exportdialog.cpp Example File

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  #include "exportdialog.h"

  #include <QApplication>
  #include <QDesktopWidget>
  #include <QDialogButtonBox>
  #include <QFileDialog>
  #include <QFormLayout>
  #include <QHBoxLayout>
  #include <QMessageBox>
  #include <QLabel>
  #include <QLineEdit>
  #include <QPushButton>
  #include <QSpinBox>
  #include <QToolButton>
  #include <QVBoxLayout>

  #include <QImageWriter>

  #include <QDebug>

  #include <QDir>
  #include <QFileInfo>

  enum { exportMinimumSize = 1, exportMaximumSize = 2000 };

  ExportDialog::ExportDialog(QWidget *parent)
      : QDialog(parent)
      , m_fileNameLineEdit(new QLineEdit(this))
      , m_widthSpinBox(new QSpinBox(this))
      , m_heightSpinBox(new QSpinBox(this))
      , m_aspectRatio(1)
  {
      typedef void (QSpinBox::*QSpinBoxIntSignal)(int);

      setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);
      setWindowTitle(tr("Export"));

      QFormLayout *formLayout = new QFormLayout(this);

      QHBoxLayout *fileLayout = new QHBoxLayout;
      fileLayout->addWidget(m_fileNameLineEdit);
      m_fileNameLineEdit->setMinimumWidth(QApplication::desktop()->availableGeometry(this).width() / 6);
      QPushButton *browseButton = new QPushButton(tr("Browse..."), this);
      fileLayout->addWidget(browseButton);
      connect(browseButton, &QAbstractButton::clicked, this, &ExportDialog::browse);
      formLayout->addRow(tr("File:"), fileLayout);

      QHBoxLayout *sizeLayout = new QHBoxLayout;
      sizeLayout->addStretch();
      m_widthSpinBox->setMinimum(exportMinimumSize);
      m_widthSpinBox->setMaximum(exportMaximumSize);
      connect(m_widthSpinBox, static_cast<QSpinBoxIntSignal>(&QSpinBox::valueChanged),
              this, &ExportDialog::exportWidthChanged);
      sizeLayout->addWidget(m_widthSpinBox);
      //: Multiplication, as in 32x32
      sizeLayout->addWidget(new QLabel(tr("x")));
      m_heightSpinBox->setMinimum(exportMinimumSize);
      m_heightSpinBox->setMaximum(exportMaximumSize);
      connect(m_heightSpinBox, static_cast<QSpinBoxIntSignal>(&QSpinBox::valueChanged),
              this, &ExportDialog::exportHeightChanged);
      sizeLayout->addWidget(m_heightSpinBox);
      QToolButton *resetButton = new QToolButton(this);
      resetButton->setIcon(QIcon(":/qt-project.org/styles/commonstyle/images/refresh-32.png"));
      sizeLayout->addWidget(resetButton);
      connect(resetButton, &QAbstractButton::clicked, this, &ExportDialog::resetExportSize);
      formLayout->addRow(tr("Size:"), sizeLayout);

      QDialogButtonBox *buttonBox = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel, this);
      connect(buttonBox, &QDialogButtonBox::accepted, this, &QDialog::accept);
      connect(buttonBox, &QDialogButtonBox::rejected, this, &QDialog::reject);
      formLayout->addRow(buttonBox);
  }

  void ExportDialog::accept()
  {
      const QString fileName = exportFileName();
      if (fileName.isEmpty()) {
          QMessageBox::warning(this, windowTitle(), tr("Please enter a file name"));
          return;
      }
      QFileInfo fi(fileName);
      if (fi.exists()) {
          const QString question = tr("%1 already exists.\nWould you like to overwrite it?").arg(QDir::toNativeSeparators(fileName));
          if (QMessageBox::question(this, windowTitle(), question, QMessageBox::Yes | QMessageBox::No) !=  QMessageBox::Yes)
              return;
      }
      QDialog::accept();
  }

  QSize ExportDialog::exportSize() const
  {
      return QSize(m_widthSpinBox->value(), m_heightSpinBox->value());
  }

  void ExportDialog::setExportSize(const QSize &size)
  {
      m_defaultSize = size;
      QSizeF defaultSizeF(m_defaultSize);
      m_aspectRatio = defaultSizeF.width() / defaultSizeF.height();
      setExportWidthBlocked(size.width());
      setExportHeightBlocked(size.height());
  }

  void ExportDialog::resetExportSize()
  {
      setExportWidthBlocked(m_defaultSize.width());
      setExportHeightBlocked(m_defaultSize.height());
  }

  void ExportDialog::setExportWidthBlocked(int width)
  {
      if (m_widthSpinBox->value() != width) {
          const bool blockSignals = m_widthSpinBox->blockSignals(true);
          m_widthSpinBox->setValue(width);
          m_widthSpinBox->blockSignals(blockSignals);
      }
  }

  void ExportDialog::setExportHeightBlocked(int height)
  {
      if (m_heightSpinBox->value() != height) {
          const bool blockSignals = m_heightSpinBox->blockSignals(true);
          m_heightSpinBox->setValue(height);
          m_heightSpinBox->blockSignals(blockSignals);
      }
  }

  void ExportDialog::exportWidthChanged(int width)
  {
      const bool square = m_defaultSize.width() == m_defaultSize.height();
      setExportHeightBlocked(square ? width : qRound(qreal(width) / m_aspectRatio));
  }

  void ExportDialog::exportHeightChanged(int height)
  {
      const bool square = m_defaultSize.width() == m_defaultSize.height();
      setExportWidthBlocked(square ? height : qRound(qreal(height) * m_aspectRatio));
  }

  QString ExportDialog::exportFileName() const
  {
      return QDir::cleanPath(m_fileNameLineEdit->text().trimmed());
  }

  void ExportDialog::setExportFileName(const QString &f)
  {
      m_fileNameLineEdit->setText(QDir::toNativeSeparators(f));
  }

  void ExportDialog::browse()
  {
      QFileDialog fileDialog(this);
      fileDialog.setAcceptMode(QFileDialog::AcceptSave);
      const QString fileName = exportFileName();
      if (!fileName.isEmpty())
          fileDialog.setDirectory(QFileInfo(fileName).absolutePath());
      QStringList mimeTypes;
      const auto supportedMimeTypes = QImageWriter::supportedMimeTypes();
      for (const QByteArray &mimeType : supportedMimeTypes)
          mimeTypes.append(QLatin1String(mimeType));
      fileDialog.setMimeTypeFilters(mimeTypes);
      const int pngIndex = mimeTypes.indexOf("image/png");
      if (pngIndex >= 0) {
          fileDialog.selectMimeTypeFilter(mimeTypes.at(pngIndex));
          fileDialog.setDefaultSuffix("png");
      }
      if (fileDialog.exec() == QDialog::Accepted)
          setExportFileName(fileDialog.selectedFiles().constFirst());
  }