JKQtPlotter/examples/jkqtmathtext_simpletest/README.md
2022-06-08 15:38:26 +02:00

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# Example (JKQTMathText): A simple usage example {#JKQTMathTextSimpleExample}
JKQTMathText is a hand-written LaTeX-renderer for Qt (implemented in native C++, using Qt). It supports a large set of standard LaTeX markup and can render it to a QPainter.
This project (see `./examples/jkqtmathtext_simpletest/`) simply creates a QLabel (as a new window) that displays a rendered LaTeX equation (here the time-dependent Schrödinger equation).
The QMake project looks like this (see [`jkqtmathtext_simpletest.pro`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/jkqtmathtext_simpletest/jkqtmathtext_simpletest.pro):
```.qmake
# include JKQTMathText source-code, including the open-source XITS fonts
include(../../lib/jkqtmathtext_with_xits.pri)
SOURCES += jkqtmathtext_simpletest.cpp
# if you don't want to use the XITS fonts, use this line (and uncomment the
# last two line!):
#include(../../lib/jkqtmathtext.pri)
CONFIG += qt
QT += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets printsupport
TARGET = jkqtmathtext_simpletest
```
And the source code of the main application is (see [`jkqtmathtext_simpletest.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/jkqtmathtext_simpletest/jkqtmathtext_simpletest.cpp):
```.cpp
#include <QApplication>
#include <QLabel>
#include <QPixmap>
#include "jkqtmathtext/jkqtmathtextlabel.h"
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
// we use a simple label to display the math text
QLabel lab;
// 1. we will paint into a QPixmap
QPixmap pix(600,400);
pix.fill(QColor("white"));
QPainter painter;
// 2. now we create a JKQTMathText object.
// Also we configure the JKQTMathText to use the XITS fonts that
// were included in the *.pro-file
JKQTMathText mathText;
mathText.useXITS();
mathText.setFontSize(20);
// 3. now we parse some LaTeX code (the Schroedinger's equation), so
// we can draw it onto the QPixmap in the next step
mathText.parse("$\\left[-\\frac{\\hbar^2}{2m}\\frac{\\partial^2}{\\partial x^2}+V(x)\\right]\\Psi(x)=\\mathrm{i}\\hbar\\frac{\\partial}{\\partial t}\\Psi(x)$");
// 3. here we do the painting
painter.begin(&pix);
mathText.draw(painter, Qt::AlignCenter, QRectF(0,0,pix.width(), pix.height()), false);
painter.end();
// now we display and resize the label as a window
lab.setPixmap(pix);
lab.show();
lab.resize(600,400);
return app.exec();
}
```
The result looks like this:
![jkqtmathtext_simpletest](https://raw.githubusercontent.com/jkriege2/JKQtPlotter/master/screenshots/jkqtmathtext_simpletest.png)