Qwt User's Guide
QwtPlotTextLabel Class Reference

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

#include <qwt_plot_textlabel.h>

Inheritance diagram for QwtPlotTextLabel:

Public Member Functions

 QwtPlotTextLabel ()
 Constructor.
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.

Protected Member Functions

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

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

Constructor.

Initializes an text label with an empty text

Sets the following item attributes:

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:
painterPainter
xMapx Scale Map
yMapy Scale Map
canvasRectContents 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:
marginMargin
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:
textText to be displayed
See also:
text(), QwtText::renderFlags()
Returns:
Text to be displayed
See also:
setText()
QRectF QwtPlotTextLabel::textRect ( const QRectF &  rect,
const QSizeF &  textSize 
) const [virtual]

Align the text label.

Parameters:
rectCanvas rectangle with margins subtracted
textSizeSize required to draw the text
Returns:
A rectangle aligned according the the alignment flags of the text.
See also:
setMargin(), QwtText::renderFlags(), QwtText::textSize()

List of all members.

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