QwtPlotTextLabel man page

QwtPlotTextLabel — A plot item, which displays a text label.  


#include <qwt_plot_textlabel.h>

Inherits QwtPlotItem.

Public Member Functions

QwtPlotTextLabel ()
virtual ~QwtPlotTextLabel ()
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.

Protected Member Functions

virtual void draw (QPainter *, const QwtScaleMap &, const QwtScaleMap &, const QRectF &) const
void invalidateCache ()
Invalidate all internal cache.

Additional Inherited Members

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.


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:


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


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

See also:


Implements QwtPlotItem.

int QwtPlotTextLabel::margin () const


Margin added to the contentsMargins() of the canvas

See also:


int QwtPlotTextLabel::rtti () const [virtual]



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.


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.


text Text to be displayed

See also:

text(), QwtText::renderFlags()

QwtText QwtPlotTextLabel::text () const


Text to be displayed

See also:


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

Align the text label.


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


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

See also:

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


Generated automatically by Doxygen for Qwt User's Guide from the source code.


Mon Jun 13 2016 Version 6.1.3 Qwt User's Guide