qt gnuplot instance set xrange with variables - qt

Question

I basically just started using Gnuplot and in trying to set xrange/yrange I am not able to find out how to set variable bounds.
For example : instance << "set yrange [-10:10]" works perfectly
but instance << "set yrange [yrange1:yrange2] doesn't.
yrange1, yrange2 are variables in which user input is stored. That way the user can decide the bounds for gnuplot
Is there a simple way to do this?
Edit : Sorry.Here is the code
qtgnuplotlib-example.cpp
//#include <QApplication>
#include "visualization.h"
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
QCoreApplication::setAttribute(Qt::AA_DontUseNativeMenuBar);
Visualization v;
v.show();
return app.exec();
}
visualization.h
#ifndef VISUALIZATION_H
#define VISUALIZATION_H
#include <QMainWindow>
#include <QtGnuplot/QtGnuplotWidget.h>
#include <QtGnuplot/QtGnuplotInstance.h>
namespace Ui {
class Visualization;
}
class Visualization : public QMainWindow
{
Q_OBJECT
public:
explicit Visualization(QWidget *parent = 0);
~Visualization();
private:
QtGnuplotWidget *widget;
QtGnuplotInstance *instance;
protected:
bool eventFilter(QObject *obj, QEvent *event);
private slots:
void on_actionExit_triggered();
void on_actionOpen_triggered();
void on_pushButton_clicked();
private:
Ui::Visualization *ui;
};
#endif // VISUALIZATION_H
visualization.cpp
#include <QFileDialog>
#include <QFile>
#include <QMessageBox>
#include <QTextStream>
#include <QString>
#include "visualization.h"
#include "ui_visualization.h"
using namespace std;
Visualization::Visualization(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::Visualization)
{
ui->setupUi(this);
widget = new QtGnuplotWidget();
widget->installEventFilter(this);
widget->setStatusLabelActive(true);
instance = new QtGnuplotInstance();
instance->setWidget(widget);
}
Visualization::~Visualization()
{
delete ui;
delete instance;
delete widget;
}
void Visualization::on_actionExit_triggered()
{
qApp->quit();
}
void Visualization::on_actionOpen_triggered()
{
QString fileName = QFileDialog::getOpenFileName(this, tr("Open File"), QString(),
tr("All Files (*.*)"));
if (!fileName.isEmpty()) {
QFile file(fileName);
if (!file.open(QIODevice::ReadOnly)) {
QMessageBox::critical(this, tr("Error"), tr("Could not open file"));
return;
}
QTextStream in(&file);
QString str = in.readAll();
ui->equationsTxt->setText(str);
file.close();
}
}
bool Visualization::eventFilter(QObject *obj, QEvent *event)
{
if (event->type() == QEvent::MouseButtonPress)
{
if (obj == this->widget) {
QMouseEvent *mouseEvent = static_cast<QMouseEvent *>(event);
if (mouseEvent->button() == Qt::LeftButton) {
ui->outputTxt->setText( this->widget->getStatusLabel()->text());
}
}
}
return QObject::eventFilter(obj, event);
}
void Visualization::on_pushButton_clicked()
{
widget->show();
widget->resize(QSize(800,600));
int yrange1 = 5;
int yrange2 = 10;
// *instance <<\
//"set yrange [-1.5:1.5]\nset xrange [-1.5:1.5]\nset isosamples 500,500\nf(x,y)= x**2+y**2-1\nset contour\nset cntrparam levels discrete 0\nset view 0,0\nunset ztics\nunset surface\nsplot f(x,y)\n";
//here is where I am stuck
*instance << "set tics scale 0.75\nset xtics 1\nset ytics 1\nset yrange [-10:10]\nset xlabel 'x'\nset ylabel 'y'\nset zeroaxis\nplot \"<echo '1 2'\" notitle\n";
}

Answer 1

The QtGnuplotInstance class provides an exec method which you can pass a QByteArray with commands:
QtGnuplotInstance instance = new QtGnuplotInstance();
QString command;
QTextStream(&command) << "set yrange [" << yrange1 << ":" << yrange2 << "]";
instance.exec(command.toLocal8Bit());
I cannot test this at the moment, but the direction should be correct.