NAME¶

QwtPlotItem - Base class for items on the plot canvas.

SYNOPSIS¶

#include <qwt_plot_item.h> Inherits QwtLegendItemManager. Inherited by QwtPlotCurve, QwtPlotGrid, QwtPlotMarker, QwtPlotRasterItem, QwtPlotScaleItem, and QwtPlotSvgItem.

Public Types¶

enum ItemAttribute { Legend = 1, AutoScale = 2 } enum RenderHint { RenderAntialiased = 1 } enum RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotSVG, Rtti_PlotUserItem = 1000 }

Public Member Functions¶

void attach (QwtPlot *plot) virtual QwtDoubleRect boundingRect () const void detach () virtual void draw (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &canvasRect) const =0 void hide () QwtDoubleRect invTransform (const QwtScaleMap &, const QwtScaleMap &, const QRect &) const bool isVisible () const virtual void itemChanged () virtual QWidget * legendItem () const QRect paintRect (const QwtScaleMap &, const QwtScaleMap &) const QwtPlot * plot () const QwtPlotItem (const QwtText &title=QwtText()) virtual int rtti () const QwtDoubleRect scaleRect (const QwtScaleMap &, const QwtScaleMap &) const void setAxis (int xAxis, int yAxis) void setItemAttribute (ItemAttribute, bool on=true) void setRenderHint (RenderHint, bool on=true) void setTitle (const QwtText &title) void setTitle (const QString &title) virtual void setVisible (bool) void setXAxis (int axis) void setYAxis (int axis) void setZ (double z) void show () bool testItemAttribute (ItemAttribute) const bool testRenderHint (RenderHint) const const QwtText & title () const QRect transform (const QwtScaleMap &, const QwtScaleMap &, const QwtDoubleRect &) const virtual void updateLegend (QwtLegend *) const virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &) int xAxis () const int yAxis () const double z () const virtual ~QwtPlotItem ()

Detailed Description¶

Base class for items on the plot canvas. A plot item is 'something', that can be painted on the plot canvas, or only affects the scales of the plot widget. They can be categorized as:

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Representator

 

A 'Representator' is an item that represents some sort of data on the plot canvas. The different representator classes are organized according to the characteristics of the data:

•

QwtPlotMarker Represents a point or a horizontal/vertical coordinate

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QwtPlotCurve Represents a series of points

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QwtPlotSpectrogram ( QwtPlotRasterItem ) Represents raster data

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•

Decorators

 

A 'Decorator' is an item, that displays additional information, that is not related to any data:

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QwtPlotGrid

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QwtPlotScaleItem

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QwtPlotSvgItem

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Depending on the QwtPlotItem::ItemAttribute flags, an item is included into autoscaling or has an entry on the legnd. Before misusing the existing item classes it might be better to implement a new type of plot item ( don't implement a watermark as spectrogram ). Deriving a new type of QwtPlotItem primarily means to implement the YourPlotItem::draw() method. See also:

Member Enumeration Documentation¶

enum QwtPlotItem::ItemAttribute Plot Item Attributes¶

•

Legend

 

The item is represented on the legend.

•

AutoScale

 

The boundingRect() of the item is included in the autoscaling calculation.

See also:

enum QwtPlotItem::RenderHint¶

Render hints.

enum QwtPlotItem::RttiValues¶

Runtime type information. RttiValues is used to cast plot items, without having to enable runtime type information of the compiler.

Constructor & Destructor Documentation¶

QwtPlotItem::QwtPlotItem (const QwtText &title = QwtText() ) [explicit] Constructor¶

Parameters:

QwtPlotItem::~QwtPlotItem () [virtual]¶

Destroy the QwtPlotItem.

Member Function Documentation¶

void QwtPlotItem::attach (QwtPlot *plot)¶

Attach the item to a plot. This method will attach a QwtPlotItem to the QwtPlot argument. It will first detach the QwtPlotItem from any plot from a previous call to attach (if necessary). If a NULL argument is passed, it will detach from any QwtPlot it was attached to. Parameters: See also:

QwtDoubleRect QwtPlotItem::boundingRect () const [virtual] Returns:¶

Reimplemented in QwtPlotCurve, QwtPlotMarker, QwtPlotSpectrogram, and QwtPlotSvgItem.

void QwtPlotItem::detach () [inline]¶

This method detaches a QwtPlotItem from any QwtPlot it has been associated with. detach() is equivalent to calling attach( NULL ) See also:

virtual void QwtPlotItem::draw (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &canvasRect) const [pure virtual]¶

Draw the item. Parameters: Implemented in QwtPlotCurve, QwtPlotGrid, QwtPlotMarker, QwtPlotRasterItem, QwtPlotScaleItem, QwtPlotSpectrogram, and QwtPlotSvgItem.

void QwtPlotItem::hide ()¶

Hide the item.

QwtDoubleRect QwtPlotItem::invTransform (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &rect) const Transform a rectangle from paint to scale coordinates¶

Parameters: Returns: See also:

bool QwtPlotItem::isVisible () const Returns:¶

See also:

void QwtPlotItem::itemChanged () [virtual] Update the legend and call QwtPlot::autoRefresh for the parent plot.¶

See also:

QWidget * QwtPlotItem::legendItem () const [virtual]¶

Allocate the widget that represents the item on the legend. The default implementation is made for QwtPlotCurve and returns a QwtLegendItem(), but an item could be represented by any type of widget, by overloading legendItem() and updateLegend(). Returns: See also: Implements QwtLegendItemManager.

QRect QwtPlotItem::paintRect (const QwtScaleMap &xMap, const QwtScaleMap &yMap) const¶

Calculate the bounding paint rect of 2 maps. Parameters: Returns:

QwtPlot * QwtPlotItem::plot () const¶

Return attached plot.

int QwtPlotItem::rtti () const [virtual] Return rtti for the specific class represented. QwtPlotItem is simply a virtual interface class, and base classes will implement this method with specific rtti values so a user can differentiate them.¶

The rtti value is useful for environments, where the runtime type information is disabled and it is not possible to do a dynamic_cast<...>. Returns: See also: Reimplemented in QwtPlotCurve, QwtPlotGrid, QwtPlotMarker, QwtPlotScaleItem, QwtPlotSpectrogram, and QwtPlotSvgItem.

QwtDoubleRect QwtPlotItem::scaleRect (const QwtScaleMap &xMap, const QwtScaleMap &yMap) const¶

Calculate the bounding scale rect of 2 maps. Parameters: Returns:

void QwtPlotItem::setAxis (intxAxis, intyAxis) Set X and Y axis¶

The item will painted according to the coordinates its Axes. Parameters: See also:

void QwtPlotItem::setItemAttribute (ItemAttributeattribute, boolon = true) Toggle an item attribute¶

Parameters: See also:

void QwtPlotItem::setRenderHint (RenderHinthint, boolon = true) Toggle an render hint¶

Parameters: See also:

void QwtPlotItem::setTitle (const QString &title) Set a new title¶

Parameters: See also:

void QwtPlotItem::setTitle (const QwtText &title) Set a new title¶

Parameters: See also:

void QwtPlotItem::setVisible (boolon) [virtual] Show/Hide the item¶

Parameters: See also:

void QwtPlotItem::setXAxis (intaxis) Set the X axis¶

The item will painted according to the coordinates its Axes. Parameters: See also:

void QwtPlotItem::setYAxis (intaxis) Set the Y axis¶

The item will painted according to the coordinates its Axes. Parameters: See also:

void QwtPlotItem::setZ (doublez)¶

Set the z value. Plot items are painted in increasing z-order. Parameters: See also:

void QwtPlotItem::show ()¶

Show the item.

bool QwtPlotItem::testItemAttribute (ItemAttributeattribute) const Test an item attribute¶

Parameters: Returns: See also:

bool QwtPlotItem::testRenderHint (RenderHinthint) const Test a render hint¶

Parameters: Returns: See also:

const QwtText & QwtPlotItem::title () const Returns:¶

See also:

QRect QwtPlotItem::transform (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtDoubleRect &rect) const Transform a rectangle¶

Parameters: Returns: See also:

void QwtPlotItem::updateLegend (QwtLegend *legend) const [virtual]¶

Update the widget that represents the item on the legend. updateLegend() is called from itemChanged() to adopt the widget representing the item on the legend to its new configuration. The default implementation is made for QwtPlotCurve and updates a QwtLegendItem(), but an item could be represented by any type of widget, by overloading legendItem() and updateLegend(). Parameters: See also: Implements QwtLegendItemManager. Reimplemented in QwtPlotCurve.

void QwtPlotItem::updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &) [virtual]¶

Update the item to changes of the axes scale division. Update the item, when the axes of plot have changed. The default implementation does nothing, but items that depend on the scale division (like QwtPlotGrid()) have to reimplement updateScaleDiv() Parameters: See also: Reimplemented in QwtPlotGrid, and QwtPlotScaleItem.

int QwtPlotItem::xAxis () const¶

Return xAxis.

int QwtPlotItem::yAxis () const¶

Return yAxis.

double QwtPlotItem::z () const Plot items are painted in increasing z-order.¶

Returns:

Author¶

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