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qwtchangelog(3) Qwt User's Guide qwtchangelog(3)


qwtchangelog - What's new in Qwt 6.2

Qt >= 4.8

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


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 ( ) has been integrated into Qwt.

MathML Text Renderer has become its own project

The code can be found at now and is intended to become a standalone lib.


The broken implementation of QwtSpline has been replaced by a bunch of classes offering all sort of functionalities around splines.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::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::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
Sun Jul 18 2021 Version 6.2.0