I am also stuck in a similar situation did you figure out a solution for it ?