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) )

@VRonin
5.9.2. I was running 5.9.1 when I first encountered this, but updating changed nothing. And yeah, I am running the same compiler in qtcreator as well, I made sure of that.

This subject is rather old but I also have not found any example and I took time to make it work.
Below my proposal
Click on the chart to randomly append data

main.cpp

#include <QQmlEngine> #include <QApplication> #include <QQmlApplicationEngine> #include "chartmodel.h" int main(int argc, char *argv[]) { #if defined(Q_OS_WIN) QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling); #endif QApplication app(argc, argv); //Use QApplication for QChart, QGuiApplication causes a bug qmlRegisterType<ChartModel> ("MainLib", 1, 0, "ChartModel"); QQmlApplicationEngine engine; engine.load(QUrl(QStringLiteral("qrc:/main.qml"))); if (engine.rootObjects().isEmpty()) return -1; return app.exec(); }

chartmodel.h

#ifndef CHARTMODEL_H #define CHARTMODEL_H #include <QVector> #include <QAbstractTableModel> //#include <QDebug> class ChartModel : public QAbstractTableModel { Q_OBJECT QVector<QPair<double,double>> vec_; double m_xMin; double m_xMax; double m_yMin; double m_yMax; Q_PROPERTY (double xMin READ get_xMin WRITE set_xMin NOTIFY xMinChanged) Q_PROPERTY (double xMax READ get_xMax WRITE set_xMax NOTIFY xMaxChanged) Q_PROPERTY (double yMin READ get_yMin WRITE set_yMin NOTIFY yMinChanged) Q_PROPERTY (double yMax READ get_yMax WRITE set_yMax NOTIFY yMaxChanged) public: explicit ChartModel(QObject *parent = nullptr); int rowCount(const QModelIndex &parent = QModelIndex()) const override; int columnCount(const QModelIndex &parent = QModelIndex()) const override; QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override; // QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override; double get_xMin() const; double get_xMax() const; double get_yMin() const; double get_yMax() const; public slots: bool set_xMin(double val); bool set_xMax(double val); bool set_yMin(double val); bool set_yMax(double val); void appendData(); signals: void xMinChanged(double); void xMaxChanged(double); void yMinChanged(double); void yMaxChanged(double); }; #endif // CHARTMODEL_H

chartmodel.cpp

#include "chartmodel.h" ChartModel::ChartModel(QObject *parent) : QAbstractTableModel(parent) { m_xMin = 0.; m_xMax = 1.; m_yMin = 0.; m_yMax = 1.; } int ChartModel::rowCount(const QModelIndex & /* parent */) const { return vec_.size(); } int ChartModel::columnCount(const QModelIndex & /* parent */) const { return 2; } QVariant ChartModel::data(const QModelIndex &index, int role) const { if (!index.isValid() || role != Qt::DisplayRole) return QVariant(); if (index.column() == 0){ return vec_.at(index.row()).first; } if (index.column() == 1){ return vec_.at(index.row()).second; } return QVariant(); } double ChartModel::get_xMin() const { return m_xMin; } double ChartModel::get_xMax() const { return m_xMax; } double ChartModel::get_yMin() const { return m_yMin; } double ChartModel::get_yMax() const { return m_yMax; } bool ChartModel::set_xMin(double val) { bool ret = false; if ((ret = (m_xMin != val))) { m_xMin = val; emit xMinChanged (m_xMin); } return ret; } bool ChartModel::set_xMax(double val) { bool ret = false; if ((ret = (m_xMax != val))) { m_xMax = val; emit xMaxChanged (m_xMax); } return ret; } bool ChartModel::set_yMin(double val) { bool ret = false; if ((ret = (m_yMin != val))) { m_yMin = val; emit yMinChanged (m_yMin); } return ret; } bool ChartModel::set_yMax(double val) { bool ret = false; if ((ret = (m_yMax != val))) { m_yMax = val; emit yMaxChanged (m_yMax); } return ret; } void ChartModel::appendData() { int const nbData = 1+qRound(10.*double(qrand())/double(RAND_MAX)); int const vecSize = vec_.size(); if (!vecSize){ m_xMin = qInf(); m_xMax = -qInf(); m_yMin = qInf(); m_yMax = -qInf(); } beginInsertRows(QModelIndex (), vecSize, vecSize+nbData); for(int seed = 0 ; seed < nbData; ++seed){ double const xVal = vec_.size(); double const yVal = double(qrand())/double(RAND_MAX); set_xMin(qMin(m_xMin, xVal)); set_xMax(qMax(m_xMax, xVal)); set_yMin(qMin(m_yMin, yVal)); set_yMax(qMax(m_yMax, yVal)); vec_.append(qMakePair<double, double>(xVal, yVal)); } endInsertRows(); }

main.qml

import QtQuick 2.10 import QtQuick.Window 2.10 import QtCharts 2.0 import MainLib 1.0 Window { visible: true width: 640 height: 480 title: qsTr("Hello World") property ChartModel chartModel : ChartModel{} ChartView { id : chart anchors.fill: parent antialiasing: true animationOptions: ChartView.AllAnimations SplineSeries { id : serie1 axisX : ValueAxis { id: xAxis min: chartModel.xMin max: chartModel.xMax } axisY : ValueAxis { id: yAxis min: chartModel.yMin max: chartModel.yMax } VXYModelMapper { id: mapper xColumn: 0 yColumn: 1 model: chartModel } } MouseArea{ anchors.fill : parent onClicked: { chartModel.appendData() } } } }

do you want to plot the axis and legend? or just the pixels?
and you want to plot the matrix from image or from data?

Works, thank you.

@awawawa

Hi.

Try in your test.h as follows:

#ifndef TEST_H #define TEST_H #include <QtCharts> QT_CHARTS_USE_NAMESPACE #include <QMainWindow> #include "ui_test.h" class test : public QMainWindow { [...]

Do not modify your ui_test.h.

Thanks a lot! solve my problem, it is really easy to foget that!

I've found out that it has already been implemented.
https://bugreports.qt.io/browse/QTBUG-50544

OK so this example is about QLineSeries, not QBarSeries, and there is a reason: QLineSeries has clicked(QPointF) and hovered(QPointF, bool) signals, QBarSeries doesn't.

So I think I'll have to simply implement a BarView that displays the value, using QGraphics framework.

You should have subscribed to the mailing list. You message would have gone through directly.

@Wieland
No problem :)

Hi and welcome to devnet,

How did you compile that module for your BBB ?

@RTjen

which begs to differ, is this a known bug with the Spline function

I don't know, as I said I don't use the module, but you could look here (you can login with your forum credentials).
One thing that caught my eye though is this bug, which doesn't speak well of the implementation of the charts module, as the developer provided some lazy excuse (this is simply implemented by notifying the owner of the destruction).
Anyway, you could either file a bug report or try something else. My father (who uses a commercial license) gave up on the charts and is currently using QCustomPlot, so you could try that if it provides what you're after.

I hope that helps.
Kind regards.

@vladstelmahovsky Thanks! That worked like a charm. It also gave me a good starting for digging into the interaction code and figuring out how the mouse handlers work between QML and C++.

Hello,

Thanks you for the answer.

Mid'.