---
name: "QwtPlotMagnifier"
section: "3"
platform: "linux"
package: "libqwt-doc"
version: "6.1.4-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/QwtPlotMagnifier"
---

# QwtPlotMagnifier(3)

QwtPlotMagnifier provides zooming, by magnifying in steps.

## NAME

QwtPlotMagnifier - **QwtPlotMagnifier** provides zooming, by magnifying in steps.

## SYNOPSIS

`#include <qwt_plot_magnifier.h>`

Inherits **QwtMagnifier**.

### Public Member Functions

**QwtPlotMagnifier** (QWidget \*)\
 virtual **~QwtPlotMagnifier** ()\
 Destructor.  void **setAxisEnabled** (int axis, bool on)\
 En/Disable an axis.  bool **isAxisEnabled** (int axis) const\
 QWidget \* **canvas** ()\
 Return observed plot canvas.  const QWidget \* **canvas** () const\
 Return Observed plot canvas.  **QwtPlot** \* **plot** ()\
 Return plot widget, containing the observed plot canvas.  const **QwtPlot** \* **plot** () const\
 Return plot widget, containing the observed plot canvas.

### Protected Member Functions

virtual void **rescale** (double factor)\

## Detailed Description

**QwtPlotMagnifier** provides zooming, by magnifying in steps.

Using **QwtPlotMagnifier** a plot can be zoomed in/out in steps using keys, the mouse wheel or moving a mouse button in vertical direction.

Together with **QwtPlotZoomer** and **QwtPlotPanner** it is possible to implement individual and powerful navigation of the plot canvas.

**See also:**

**QwtPlotZoomer**, **QwtPlotPanner**, **QwtPlot**

## Constructor & Destructor Documentation

### QwtPlotMagnifier::QwtPlotMagnifier (QWidget \* canvas)` [explicit]`

Constructor

**Parameters:**

*canvas* Plot canvas to be magnified

## Member Function Documentation

### bool QwtPlotMagnifier::isAxisEnabled (int axis) const

Test if an axis is enabled

**Parameters:**

*axis* Axis, see **QwtPlot::Axis**

**Returns:**

True, if the axis is enabled

**See also:**

**setAxisEnabled()**

### void QwtPlotMagnifier::rescale (double factor)` [protected]`, ` [virtual]`

Zoom in/out the axes scales

**Parameters:**

*factor* A value \< 1.0 zooms in, a value \> 1.0 zooms out.

Implements **QwtMagnifier**.

### void QwtPlotMagnifier::setAxisEnabled (int axis, bool on)

En/Disable an axis. Only Axes that are enabled will be zoomed. All other axes will remain unchanged.

**Parameters:**

*axis* Axis, see **QwtPlot::Axis** \
 *on* On/Off

**See also:**

**isAxisEnabled()**

## Author

Generated automatically by Doxygen for Qwt User's Guide from the source code.