mainwindow.cpp Example File | Qt WebEngine 5.10

Qt 5.10 | Qt WebEngine | WebEngine Markdown Editor Example | mainwindow.cpp Example File

Qt 5.10.1 Reference Documentation

# mainwindow.cpp Example File

webenginewidgets/markdowneditor/mainwindow.cpp

      /****************************************************************************
      **
      ** Copyright (C) 2016 The Qt Company Ltd.
      ** Contact: https://www.qt.io/licensing/
      **
      ** This file is part of the examples of the Qt Toolkit.
      **
      ** $QT_BEGIN_LICENSE:BSD$
      ** Commercial License Usage
      ** Licensees holding valid commercial Qt licenses may use this file in
      ** accordance with the commercial license agreement provided with the
      ** Software or, alternatively, in accordance with the terms contained in
      ** a written agreement between you and The Qt Company. For licensing terms
      ** and conditions see https://www.qt.io/terms-conditions. For further
      ** information use the contact form at https://www.qt.io/contact-us.
      **
      ** BSD License Usage
      ** Alternatively, you may use this file under the terms of the BSD license
      ** as follows:
      **
      ** "Redistribution and use in source and binary forms, with or without
      ** modification, are permitted provided that the following conditions are
      ** met:
      **   * Redistributions of source code must retain the above copyright
      **     notice, this list of conditions and the following disclaimer.
      **   * Redistributions in binary form must reproduce the above copyright
      **     notice, this list of conditions and the following disclaimer in
      **     the documentation and/or other materials provided with the
      **     distribution.
      **   * Neither the name of The Qt Company Ltd nor the names of its
      **     contributors may be used to endorse or promote products derived
      **     from this software without specific prior written permission.
      **
      **
      ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
      ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
      ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
      ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
      ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
      ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
      ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
      ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
      ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
      ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
      **
      ** $QT_END_LICENSE$
      **
      ****************************************************************************/

      #include "mainwindow.h"
      #include "previewpage.h"
      #include "ui_mainwindow.h"

      #include <QFile>
      #include <QFileDialog>
      #include <QFontDatabase>
      #include <QMessageBox>
      #include <QTextStream>
      #include <QWebChannel>

      MainWindow::MainWindow(QWidget *parent) :
          QMainWindow(parent),
          ui(new Ui::MainWindow)
      {
          ui->setupUi(this);
          ui->editor->setFont(QFontDatabase::systemFont(QFontDatabase::FixedFont));
          ui->preview->setContextMenuPolicy(Qt::NoContextMenu);

          PreviewPage *page = new PreviewPage(this);
          ui->preview->setPage(page);

          connect(ui->editor, &QPlainTextEdit::textChanged,
                  [this]() { m_content.setText(ui->editor->toPlainText()); });

          QWebChannel *channel = new QWebChannel(this);
          channel->registerObject(QStringLiteral("content"), &m_content);
          page->setWebChannel(channel);

          ui->preview->setUrl(QUrl("qrc:/index.html"));

          connect(ui->actionNew, &QAction::triggered, this, &MainWindow::onFileNew);
          connect(ui->actionOpen, &QAction::triggered, this, &MainWindow::onFileOpen);
          connect(ui->actionSave, &QAction::triggered, this, &MainWindow::onFileSave);
          connect(ui->actionSaveAs, &QAction::triggered, this, &MainWindow::onFileSaveAs);
          connect(ui->actionExit, &QAction::triggered, this, &MainWindow::onExit);

          connect(ui->editor->document(), &QTextDocument::modificationChanged,
                  ui->actionSave, &QAction::setEnabled);

          QFile defaultTextFile(":/default.md");
          defaultTextFile.open(QIODevice::ReadOnly);
          ui->editor->setPlainText(defaultTextFile.readAll());
      }

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

      void MainWindow::openFile(const QString &path)
      {
          QFile f(path);
          if (!f.open(QIODevice::ReadOnly)) {
              QMessageBox::warning(this, windowTitle(),
                                   tr("Could not open file %1: %2").arg(
                                       QDir::toNativeSeparators(path), f.errorString()));
              return;
          }
          m_filePath = path;
          ui->editor->setPlainText(f.readAll());
      }

      bool MainWindow::isModified() const
      {
          return ui->editor->document()->isModified();
      }

      void MainWindow::onFileNew()
      {
          if (isModified()) {
              QMessageBox::StandardButton button = QMessageBox::question(this, windowTitle(),
                                   tr("You have unsaved changes. Do you want to create a new document anyway?"));
              if (button != QMessageBox::Yes)
                  return;
          }

          m_filePath.clear();
          ui->editor->setPlainText(tr("## New document"));
          ui->editor->document()->setModified(false);
      }

      void MainWindow::onFileOpen()
      {
          if (isModified()) {
              QMessageBox::StandardButton button = QMessageBox::question(this, windowTitle(),
                                   tr("You have unsaved changes. Do you want to open a new document anyway?"));
              if (button != QMessageBox::Yes)
                  return;
          }

          QString path = QFileDialog::getOpenFileName(this,
              tr("Open MarkDown File"), "", tr("MarkDown File (*.md)"));
          if (path.isEmpty())
              return;

          openFile(path);
      }

      void MainWindow::onFileSave()
      {
          if (m_filePath.isEmpty()) {
              onFileSaveAs();
              return;
          }

          QFile f(m_filePath);
          if (!f.open(QIODevice::WriteOnly | QIODevice::Text))  {
              QMessageBox::warning(this, windowTitle(),
                                   tr("Could not write to file %1: %2").arg(
                                       QDir::toNativeSeparators(m_filePath), f.errorString()));
              return;
          }
          QTextStream str(&f);
          str << ui->editor->toPlainText();

          ui->editor->document()->setModified(false);
      }

      void MainWindow::onFileSaveAs()
      {
          QString path = QFileDialog::getSaveFileName(this,
              tr("Save MarkDown File"), "", tr("MarkDown File (*.md, *.markdown)"));
          if (path.isEmpty())
              return;
          m_filePath = path;
          onFileSave();
      }

      void MainWindow::onExit()
      {
          if (isModified()) {
              QMessageBox::StandardButton button = QMessageBox::question(this, windowTitle(),
                                   tr("You have unsaved changes. Do you want to exit anyway?"));
              if (button != QMessageBox::Yes)
                  return;
          }
          close();
      }