QwtPlot(3)

NAME
QwtPlot - A 2-D plotting widget.

SYNOPSIS

#include <qwt_plot.h>

Inherits QFrame, and QwtPlotDict.

  Public Types
enum Axis { yLeft, yRight, xBottom, xTop, axisCnt }
Axis index.
enum LegendPosition { LeftLegend, RightLegend, BottomLegend, TopLegend }

  Public Slots
virtual void replot ()
Redraw the plot.
void autoRefresh ()
Replots the plot if autoReplot() is true.

  Signals
void itemAttached (QwtPlotItem *plotItem, bool on)
void legendDataChanged (const QVariant &itemInfo, const QList< QwtLegendData > &data)

  Public Member Functions
QwtPlot (QWidget *=NULL)
Constructor.
QwtPlot (const QwtText &title, QWidget *=NULL)
Constructor.
virtual ~QwtPlot ()
Destructor.
void applyProperties (const QString &)
QString grabProperties () const
void setAutoReplot (bool=true)
Set or reset the autoReplot option.
bool autoReplot () const
void setPlotLayout (QwtPlotLayout *)
Assign a new plot layout.
QwtPlotLayout * plotLayout ()
const QwtPlotLayout * plotLayout () const
void setTitle (const QString &)
void setTitle (const QwtText &)
QwtText title () const
QwtTextLabel * titleLabel ()
const QwtTextLabel * titleLabel () const
void setFooter (const QString &)
void setFooter (const QwtText &)
QwtText footer () const
QwtTextLabel * footerLabel ()
const QwtTextLabel * footerLabel () const
void setCanvas (QWidget *)
Set the drawing canvas of the plot widget.
QWidget * canvas ()
const QWidget * canvas () const
void setCanvasBackground (const QBrush &)
Change the background of the plotting area.
QBrush canvasBackground () const
virtual QwtScaleMap canvasMap (int axisId) const
double invTransform (int axisId, int pos) const
double transform (int axisId, double value) const
Transform a value into a coordinate in the plotting region.
QwtScaleEngine * axisScaleEngine (int axisId)
const QwtScaleEngine * axisScaleEngine (int axisId) const
void setAxisScaleEngine (int axisId, QwtScaleEngine *)
void setAxisAutoScale (int axisId, bool on=true)
Enable autoscaling for a specified axis.
bool axisAutoScale (int axisId) const
void enableAxis (int axisId, bool tf=true)
Enable or disable a specified axis.
bool axisEnabled (int axisId) const
void setAxisFont (int axisId, const QFont &)
Change the font of an axis.
QFont axisFont (int axisId) const
void setAxisScale (int axisId, double min, double max, double stepSize=0)
Disable autoscaling and specify a fixed scale for a selected axis.
void setAxisScaleDiv (int axisId, const QwtScaleDiv &)
Disable autoscaling and specify a fixed scale for a selected axis.
void setAxisScaleDraw (int axisId, QwtScaleDraw *)
Set a scale draw.
double axisStepSize (int axisId) const
Return the step size parameter that has been set in setAxisScale.
QwtInterval axisInterval (int axisId) const
Return the current interval of the specified axis.
const QwtScaleDiv & axisScaleDiv (int axisId) const
Return the scale division of a specified axis.
const QwtScaleDraw * axisScaleDraw (int axisId) const
Return the scale draw of a specified axis.
QwtScaleDraw * axisScaleDraw (int axisId)
Return the scale draw of a specified axis.
const QwtScaleWidget * axisWidget (int axisId) const
QwtScaleWidget * axisWidget (int axisId)
void setAxisLabelAlignment (int axisId, Qt::Alignment)
void setAxisLabelRotation (int axisId, double rotation)
void setAxisTitle (int axisId, const QString &)
Change the title of a specified axis.
void setAxisTitle (int axisId, const QwtText &)
Change the title of a specified axis.
QwtText axisTitle (int axisId) const
void setAxisMaxMinor (int axisId, int maxMinor)
int axisMaxMinor (int axisId) const
void setAxisMaxMajor (int axisId, int maxMajor)
int axisMaxMajor (int axisId) const
void insertLegend (QwtAbstractLegend *, LegendPosition=QwtPlot::RightLegend, double ratio=-1.0)
Insert a legend.
QwtAbstractLegend * legend ()
const QwtAbstractLegend * legend () const
void updateLegend ()
void updateLegend (const QwtPlotItem *)
virtual QSize sizeHint () const
virtual QSize minimumSizeHint () const
Return a minimum size hint.
virtual void updateLayout ()
Adjust plot content to its current size.
virtual void drawCanvas (QPainter *)
void updateAxes ()
Rebuild the axes scales.
void updateCanvasMargins ()
Update the canvas margins.
virtual void getCanvasMarginsHint (const QwtScaleMap maps[], const QRectF &canvasRect, double &left, double &top, double &right, double &bottom) const
Calculate the canvas margins.
virtual bool event (QEvent *)
Adds handling of layout requests.
virtual bool eventFilter (QObject *, QEvent *)
Event filter.
virtual void drawItems (QPainter *, const QRectF &, const QwtScaleMap maps[axisCnt]) const
virtual QVariant itemToInfo (QwtPlotItem *) const
Build an information, that can be used to identify a plot item on the legend.
virtual QwtPlotItem * infoToItem (const QVariant &) const
Identify the plot item according to an item info object, that has bee generated from itemToInfo().

  Protected Member Functions
virtual void resizeEvent (QResizeEvent *e)

  Static Protected Member Functions
static bool axisValid (int axisId)

Detailed Description

A 2-D plotting widget. QwtPlot is a widget for plotting two-dimensional graphs. An unlimited number of plot items can be displayed on its canvas. Plot items might be curves (QwtPlotCurve), markers (QwtPlotMarker), the grid (QwtPlotGrid), or anything else derived from QwtPlotItem. A plot can have up to four axes, with each plot item attached to an x- and a y axis. The scales at the axes can be explicitly set (QwtScaleDiv), or are calculated from the plot items, using algorithms (QwtScaleEngine) which can be configured separately for each axis.

The simpleplot example is a good starting point to see how to set up a plot widget.

Example
    The following example shows (schematically) the most simple way to use QwtPlot. By default, only the left and bottom axes are visible and their scales are computed automatically.

    #include <qwt_plot.h>
    #include <qwt_plot_curve.h>
    QwtPlot *myPlot = new QwtPlot( "Two Curves", parent );
    // add curves
    QwtPlotCurve *curve1 = new QwtPlotCurve( "Curve 1" );
    QwtPlotCurve *curve2 = new QwtPlotCurve( "Curve 2" );
    // connect or copy the data to the curves
    curve1->setData( ... );
    curve2->setData( ... );
    curve1->attach( myPlot );
    curve2->attach( myPlot );
    // finally, refresh the plot
    myPlot->replot();

     \endpar

Member Enumeration Documentation

  enum QwtPlot::Axis

Axis index.

Enumerator

yLeft
    Y axis left of the canvas.

yRight
    Y axis right of the canvas.

xBottom
    X axis below the canvas.

xTop
    X axis above the canvas.

axisCnt
    Number of axes.

  enum QwtPlot::LegendPosition
Position of the legend, relative to the canvas.

See also
    insertLegend()

Enumerator

LeftLegend
    The legend will be left from the QwtPlot::yLeft axis.

RightLegend
    The legend will be right from the QwtPlot::yRight axis.

BottomLegend
    The legend will be below the footer.

TopLegend
    The legend will be above the title.

Constructor & Destructor Documentation

  QwtPlot::QwtPlot (QWidget * parent = NULL) [explicit]

Constructor.

Parameters
    parent Parent widget

  QwtPlot::QwtPlot (const QwtText & title, QWidget * parent = NULL) [explicit]

Constructor.

Parameters
    title Title text
    parent Parent widget

Member Function Documentation

  void QwtPlot::applyProperties (const QString &)
This method is intended for manipulating the plot widget from a specific editor in the Qwt designer plugin.

Warning
    The plot editor has never been implemented.

  bool QwtPlot::autoReplot () const

Returns
    true if the autoReplot option is set.

See also
    setAutoReplot()

  bool QwtPlot::axisAutoScale (int axisId) const

Returns
    True, if autoscaling is enabled

Parameters
    axisId Axis index

  bool QwtPlot::axisEnabled (int axisId) const

Returns
    True, if a specified axis is enabled

Parameters
    axisId Axis index

  QFont QwtPlot::axisFont (int axisId) const

Returns
    The font of the scale labels for a specified axis

Parameters
    axisId Axis index

  QwtInterval QwtPlot::axisInterval (int axisId) const

Return the current interval of the specified axis. This is only a convenience function for axisScaleDiv( axisId )->interval();

Parameters
    axisId Axis index

Returns
    Scale interval

See also
    QwtScaleDiv, axisScaleDiv()

  int QwtPlot::axisMaxMajor (int axisId) const

Returns
    The maximum number of major ticks for a specified axis

Parameters
    axisId Axis index

See also
    setAxisMaxMajor(), QwtScaleEngine::divideScale()

  int QwtPlot::axisMaxMinor (int axisId) const

Returns
    the maximum number of minor ticks for a specified axis

Parameters
    axisId Axis index

See also
    setAxisMaxMinor(), QwtScaleEngine::divideScale()

  const QwtScaleDiv & QwtPlot::axisScaleDiv (int axisId) const

Return the scale division of a specified axis. axisScaleDiv(axisId).lowerBound(), axisScaleDiv(axisId).upperBound() are the current limits of the axis scale.

Parameters
    axisId Axis index

Returns
    Scale division

See also
    QwtScaleDiv, setAxisScaleDiv(), QwtScaleEngine::divideScale()

  QwtScaleDraw * QwtPlot::axisScaleDraw (int axisId)

Return the scale draw of a specified axis.

Parameters
    axisId Axis index

Returns
    Specified scaleDraw for axis, or NULL if axis is invalid.

  const QwtScaleDraw * QwtPlot::axisScaleDraw (int axisId) const

Return the scale draw of a specified axis.

Parameters
    axisId Axis index

Returns
    Specified scaleDraw for axis, or NULL if axis is invalid.

  QwtScaleEngine * QwtPlot::axisScaleEngine (int axisId)

Parameters
    axisId Axis index

Returns
    Scale engine for a specific axis

  const QwtScaleEngine * QwtPlot::axisScaleEngine (int axisId) const

Parameters
    axisId Axis index

Returns
    Scale engine for a specific axis

  double QwtPlot::axisStepSize (int axisId) const

Return the step size parameter that has been set in setAxisScale. This doesn't need to be the step size of the current scale.

Parameters
    axisId Axis index

Returns
    step size parameter value

See also
    setAxisScale(), QwtScaleEngine::divideScale()

  QwtText QwtPlot::axisTitle (int axisId) const

Returns
    Title of a specified axis

Parameters
    axisId Axis index

  bool QwtPlot::axisValid (int axisId) [static], [protected]

Returns
    true if the specified axis exists, otherwise false

Parameters
    axisId axis index

  QwtScaleWidget * QwtPlot::axisWidget (int axisId)

Returns
    Scale widget of the specified axis, or NULL if axisId is invalid.

Parameters
    axisId Axis index

  const QwtScaleWidget * QwtPlot::axisWidget (int axisId) const

Returns
    Scale widget of the specified axis, or NULL if axisId is invalid.

Parameters
    axisId Axis index

  QWidget * QwtPlot::canvas ()

Returns
    the plot's canvas

  const QWidget * QwtPlot::canvas () const

Returns
    the plot's canvas

  QBrush QwtPlot::canvasBackground () const
Nothing else than: canvas()->palette().brush( QPalette::Normal, QPalette::Window);

Returns
    Background brush of the plotting area.

See also
    setCanvasBackground()

  QwtScaleMap QwtPlot::canvasMap (int axisId) const [virtual]

Parameters
    axisId Axis

Returns
    Map for the axis on the canvas. With this map pixel coordinates can translated to plot coordinates and vice versa.

See also
    QwtScaleMap, transform(), invTransform()

  void QwtPlot::drawCanvas (QPainter * painter) [virtual]
Redraw the canvas.

Parameters
    painter Painter used for drawing

Warning
    drawCanvas calls drawItems what is also used for printing. Applications that like to add individual plot items better overload drawItems()

See also
    drawItems()

  void QwtPlot::drawItems (QPainter * painter, const QRectF & canvasRect, const QwtScaleMap maps[axisCnt]) const [virtual]
Redraw the canvas items.

Parameters
    painter Painter used for drawing
    canvasRect Bounding rectangle where to paint
    maps QwtPlot::axisCnt maps, mapping between plot and paint device coordinates

Note
    Usually canvasRect is contentsRect() of the plot canvas. Due to a bug in Qt this rectangle might be wrong for certain frame styles ( f.e QFrame::Box ) and it might be necessary to fix the margins manually using QWidget::setContentsMargins()

  void QwtPlot::enableAxis (int axisId, bool tf = true)

Enable or disable a specified axis. When an axis is disabled, this only means that it is not visible on the screen. Curves, markers and can be attached to disabled axes, and transformation of screen coordinates into values works as normal.

Only xBottom and yLeft are enabled by default.

Parameters
    axisId Axis index
    tf true (enabled) or false (disabled)

  bool QwtPlot::event (QEvent * event) [virtual]

Adds handling of layout requests.

Parameters
    event Event

Returns
    See QFrame::event()

  bool QwtPlot::eventFilter (QObject * object, QEvent * event) [virtual]

Event filter. The plot handles the following events for the canvas:

•   QEvent::Resize The canvas margins might depend on its size

•   QEvent::ContentsRectChange The layout needs to be recalculated

Parameters
    object Object to be filtered
    event Event

Returns
    See QFrame::eventFilter()

See also
    updateCanvasMargins(), updateLayout()

  QwtText QwtPlot::footer () const

Returns
    Text of the footer

  QwtTextLabel * QwtPlot::footerLabel ()

Returns
    Footer label widget.

  const QwtTextLabel * QwtPlot::footerLabel () const

Returns
    Footer label widget.

  void QwtPlot::getCanvasMarginsHint (const QwtScaleMap maps[], const QRectF & canvasRect, double & left, double & top, double & right, double & bottom) const [virtual]

Calculate the canvas margins.

Parameters
    maps QwtPlot::axisCnt maps, mapping between plot and paint device coordinates
    canvasRect Bounding rectangle where to paint
    left Return parameter for the left margin
    top Return parameter for the top margin
    right Return parameter for the right margin
    bottom Return parameter for the bottom margin

Plot items might indicate, that they need some extra space at the borders of the canvas by the QwtPlotItem::Margins flag.

updateCanvasMargins(), QwtPlotItem::getCanvasMarginHint()

  QString QwtPlot::grabProperties () const
This method is intended for manipulating the plot widget from a specific editor in the Qwt designer plugin.

Returns
    QString()

Warning
    The plot editor has never been implemented.

  QwtPlotItem * QwtPlot::infoToItem (const QVariant & itemInfo) const [virtual]

Identify the plot item according to an item info object, that has bee generated from itemToInfo(). The default implementation simply tries to unwrap a QwtPlotItem pointer:

if ( itemInfo.canConvert<QwtPlotItem *>() )
    return qvariant_cast<QwtPlotItem *>( itemInfo );

Parameters
    itemInfo Plot item

Returns
    A plot item, when successful, otherwise a NULL pointer.

See also
    itemToInfo()

  void QwtPlot::insertLegend (QwtAbstractLegend * legend, QwtPlot::LegendPosition pos = QwtPlot::RightLegend, double ratio = -1.0)

Insert a legend. If the position legend is QwtPlot::LeftLegend or QwtPlot::RightLegend the legend will be organized in one column from top to down. Otherwise the legend items will be placed in a table with a best fit number of columns from left to right.

insertLegend() will set the plot widget as parent for the legend. The legend will be deleted in the destructor of the plot or when another legend is inserted.

Legends, that are not inserted into the layout of the plot widget need to connect to the legendDataChanged() signal. Calling updateLegend() initiates this signal for an initial update. When the application code wants to implement its own layout this also needs to be done for rendering plots to a document ( see QwtPlotRenderer ).

Parameters
    legend Legend
    pos The legend's position. For top/left position the number of columns will be limited to 1, otherwise it will be set to unlimited.
    ratio Ratio between legend and the bounding rectangle of title, canvas and axes. The legend will be shrunk if it would need more space than the given ratio. The ratio is limited to ]0.0 .. 1.0]. In case of <= 0.0 it will be reset to the default ratio. The default vertical/horizontal ratio is 0.33/0.5.

See also
    legend(), QwtPlotLayout::legendPosition(), QwtPlotLayout::setLegendPosition()

  double QwtPlot::invTransform (int axisId, int pos) const
Transform the x or y coordinate of a position in the drawing region into a value.

Parameters
    axisId Axis index
    pos position

Returns
    Position as axis coordinate

Warning
    The position can be an x or a y coordinate, depending on the specified axis.

  void QwtPlot::itemAttached (QwtPlotItem * plotItem, bool on) [signal]
A signal indicating, that an item has been attached/detached

Parameters
    plotItem Plot item
    on Attached/Detached

  QVariant QwtPlot::itemToInfo (QwtPlotItem * plotItem) const [virtual]

Build an information, that can be used to identify a plot item on the legend. The default implementation simply wraps the plot item into a QVariant object. When overloading itemToInfo() usually infoToItem() needs to reimplemeted too.

QVariant itemInfo;
qVariantSetValue( itemInfo, plotItem );

Parameters
    plotItem Plot item

Returns
    Plot item embedded in a QVariant

See also
    infoToItem()

  QwtAbstractLegend * QwtPlot::legend ()

Returns
    the plot's legend

See also
    insertLegend()

  const QwtAbstractLegend * QwtPlot::legend () const

Returns
    the plot's legend

See also
    insertLegend()

  void QwtPlot::legendDataChanged (const QVariant & itemInfo, const QList< QwtLegendData > & data) [signal]
A signal with the attributes how to update the legend entries for a plot item.

Parameters
    itemInfo Info about a plot item, build from itemToInfo()
    data Attributes of the entries ( usually <= 1 ) for the plot item.

See also
    itemToInfo(), infoToItem(), QwtAbstractLegend::updateLegend()

  QwtPlotLayout * QwtPlot::plotLayout ()

Returns
    the plot's layout

  const QwtPlotLayout * QwtPlot::plotLayout () const

Returns
    the plot's layout

  void QwtPlot::replot () [virtual], [slot]

Redraw the plot. If the autoReplot option is not set (which is the default) or if any curves are attached to raw data, the plot has to be refreshed explicitly in order to make changes visible.

See also
    updateAxes(), setAutoReplot()

  void QwtPlot::resizeEvent (QResizeEvent * e) [protected], [virtual]
Resize and update internal layout

Parameters
    e Resize event

  void QwtPlot::setAutoReplot (bool tf = true)

Set or reset the autoReplot option. If the autoReplot option is set, the plot will be updated implicitly by manipulating member functions. Since this may be time-consuming, it is recommended to leave this option switched off and call replot() explicitly if necessary.

The autoReplot option is set to false by default, which means that the user has to call replot() in order to make changes visible.

Parameters
    tf true or false. Defaults to true.

See also
    replot()

  void QwtPlot::setAxisAutoScale (int axisId, bool on = true)

Enable autoscaling for a specified axis. This member function is used to switch back to autoscaling mode after a fixed scale has been set. Autoscaling is enabled by default.

Parameters
    axisId Axis index
    on On/Off

See also
    setAxisScale(), setAxisScaleDiv(), updateAxes()

Note
    The autoscaling flag has no effect until updateAxes() is executed ( called by replot() ).

  void QwtPlot::setAxisFont (int axisId, const QFont & font)

Change the font of an axis.

Parameters
    axisId Axis index
    font Font

Warning
    This function changes the font of the tick labels, not of the axis title.

  void QwtPlot::setAxisLabelAlignment (int axisId, Qt::Alignment alignment)
Change the alignment of the tick labels

Parameters
    axisId Axis index
    alignment Or'd Qt::AlignmentFlags see <qnamespace.h>

See also
    QwtScaleDraw::setLabelAlignment()

  void QwtPlot::setAxisLabelRotation (int axisId, double rotation)
Rotate all tick labels

Parameters
    axisId Axis index
    rotation Angle in degrees. When changing the label rotation, the label alignment might be adjusted too.

See also
    QwtScaleDraw::setLabelRotation(), setAxisLabelAlignment()

  void QwtPlot::setAxisMaxMajor (int axisId, int maxMajor)
Set the maximum number of major scale intervals for a specified axis

Parameters
    axisId Axis index
    maxMajor Maximum number of major steps

See also
    axisMaxMajor()

  void QwtPlot::setAxisMaxMinor (int axisId, int maxMinor)
Set the maximum number of minor scale intervals for a specified axis

Parameters
    axisId Axis index
    maxMinor Maximum number of minor steps

See also
    axisMaxMinor()

  void QwtPlot::setAxisScale (int axisId, double min, double max, double stepSize = 0)

Disable autoscaling and specify a fixed scale for a selected axis. In updateAxes() the scale engine calculates a scale division from the specified parameters, that will be assigned to the scale widget. So updates of the scale widget usually happen delayed with the next replot.

Parameters
    axisId Axis index
    min Minimum of the scale
    max Maximum of the scale
    stepSize Major step size. If step == 0, the step size is calculated automatically using the maxMajor setting.

See also
    setAxisMaxMajor(), setAxisAutoScale(), axisStepSize(), QwtScaleEngine::divideScale()

  void QwtPlot::setAxisScaleDiv (int axisId, const QwtScaleDiv & scaleDiv)

Disable autoscaling and specify a fixed scale for a selected axis. The scale division will be stored locally only until the next call of updateAxes(). So updates of the scale widget usually happen delayed with the next replot.

Parameters
    axisId Axis index
    scaleDiv Scale division

See also
    setAxisScale(), setAxisAutoScale()

  void QwtPlot::setAxisScaleDraw (int axisId, QwtScaleDraw * scaleDraw)

Set a scale draw.

Parameters
    axisId Axis index
    scaleDraw Object responsible for drawing scales.

By passing scaleDraw it is possible to extend QwtScaleDraw functionality and let it take place in QwtPlot. Please note that scaleDraw has to be created with new and will be deleted by the corresponding QwtScale member ( like a child object ).

See also
    QwtScaleDraw, QwtScaleWidget

Warning
    The attributes of scaleDraw will be overwritten by those of the previous QwtScaleDraw.

  void QwtPlot::setAxisScaleEngine (int axisId, QwtScaleEngine * scaleEngine)
Change the scale engine for an axis

Parameters
    axisId Axis index
    scaleEngine Scale engine

See also
    axisScaleEngine()

  void QwtPlot::setAxisTitle (int axisId, const QString & title)

Change the title of a specified axis.

Parameters
    axisId Axis index
    title axis title

  void QwtPlot::setAxisTitle (int axisId, const QwtText & title)

Change the title of a specified axis.

Parameters
    axisId Axis index
    title Axis title

  void QwtPlot::setCanvas (QWidget * canvas)

Set the drawing canvas of the plot widget. QwtPlot invokes methods of the canvas as meta methods ( see QMetaObject ). In opposite to using conventional C++ techniques like virtual methods they allow to use canvas implementations that are derived from QWidget or QGLWidget.

The following meta methods could be implemented:

•   replot() When the canvas doesn't offer a replot method, QwtPlot calls update() instead.

•   borderPath() The border path is necessary to clip the content of the canvas When the canvas doesn't have any special border ( f.e rounded corners ) it is o.k. not to implement this method.

The default canvas is a QwtPlotCanvas

Parameters
    canvas Canvas Widget

See also
    canvas()

  void QwtPlot::setCanvasBackground (const QBrush & brush)

Change the background of the plotting area. Sets brush to QPalette::Window of all color groups of the palette of the canvas. Using canvas()->setPalette() is a more powerful way to set these colors.

Parameters
    brush New background brush

See also
    canvasBackground()

  void QwtPlot::setFooter (const QString & text)
Change the text the footer

Parameters
    text New text of the footer

  void QwtPlot::setFooter (const QwtText & text)
Change the text the footer

Parameters
    text New text of the footer

  void QwtPlot::setPlotLayout (QwtPlotLayout * layout)

Assign a new plot layout.

Parameters
    layout Layout()

See also
    plotLayout()

  void QwtPlot::setTitle (const QString & title)
Change the plot's title

Parameters
    title New title

  void QwtPlot::setTitle (const QwtText & title)
Change the plot's title

Parameters
    title New title

  QSize QwtPlot::sizeHint () const [virtual]

Returns
    Size hint for the plot widget

See also
    minimumSizeHint()

  QwtText QwtPlot::title () const

Returns
    Title of the plot

  QwtTextLabel * QwtPlot::titleLabel ()

Returns
    Title label widget.

  const QwtTextLabel * QwtPlot::titleLabel () const

Returns
    Title label widget.

  double QwtPlot::transform (int axisId, double value) const

Transform a value into a coordinate in the plotting region.

Parameters
    axisId Axis index
    value value

Returns
    X or Y coordinate in the plotting region corresponding to the value.

  void QwtPlot::updateAxes ()

Rebuild the axes scales. In case of autoscaling the boundaries of a scale are calculated from the bounding rectangles of all plot items, having the QwtPlotItem::AutoScale flag enabled ( QwtScaleEngine::autoScale() ). Then a scale division is calculated ( QwtScaleEngine::didvideScale() ) and assigned to scale widget.

When the scale boundaries have been assigned with setAxisScale() a scale division is calculated ( QwtScaleEngine::didvideScale() ) for this interval and assigned to the scale widget.

When the scale has been set explicitly by setAxisScaleDiv() the locally stored scale division gets assigned to the scale widget.

The scale widget indicates modifications by emitting a QwtScaleWidget::scaleDivChanged() signal.

updateAxes() is usually called by replot().

See also
    setAxisAutoScale(), setAxisScale(), setAxisScaleDiv(), replot() QwtPlotItem::boundingRect()

  void QwtPlot::updateCanvasMargins ()

Update the canvas margins. Plot items might indicate, that they need some extra space at the borders of the canvas by the QwtPlotItem::Margins flag.

getCanvasMarginsHint(), QwtPlotItem::getCanvasMarginHint()

  void QwtPlot::updateLayout () [virtual]

Adjust plot content to its current size.

See also
    resizeEvent()

  void QwtPlot::updateLegend ()
Emit legendDataChanged() for all plot item

See also
    QwtPlotItem::legendData(), legendDataChanged()

  void QwtPlot::updateLegend (const QwtPlotItem * plotItem)
Emit legendDataChanged() for a plot item

Parameters
    plotItem Plot item

See also
    QwtPlotItem::legendData(), legendDataChanged()

Author

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