QwtPlotItem - Man Page
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:
- ·
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
- ·
QwtPlotCurve Represents a series of points
- ·
QwtPlotSpectrogram ( QwtPlotRasterItem ) Represents raster data
- ·
- ·
Decorators
A 'Decorator' is an item, that displays additional information, that is not related to any data:- ·
QwtPlotGrid
- ·
QwtPlotScaleItem
- ·
QwtPlotSvgItem
·
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:
The cpuplot example shows the implementation of additional plot items.
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:
setItemAttribute(), testItemAttribute()
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:
title Title of the item
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:
plot Plot widget
- See also:
QwtPlotItem::detach()
QwtDoubleRect QwtPlotItem::boundingRect () const [virtual] Returns
An invalid bounding rect: QwtDoubleRect(1.0, 1.0, -2.0, -2.0)
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:
attach( QwtPlot* plot )
virtual void QwtPlotItem::draw (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &canvasRect) const [pure virtual]
Draw the item. Parameters:
painter Painter
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
canvasRect Contents rect of the canvas in painter coordinates
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:
xMap X map
yMap Y map
rect Rectangle in paint coordinates- Returns:
Rectangle in scale coordinates
- See also:
transform()
bool QwtPlotItem::isVisible () const Returns
true if visible
See also:
setVisible(), show(), hide()
void QwtPlotItem::itemChanged () [virtual] Update the legend and call QwtPlot::autoRefresh for the parent plot.
See also:
updateLegend()
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:
QwtLegendItem()
- See also:
updateLegend() QwtLegend()
Implements QwtLegendItemManager.
QRect QwtPlotItem::paintRect (const QwtScaleMap &xMap, const QwtScaleMap &yMap) const
Calculate the bounding paint rect of 2 maps. Parameters:
xMap X map
yMap X map
- Returns:
Bounding rect of the scale maps
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:
rtti value
- See also:
RttiValues
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:
xMap X map
yMap X map
- Returns:
Bounding rect of the scale maps
void QwtPlotItem::setAxis (intxAxis, intyAxis) Set X and Y axis
The item will painted according to the coordinates its Axes.
- Parameters:
xAxis X Axis
yAxis Y Axis- See also:
setXAxis(), setYAxis(), xAxis(), yAxis()
void QwtPlotItem::setItemAttribute (ItemAttributeattribute, boolon = true) Toggle an item attribute
- Parameters:
attribute Attribute type
on true/false- See also:
testItemAttribute(), ItemAttribute
void QwtPlotItem::setRenderHint (RenderHinthint, boolon = true) Toggle an render hint
- Parameters:
hint Render hint
on true/false- See also:
testRenderHint(), RenderHint
void QwtPlotItem::setTitle (const QString &title) Set a new title
- Parameters:
title Title
- See also:
title()
void QwtPlotItem::setTitle (const QwtText &title) Set a new title
- Parameters:
title Title
- See also:
title()
void QwtPlotItem::setVisible (boolon) [virtual] Show/Hide the item
- Parameters:
on Show if true, otherwise hide
- See also:
isVisible(), show(), hide()
void QwtPlotItem::setXAxis (intaxis) Set the X axis
The item will painted according to the coordinates its Axes.
- Parameters:
axis X Axis
- See also:
setAxis(), setYAxis(), xAxis()
void QwtPlotItem::setYAxis (intaxis) Set the Y axis
The item will painted according to the coordinates its Axes.
- Parameters:
axis Y Axis
- See also:
setAxis(), setXAxis(), yAxis()
void QwtPlotItem::setZ (doublez)
Set the z value. Plot items are painted in increasing z-order.
- Parameters:
z Z-value
- See also:
z(), QwtPlotDict::itemList()
void QwtPlotItem::show ()
Show the item.
bool QwtPlotItem::testItemAttribute (ItemAttributeattribute) const Test an item attribute
- Parameters:
attribute Attribute type
- Returns:
true/false
- See also:
setItemAttribute(), ItemAttribute
bool QwtPlotItem::testRenderHint (RenderHinthint) const Test a render hint
- Parameters:
hint Render hint
- Returns:
true/false
- See also:
setRenderHint(), RenderHint
const QwtText & QwtPlotItem::title () const Returns
Title of the item
See also:
setTitle()
QRect QwtPlotItem::transform (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtDoubleRect &rect) const Transform a rectangle
- Parameters:
xMap X map
yMap Y map
rect Rectangle in scale coordinates- Returns:
Rectangle in paint coordinates
- See also:
invTransform()
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:
legend Legend
- See also:
legendItem(), itemChanged(), QwtLegend()
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:
xScaleDiv Scale division of the x-axis
yScaleDiv Scale division of the y-axis- See also:
QwtPlot::updateAxes()
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:
setZ(), QwtPlotDict::itemList()
Author
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