iconpreviewarea.cpp Example File

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 #include <QtWidgets>

 #include "iconpreviewarea.h"

 IconPreviewArea::IconPreviewArea(QWidget *parent)
     : QWidget(parent)
 {
     QGridLayout *mainLayout = new QGridLayout(this);

     for (int row = 0; row < NumStates; ++row) {
         stateLabels[row] = createHeaderLabel(IconPreviewArea::iconStateNames().at(row));
         mainLayout->addWidget(stateLabels[row], row + 1, 0);
     }
     Q_ASSERT(NumStates == 2);

     for (int column = 0; column < NumModes; ++column) {
         modeLabels[column] = createHeaderLabel(IconPreviewArea::iconModeNames().at(column));
         mainLayout->addWidget(modeLabels[column], 0, column + 1);
     }
     Q_ASSERT(NumModes == 4);

     for (int column = 0; column < NumModes; ++column) {
         for (int row = 0; row < NumStates; ++row) {
             pixmapLabels[column][row] = createPixmapLabel();
             mainLayout->addWidget(pixmapLabels[column][row], row + 1, column + 1);
         }
     }
 }

 #ifdef Q_COMPILER_INITIALIZER_LISTS

 QVector<QIcon::Mode> IconPreviewArea::iconModes()
 {
     static const QVector<QIcon::Mode> result = {QIcon::Normal, QIcon::Active, QIcon::Disabled, QIcon::Selected};
     return result;
 }

 QVector<QIcon::State> IconPreviewArea::iconStates()
 {
     static const QVector<QIcon::State> result = {QIcon::Off, QIcon::On};
     return result;
 }

 QStringList IconPreviewArea::iconModeNames()
 {
     static const QStringList result = {tr("Normal"), tr("Active"), tr("Disabled"), tr("Selected")};
     return result;
 }

 QStringList IconPreviewArea::iconStateNames()
 {
     static const QStringList result = {tr("Off"), tr("On")};
     return result;
 }

 #else // Q_COMPILER_INITIALIZER_LISTS

 QVector<QIcon::Mode> IconPreviewArea::iconModes()
 {
     static QVector<QIcon::Mode> result;
     if (result.isEmpty())
         result << QIcon::Normal << QIcon::Active << QIcon::Disabled << QIcon::Selected;
     return result;
 }

 QVector<QIcon::State> IconPreviewArea::iconStates()
 {
     static QVector<QIcon::State> result;
     if (result.isEmpty())
         result << QIcon::Off << QIcon::On;
     return result;
 }

 QStringList IconPreviewArea::iconModeNames()
 {
     static QStringList result;
     if (result.isEmpty())
         result << tr("Normal") << tr("Active") << tr("Disabled") << tr("Selected");
     return result;
 }

 QStringList IconPreviewArea::iconStateNames()
 {
     static QStringList result;
     if (result.isEmpty())
         result << tr("Off") << tr("On");
     return result;
 }

 #endif // !Q_COMPILER_INITIALIZER_LISTS

 void IconPreviewArea::setIcon(const QIcon &icon)
 {
     this->icon = icon;
     updatePixmapLabels();
 }

 void IconPreviewArea::setSize(const QSize &size)
 {
     if (size != this->size) {
         this->size = size;
         updatePixmapLabels();
     }
 }

 QLabel *IconPreviewArea::createHeaderLabel(const QString &text)
 {
     QLabel *label = new QLabel(tr("<b>%1</b>").arg(text));
     label->setAlignment(Qt::AlignCenter);
     return label;
 }

 QLabel *IconPreviewArea::createPixmapLabel()
 {
     QLabel *label = new QLabel;
     label->setEnabled(false);
     label->setAlignment(Qt::AlignCenter);
     label->setFrameShape(QFrame::Box);
     label->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
     label->setBackgroundRole(QPalette::Base);
     label->setAutoFillBackground(true);
     label->setMinimumSize(132, 132);
     return label;
 }

 void IconPreviewArea::updatePixmapLabels()
 {
     QWindow *window = nullptr;
     if (const QWidget *nativeParent = nativeParentWidget())
         window = nativeParent->windowHandle();
     for (int column = 0; column < NumModes; ++column) {
         for (int row = 0; row < NumStates; ++row) {
             const QPixmap pixmap =
                 icon.pixmap(window, size, IconPreviewArea::iconModes().at(column),
                             IconPreviewArea::iconStates().at(row));
             QLabel *pixmapLabel = pixmapLabels[column][row];
             pixmapLabel->setPixmap(pixmap);
             pixmapLabel->setEnabled(!pixmap.isNull());
             QString toolTip;
             if (!pixmap.isNull()) {
                 const QSize actualSize = icon.actualSize(size);
                 toolTip =
                     tr("Size: %1x%2\nActual size: %3x%4\nDevice pixel ratio: %5")
                         .arg(size.width()).arg(size.height())
                         .arg(actualSize.width()).arg(actualSize.height())
                         .arg(pixmap.devicePixelRatioF());
             }
             pixmapLabel->setToolTip(toolTip);
         }
     }
 }