What's new in Qwt 6.2

Table of Contents

• Qt >= 4.8
• Includes
• QwtPolar has become part of Qwt
• MathML Text Renderer has become its own project
• Spline
• Better OpenGL support
• New plot items
• QwtPlotCurve
• QwtPlotSpectrogram
• Other changes

Qt >= 4.8

Support for Qt < Qt 4.8 has been dropped, support for Qt6 has been added.

Includes

Include files, that match the class names are available now. So it is possible to write "#include <QwtPlot>" now instead of "include qwt_plot.h"

QwtPolar has become part of Qwt

The QwtPolar project ( https://qwtpolar.sourceforge.io ) has been integrated into Qwt.

MathML Text Renderer has become its own project

The code can be found at https://github.com/uwerat/qwt-mml-dev now and is intended to become a standalone lib.

Spline

The broken implementation of QwtSpline has been replaced by a bunch of classes offering all sort of functionalities around splines.

The most popular spline approximation/interpolation algos have been implemented:

- Basis
- Cardinal
- ParabolicBlending
- Akima
- The one used in a proprietory office package
- Cubic

Better OpenGL support

QwtPlotOpenGLCanvas added to support rendering to a QOpenGLWidget

New plot items

- QwtPlotVectorField
  A new type of plot item for vector fields

- QwtPlotGraphicItem
  An item displaying a QwtGraphic image ( f.e used by QwtPlotSvgItem )

QwtPlotCurve

- QwtPlotCurve::FilterPointsAggressive
  A fast weeding algo for huge datasets with increasing x or y values

- QwtPlotCurve::closestPoint
  Is virtual now

- Line Clipping
  Includes the painter clip now

- QwtValuePointData
  A new type of data added, where the x values are the index

- QwtPlotCurve::setSamples
  more type of setters

QwtPlotSpectrogram

- QwtPlotSpectrogram::setColorTableSize
  Using individual RGB tables

- QwtRasterData::setInterval/interval
  API cleanup

- QwtHueColorMap, QwtSaturationValueColorMap
  New type of color maps

- QwtMatrixRasterData::BicubicInterpolation
  Implementation of bicubic interpolation added

- Handling of NaN values
  NaN values are interpreted as gaps, when QwtRasterData::WithoutGaps
  is not set

Other changes

- QwtPlotRenderer
  Using QPdfWriter instead of QPrinter, where possible

- Handling of Unknown Paint Engines
  Not aligning unknown paint engines ( f.e EMF ), QwtNullPaintDevice is not using
  QPaintEngine::User anymore

- QwtTransform::LogMin/LogMax
  LOG_MIN/LOG_MAX have been reomed ( values differ ! 

- qwt_compat.h
  Removed

- qwtFuzzyGreaterOrEqual/qwtFuzzyLessOrEqual
  Removed

- qwtGetMin/qwtGetMax
  Removed