Qt5/Qt-Creator Opening Files in TextEdit

--D. Thiebaut (talk) 18:30, 24 February 2014 (EST)

---

This tutorial shows how to create a simple Qt5 GUI window with two buttons and a TextEdit where the contents of a text file is displayed with fixed-size font.

The GUI

• Create a GUI with two buttons, a horizontal spacer, and a textEdit, and group them in a grid.
• Label the two buttons Clear and Go
• Connect the Clicked() signal of the Clear button to the clear() slot of the textEdit.
• Connect the Clicked() signal of the Go button to a new slot of the MainWindow application.

Source Files

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
  class MainWindow;
}

class MainWindow : public QMainWindow {
  Q_OBJECT

public:
  explicit MainWindow(QWidget *parent = 0);
  ~MainWindow();

private slots:
  void on_pushButton_2_clicked();

private:
  Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

main.cpp

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[]) {
  QApplication a(argc, argv);
  MainWindow w;
  w.show();

  return a.exec();
}

mainwindow.cpp

The highlighted sections show code added to set the font of the textEdit to courier, and to open a file with a dialog and display its contents in the textEdit.

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QFileDialog>
#include <QFile>
#include <QString>
#include <QTextStream>

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent),  ui(new Ui::MainWindow) {
  ui->setupUi(this);
  QFont font;
  font.setFamily("Courier");
  font.setStyleHint(QFont::Monospace);
  font.setFixedPitch(true);
  font.setPointSize(10);

  ui->textEdit->setFont(font);
}

MainWindow::~MainWindow() {
  delete ui;
}

// SLOT
// Reads a maze and displays it
void MainWindow::on_pushButton_2_clicked() {
    QString fileName = QFileDialog::getOpenFileName(this,
                       "Open Image", ".", "Maze files (*.dat)" );
    if ( fileName.isEmpty() )
      return;

    QFile file( fileName );
    if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
       return;

    QTextStream in( &file );
    while (!in.atEnd()) {
       QString line = in.readLine();
       ui->textEdit->append( line );
    }
}

maze.pro

#-------------------------------------------------
#
# Project created by QtCreator 2014-02-24T16:46:20
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = maze
TEMPLATE = app


SOURCES += main.cpp\
        mainwindow.cpp

HEADERS  += mainwindow.h

FORMS    += mainwindow.ui