QwtPlotTextLabel(3) Qwt User's Guide QwtPlotTextLabel(3)

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

#include <qwt_plot_textlabel.h>

Inherits QwtPlotItem.


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.


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

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( plot );

See also:

QwtPlotMarker

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()

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.

Returns:

Margin added to the contentsMargins() of the canvas

See also:

setMargin()

Returns:

QwtPlotItem::Rtti_PlotTextLabel

Reimplemented from QwtPlotItem.

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()

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()

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()

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Wed Jan 2 2019 Version 6.1.4