#include <QGuiApplication>
#include <QQuickPaintedItem>
#include <QQuickWindow>
#include <QPainter>

const QRect WINDOW_RECT{0, 0, 1600, 1000};
const QSize FONT_RECT_SIZE{300, 230};
const int FONT_SPACING = 20;
const int COLUMNS = std::floor(WINDOW_RECT.width() / (FONT_RECT_SIZE.width() + FONT_SPACING));

const QStringList FONTS{
    // Font with correct result
    "Arial",
    // Fonts with wrong results
    "Sitka Small",
    "Sitka Subheading",
    "Sitka Text",
    "PMingLiU-ExtB",
    "MingLiU-ExtB",
    "Liberation Sans Narrow",
    "Gabriola",
    "DejaVu Math TeX Gyre",
    "Bahnschrift",
    "Bahnschrift Condensed",
    "Bahnschrift SemiBold",
    "Amiri",
};

class Paintable final : public QQuickPaintedItem
{
public:
    explicit Paintable(QQuickItem* parent = nullptr)
    : QQuickPaintedItem(parent)
    {
        setOpaquePainting(true);
    }

    void paintFontDemo(QPainter* painter, QString fontName)
    {
        const QString text("Übgo");

        // Get font
        QFont font(fontName);
        font.setPixelSize(70);

        // Calculate bounding rect and baseline position
        QFontMetricsF fontMetrics(font);
        QRectF boundingRect = fontMetrics.boundingRect(text);
        QLine baseline(0, 0, boundingRect.width(), 0); // the bounding rect is aligned such that the baseline is at y=0

        // Draw bounding rect
        painter->fillRect(boundingRect, Qt::GlobalColor::yellow);

        // Draw baseline
        QPen pen1(Qt::GlobalColor::red, 1);
        painter->setPen(pen1);
        painter->drawLine(baseline);

        // Draw text
        QPen pen2(Qt::GlobalColor::black, 1);
        painter->setPen(pen2);
        painter->setFont(font);
        painter->drawText(boundingRect, Qt::TextDontClip, text);
    }

    void paint(QPainter* painter) override
    {
        painter->fillRect(WINDOW_RECT, Qt::GlobalColor::white);

        for (int i = 0; i < FONTS.size(); i++) {
            const int col = std::floor(i % COLUMNS);
            const int row = std::floor(i / COLUMNS);

            const QTransform transform = QTransform::fromTranslate(
                        FONT_RECT_SIZE.width() / 4 + col * (FONT_RECT_SIZE.width() + FONT_SPACING),
                        FONT_RECT_SIZE.height() * 0.75 + row * (FONT_RECT_SIZE.height() + FONT_SPACING));

            painter->setWorldTransform(transform);

            paintFontDemo(painter, FONTS[i]);
        }
    }
};

int main(int argc, char* argv[])
{
    QGuiApplication app(argc, argv);

    auto* qquickWindow = new QQuickWindow();
    qquickWindow->setTitle("Windows bounding rect demo");
    qquickWindow->setWidth(WINDOW_RECT.width());
    qquickWindow->setHeight(WINDOW_RECT.height());

    auto* paintable = new Paintable(qquickWindow->contentItem());
    paintable->setSize(WINDOW_RECT.size());
    paintable->setVisible(true);

    qquickWindow->show();

    return app.exec();
}