diff --git a/scalepicker.h b/scalepicker.h
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+/*
+  Copyright © 2015 Hasan Yavuz Özderya
+
+  This file is part of serialplot.
+
+  serialplot is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  serialplot is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with serialplot.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef SCALEPICKER_H
+#define SCALEPICKER_H
+
+#include <QObject>
+#include <QMouseEvent>
+#include <QPen>
+#include <QWidget>
+#include <qwt_scale_widget.h>
+#include <qwt_widget_overlay.h>
+
+class ScalePicker : public QObject
+{
+    Q_OBJECT
+
+public:
+    ScalePicker(QwtScaleWidget* scaleWidget, QWidget* canvas);
+    virtual bool eventFilter(QObject*, QEvent*);
+
+    void drawPlotOverlay(QPainter*); // called from ScalePickerOverlay
+    void drawScaleOverlay(QPainter*); // called from ScaleOverlay
+    void setPen(QPen pen);
+
+signals:
+    void pickStarted(double pos);
+    void picking(double firstPos, double lastPos);
+    void picked(double firstPos, double lastPos);
+
+private:
+    QwtScaleWidget* _scaleWidget;
+    QWidget* _canvas;
+    QwtWidgetOverlay* pickerOverlay; // will be PlotOverlay
+    QwtWidgetOverlay* scaleOverlay;  // will be ScaleOverlay
+    QPen _pen;
+
+    bool pressed;
+    bool started;
+    double firstPos; // converted to plot coordinates
+    double firstPosPx; // pixel coordinates
+    double currentPosPx; // current position in pixel coordinates
+
+    double position(QMouseEvent*); // returns the axis mouse position relative to plot coordinates
+    double positionPx(QMouseEvent*); // returns the axis mouse position in pixels
+    double posCanvasPx(double pos); // returns the given position in canvas coordinates
+};
+
+#endif // SCALEPICKER_H