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#include <QBuffer>
#include "imgrunnable.h"

MapImageRunnable::MapImageRunnable(const QImage &sourceImage, int zoom, int row,
                                   int column)
    : m_sourceImage(sourceImage), m_zoom(zoom), m_row(row), m_column(column)
{
}

void MapImageRunnable::run()
{
    // The number of tiles along each axis is 2^zoom.
    // zoom is a value from 0 to 4, so the number of tiles are 1 to 16.
    int number = 1 << m_zoom;

    // Divide the source image into 2^zoom by 2^zoom tiles.
    int tileWidth = m_sourceImage.size().width() / number;
    int tileHeight = m_sourceImage.size().height() / number;

    // Calculate the coordinates for the top-left corner of the tile.
    int tx = m_column * tileWidth;
    int ty = m_row * tileHeight;

    QImage tileImage = m_sourceImage.copy(tx, ty, tileWidth, tileHeight);
    QImage scaledImage = tileImage.scaled(256, 256);

    QByteArray data;
    QBuffer buffer(&data);
    buffer.open(QBuffer::WriteOnly);
    scaledImage.save(&buffer, "PNG");
    buffer.close();

    emit finished(data);
}