# QwtData Class Reference

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

`#include <qwt_data.h>`

Inheritance diagram for QwtData:
[legend]

List of all members.

## Public Member Functions
| QwtData ()
virtual | ~QwtData ()
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
virtual QwtDoubleRect | boundingRect () const
## 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

## Constructor & Destructor Documentation

QwtData::QwtData | ( |  | ) |

Constructor.

QwtData::~QwtData | ( |  | ) | `[virtual]`

Destructor.

## 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 QwtArrayData, and QwtCPointerData.

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

Returns:
  Pointer to a copy (virtual copy constructor)

Implemented in QwtPolygonFData, QwtArrayData, and QwtCPointerData.

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 QwtPolygonFData, QwtArrayData, and QwtCPointerData.

virtual double QwtData::x | ( | size_t | i | ) | const`[pure virtual]`

Return the x value of data point i

Parameters:

  | i | Index

Returns:
  x X value of data point i

Implemented in QwtPolygonFData, QwtArrayData, and QwtCPointerData.

virtual double QwtData::y | ( | size_t | i | ) | const`[pure virtual]`

Return the y value of data point i

Parameters:

  | i | Index

Returns:
  y Y value of data point i

Implemented in QwtPolygonFData, QwtArrayData, and QwtCPointerData.