screenshot.cpp Example File

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  #include <QtWidgets>

  #include "screenshot.h"

  Screenshot::Screenshot()
      :  screenshotLabel(new QLabel(this))
  {
      screenshotLabel->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
      screenshotLabel->setAlignment(Qt::AlignCenter);

      const QRect screenGeometry = QApplication::desktop()->screenGeometry(this);
      screenshotLabel->setMinimumSize(screenGeometry.width() / 8, screenGeometry.height() / 8);

      QVBoxLayout *mainLayout = new QVBoxLayout(this);
      mainLayout->addWidget(screenshotLabel);

      QGroupBox *optionsGroupBox = new QGroupBox(tr("Options"), this);
      delaySpinBox = new QSpinBox(optionsGroupBox);
      delaySpinBox->setSuffix(tr(" s"));
      delaySpinBox->setMaximum(60);

      connect(delaySpinBox, QOverload<int>::of(&QSpinBox::valueChanged),
              this, &Screenshot::updateCheckBox);

      hideThisWindowCheckBox = new QCheckBox(tr("Hide This Window"), optionsGroupBox);

      QGridLayout *optionsGroupBoxLayout = new QGridLayout(optionsGroupBox);
      optionsGroupBoxLayout->addWidget(new QLabel(tr("Screenshot Delay:"), this), 0, 0);
      optionsGroupBoxLayout->addWidget(delaySpinBox, 0, 1);
      optionsGroupBoxLayout->addWidget(hideThisWindowCheckBox, 1, 0, 1, 2);

      mainLayout->addWidget(optionsGroupBox);

      QHBoxLayout *buttonsLayout = new QHBoxLayout;
      newScreenshotButton = new QPushButton(tr("New Screenshot"), this);
      connect(newScreenshotButton, &QPushButton::clicked, this, &Screenshot::newScreenshot);
      buttonsLayout->addWidget(newScreenshotButton);
      QPushButton *saveScreenshotButton = new QPushButton(tr("Save Screenshot"), this);
      connect(saveScreenshotButton, &QPushButton::clicked, this, &Screenshot::saveScreenshot);
      buttonsLayout->addWidget(saveScreenshotButton);
      QPushButton *quitScreenshotButton = new QPushButton(tr("Quit"), this);
      quitScreenshotButton->setShortcut(Qt::CTRL + Qt::Key_Q);
      connect(quitScreenshotButton, &QPushButton::clicked, this, &QWidget::close);
      buttonsLayout->addWidget(quitScreenshotButton);
      buttonsLayout->addStretch();
      mainLayout->addLayout(buttonsLayout);

      shootScreen();
      delaySpinBox->setValue(5);

      setWindowTitle(tr("Screenshot"));
      resize(300, 200);
  }

  void Screenshot::resizeEvent(QResizeEvent * /* event */)
  {
      QSize scaledSize = originalPixmap.size();
      scaledSize.scale(screenshotLabel->size(), Qt::KeepAspectRatio);
      if (!screenshotLabel->pixmap() || scaledSize != screenshotLabel->pixmap()->size())
          updateScreenshotLabel();
  }

  void Screenshot::newScreenshot()
  {
      if (hideThisWindowCheckBox->isChecked())
          hide();
      newScreenshotButton->setDisabled(true);

      QTimer::singleShot(delaySpinBox->value() * 1000, this, &Screenshot::shootScreen);
  }

  void Screenshot::saveScreenshot()
  {
      const QString format = "png";
      QString initialPath = QStandardPaths::writableLocation(QStandardPaths::PicturesLocation);
      if (initialPath.isEmpty())
          initialPath = QDir::currentPath();
      initialPath += tr("/untitled.") + format;

      QFileDialog fileDialog(this, tr("Save As"), initialPath);
      fileDialog.setAcceptMode(QFileDialog::AcceptSave);
      fileDialog.setFileMode(QFileDialog::AnyFile);
      fileDialog.setDirectory(initialPath);
      QStringList mimeTypes;
      foreach (const QByteArray &bf, QImageWriter::supportedMimeTypes())
          mimeTypes.append(QLatin1String(bf));
      fileDialog.setMimeTypeFilters(mimeTypes);
      fileDialog.selectMimeTypeFilter("image/" + format);
      fileDialog.setDefaultSuffix(format);
      if (fileDialog.exec() != QDialog::Accepted)
          return;
      const QString fileName = fileDialog.selectedFiles().first();
      if (!originalPixmap.save(fileName)) {
          QMessageBox::warning(this, tr("Save Error"), tr("The image could not be saved to \"%1\".")
                               .arg(QDir::toNativeSeparators(fileName)));
      }
  }

  void Screenshot::shootScreen()
  {
      QScreen *screen = QGuiApplication::primaryScreen();
      if (const QWindow *window = windowHandle())
          screen = window->screen();
      if (!screen)
          return;

      if (delaySpinBox->value() != 0)
          QApplication::beep();

      originalPixmap = screen->grabWindow(0);
      updateScreenshotLabel();

      newScreenshotButton->setDisabled(false);
      if (hideThisWindowCheckBox->isChecked())
          show();
  }

  void Screenshot::updateCheckBox()
  {
      if (delaySpinBox->value() == 0) {
          hideThisWindowCheckBox->setDisabled(true);
          hideThisWindowCheckBox->setChecked(false);
      } else {
          hideThisWindowCheckBox->setDisabled(false);
      }
  }

  void Screenshot::updateScreenshotLabel()
  {
      screenshotLabel->setPixmap(originalPixmap.scaled(screenshotLabel->size(),
                                                       Qt::KeepAspectRatio,
                                                       Qt::SmoothTransformation));
  }