---
name: "QwtData"
section: "3"
platform: "linux"
package: "libqwt5-doc"
version: "5.2.3-1"
release: "Debian 10 (Buster)"
platforms: ["linux"]
url: "https://new.carta.tech/QwtData"
---

# QwtData(3)

## NAME

QwtData -

## SYNOPSIS

`#include <qwt_data.h>`

Inherited by **QwtArrayData**, **QwtCPointerData**, and **QwtPolygonFData**.

### Public Member Functions

**QwtData** ()\
 virtual **~QwtData** ()\
 virtual QwtDoubleRect **boundingRect** () const \
 virtual **QwtData** \* **copy** () const =0\
 virtual size\_t **size** () const =0\
 virtual double **x** (size\_t i) const =0\
 virtual double **y** (size\_t i) const =0\

### Protected Member Functions

**QwtData** & **operator=** (const **QwtData** &)\

## Detailed Description

**QwtData** defines an interface to any type of curve data.

Classes, derived from **QwtData** may:

- •

  store the data in almost any type of container

- •

  calculate the data on the fly instead of storing it

## Member Function Documentation

### QwtDoubleRect QwtData::boundingRect () const` [virtual]`

Returns the bounding rectangle of the data. If there is no bounding rect, like for empty data the rectangle is invalid: QwtDoubleRect::isValid() == false

**Warning:**

This is an slow implementation iterating over all points. It is intended to be overloaded by derived classes. In case of auto scaling **boundingRect()** is called for every replot, so it might be worth to implement a cache, or use x(0), x(**size()** - 1) for ordered data ...

Reimplemented in **QwtCPointerData**, and **QwtArrayData**.

### virtual QwtData\* QwtData::copy () const` [pure virtual]`

**Returns:**

Pointer to a copy (virtual copy constructor)

Implemented in **QwtCPointerData**, **QwtArrayData**, and **QwtPolygonFData**.

### QwtData& QwtData::operator= (const QwtData &)` [protected]`

Assignment operator (virtualized)

### virtual size\_t QwtData::size () const` [pure virtual]`

**Returns:**

Size of the data set

Implemented in **QwtCPointerData**, **QwtArrayData**, and **QwtPolygonFData**.

### virtual double QwtData::x (size\_ti) const` [pure virtual]`

Return the x value of data point i

**Parameters:**

*i* Index

**Returns:**

x X value of data point i

Implemented in **QwtCPointerData**, **QwtArrayData**, and **QwtPolygonFData**.

### virtual double QwtData::y (size\_ti) const` [pure virtual]`

Return the y value of data point i

**Parameters:**

*i* Index

**Returns:**

y Y value of data point i

Implemented in **QwtCPointerData**, **QwtArrayData**, and **QwtPolygonFData**.

## Author

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