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

# QwtPlotPicker(3)

QwtPlotPicker provides selections on a plot canvas.

## NAME

QwtPlotPicker - **QwtPlotPicker** provides selections on a plot canvas.

## SYNOPSIS

`#include <qwt_plot_picker.h>`

Inherits **QwtPicker**.

Inherited by **QwtPlotZoomer**.

### Signals

void **selected** (const QPointF &pos)\
 void **selected** (const QRectF &rect)\
 void **selected** (const QVector\< QPointF \> &pa)\
 void **appended** (const QPointF &pos)\
 void **moved** (const QPointF &pos)\

### Public Member Functions

**QwtPlotPicker** (QWidget \***canvas**)\
 Create a plot picker.  virtual **~QwtPlotPicker** ()\
 Destructor.  **QwtPlotPicker** (int **xAxis**, int **yAxis**, QWidget \*)\
 **QwtPlotPicker** (int **xAxis**, int **yAxis**, **RubberBand** **rubberBand**, **DisplayMode** **trackerMode**, QWidget \*)\
 virtual void **setAxis** (int **xAxis**, int **yAxis**)\
 int **xAxis** () const\
 Return x axis.  int **yAxis** () const\
 Return y axis.  **QwtPlot** \* **plot** ()\
 const **QwtPlot** \* **plot** () const\
 QWidget \* **canvas** ()\
 const QWidget \* **canvas** () const\

### Protected Member Functions

QRectF **scaleRect** () const\
 QRectF **invTransform** (const QRect &) const\
 QRect **transform** (const QRectF &) const\
 QPointF **invTransform** (const QPoint &) const\
 QPoint **transform** (const QPointF &) const\
 virtual **QwtText** **trackerText** (const QPoint &) const\
 virtual **QwtText** **trackerTextF** (const QPointF &) const\
 Translate a position into a position string.  virtual void **move** (const QPoint &)\
 virtual void **append** (const QPoint &)\
 virtual bool **end** (bool ok=true)\

### Additional Inherited Members

## Detailed Description

**QwtPlotPicker** provides selections on a plot canvas.

**QwtPlotPicker** is a **QwtPicker** tailored for selections on a plot canvas. It is set to a x-Axis and y-Axis and translates all pixel coordinates into this coordinate system.

## Constructor & Destructor Documentation

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

Create a plot picker. The picker is set to those x- and y-axis of the plot that are enabled. If both or no x-axis are enabled, the picker is set to **QwtPlot::xBottom**. If both or no y-axis are enabled, it is set to **QwtPlot::yLeft**.

**Parameters:**

*canvas* Plot canvas to observe, also the parent object

**See also:**

**QwtPlot::autoReplot()**, **QwtPlot::replot()**, **scaleRect()**

### QwtPlotPicker::QwtPlotPicker (int xAxis, int yAxis, QWidget \* canvas)` [explicit]`

Create a plot picker

**Parameters:**

*xAxis* Set the x axis of the picker \
 *yAxis* Set the y axis of the picker \
 *canvas* Plot canvas to observe, also the parent object

**See also:**

**QwtPlot::autoReplot()**, **QwtPlot::replot()**, **scaleRect()**

### QwtPlotPicker::QwtPlotPicker (int xAxis, int yAxis, RubberBand rubberBand, DisplayMode trackerMode, QWidget \* canvas)` [explicit]`

Create a plot picker

**Parameters:**

*xAxis* X axis of the picker \
 *yAxis* Y axis of the picker \
 *rubberBand* Rubber band style \
 *trackerMode* Tracker mode \
 *canvas* Plot canvas to observe, also the parent object

**See also:**

**QwtPicker**, QwtPicker::setSelectionFlags(), **QwtPicker::setRubberBand()**, **QwtPicker::setTrackerMode**

**QwtPlot::autoReplot()**, **QwtPlot::replot()**, **scaleRect()**

## Member Function Documentation

### void QwtPlotPicker::append (const QPoint & pos)` [protected]`, ` [virtual]`

Append a point to the selection and update rubber band and tracker.

**Parameters:**

*pos* Additional point

**See also:**

**isActive**, **begin()**, **end()**, **move()**, **appended()**

**Note:**

The **appended(const QPoint &)**, appended(const QDoublePoint &) signals are emitted.

Reimplemented from **QwtPicker**.

### void QwtPlotPicker::appended (const QPointF & pos)` [signal]`

A signal emitted when a point has been appended to the selection

**Parameters:**

*pos* Position of the appended point.

**See also:**

**append()**. **moved()**

### QWidget \* QwtPlotPicker::canvas ()

**Returns:**

Observed plot canvas

### const QWidget \* QwtPlotPicker::canvas () const

**Returns:**

Observed plot canvas

### bool QwtPlotPicker::end (bool ok = `true`)` [protected]`, ` [virtual]`

Close a selection setting the state to inactive.

**Parameters:**

*ok* If true, complete the selection and emit selected signals otherwise discard the selection.

**Returns:**

True if the selection has been accepted, false otherwise

Reimplemented from **QwtPicker**.

Reimplemented in **QwtPlotZoomer**.

### QRectF QwtPlotPicker::invTransform (const QRect & rect) const` [protected]`

Translate a rectangle from pixel into plot coordinates

**Returns:**

Rectangle in plot coordinates

**See also:**

**transform()**

### QPointF QwtPlotPicker::invTransform (const QPoint & pos) const` [protected]`

Translate a point from pixel into plot coordinates

**Returns:**

Point in plot coordinates

**See also:**

**transform()**

### void QwtPlotPicker::move (const QPoint & pos)` [protected]`, ` [virtual]`

Move the last point of the selection

**Parameters:**

*pos* New position

**See also:**

**isActive**, **begin()**, **end()**, **append()**

**Note:**

The **moved(const QPoint &)**, moved(const QDoublePoint &) signals are emitted.

Reimplemented from **QwtPicker**.

### void QwtPlotPicker::moved (const QPointF & pos)` [signal]`

A signal emitted whenever the last appended point of the selection has been moved.

**Parameters:**

*pos* Position of the moved last point of the selection.

**See also:**

**move()**, **appended()**

### QwtPlot \* QwtPlotPicker::plot ()

**Returns:**

Plot widget, containing the observed plot canvas

### const QwtPlot \* QwtPlotPicker::plot () const

**Returns:**

Plot widget, containing the observed plot canvas

### QRectF QwtPlotPicker::scaleRect () const` [protected]`

**Returns:**

Normalized bounding rectangle of the axes

**See also:**

**QwtPlot::autoReplot()**, **QwtPlot::replot()**.

### void QwtPlotPicker::selected (const QPointF & pos)` [signal]`

A signal emitted in case of **QwtPickerMachine::PointSelection**.

**Parameters:**

*pos* Selected point

### void QwtPlotPicker::selected (const QRectF & rect)` [signal]`

A signal emitted in case of **QwtPickerMachine::RectSelection**.

**Parameters:**

*rect* Selected rectangle

### void QwtPlotPicker::selected (const QVector\< QPointF \> & pa)` [signal]`

A signal emitting the selected points, at the end of a selection.

**Parameters:**

*pa* Selected points

### void QwtPlotPicker::setAxis (int xAxis, int yAxis)` [virtual]`

Set the x and y axes of the picker

**Parameters:**

*xAxis* X axis \
 *yAxis* Y axis

Reimplemented in **QwtPlotZoomer**.

### QwtText QwtPlotPicker::trackerText (const QPoint & pos) const` [protected]`, ` [virtual]`

Translate a pixel position into a position string

**Parameters:**

*pos* Position in pixel coordinates

**Returns:**

Position string

Reimplemented from **QwtPicker**.

### QwtText QwtPlotPicker::trackerTextF (const QPointF & pos) const` [protected]`, ` [virtual]`

Translate a position into a position string. In case of HLineRubberBand the label is the value of the y position, in case of VLineRubberBand the value of the x position. Otherwise the label contains x and y position separated by a ',' .

The format for the double to string conversion is '%.4f'.

**Parameters:**

*pos* Position

**Returns:**

Position string

### QRect QwtPlotPicker::transform (const QRectF & rect) const` [protected]`

Translate a rectangle from plot into pixel coordinates

**Returns:**

Rectangle in pixel coordinates

**See also:**

**invTransform()**

### QPoint QwtPlotPicker::transform (const QPointF & pos) const` [protected]`

Translate a point from plot into pixel coordinates

**Returns:**

Point in pixel coordinates

**See also:**

**invTransform()**

## Author

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