Qwt User's Guide 6.1.2

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QwtPlotTextLabel Class Reference

A plot item, which displays a text label. More...

`#include <qwt_plot_textlabel.h>`

Inheritance diagram for QwtPlotTextLabel:
[legend]

## Public Member Functions
| QwtPlotTextLabel ()
| Constructor. More...
virtual | ~QwtPlotTextLabel ()
| Destructor.
virtual int | rtti () const
void | setText (const QwtText &)
QwtText | text () const
void | setMargin (int margin)
int | margin () const
virtual QRectF | textRect (const QRectF &, const QSizeF &) const
| Align the text label. More...
Public Member Functions inherited from QwtPlotItem
| QwtPlotItem (const QwtText &title=QwtText())
virtual | ~QwtPlotItem ()
| Destroy the QwtPlotItem.
void | attach (QwtPlot *plot)
| Attach the item to a plot. More...
void | detach ()
| This method detaches a QwtPlotItem from any QwtPlot it has been associated with. More...
QwtPlot * | plot () const
| Return attached plot.
void | setTitle (const QString &title)
void | setTitle (const QwtText &title)
const QwtText & | title () 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. More...
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 QRectF | boundingRect () const
virtual void | getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasSize, double &left, double &top, double &right, double &bottom) const
| Calculate a hint for the canvas margin. More...
virtual void | updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
| Update the item to changes of the axes scale division. More...
virtual void | updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &)
| Update the item to changes of the legend info. More...
QRectF | scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
| Calculate the bounding scale rectangle of 2 maps. More...
QRectF | paintRect (const QwtScaleMap &, const QwtScaleMap &) const
| Calculate the bounding paint rectangle of 2 maps. More...
virtual QList< QwtLegendData > | legendData () const
| Return all information, that is needed to represent the item on the legend. More...
virtual QwtGraphic | legendIcon (int index, const QSizeF &) const

## Protected Member Functions
virtual void | draw (QPainter *, const QwtScaleMap &, const QwtScaleMap &, const QRectF &) const
void | invalidateCache ()
| Invalidate all internal cache.
Protected Member Functions inherited from QwtPlotItem
QwtGraphic | defaultIcon (const QBrush &, const QSizeF &) const
| Return a default icon from a brush. More...

## Additional Inherited Members
Public Types inherited from QwtPlotItem
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. More...
enum | ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 }
| Plot Item Attributes. More...
enum | ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 }
| Plot Item Interests. More...
enum | RenderHint { RenderAntialiased = 0x1 }
| Render hints. More...
typedef QFlags< ItemAttribute > | ItemAttributes
| Plot Item Attributes.
typedef QFlags< ItemInterest > | ItemInterests
| Plot Item Interests.
typedef QFlags< RenderHint > | RenderHints
| Render hints.

## Detailed Description

A plot item, which displays a text label.

QwtPlotTextLabel displays a text label aligned to the plot canvas.

In opposite to QwtPlotMarker the position of the label is unrelated to plot coordinates.

As drawing a text is an expensive operation the label is cached in a pixmap to speed up replots.

Example
  The following code shows how to add a title.

        QwtText title( "Plot Title" );
        title.setRenderFlags( Qt::AlignHCenter | Qt::AlignTop );

        QFont font;
        font.setBold( true );
        title.setFont( font );

        QwtPlotTextLabel *titleItem = new QwtPlotTextLabel();
        titleItem->setText( title );
        titleItem->attach( this );

See Also
  QwtPlotMarker

## Constructor & Destructor Documentation

QwtPlotTextLabel::QwtPlotTextLabel | ( |  | ) |

Constructor.

Initializes an text label with an empty text

Sets the following item attributes:

- QwtPlotItem::AutoScale: true
- QwtPlotItem::Legend: false

The z value is initialized by 150

See Also
  QwtPlotItem::setItemAttribute(), QwtPlotItem::setZ()

## Member Function Documentation

void QwtPlotTextLabel::draw | ( | QPainter * | painter,
|  | const QwtScaleMap & | xMap,
|  | const QwtScaleMap & | yMap,
|  | const QRectF & | canvasRect
| ) |  | const
| protected virtual

Draw the text label

Parameters

  painter | Painter
  xMap | x Scale Map
  yMap | y Scale Map
  canvasRect | Contents rectangle of the canvas in painter coordinates

See Also
  textRect()

Implements QwtPlotItem.

int QwtPlotTextLabel::margin | ( |  | ) | const

Returns
  Margin added to the contentsMargins() of the canvas

See Also
  setMargin()

int QwtPlotTextLabel::rtti | ( |  | ) | const
| virtual

Returns
  QwtPlotItem::Rtti_PlotTextLabel

Reimplemented from QwtPlotItem.

void QwtPlotTextLabel::setMargin | ( | int | margin | ) |

Set the margin

The margin is the distance between the contentsRect() of the plot canvas and the rectangle where the label can be displayed.

Parameters

  margin | Margin

See Also
  margin(), textRect()

void QwtPlotTextLabel::setText | ( | const QwtText & | text | ) |

Set the text

The label will be aligned to the plot canvas according to the alignment flags of text.

Parameters

  text | Text to be displayed

See Also
  text(), QwtText::renderFlags()

QwtText QwtPlotTextLabel::text | ( |  | ) | const

Returns
  Text to be displayed

See Also
  setText()

QRectF QwtPlotTextLabel::textRect | ( | const QRectF & | rect,
|  | const QSizeF & | textSize
| ) |  | const
| virtual

Align the text label.

Parameters

  rect | Canvas rectangle with margins subtracted
  textSize | Size required to draw the text

Returns
  A rectangle aligned according the the alignment flags of the text.

See Also
  setMargin(), QwtText::renderFlags(), QwtText::textSize()