Sources_For_Linux/Qwt/doc/man/man3/qwtchangelog.3

.TH "qwtchangelog" 3 "Mon Dec 28 2020" "Version 6.1.6" "Qwt User's Guide" \" -*- nroff -*-
.ad l
.nh
.SH NAME
qwtchangelog \- What's new in Qwt 6\&.1 

.SH "New plot items"
.PP
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\fBQwtPlotBarChart\fP
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 Bar chart, see 'examples/distrowatch'
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\fBQwtPlotMultiBarChart\fP
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 Chart of grouped bars - stacked or aligned side by side\&. See 'examples/barchart'
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\fBQwtPlotTradingCurve\fP
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 Candlestick or OHLC charts typically used to describe price movements over time\&. See 'examples/stockchart'
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\fBQwtPlotShapeItem\fP
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 A plot item to display rectangles, circles, polygons and all other type of shapes ( built from intersections or unifications ), that can be expressed by a QPainterPath\&. See 'examples/itemeditor'
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\fBQwtPlotLegendItem\fP
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 A legend on the plot canvas\&. See 'examples/legends'
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\fBQwtPlotZoneItem\fP
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 A horizontal or vertical section
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\fBQwtPlotTextLabel\fP
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 In opposite to a \fBQwtPlotMarker\fP the text is not aligned to a plot coordinate but according to the geometry of the canvas ( f\&.e top/centered for a title )\&. See 'playground/curvetracker'\&.
.PP
.SH "Scales beyond linear and logarithmic transformations"
.PP
QwtScaleTransformation has been replaced by \fBQwtTransform\fP and its derived classes:
.PP
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\fBQwtTransform\fP
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\fBQwtNullTransform\fP
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\fBQwtLogTransform\fP
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\fBQwtPowerTransform\fP
.PP
.PP
Individual transformations ( f\&.e\&. different scaling for special sections ) can be implemented by overloading \fBQwtTransform\fP ( see playground/scaleengine )\&.
.PP
\fBQwtLinearScaleEngine\fP and \fBQwtLogScaleEngine\fP are not limited to base 10 anymore\&.
.SS "Datetime scales"
A set of a new classes for displaying datetime values:
.PP
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\fBQwtDate\fP
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 A collection of methods to convert between QDateTime and doubles
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\fBQwtDateScaleEngine\fP
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 A scale engine that aligns and finds ticks in terms of datetime units\&.
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\fBQwtDateScaleDraw\fP
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 A scale draw mapping values to datetime strings\&.
.PP
.PP
Scales for Qt::UTC and Qt::LocalTime are supported\&.
.SH "Redesign of the dial and meter widgets"
.PP
Many parts of the class design of the dial and meter widgets were left over from the 90s ( Qwt 0\&.2, Qt 1\&.1 )\&.
.PP
The derivation tree is simpler and more logical:
.PP
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\fBQwtAbstractScale\fP is a QWidget
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\fBQwtAbstractSlider\fP is a \fBQwtAbstractScale\fP\&. ( for sliders without scales QAbstractSlider should be the base class )
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\fBQwtThermo\fP is also a \fBQwtAbstractScale\fP
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\fBQwtDial\fP, \fBQwtKnob\fP, \fBQwtSlider\fP are derived from \fBQwtAbstractSlider\fP
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\fBQwtCounter\fP is derived from QWidget
.PP
.PP
QwtDoubleRange has been removed\&.
.PP
All classes use the terminology known from QAbstractSlider - as far as possible\&. The extended \fBsystem for scales\fP is completely supported\&.
.SH "Basic support for an OpenGL plot canvas"
.PP
\fBQwtPlotGLCanvas\fP offers the option to draw plot items using an OpenGL paint engine ( QPaintEngine::OpenGL/OpenGL2 ), This is not what could be implemented with native OpenGL, but it offers hardware acceleration in environments, where the raster paint engine is the only option\&. ( f\&.e Qt4/Windows, or Qt5 on all platforms )\&.
.PP
\fBQwtPlotGLCanvas\fP is in an experimental state and is not recommended for average use cases\&.
.SH "A new system for plot legends"
.PP
\fBQwtLegend\fP has been decoupled from \fBQwtPlot\fP and can be replaced by application specific implementations\&. Plot items and the legend exchange the information using \fBQwtLegendData\fP\&.
.PP
\fBQwtPlotLegendItem\fP is a new plot item that displays a legend on the plot canvas\&.
.PP
The following examples demonstrate how to use the new system:
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examples/legends
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 shows how to use the new legend system
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examples/stockchart
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 implementats a QTreeView with checkable items as legend
.PP
.SH "Off-screen paint device for vector graphics"
.PP
\fBQwtGraphic\fP can be copied like QImage or QPixmap but is scalable like QSvgGenerator\&. It is implemented as a record/replay paint device like QPicture\&.
.SH "QwtWidgetOverlay"
.PP
\fBQwtWidgetOverlay\fP is a base class for implementing widget overlays - primarily used for use cases like graphical editors or running cursors for the plot canvas\&.
.PP
The following examples show how to use overlays:
.PP
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examples/itemeditor
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examples/curvetracker
.PP
.PP
\fBQwtPicker\fP ( -> \fBQwtPlotPicker\fP, \fBQwtPlotZoomer\fP ) internally uses \fBQwtWidgetOverlay\fP now, making it easier to implement individual rubber bands\&.
.SH "QwtSymbol"
.PP
New symbol types have been introduced:
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\fBQwtSymbol::Path\fP
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\fBQwtSymbol::Pixmap\fP
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\fBQwtSymbol::Graphic\fP
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\fBQwtSymbol::SvgDocument\fP
.PP
.PP
\fBQwtSymbol\fP autodetect the most performant paint strategy for a paint device what is in most situations using a QPixmap cache\&.
.PP
\fBQwtSymbol::setPinPoint()\fP allows one to align the symbol individually, f\&.e to the position of the peak of an arrow\&.
.SH "QwtPlotCurve"
.PP
Some optimizations that got lost with introducing the floating point based render code with Qwt 6\&.0 have been reenabled\&. Other specific optimizations have been added\&.
.PP
New paint attributes:
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\fBQwtPlotCurve::FilterPoints\fP
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\fBQwtPlotCurve::MinimizeMemory\fP
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\fBQwtPlotCurve::ImageBuffer\fP
.PP
.PP
QwtPlotCurve::CacheSymbols has been removed, as caching is implemented in \fBQwtSymbol\fP now\&. 
.br
.PP
\fBQwtPlotCurve::drawLines()\fP, \fBQwtPlotCurve::drawDots()\fP, \fBQwtPlotCurve::drawSteps()\fP and \fBQwtPlotCurve::drawSticks()\fP are virtual now\&.
.SH "QwtPlot"
.PP
A footer similar to a title has been added\&.
.PP
QwtPlot::ExternalLegend is obsolete with the new \fBsystem for legends\fP\&. The signals QwtPlot::legendClicked(), QwtPlot::legendChecked() have been removed\&. Applications need to connect to \fBQwtLegend::clicked()\fP and \fBQwtLegend::checked()\fP\&.
.PP
To support using an OpenGL canvas \fBQwtPlot::setCanvas\fP has been added\&. This has 2 important implications for the application code:
.PP
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\fBQwtPlot::canvas()\fP returns QWidget and needs to be casted, when using methods of \fBQwtPlotCanvas\fP\&.
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\fBQwtPlotCanvas\fP can be created and assigned in application code, what makes it possible to derive and overload methods\&.
.PP
.PP
The initialization of a plot canvas with Qwt 6\&.1 will probably look like this:
.PP
.PP
.nf
QwtPlotCanvas* canvas = new QwtPlotCanvas();
canvas->setXY( \&.\&.\&. );
\&.\&.\&.

plot->setCanvas( canvas );
.fi
.PP
.PP
To have a consistent API \fBQwtPlot::setPlotLayout()\fP has been added,
.SH "Other"
.PP
.SS "QwtScaleDiv"
The following methods have been added:
.PP
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\fBQwtScaleDiv::inverted()\fP
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\fBQwtScaleDiv::bounded()\fP
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\fBQwtScaleDiv::isEmpty()\fP
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\fBQwtScaleDiv::isIncreasing()\fP
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QDebug operator
.PP
.PP
The following methods have been removed:
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QwtScaleDiv::isValid(), QwtScaleDiv::invalidate()
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 The valid state was left over from early Qwt versions indicating a state of the autoscaler\&.
.PP
.SS "QwtScaleEngine"
The following methods have been added:
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\fBQwtScaleEngine::setBase()\fP
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\fBQwtScaleEngine::setTransformation()\fP
.PP
.SS "QwtPlotLayout"
The following flags have been added:
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\fBQwtPlotLayout::IgnoreTitle\fP
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\fBQwtPlotLayout::IgnoreFooter\fP
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\fBQwtPlotLayout::setAlignCanvasToScale()\fP
.PP
.SS "QwtPlotCanvas"
Rounded borders ( like with style sheets ) can configured using \fBQwtPlotCanvas::setBorderRadius()\fP;
.SS "Other changes"
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\fBQwtWeedingCurveFitter\fP
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 \fBQwtWeedingCurveFitter::setChunkSize()\fP has been added, with drastic performance improvements for huge sets of points\&.
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\fBQwtPlotRenderer\fP The frame of the plot canvas can be rendered, what makes the result even closer to WYSWYG\&. \fBQwtPlotRenderer::exportTo()\fP has been added\&.
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\fBQwtSystemClock\fP For Qt >= 4\&.9 \fBQwtSystemClock\fP uses QElapsedTimer internally\&. As it doesn't support a similar feature, QwtSystemClock::precision() has been removed\&.
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QwtPlotAbstractSeriesItem
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 QwtPlotAbstractSeriesItem has been split into \fBQwtPlotSeriesItem\fP and QwtPlotAbstractSeriesStore\&.
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\fBQwtText\fP
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 A metatype declaration has been added, so that \fBQwtText\fP can be used with QVariant\&.
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\fBQwtEventPattern\fP, \fBQwtPanner\fP, \fBQwtMagnifier\fP
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 Forgotten Qt3 leftovers have been fixed: int -> Qt::KeyboardModifiers
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QPen Qt5/Qt4 incompatibility The default pen width for Qt5 is 1, what makes it a non cosmetic\&. To hide this nasty incompatibility several setPen() methods have been added the build pens with a width 0\&. See QPen::isCosmetic(),
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qwtUpperSampleIndex()
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 A binary search algorithm for sorted samples
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\fBQwtMatrixRasterData\fP \fBQwtMatrixRasterData::setValue()\fP has been added
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\fBQwtPicker\fP QwtPicker::rubberBandWidget(), QwtPicker::trackerWidget() have been replaced by \fBQwtPicker::rubberBandOverlay()\fP, \fBQwtPicker::trackerOverlay()\fP\&. \fBQwtPicker::rubberBandMask()\fP has been added\&. QwtPicker::pickRect() has been replaced by \fBQwtPicker::pickArea()\fP
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\fBQwtPlotItem\fP \fBQwtPlotItem::ItemInterest\fP has been added\&. \fBQwtPlotItem::setRenderThreadCount()\fP was shifted from \fBQwtPlotRasterItem\fP\&.
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\&.\&.\&.
.PP
.SH "Summary of the new classes"
.PP
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\fBQwtAbstractLegend\fP
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\fBQwtDate\fP
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\fBQwtDateScaleDraw\fP
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\fBQwtDateScaleEngine\fP
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\fBQwtGraphic\fP
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\fBQwtLegendData\fP
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\fBQwtLegendLabel\fP
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\fBQwtPainterCommand\fP
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\fBQwtPixelMatrix\fP
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\fBQwtPlotAbstractBarChart\fP
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\fBQwtPlotBarChart\fP
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\fBQwtPlotMultiBarChart\fP
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\fBQwtPlotGLCanvas\fP
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\fBQwtPlotLegendItem\fP
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\fBQwtPlotShapeItem\fP
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\fBQwtPlotTextLabel\fP
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\fBQwtPlotTradingCurve\fP
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\fBQwtPlotZoneItem\fP
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QwtPointData
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\fBQwtPointMapper\fP
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\fBQwtTransform\fP, \fBQwtNullTransform\fP, \fBQwtLogTransform\fP, \fBQwtPowerTransform\fP
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\fBQwtWidgetOverlay\fP 
.PP