Icons Example | Qt Widgets 5.13.0

Qt 5.13 | Qt Widgets | Icons Example

Qt 5.13.0 Reference Documentation

# Icons Example

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      #include <QtWidgets>

      #include "iconpreviewarea.h"
      #include "iconsizespinbox.h"
      #include "imagedelegate.h"
      #include "mainwindow.h"

      enum { OtherSize = QStyle::PM_CustomBase };

      MainWindow::MainWindow(QWidget *parent)
          : QMainWindow(parent)
      {
          QWidget *centralWidget = new QWidget(this);
          setCentralWidget(centralWidget);

          createActions();

          QGridLayout *mainLayout = new QGridLayout(centralWidget);

          QGroupBox *previewGroupBox = new QGroupBox(tr("Preview"));
          previewArea = new IconPreviewArea(previewGroupBox);
          QVBoxLayout *previewLayout = new QVBoxLayout(previewGroupBox);
          previewLayout->addWidget(previewArea);

          mainLayout->addWidget(previewGroupBox, 0, 0, 1, 2);
          mainLayout->addWidget(createImagesGroupBox(), 1, 0);
          QVBoxLayout *vBox = new QVBoxLayout;
          vBox->addWidget(createIconSizeGroupBox());
          vBox->addWidget(createHighDpiIconSizeGroupBox());
          vBox->addItem(new QSpacerItem(0, 0, QSizePolicy::Ignored, QSizePolicy::MinimumExpanding));
          mainLayout->addLayout(vBox, 1, 1);
          createContextMenu();

          setWindowTitle(tr("Icons"));
          checkCurrentStyle();
          sizeButtonGroup->button(OtherSize)->click();
      }

      void MainWindow::show()
      {
          QMainWindow::show();
          connect(windowHandle(), &QWindow::screenChanged, this, &MainWindow::screenChanged);
          screenChanged();
      }

      void MainWindow::about()
      {
          QMessageBox::about(this, tr("About Icons"),
                  tr("The <b>Icons</b> example illustrates how Qt renders an icon in "
                     "different modes (active, normal, disabled, and selected) and "
                     "states (on and off) based on a set of images."));
      }

      void MainWindow::changeStyle(bool checked)
      {
          if (!checked)
              return;

          const QAction *action = qobject_cast<QAction *>(sender());
          QStyle *style = QStyleFactory::create(action->data().toString());
          Q_ASSERT(style);
          QApplication::setStyle(style);

          const QList<QAbstractButton*> buttons = sizeButtonGroup->buttons();
          for (QAbstractButton *button : buttons) {
              const QStyle::PixelMetric metric = static_cast<QStyle::PixelMetric>(sizeButtonGroup->id(button));
              const int value = style->pixelMetric(metric);
              switch (metric) {
              case QStyle::PM_SmallIconSize:
                  button->setText(tr("Small (%1 x %1)").arg(value));
                  break;
              case QStyle::PM_LargeIconSize:
                  button->setText(tr("Large (%1 x %1)").arg(value));
                  break;
              case QStyle::PM_ToolBarIconSize:
                  button->setText(tr("Toolbars (%1 x %1)").arg(value));
                  break;
              case QStyle::PM_ListViewIconSize:
                  button->setText(tr("List views (%1 x %1)").arg(value));
                  break;
              case QStyle::PM_IconViewIconSize:
                  button->setText(tr("Icon views (%1 x %1)").arg(value));
                  break;
              case QStyle::PM_TabBarIconSize:
                  button->setText(tr("Tab bars (%1 x %1)").arg(value));
                  break;
              default:
                  break;
              }
          }

          triggerChangeSize();
      }

      void MainWindow::changeSize(int id, bool checked)
      {
          if (!checked)
              return;

          const bool other = id == int(OtherSize);
          const int extent = other
              ? otherSpinBox->value()
              : QApplication::style()->pixelMetric(static_cast<QStyle::PixelMetric>(id));

          previewArea->setSize(QSize(extent, extent));
          otherSpinBox->setEnabled(other);
      }

      void MainWindow::triggerChangeSize()
      {
          changeSize(sizeButtonGroup->checkedId(), true);
      }

      void MainWindow::changeIcon()
      {
          QIcon icon;

          for (int row = 0; row < imagesTable->rowCount(); ++row) {
              const QTableWidgetItem *fileItem = imagesTable->item(row, 0);
              const QTableWidgetItem *modeItem = imagesTable->item(row, 1);
              const QTableWidgetItem *stateItem = imagesTable->item(row, 2);

              if (fileItem->checkState() == Qt::Checked) {
                  const int modeIndex = IconPreviewArea::iconModeNames().indexOf(modeItem->text());
                  Q_ASSERT(modeIndex >= 0);
                  const int stateIndex = IconPreviewArea::iconStateNames().indexOf(stateItem->text());
                  Q_ASSERT(stateIndex >= 0);
                  const QIcon::Mode mode = IconPreviewArea::iconModes().at(modeIndex);
                  const QIcon::State state = IconPreviewArea::iconStates().at(stateIndex);

                  const QString fileName = fileItem->data(Qt::UserRole).toString();
                  QImage image(fileName);
                  if (!image.isNull())
                      icon.addPixmap(QPixmap::fromImage(image), mode, state);
              }
          }

          previewArea->setIcon(icon);
      }

      void MainWindow::addSampleImages()
      {
          addImages(QLatin1String(SRCDIR) + QLatin1String("/images"));
      }

      void MainWindow::addOtherImages()
      {
          static bool firstInvocation = true;
          QString directory;
          if (firstInvocation) {
              firstInvocation = false;
              directory = QStandardPaths::standardLocations(QStandardPaths::PicturesLocation).value(0, QString());
          }
          addImages(directory);
      }

      void MainWindow::addImages(const QString &directory)
      {
          QFileDialog fileDialog(this, tr("Open Images"), directory);
          QStringList mimeTypeFilters;
          const QList<QByteArray> mimeTypes = QImageReader::supportedMimeTypes();
          for (const QByteArray &mimeTypeName : mimeTypes)
              mimeTypeFilters.append(mimeTypeName);
          mimeTypeFilters.sort();
          fileDialog.setMimeTypeFilters(mimeTypeFilters);
          fileDialog.selectMimeTypeFilter(QLatin1String("image/png"));
          fileDialog.setAcceptMode(QFileDialog::AcceptOpen);
          fileDialog.setFileMode(QFileDialog::ExistingFiles);
          if (!nativeFileDialogAct->isChecked())
              fileDialog.setOption(QFileDialog::DontUseNativeDialog);
          if (fileDialog.exec() == QDialog::Accepted)
              loadImages(fileDialog.selectedFiles());
      }

      void MainWindow::loadImages(const QStringList &fileNames)
      {
          for (const QString &fileName : fileNames) {
              const int row = imagesTable->rowCount();
              imagesTable->setRowCount(row + 1);
              const QFileInfo fileInfo(fileName);
              const QString imageName = fileInfo.baseName();
              const QString fileName2x = fileInfo.absolutePath()
                  + QLatin1Char('/') + imageName + QLatin1String("@2x.") + fileInfo.suffix();
              const QFileInfo fileInfo2x(fileName2x);
              const QImage image(fileName);
              const QString toolTip =
                  tr("Directory: %1\nFile: %2\nFile@2x: %3\nSize: %4x%5")
                     .arg(QDir::toNativeSeparators(fileInfo.absolutePath()), fileInfo.fileName())
                     .arg(fileInfo2x.exists() ? fileInfo2x.fileName() : tr("<None>"))
                     .arg(image.width()).arg(image.height());
              QTableWidgetItem *fileItem = new QTableWidgetItem(imageName);
              fileItem->setData(Qt::UserRole, fileName);
              fileItem->setIcon(QPixmap::fromImage(image));
              fileItem->setFlags((fileItem->flags() | Qt::ItemIsUserCheckable) & ~Qt::ItemIsEditable);
              fileItem->setToolTip(toolTip);

              QIcon::Mode mode = QIcon::Normal;
              QIcon::State state = QIcon::Off;
              if (guessModeStateAct->isChecked()) {
                  if (imageName.contains(QLatin1String("_act"), Qt::CaseInsensitive))
                      mode = QIcon::Active;
                  else if (imageName.contains(QLatin1String("_dis"), Qt::CaseInsensitive))
                      mode = QIcon::Disabled;
                  else if (imageName.contains(QLatin1String("_sel"), Qt::CaseInsensitive))
                      mode = QIcon::Selected;

                  if (imageName.contains(QLatin1String("_on"), Qt::CaseInsensitive))
                      state = QIcon::On;
              }

              imagesTable->setItem(row, 0, fileItem);
              QTableWidgetItem *modeItem =
                  new QTableWidgetItem(IconPreviewArea::iconModeNames().at(IconPreviewArea::iconModes().indexOf(mode)));
              modeItem->setToolTip(toolTip);
              imagesTable->setItem(row, 1, modeItem);
              QTableWidgetItem *stateItem =
                  new QTableWidgetItem(IconPreviewArea::iconStateNames().at(IconPreviewArea::iconStates().indexOf(state)));
              stateItem->setToolTip(toolTip);
              imagesTable->setItem(row, 2, stateItem);
              imagesTable->openPersistentEditor(modeItem);
              imagesTable->openPersistentEditor(stateItem);

              fileItem->setCheckState(Qt::Checked);
          }
      }

      void MainWindow::useHighDpiPixmapsChanged(int checkState)
      {
          QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps, checkState == Qt::Checked);
          changeIcon();
      }

      void MainWindow::removeAllImages()
      {
          imagesTable->setRowCount(0);
          changeIcon();
      }

      QWidget *MainWindow::createImagesGroupBox()
      {
          QGroupBox *imagesGroupBox = new QGroupBox(tr("Images"));

          imagesTable = new QTableWidget;
          imagesTable->setSelectionMode(QAbstractItemView::NoSelection);
          imagesTable->setItemDelegate(new ImageDelegate(this));

          QStringList labels;
          labels << tr("Image") << tr("Mode") << tr("State");

          imagesTable->horizontalHeader()->setDefaultSectionSize(90);
          imagesTable->setColumnCount(3);
          imagesTable->setHorizontalHeaderLabels(labels);
          imagesTable->horizontalHeader()->setSectionResizeMode(0, QHeaderView::Stretch);
          imagesTable->horizontalHeader()->setSectionResizeMode(1, QHeaderView::Fixed);
          imagesTable->horizontalHeader()->setSectionResizeMode(2, QHeaderView::Fixed);
          imagesTable->verticalHeader()->hide();

          connect(imagesTable, &QTableWidget::itemChanged,
                  this, &MainWindow::changeIcon);

          QVBoxLayout *layout = new QVBoxLayout(imagesGroupBox);
          layout->addWidget(imagesTable);
          return imagesGroupBox;
      }

      QWidget *MainWindow::createIconSizeGroupBox()
      {
          QGroupBox *iconSizeGroupBox = new QGroupBox(tr("Icon Size"));

          sizeButtonGroup = new QButtonGroup(this);
          sizeButtonGroup->setExclusive(true);

          connect(sizeButtonGroup, QOverload<int, bool>::of(&QButtonGroup::buttonToggled),
                  this, &MainWindow::changeSize);

          QRadioButton *smallRadioButton = new QRadioButton;
          sizeButtonGroup->addButton(smallRadioButton, QStyle::PM_SmallIconSize);
          QRadioButton *largeRadioButton = new QRadioButton;
          sizeButtonGroup->addButton(largeRadioButton, QStyle::PM_LargeIconSize);
          QRadioButton *toolBarRadioButton = new QRadioButton;
          sizeButtonGroup->addButton(toolBarRadioButton, QStyle::PM_ToolBarIconSize);
          QRadioButton *listViewRadioButton = new QRadioButton;
          sizeButtonGroup->addButton(listViewRadioButton, QStyle::PM_ListViewIconSize);
          QRadioButton *iconViewRadioButton = new QRadioButton;
          sizeButtonGroup->addButton(iconViewRadioButton, QStyle::PM_IconViewIconSize);
          QRadioButton *tabBarRadioButton = new QRadioButton;
          sizeButtonGroup->addButton(tabBarRadioButton, QStyle::PM_TabBarIconSize);
          QRadioButton *otherRadioButton = new QRadioButton(tr("Other:"));
          sizeButtonGroup->addButton(otherRadioButton, OtherSize);
          otherSpinBox = new IconSizeSpinBox;
          otherSpinBox->setRange(8, 256);
          const QString spinBoxToolTip =
              tr("Enter a custom size within %1..%2")
                 .arg(otherSpinBox->minimum()).arg(otherSpinBox->maximum());
          otherSpinBox->setValue(64);
          otherSpinBox->setToolTip(spinBoxToolTip);
          otherRadioButton->setToolTip(spinBoxToolTip);

          connect(otherSpinBox, QOverload<int>::of(&QSpinBox::valueChanged),
                  this, &MainWindow::triggerChangeSize);

          QHBoxLayout *otherSizeLayout = new QHBoxLayout;
          otherSizeLayout->addWidget(otherRadioButton);
          otherSizeLayout->addWidget(otherSpinBox);
          otherSizeLayout->addStretch();

          QGridLayout *layout = new QGridLayout(iconSizeGroupBox);
          layout->addWidget(smallRadioButton, 0, 0);
          layout->addWidget(largeRadioButton, 1, 0);
          layout->addWidget(toolBarRadioButton, 2, 0);
          layout->addWidget(listViewRadioButton, 0, 1);
          layout->addWidget(iconViewRadioButton, 1, 1);
          layout->addWidget(tabBarRadioButton, 2, 1);
          layout->addLayout(otherSizeLayout, 3, 0, 1, 2);
          layout->setRowStretch(4, 1);
          return iconSizeGroupBox;
      }

      void MainWindow::screenChanged()
      {
          devicePixelRatioLabel->setText(QString::number(devicePixelRatioF()));
          if (const QWindow *window = windowHandle()) {
              const QScreen *screen = window->screen();
              const QString screenDescription =
                  tr("\"%1\" (%2x%3)").arg(screen->name())
                     .arg(screen->geometry().width()).arg(screen->geometry().height());
              screenNameLabel->setText(screenDescription);
          }
          changeIcon();
      }

      QWidget *MainWindow::createHighDpiIconSizeGroupBox()
      {
          QGroupBox *highDpiGroupBox = new QGroupBox(tr("High DPI Scaling"));
          QFormLayout *layout = new QFormLayout(highDpiGroupBox);
          devicePixelRatioLabel = new QLabel(highDpiGroupBox);
          screenNameLabel = new QLabel(highDpiGroupBox);
          layout->addRow(tr("Screen:"), screenNameLabel);
          layout->addRow(tr("Device pixel ratio:"), devicePixelRatioLabel);
          QCheckBox *highDpiPixmapsCheckBox = new QCheckBox(QLatin1String("Qt::AA_UseHighDpiPixmaps"));
          highDpiPixmapsCheckBox->setChecked(QCoreApplication::testAttribute(Qt::AA_UseHighDpiPixmaps));
          connect(highDpiPixmapsCheckBox, &QCheckBox::stateChanged, this, &MainWindow::useHighDpiPixmapsChanged);
          layout->addRow(highDpiPixmapsCheckBox);
          return highDpiGroupBox;
      }

      void MainWindow::createActions()
      {
          QMenu *fileMenu = menuBar()->addMenu(tr("&File"));

          addSampleImagesAct = new QAction(tr("Add &Sample Images..."), this);
          addSampleImagesAct->setShortcut(tr("Ctrl+A"));
          connect(addSampleImagesAct, &QAction::triggered, this, &MainWindow::addSampleImages);
          fileMenu->addAction(addSampleImagesAct);

          addOtherImagesAct = new QAction(tr("&Add Images..."), this);
          addOtherImagesAct->setShortcut(QKeySequence::Open);
          connect(addOtherImagesAct, &QAction::triggered, this, &MainWindow::addOtherImages);
          fileMenu->addAction(addOtherImagesAct);

          removeAllImagesAct = new QAction(tr("&Remove All Images"), this);
          removeAllImagesAct->setShortcut(tr("Ctrl+R"));
          connect(removeAllImagesAct, &QAction::triggered,
                  this, &MainWindow::removeAllImages);
          fileMenu->addAction(removeAllImagesAct);

          fileMenu->addSeparator();

          QAction *exitAct = fileMenu->addAction(tr("&Quit"), this, &QWidget::close);
          exitAct->setShortcuts(QKeySequence::Quit);

          QMenu *viewMenu = menuBar()->addMenu(tr("&View"));

          styleActionGroup = new QActionGroup(this);
          const QStringList styleKeys = QStyleFactory::keys();
          for (const QString &styleName : styleKeys) {
              QAction *action = new QAction(tr("%1 Style").arg(styleName), styleActionGroup);
              action->setData(styleName);
              action->setCheckable(true);
              connect(action, &QAction::triggered, this, &MainWindow::changeStyle);
              viewMenu->addAction(action);
          }

          QMenu *settingsMenu = menuBar()->addMenu(tr("&Settings"));

          guessModeStateAct = new QAction(tr("&Guess Image Mode/State"), this);
          guessModeStateAct->setCheckable(true);
          guessModeStateAct->setChecked(true);
          settingsMenu->addAction(guessModeStateAct);

          nativeFileDialogAct = new QAction(tr("&Use Native File Dialog"), this);
          nativeFileDialogAct->setCheckable(true);
          nativeFileDialogAct->setChecked(true);
          settingsMenu->addAction(nativeFileDialogAct);

          QMenu *helpMenu = menuBar()->addMenu(tr("&Help"));
          helpMenu->addAction(tr("&About"), this, &MainWindow::about);
          helpMenu->addAction(tr("About &Qt"), qApp, &QApplication::aboutQt);
      }

      void MainWindow::createContextMenu()
      {
          imagesTable->setContextMenuPolicy(Qt::ActionsContextMenu);
          imagesTable->addAction(addSampleImagesAct);
          imagesTable->addAction(addOtherImagesAct);
          imagesTable->addAction(removeAllImagesAct);
      }

      void MainWindow::checkCurrentStyle()
      {
          const QList<QAction *> actions = styleActionGroup->actions();
          for (QAction *action : actions) {
              const QString styleName = action->data().toString();
              QScopedPointer<QStyle> candidate(QStyleFactory::create(styleName));
              Q_ASSERT(!candidate.isNull());
              if (candidate->metaObject()->className()
                      == QApplication::style()->metaObject()->className()) {
                  action->trigger();
                  return;
              }
          }
      }