qwt_plot_axis_wheel_interaction.h

/******************************************************************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *
 * This file is a new addition to the Qwt 7.x maintenance branch.
 *****************************************************************************/
 
#ifndef QWT_PLOT_AXIS_WHEEL_INTERACTION_H
#define QWT_PLOT_AXIS_WHEEL_INTERACTION_H
 
#include "qwt_global.h"
#include "qwt_axis_id.h"
 
#include <qobject.h>
 
class QWheelEvent;
class QEvent;
class QWidget;
class QwtPlot;
class QwtScaleWidget;
 
class QWT_EXPORT QwtPlotAxisWheelInteraction : public QObject
{
    Q_OBJECT
 
public:
    // Construct from a plot and axis id
    explicit QwtPlotAxisWheelInteraction(QwtPlot* plot, QwtAxisId axisId);
 
    // Construct from a scale widget (auto-derives plot and axis id)
    explicit QwtPlotAxisWheelInteraction(QwtScaleWidget* scaleWidget);
 
    // Destructor
    ~QwtPlotAxisWheelInteraction() override;
 
    // Enable or disable the interaction
    void setEnabled(bool on);
    // Return whether the interaction is enabled
    bool isEnabled() const;
 
    // ---- Zoom configuration (plain wheel by default) ----
 
    // Set keyboard modifiers for zoom mode (default: Qt::NoModifier)
    void setZoomModifiers(Qt::KeyboardModifiers modifiers);
    // Return the zoom modifiers
    Qt::KeyboardModifiers zoomModifiers() const;
 
    // Set the zoom factor per wheel step (default: 1.2; >1 zoom in, <1 zoom out)
    void setZoomFactor(double factor);
    // Return the zoom factor
    double zoomFactor() const;
 
    // ---- Pan configuration (Ctrl+wheel by default) ----
 
    // Set keyboard modifiers for pan mode (default: Qt::ControlModifier)
    void setPanModifiers(Qt::KeyboardModifiers modifiers);
    // Return the pan modifiers
    Qt::KeyboardModifiers panModifiers() const;
 
    // Set pixels to pan per wheel step (default: 30)
    void setPanFactor(int pixelsPerStep);
    // Return the pan factor in pixels
    int panFactor() const;
 
    // Return the observed scale widget
    QwtScaleWidget* scaleWidget();
    // Return the observed scale widget (const version)
    const QwtScaleWidget* scaleWidget() const;
 
    // Return the plot that owns the axis
    QwtPlot* plot();
    // Return the plot that owns the axis (const version)
    const QwtPlot* plot() const;
 
    // Return the axis id
    QwtAxisId axisId() const;
 
protected:
    // Event filter — intercepts wheel events on the scale widget
    virtual bool eventFilter(QObject* obj, QEvent* event) override;
 
    // Top-level wheel handler. Override for completely custom behavior.
    // Return true if handled (event consumed), false to pass through.
    virtual bool handleWheelEvent(QWheelEvent* event);
 
    // Called when zoom action is triggered. Override to customize zoom.
    // @param factor Zoom factor (>1 zoom in, <1 zoom out)
    // @param cursorPos Cursor position in canvas coordinates
    virtual void wheelZoom(double factor, const QPoint& cursorPos);
 
    // Called when pan action is triggered. Override to customize pan.
    // @param deltaPixels Pixel offset (positive = right/down, negative = left/up)
    virtual void wheelPan(int deltaPixels);
 
private:
    QWT_DECLARE_PRIVATE(QwtPlotAxisWheelInteraction)
};
 
#endif  // QWT_PLOT_AXIS_WHEEL_INTERACTION_H