UImageView.h

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/*
 * ImageView.h
 *
 *  Created on: 2012-06-20
 *      Author: mathieu
 */

#ifndef IMAGEVIEW_H_
#define IMAGEVIEW_H_

#include <QWidget>
#include <QtGui/QPainter>

class UImageView : public QWidget
{
        Q_OBJECT;
public:
        UImageView(QWidget * parent = 0) : QWidget(parent) {}
        ~UImageView() {}
        void setBackgroundBrush(const QBrush & brush) {brush_ = brush;}

public slots:
        void setImage(const QImage & image)
        {
                pixmap_ = QPixmap::fromImage(image);
                this->update();
        }

private:
        void computeScaleOffsets(float & scale, float & offsetX, float & offsetY)
        {
                scale = 1.0f;
                offsetX = 0.0f;
                offsetY = 0.0f;

                if(!pixmap_.isNull())
                {
                        float w = pixmap_.width();
                        float h = pixmap_.height();
                        float widthRatio = float(this->rect().width()) / w;
                        float heightRatio = float(this->rect().height()) / h;

                        if(widthRatio < heightRatio)
                        {
                                scale = widthRatio;
                        }
                        else
                        {
                                scale = heightRatio;
                        }

                        w *= scale;
                        h *= scale;

                        if(w < this->rect().width())
                        {
                                offsetX = (this->rect().width() - w)/2.0f;
                        }
                        if(h < this->rect().height())
                        {
                                offsetY = (this->rect().height() - h)/2.0f;
                        }
                }
        }

protected:
        virtual void paintEvent(QPaintEvent *event)
        {
                QPainter painter(this);

                //Draw background
                painter.save();
                painter.setBrush(brush_);
                painter.drawRect(this->rect());
                painter.restore();

                if(!pixmap_.isNull())
                {
                        painter.save();
                        //Scale
                        float ratio, offsetX, offsetY;
                        this->computeScaleOffsets(ratio, offsetX, offsetY);
                        painter.translate(offsetX, offsetY);
                        painter.scale(ratio, ratio);
                        painter.drawPixmap(QPoint(0,0), pixmap_);
                        painter.restore();
                }
        }

private:
        QPixmap pixmap_;
        QBrush brush_;
};


#endif /* IMAGEVIEW_H_ */