mainwindow.cpp Example File

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  #include <QtWidgets>

  #include "characterwidget.h"
  #include "mainwindow.h"


  Q_DECLARE_METATYPE(QFontComboBox::FontFilter)

  MainWindow::MainWindow()
  {
      QMenu *fileMenu = menuBar()->addMenu(tr("File"));
      fileMenu->addAction(tr("Quit"), this, &QWidget::close);
      QMenu *helpMenu = menuBar()->addMenu(tr("&Help"));
      helpMenu->addAction(tr("Show Font Info"), this, &MainWindow::showInfo);
      helpMenu->addAction(tr("About &Qt"), qApp, &QApplication::aboutQt);

      QWidget *centralWidget = new QWidget;

      QLabel *filterLabel = new QLabel(tr("Filter:"));
      filterCombo = new QComboBox;
      filterCombo->addItem(tr("All"), QVariant::fromValue(QFontComboBox::AllFonts));
      filterCombo->addItem(tr("Scalable"), QVariant::fromValue(QFontComboBox::ScalableFonts));
      filterCombo->addItem(tr("Monospaced"), QVariant::fromValue(QFontComboBox::MonospacedFonts));
      filterCombo->addItem(tr("Proportional"), QVariant::fromValue(QFontComboBox::ProportionalFonts));
      filterCombo->setCurrentIndex(0);
      typedef void (QComboBox::*QComboBoxIntSignal)(int);
      connect(filterCombo, static_cast<QComboBoxIntSignal>(&QComboBox::currentIndexChanged),
              this, &MainWindow::filterChanged);

      QLabel *fontLabel = new QLabel(tr("Font:"));
      fontCombo = new QFontComboBox;
      QLabel *sizeLabel = new QLabel(tr("Size:"));
      sizeCombo = new QComboBox;
      QLabel *styleLabel = new QLabel(tr("Style:"));
      styleCombo = new QComboBox;
      QLabel *fontMergingLabel = new QLabel(tr("Automatic Font Merging:"));
      fontMerging = new QCheckBox;
      fontMerging->setChecked(true);

      scrollArea = new QScrollArea;
      characterWidget = new CharacterWidget;
      scrollArea->setWidget(characterWidget);

      findStyles(fontCombo->currentFont());
      findSizes(fontCombo->currentFont());

      lineEdit = new QLineEdit;
      lineEdit->setClearButtonEnabled(true);
  #ifndef QT_NO_CLIPBOARD
      QPushButton *clipboardButton = new QPushButton(tr("&To clipboard"));

  #endif

      connect(fontCombo, &QFontComboBox::currentFontChanged,
              this, &MainWindow::findStyles);
      connect(fontCombo, &QFontComboBox::currentFontChanged,
              this, &MainWindow::findSizes);
      connect(fontCombo, &QFontComboBox::currentFontChanged,
              characterWidget, &CharacterWidget::updateFont);
      typedef void (QComboBox::*QComboBoxStringSignal)(const QString &);
      connect(sizeCombo, static_cast<QComboBoxStringSignal>(&QComboBox::currentIndexChanged),
              characterWidget, &CharacterWidget::updateSize);
      connect(styleCombo, static_cast<QComboBoxStringSignal>(&QComboBox::currentIndexChanged),
              characterWidget, &CharacterWidget::updateStyle);
      connect(characterWidget, &CharacterWidget::characterSelected,
              this, &MainWindow::insertCharacter);

  #ifndef QT_NO_CLIPBOARD
      connect(clipboardButton, &QAbstractButton::clicked, this, &MainWindow::updateClipboard);
  #endif
      connect(fontMerging, &QAbstractButton::toggled, characterWidget, &CharacterWidget::updateFontMerging);

      QHBoxLayout *controlsLayout = new QHBoxLayout;
      controlsLayout->addWidget(filterLabel);
      controlsLayout->addWidget(filterCombo, 1);
      controlsLayout->addWidget(fontLabel);
      controlsLayout->addWidget(fontCombo, 1);
      controlsLayout->addWidget(sizeLabel);
      controlsLayout->addWidget(sizeCombo, 1);
      controlsLayout->addWidget(styleLabel);
      controlsLayout->addWidget(styleCombo, 1);
      controlsLayout->addWidget(fontMergingLabel);
      controlsLayout->addWidget(fontMerging, 1);
      controlsLayout->addStretch(1);

      QHBoxLayout *lineLayout = new QHBoxLayout;
      lineLayout->addWidget(lineEdit, 1);
      lineLayout->addSpacing(12);
  #ifndef QT_NO_CLIPBOARD
      lineLayout->addWidget(clipboardButton);
  #endif

      QVBoxLayout *centralLayout = new QVBoxLayout;
      centralLayout->addLayout(controlsLayout);
      centralLayout->addWidget(scrollArea, 1);
      centralLayout->addSpacing(4);
      centralLayout->addLayout(lineLayout);
      centralWidget->setLayout(centralLayout);

      setCentralWidget(centralWidget);
      setWindowTitle(tr("Character Map"));
  }

  void MainWindow::findStyles(const QFont &font)
  {
      QFontDatabase fontDatabase;
      QString currentItem = styleCombo->currentText();
      styleCombo->clear();

      QString style;
      foreach (style, fontDatabase.styles(font.family()))
          styleCombo->addItem(style);

      int styleIndex = styleCombo->findText(currentItem);

      if (styleIndex == -1)
          styleCombo->setCurrentIndex(0);
      else
          styleCombo->setCurrentIndex(styleIndex);
  }

  void MainWindow::filterChanged(int f)
  {
      const QFontComboBox::FontFilter filter =
          filterCombo->itemData(f).value<QFontComboBox::FontFilter>();
      fontCombo->setFontFilters(filter);
      statusBar()->showMessage(tr("%n font(s) found", 0, fontCombo->count()));
  }

  void MainWindow::findSizes(const QFont &font)
  {
      QFontDatabase fontDatabase;
      QString currentSize = sizeCombo->currentText();

      {
          const QSignalBlocker blocker(sizeCombo);
          // sizeCombo signals are now blocked until end of scope
          sizeCombo->clear();

          int size;
          if (fontDatabase.isSmoothlyScalable(font.family(), fontDatabase.styleString(font))) {
              foreach (size, QFontDatabase::standardSizes()) {
                  sizeCombo->addItem(QVariant(size).toString());
                  sizeCombo->setEditable(true);
              }

          } else {
              foreach (size, fontDatabase.smoothSizes(font.family(), fontDatabase.styleString(font))) {
                  sizeCombo->addItem(QVariant(size).toString());
                  sizeCombo->setEditable(false);
              }
          }
      }

      int sizeIndex = sizeCombo->findText(currentSize);

      if(sizeIndex == -1)
          sizeCombo->setCurrentIndex(qMax(0, sizeCombo->count() / 3));
      else
          sizeCombo->setCurrentIndex(sizeIndex);
  }

  void MainWindow::insertCharacter(const QString &character)
  {
      lineEdit->insert(character);
  }

  #ifndef QT_NO_CLIPBOARD
  void MainWindow::updateClipboard()
  {
      QGuiApplication::clipboard()->setText(lineEdit->text(), QClipboard::Clipboard);
      QGuiApplication::clipboard()->setText(lineEdit->text(), QClipboard::Selection);
  }
  #endif

  class FontInfoDialog : public QDialog
  {
  public:
      explicit FontInfoDialog(QWidget *parent = Q_NULLPTR);

  private:
      QString text() const;
  };

  FontInfoDialog::FontInfoDialog(QWidget *parent) : QDialog(parent)
  {
      setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);
      QVBoxLayout *mainLayout = new QVBoxLayout(this);
      QPlainTextEdit *textEdit = new QPlainTextEdit(text(), this);
      textEdit->setReadOnly(true);
      textEdit->setFont(QFontDatabase::systemFont(QFontDatabase::FixedFont));
      mainLayout->addWidget(textEdit);
      QDialogButtonBox *buttonBox = new QDialogButtonBox(QDialogButtonBox::Close, this);
      connect(buttonBox, &QDialogButtonBox::rejected, this, &QDialog::reject);
      mainLayout->addWidget(buttonBox);
  }

  QString FontInfoDialog::text() const
  {
      QString text;
      QTextStream str(&text);
      const QFont defaultFont = QFontDatabase::systemFont(QFontDatabase::GeneralFont);
      const QFont fixedFont = QFontDatabase::systemFont(QFontDatabase::FixedFont);
      const QFont titleFont = QFontDatabase::systemFont(QFontDatabase::TitleFont);
      const QFont smallestReadableFont = QFontDatabase::systemFont(QFontDatabase::SmallestReadableFont);

      str << "Qt " << QT_VERSION_STR << " on " << QGuiApplication::platformName()
          << ", " << logicalDpiX() << "DPI";
      if (!qFuzzyCompare(devicePixelRatioF(), qreal(1)))
          str  << ", device pixel ratio: " << devicePixelRatioF();
      str << "\n\nDefault font : " << defaultFont.family() << ", " << defaultFont.pointSizeF() << "pt\n"
          << "Fixed font   : " << fixedFont.family() << ", " << fixedFont.pointSizeF() << "pt\n"
          << "Title font   : " << titleFont.family() << ", " << titleFont.pointSizeF() << "pt\n"
          << "Smallest font: " << smallestReadableFont.family() << ", " << smallestReadableFont.pointSizeF() << "pt\n";

      return text;
  }

  void MainWindow::showInfo()
  {
      const QRect screenGeometry = QApplication::desktop()->screenGeometry(this);
      FontInfoDialog *dialog = new FontInfoDialog(this);
      dialog->setWindowTitle(tr("Fonts"));
      dialog->setAttribute(Qt::WA_DeleteOnClose);
      dialog->resize(screenGeometry.width() / 4, screenGeometry.height() / 4);
      dialog->show();
  }