Google MapのスクロールをQGraphicsViewで再現したい

smoothzoom

#include <QtGui>

class GraphicsView : public QGraphicsView
{
    Q_OBJECT

public:
    GraphicsView(QWidget *parent = 0) : QGraphicsView(parent), mousePressed_(false)
    {
        init();
    }

protected:
    void mousePressEvent(QMouseEvent *event)
    {
        if (event->buttons() & Qt::LeftButton)
        {
            mousePressed_ = true;
            timerId_ = startTimer(20);
            prePosition_ = event->pos();
            delta_ = QPoint();
            ratio_ = 1;
        }

        QGraphicsView::mousePressEvent(event);
    }

    void mouseMoveEvent(QMouseEvent *event)
    {
        if (mousePressed_)
        {
            delta_ = event->pos() - prePosition_;
            prePosition_ = event->pos();
        }

        QGraphicsView::mouseMoveEvent(event);
    }

    void mouseReleaseEvent(QMouseEvent *event)
    {
        if (mousePressed_)
            mousePressed_ = false;

        QGraphicsView::mouseReleaseEvent(event);
    }

    void timerEvent(QTimerEvent *event)
    {
        if (event->timerId() == timerId_ && !mousePressed_)
        {
            if (delta_ == QPoint() || ratio_ < 0.01)
            {
                killTimer(timerId_);
                return;
            }
            scroll(horizontalScrollBar(), delta_.x() * ratio_);
            scroll(verticalScrollBar(), delta_.y() * ratio_);
            // ここを有効にすると減衰する
            //            ratio_ *= 0.95;
        }

        QGraphicsView::timerEvent(event);
    }

private:
    void init()
    {
        setAlignment(Qt::AlignCenter);
        setDragMode(ScrollHandDrag);
    }

    void scroll(QScrollBar *bar, int point)
    {
        bar->setValue(bar->value() - point);
    }

private:
    bool mousePressed_;
    QPoint prePosition_;
    QPoint delta_;
    int timerId_;
    qreal ratio_;
};

void setScene(GraphicsView &view, int row, int width)
{
    view.setScene(new QGraphicsScene(&view));
    for (int i = 0; i < row; ++i)
    {
        int j = i * width;
        view.scene()->addLine(j, 0, j, width * row);
        view.scene()->addLine(0, j, width * row, j);
    }
    view.setSceneRect(0,0, row * width, row * width);
    view.scale(2, 2);
}

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    GraphicsView view;
    setScene(view, 100, 10);
    view.show();
    return app.exec();
}

#include "smoothzoom.moc"

ファイル名間違えてた。smoothmoveと書きたかった。mocもzoomになっちゃってるからもういい。（酔っぱらいですし