QwtPlotAxisWheelInteraction类 参考

Configurable wheel interaction for a single plot axis 更多...

#include <qwt_plot_axis_wheel_interaction.h>

类 QwtPlotAxisWheelInteraction 继承关系图:

类
class	PrivateData

Public 成员函数
	QwtPlotAxisWheelInteraction (QwtPlot *plot, QwtAxisId axisId)
	Constructor from plot and axis id
	QwtPlotAxisWheelInteraction (QwtScaleWidget *scaleWidget)
void	setEnabled (bool on)
	Enable or disable the interaction
bool	isEnabled () const
	Return whether the interaction is enabled
void	setZoomModifiers (Qt::KeyboardModifiers modifiers)
	Set keyboard modifiers for zoom mode
Qt::KeyboardModifiers	zoomModifiers () const
	Return the zoom modifiers
void	setZoomFactor (double factor)
	Set the zoom factor per wheel step
double	zoomFactor () const
	Return the zoom factor
void	setPanModifiers (Qt::KeyboardModifiers modifiers)
	Set keyboard modifiers for pan mode
Qt::KeyboardModifiers	panModifiers () const
	Return the pan modifiers
void	setPanFactor (int pixelsPerStep)
	Set the pan distance per wheel step
int	panFactor () const
	Return the pan factor in pixels
QwtScaleWidget *	scaleWidget ()
	Return the observed scale widget
const QwtScaleWidget *	scaleWidget () const
	Return the observed scale widget (const version)
QwtPlot *	plot ()
	Return the plot that owns the axis
const QwtPlot *	plot () const
	Return the plot that owns the axis (const version)
QwtAxisId	axisId () const
	Return the axis id

Protected 成员函数
virtual bool	eventFilter (QObject *obj, QEvent *event) override
	Event filter for wheel events on the scale widget
virtual bool	handleWheelEvent (QWheelEvent *event)
	Handle a wheel event on the scale widget
virtual void	wheelZoom (double factor, const QPoint &cursorPos)
	Perform a zoom on the axis
virtual void	wheelPan (int deltaPixels)
	Perform a pan on the axis

详细描述

Configurable wheel interaction for a single plot axis

QwtPlotAxisWheelInteraction installs an event filter on a QwtScaleWidget (the axis tick area) and provides two configurable wheel actions:

• Zoom (plain wheel by default): zooms the axis centered at the cursor position using QwtPlot::zoomAxis().
• Pan (Ctrl+wheel by default): pans the axis by a fixed pixel amount per step using QwtPlot::panAxis().

Unlike the built-in QwtPlotScaleEventDispatcher (which hardcodes wheel=zoom and requires the axis to be clicked/selected first), this class:

• Supports keyboard modifiers to switch between zoom and pan.
• Works immediately without needing to select the axis first.
• Is fully configurable (modifiers, factors, enable/disable).
• Is designed for inheritance — override wheelZoom(), wheelPan(), or handleWheelEvent() to implement custom behavior.

When the modifier matches zoom or pan, the event is consumed (return true) so the dispatcher does not also process it. When the modifier matches neither, the event is passed through to the dispatcher for default handling.

Typical usage:

// Plain wheel zooms XBottom at cursor; Ctrl+wheel pans it
new QwtPlotAxisWheelInteraction(plot, QwtAxis::XBottom);
 
// Customize: Shift+wheel zooms YLeft, plain wheel pans
auto* ix = new QwtPlotAxisWheelInteraction(plot, QwtAxis::YLeft);
ix->setZoomModifiers(Qt::ShiftModifier);
ix->setPanModifiers(Qt::NoModifier);

Inheritance example:

class CenterZoom : public QwtPlotAxisWheelInteraction {
public:
    using QwtPlotAxisWheelInteraction::QwtPlotAxisWheelInteraction;
protected:
    void wheelZoom(double factor, const QPoint&) override {
        // Zoom centered on axis midpoint instead of cursor
        const QwtScaleMap m = plot()->canvasMap(axisId());
        const int mid = static_cast<int>((m.p1() + m.p2()) / 2);
        QwtPlotAxisWheelInteraction::wheelZoom(factor, QPoint(mid, 0));
    }
};

参见

QwtPlotScaleEventDispatcher, QwtPlot::zoomAxis(), QwtPlot::panAxis()

构造及析构函数说明

QwtPlotAxisWheelInteraction()

QwtPlotAxisWheelInteraction::QwtPlotAxisWheelInteraction ( QwtPlot *  plot, QwtAxisId  axisId  )

explicit

Constructor from plot and axis id

参数

[in]	plot	The plot that owns the axis
[in]	axisId	The axis to attach the interaction to

The event filter is installed on the QwtScaleWidget for the given axis. The interaction is enabled by default.

Constructor from a scale widget

参数

[in]

scaleWidget

The axis scale widget to observe

The plot and axis id are auto-derived from the scale widget's parent (which must be a QwtPlot) using QwtPlotScaleEventDispatcher::findAxisIdByScaleWidget().

Destructor

成员函数说明

axisId()

QwtAxisId QwtPlotAxisWheelInteraction::axisId

(

)

const

Return the axis id

返回

Axis identifier

eventFilter()

bool QwtPlotAxisWheelInteraction::eventFilter ( QObject *  obj, QEvent *  event  )

overrideprotectedvirtual

Event filter for wheel events on the scale widget

参数

[in]	obj	Object receiving the event (should be the scale widget)
[in]	event	Event

返回

true when the wheel event was handled (consumed), false otherwise

参见

handleWheelEvent()

handleWheelEvent()

bool QwtPlotAxisWheelInteraction::handleWheelEvent ( QWheelEvent *  event )

protectedvirtual

Handle a wheel event on the scale widget

The wheel delta is read via qwt::compat::wheelEventDelta() for Qt5/Qt6 compatibility. When the current modifiers match the zoom modifiers, wheelZoom() is called. When they match the pan modifiers, wheelPan() is called. Otherwise the event is passed through (return false) so the QwtPlotScaleEventDispatcher can handle it.

参数

[in]

event

Wheel event

返回

true if the event was handled, false if modifiers matched neither zoom nor pan mode

isEnabled()

bool QwtPlotAxisWheelInteraction::isEnabled

(

)

const

Return whether the interaction is enabled

返回

true when enabled, false otherwise

参见

setEnabled()

panFactor()

int QwtPlotAxisWheelInteraction::panFactor

(

)

const

Return the pan factor in pixels

返回

Pixels per wheel step

参见

setPanFactor()

panModifiers()

Qt::KeyboardModifiers QwtPlotAxisWheelInteraction::panModifiers

(

)

const

Return the pan modifiers

返回

Keyboard modifiers for pan mode

参见

setPanModifiers()

plot() [1/2]

QwtPlot * QwtPlotAxisWheelInteraction::plot

(

)

Return the plot that owns the axis

返回

Pointer to the QwtPlot widget

plot() [2/2]

const QwtPlot * QwtPlotAxisWheelInteraction::plot

(

)

const

Return the plot that owns the axis (const version)

返回

Const pointer to the QwtPlot widget

scaleWidget() [1/2]

QwtScaleWidget * QwtPlotAxisWheelInteraction::scaleWidget

(

)

Return the observed scale widget

返回

Pointer to the scale widget

scaleWidget() [2/2]

const QwtScaleWidget * QwtPlotAxisWheelInteraction::scaleWidget

(

)

const

Return the observed scale widget (const version)

返回

Const pointer to the scale widget

setEnabled()

void QwtPlotAxisWheelInteraction::setEnabled

(

bool

on

)

Enable or disable the interaction

When enabled, an event filter is installed on the observed scale widget to intercept wheel events before they reach the QwtPlotScaleEventDispatcher. When disabled, the filter is removed and the dispatcher regains full control.

参数

[in]

on

true to enable, false to disable

参见

isEnabled(), eventFilter()

setPanFactor()

void QwtPlotAxisWheelInteraction::setPanFactor

(

int

pixelsPerStep

)

Set the pan distance per wheel step

参数

[in]

pixelsPerStep

Number of pixels to pan per wheel notch (default: 30)

参见

panFactor()

setPanModifiers()

void QwtPlotAxisWheelInteraction::setPanModifiers

(

Qt::KeyboardModifiers

modifiers

)

Set keyboard modifiers for pan mode

When the wheel is rotated with these modifiers on the scale widget, the axis is panned. The default is Qt::ControlModifier.

参数

[in]

modifiers

Keyboard modifiers

参见

panModifiers()

setZoomFactor()

void QwtPlotAxisWheelInteraction::setZoomFactor

(

double

factor

)

Set the zoom factor per wheel step

Values > 1 zoom in (range shrinks), values < 1 zoom out (range expands). The default is 1.2. For multi-step wheels the factor is compounded: pow(zoomFactor, abs(delta/120)).

参数

[in]

factor

Zoom factor

参见

zoomFactor()

setZoomModifiers()

void QwtPlotAxisWheelInteraction::setZoomModifiers

(

Qt::KeyboardModifiers

modifiers

)

Set keyboard modifiers for zoom mode

When the wheel is rotated with these modifiers on the scale widget, the axis is zoomed. The default is Qt::NoModifier (plain wheel).

参数

[in]

modifiers

Keyboard modifiers

参见

zoomModifiers()

wheelPan()

void QwtPlotAxisWheelInteraction::wheelPan ( int  deltaPixels )

protectedvirtual

Perform a pan on the axis

Default implementation calls QwtPlot::panAxis() with the given pixel delta, then replotAll(). Auto-replot is temporarily disabled to avoid redundant repaints.

Override this method to customize pan behavior, e.g. invert direction or add momentum.

参数

[in]

deltaPixels

Pixel offset (positive = right/down, negative = left/up)

wheelZoom()

void QwtPlotAxisWheelInteraction::wheelZoom ( double  factor, const QPoint &  cursorPos  )

protectedvirtual

Perform a zoom on the axis

Default implementation calls QwtPlot::zoomAxis() with the given factor and cursor position, then replotAll(). Auto-replot is temporarily disabled to avoid redundant repaints.

Override this method to customize zoom behavior, e.g. zoom centered on the axis midpoint instead of the cursor position.

参数

[in]	factor	Zoom factor (>1 zoom in, <1 zoom out)
[in]	cursorPos	Cursor position in canvas coordinates

zoomFactor()

double QwtPlotAxisWheelInteraction::zoomFactor

(

)

const

Return the zoom factor

返回

Zoom factor

参见

setZoomFactor()

zoomModifiers()

Qt::KeyboardModifiers QwtPlotAxisWheelInteraction::zoomModifiers

(

)

const

Return the zoom modifiers

返回

Keyboard modifiers for zoom mode

参见

setZoomModifiers()

---

该类的文档由以下文件生成:

• /home/runner/work/QWT/QWT/src/plot/qwt_plot_axis_wheel_interaction.h
• /home/runner/work/QWT/QWT/src/plot/qwt_plot_axis_wheel_interaction.cpp