QwtPlotItem - Man Page
Base class for items on the plot canvas.
Synopsis
#include <qwt_plot_item.h>
Inherited by QwtPlotGrid, QwtPlotLegendItem, QwtPlotMarker, QwtPlotRasterItem, QwtPlotScaleItem, QwtPlotSeriesItem, QwtPlotShapeItem, QwtPlotSvgItem, QwtPlotTextLabel, and QwtPlotZoneItem.
Public Types
enum RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotLegend, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotSpectroCurve, Rtti_PlotIntervalCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotSVG, Rtti_PlotTradingCurve, Rtti_PlotBarChart, Rtti_PlotMultiBarChart, Rtti_PlotShape, Rtti_PlotTextLabel, Rtti_PlotZone, Rtti_PlotUserItem = 1000 }
Runtime type information.
enum ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 }
Plot Item Attributes.
enum ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 }
Plot Item Interests.
enum RenderHint { RenderAntialiased = 0x1 }
Render hints.
typedef QFlags< ItemAttribute > ItemAttributes
Plot Item Attributes.
typedef QFlags< ItemInterest > ItemInterests
Plot Item Interests.
typedef QFlags< RenderHint > RenderHints
Render hints.
Public Member Functions
QwtPlotItem (const QwtText &title=QwtText())
virtual ~QwtPlotItem ()
Destroy the QwtPlotItem.
void attach (QwtPlot *plot)
Attach the item to a plot.
void detach ()
This method detaches a QwtPlotItem from any QwtPlot it has been associated with.
QwtPlot * plot () const
Return attached plot.
void setTitle (const QString &title)
void setTitle (const QwtText &title)
const QwtText & title () const
virtual int rtti () const
void setItemAttribute (ItemAttribute, bool on=true)
bool testItemAttribute (ItemAttribute) const
void setItemInterest (ItemInterest, bool on=true)
bool testItemInterest (ItemInterest) const
void setRenderHint (RenderHint, bool on=true)
bool testRenderHint (RenderHint) const
void setRenderThreadCount (uint numThreads)
uint renderThreadCount () const
void setLegendIconSize (const QSize &)
QSize legendIconSize () const
double z () const
void setZ (double z)
Set the z value.
void show ()
Show the item.
void hide ()
Hide the item.
virtual void setVisible (bool)
bool isVisible () const
void setAxes (int xAxis, int yAxis)
void setXAxis (int axis)
int xAxis () const
Return xAxis.
void setYAxis (int axis)
int yAxis () const
Return yAxis.
virtual void itemChanged ()
virtual void legendChanged ()
virtual void draw (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const =0
Draw the item.
virtual QRectF boundingRect () const
virtual void getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, double &left, double &top, double &right, double &bottom) const
Calculate a hint for the canvas margin.
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
Update the item to changes of the axes scale division.
virtual void updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &)
Update the item to changes of the legend info.
QRectF scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
Calculate the bounding scale rectangle of 2 maps.
QRectF paintRect (const QwtScaleMap &, const QwtScaleMap &) const
Calculate the bounding paint rectangle of 2 maps.
virtual QList< QwtLegendData > legendData () const
Return all information, that is needed to represent the item on the legend.
virtual QwtGraphic legendIcon (int index, const QSizeF &) const
Protected Member Functions
QwtGraphic defaultIcon (const QBrush &, const QSizeF &) const
Return a default icon from a brush.
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 legend.
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. Various aspects of a plot widget depend on the attributes of the attached plot items. If and how a single plot item participates in these updates depends on its attributes.
- See also
setItemAttribute(), testItemAttribute(), ItemInterest
Enumerator
- Legend
The item is represented on the legend.
- AutoScale
The boundingRect() of the item is included in the autoscaling calculation as long as its width or height is >= 0.0.
- Margins
The item needs extra space to display something outside its bounding rectangle.
- See also
getCanvasMarginHint()
enum QwtPlotItem::ItemInterest
Plot Item Interests. Plot items might depend on the situation of the corresponding plot widget. By enabling an interest the plot item will be notified, when the corresponding attribute of the plot widgets has changed.
- See also
setItemAttribute(), testItemAttribute(), ItemInterest
Enumerator
- ScaleInterest
The item is interested in updates of the scales
- See also
updateScaleDiv()
- LegendInterest
The item is interested in updates of the legend ( of other items ) This flag is intended for items, that want to implement a legend for displaying entries of other plot item.
- Note
If the plot item wants to be represented on a legend enable QwtPlotItem::Legend instead.
- See also
updateLegend()
enum QwtPlotItem::RenderHint
Render hints.
Enumerator
- RenderAntialiased
Enable antialiasing.
enum QwtPlotItem::RttiValues
Runtime type information. RttiValues is used to cast plot items, without having to enable runtime type information of the compiler.
Enumerator
- Rtti_PlotItem
Unspecific value, that can be used, when it doesn't matter.
- Rtti_PlotGrid
For QwtPlotGrid.
- Rtti_PlotScale
For QwtPlotScaleItem.
- Rtti_PlotLegend
For QwtPlotLegendItem.
- Rtti_PlotMarker
For QwtPlotMarker.
- Rtti_PlotCurve
For QwtPlotCurve.
- Rtti_PlotSpectroCurve
For QwtPlotSpectroCurve.
- Rtti_PlotIntervalCurve
For QwtPlotIntervalCurve.
- Rtti_PlotHistogram
For QwtPlotHistogram.
- Rtti_PlotSpectrogram
For QwtPlotSpectrogram.
- Rtti_PlotSVG
For QwtPlotSvgItem.
- Rtti_PlotTradingCurve
For QwtPlotTradingCurve.
- Rtti_PlotBarChart
For QwtPlotBarChart.
- Rtti_PlotMultiBarChart
For QwtPlotMultiBarChart.
- Rtti_PlotShape
For QwtPlotShapeItem.
- Rtti_PlotTextLabel
For QwtPlotTextLabel.
- Rtti_PlotZone
For QwtPlotZoneItem.
- Rtti_PlotUserItem
Values >= Rtti_PlotUserItem are reserved for plot items not implemented in the Qwt library.
Constructor & Destructor Documentation
QwtPlotItem::QwtPlotItem (const QwtText & title = QwtText()) [explicit]
Constructor
- Parameters
title Title of the item
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
detach()
QRectF QwtPlotItem::boundingRect () const [virtual]
- Returns
An invalid bounding rect: QRectF(1.0, 1.0, -2.0, -2.0)
- Note
A width or height < 0.0 is ignored by the autoscaler
Reimplemented in QwtPlotTradingCurve, QwtPlotMarker, QwtPlotIntervalCurve, QwtPlotHistogram, QwtPlotRasterItem, QwtPlotShapeItem, QwtPlotBarChart, QwtPlotMultiBarChart, QwtPlotZoneItem, QwtPlotSeriesItem, and QwtPlotSvgItem.
QwtGraphic QwtPlotItem::defaultIcon (const QBrush & brush, const QSizeF & size) const [protected]
Return a default icon from a brush. The default icon is a filled rectangle used in several derived classes as legendIcon().
- Parameters
brush Fill brush
size Icon size- Returns
A filled rectangle
void QwtPlotItem::detach ()
This method detaches a QwtPlotItem from any QwtPlot it has been associated with. detach() is equivalent to calling attach( NULL )
- See also
attach()
virtual void QwtPlotItem::draw (QPainter * painter, const QwtScaleMap & xMap, const QwtScaleMap & yMap, const QRectF & 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 QwtPlotLegendItem, QwtPlotRasterItem, QwtPlotShapeItem, QwtPlotSpectrogram, QwtPlotScaleItem, QwtPlotGrid, QwtPlotSvgItem, QwtPlotMarker, QwtPlotSeriesItem, QwtPlotTextLabel, and QwtPlotZoneItem.
void QwtPlotItem::getCanvasMarginHint (const QwtScaleMap & xMap, const QwtScaleMap & yMap, const QRectF & canvasRect, double & left, double & top, double & right, double & bottom) const [virtual]
Calculate a hint for the canvas margin. When the QwtPlotItem::Margins flag is enabled the plot item indicates, that it needs some margins at the borders of the canvas. This is f.e. used by bar charts to reserve space for displaying the bars.
The margins are in target device coordinates ( pixels on screen )
- Parameters
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.
canvasRect Contents rectangle of the canvas in painter coordinates
left Returns the left margin
top Returns the top margin
right Returns the right margin
bottom Returns the bottom margin
The default implementation returns 0 for all margins
- See also
QwtPlot::getCanvasMarginsHint(), QwtPlot::updateCanvasMargins()
Reimplemented in QwtPlotAbstractBarChart.
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
QwtPlot::legendChanged(), QwtPlot::autoRefresh()
void QwtPlotItem::legendChanged () [virtual]
Update the legend of the parent plot.
- See also
QwtPlot::updateLegend(), itemChanged()
QList< QwtLegendData > QwtPlotItem::legendData () const [virtual]
Return all information, that is needed to represent the item on the legend. Most items are represented by one entry on the legend showing an icon and a text, but f.e. QwtPlotMultiBarChart displays one entry for each bar.
QwtLegendData is basically a list of QVariants that makes it possible to overload and reimplement legendData() to return almost any type of information, that is understood by the receiver that acts as the legend.
The default implementation returns one entry with the title() of the item and the legendIcon().
- Returns
Data, that is needed to represent the item on the legend
- See also
title(), legendIcon(), QwtLegend, QwtPlotLegendItem
Reimplemented in QwtPlotBarChart, and QwtPlotMultiBarChart.
QwtGraphic QwtPlotItem::legendIcon (int index, const QSizeF & size) const [virtual]
- Returns
Icon representing the item on the legend
The default implementation returns an invalid icon
- Parameters
index Index of the legend entry ( usually there is only one )
size Icon size- See also
setLegendIconSize(), legendData()
Reimplemented in QwtPlotCurve, QwtPlotTradingCurve, QwtPlotMarker, QwtPlotIntervalCurve, QwtPlotHistogram, QwtPlotBarChart, QwtPlotShapeItem, and QwtPlotMultiBarChart.
QSize QwtPlotItem::legendIconSize () const
- Returns
Legend icon size
- See also
setLegendIconSize(), legendIcon()
QRectF QwtPlotItem::paintRect (const QwtScaleMap & xMap, const QwtScaleMap & yMap) const
Calculate the bounding paint rectangle of 2 maps.
- Parameters
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.- Returns
Bounding paint rectangle of the scale maps, not normalized
uint QwtPlotItem::renderThreadCount () const
- Returns
Number of threads to be used for rendering. If numThreads() is set to 0, the system specific ideal thread count is used.
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, QwtPlotTradingCurve, QwtPlotShapeItem, QwtPlotSpectrogram, QwtPlotIntervalCurve, QwtPlotHistogram, QwtPlotMarker, QwtPlotBarChart, QwtPlotMultiBarChart, QwtPlotLegendItem, QwtPlotScaleItem, QwtPlotTextLabel, QwtPlotSpectroCurve, QwtPlotSvgItem, QwtPlotGrid, and QwtPlotZoneItem.
QRectF QwtPlotItem::scaleRect (const QwtScaleMap & xMap, const QwtScaleMap & yMap) const
Calculate the bounding scale rectangle of 2 maps.
- Parameters
xMap Maps x-values into pixel coordinates.
yMap Maps y-values into pixel coordinates.- Returns
Bounding scale rect of the scale maps, not normalized
void QwtPlotItem::setAxes (int xAxis, int yAxis)
Set X and Y axis
The item will painted according to the coordinates of its Axes.
- Parameters
xAxis X Axis ( QwtPlot::xBottom or QwtPlot::xTop )
yAxis Y Axis ( QwtPlot::yLeft or QwtPlot::yRight )- See also
setXAxis(), setYAxis(), xAxis(), yAxis(), QwtPlot::Axis
void QwtPlotItem::setItemAttribute (ItemAttribute attribute, bool on = true)
Toggle an item attribute
- Parameters
attribute Attribute type
on true/false- See also
testItemAttribute(), ItemInterest
void QwtPlotItem::setItemInterest (ItemInterest interest, bool on = true)
Toggle an item interest
- Parameters
interest Interest type
on true/false- See also
testItemInterest(), ItemAttribute
void QwtPlotItem::setLegendIconSize (const QSize & size)
Set the size of the legend icon
The default setting is 8x8 pixels
- Parameters
size Size
- See also
legendIconSize(), legendIcon()
void QwtPlotItem::setRenderHint (RenderHint hint, bool on = true)
Toggle an render hint
- Parameters
hint Render hint
on true/false- See also
testRenderHint(), RenderHint
void QwtPlotItem::setRenderThreadCount (uint numThreads)
On multi core systems rendering of certain plot item ( f.e QwtPlotRasterItem ) can be done in parallel in several threads.
The default setting is set to 1.
- Parameters
numThreads Number of threads to be used for rendering. If numThreads is set to 0, the system specific ideal thread count is used.
The default thread count is 1 ( = no additional threads )
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 (bool on) [virtual]
Show/Hide the item
- Parameters
on Show if true, otherwise hide
- See also
isVisible(), show(), hide()
void QwtPlotItem::setXAxis (int axis)
Set the X axis
The item will painted according to the coordinates its Axes.
- Parameters
axis X Axis ( QwtPlot::xBottom or QwtPlot::xTop )
- See also
setAxes(), setYAxis(), xAxis(), QwtPlot::Axis
void QwtPlotItem::setYAxis (int axis)
Set the Y axis
The item will painted according to the coordinates its Axes.
- Parameters
axis Y Axis ( QwtPlot::yLeft or QwtPlot::yRight )
- See also
setAxes(), setXAxis(), yAxis(), QwtPlot::Axis
void QwtPlotItem::setZ (double z)
Set the z value. Plot items are painted in increasing z-order.
- Parameters
z Z-value
- See also
z(), QwtPlotDict::itemList()
bool QwtPlotItem::testItemAttribute (ItemAttribute attribute) const
Test an item attribute
- Parameters
attribute Attribute type
- Returns
true/false
- See also
setItemAttribute(), ItemInterest
bool QwtPlotItem::testItemInterest (ItemInterest interest) const
Test an item interest
- Parameters
interest Interest type
- Returns
true/false
- See also
setItemInterest(), ItemAttribute
bool QwtPlotItem::testRenderHint (RenderHint hint) 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()
void QwtPlotItem::updateLegend (const QwtPlotItem * item, const QList< QwtLegendData > & data) [virtual]
Update the item to changes of the legend info. Plot items that want to display a legend ( not those, that want to be displayed on a legend ! ) will have to implement updateLegend().
updateLegend() is only called when the LegendInterest interest is enabled. The default implementation does nothing.
- Parameters
item Plot item to be displayed on a legend
data Attributes how to display item on the legend- See also
QwtPlotLegendItem
- Note
Plot items, that want to be displayed on a legend need to enable the QwtPlotItem::Legend flag and to implement legendData() and legendIcon()
Reimplemented in QwtPlotLegendItem.
void QwtPlotItem::updateScaleDiv (const QwtScaleDiv & xScaleDiv, const QwtScaleDiv & yScaleDiv) [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()
updateScaleDiv() is only called when the ScaleInterest interest is enabled. The default implementation does nothing.
- Parameters
xScaleDiv Scale division of the x-axis
yScaleDiv Scale division of the y-axis- See also
QwtPlot::updateAxes(), ScaleInterest
Reimplemented in QwtPlotGrid, QwtPlotScaleItem, and QwtPlotSeriesItem.
double QwtPlotItem::z () const
Plot items are painted in increasing z-order.
- Returns
setZ(), QwtPlotDict::itemList()
Author
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