bar_delegate.cpp

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// Renders a colored bar graph behind the data
// Author: Max Schwarz <max.schwarz@uni-bonn.de>

#include "bar_delegate.h"

#include <QPainter>

namespace rqt_rosmon
{

BarDelegate::BarDelegate(QObject* parent)
 : QStyledItemDelegate(parent)
 , m_min(0.0)
 , m_max(100.0)
{
}

void BarDelegate::setRange(double min, double max)
{
        m_min = min;
        m_max = max;
}

void BarDelegate::paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const
{
        double data;

        QVariant var = index.data(Qt::EditRole);
        if(var.isValid())
                data = var.toDouble();
        else
                data = index.data(Qt::DisplayRole).toDouble();

        double alpha = std::min(1.0, std::max(0.0, (data - m_min) / (m_max - m_min)));

        QRect rect = option.rect;
        rect.setWidth(static_cast<int>(alpha * rect.width()));

        QColor color(
                static_cast<int>(alpha * 255),
                static_cast<int>((1.0f - alpha) * 255),
                0
//              (1.0f - alpha) * 255
        );

        painter->fillRect(rect, color);

        QStyledItemDelegate::paint(painter, option, index);
}

}