Qwt User's Guide  6.1.1
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Public Member Functions | Protected Member Functions | List of all members
QwtTextEngine Class Referenceabstract

Abstract base class for rendering text strings. More...

#include <qwt_text_engine.h>

Inheritance diagram for QwtTextEngine:
Inheritance graph
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Public Member Functions

virtual ~QwtTextEngine ()
 Destructor.
 
virtual double heightForWidth (const QFont &font, int flags, const QString &text, double width) const =0
 
virtual QSizeF textSize (const QFont &font, int flags, const QString &text) const =0
 
virtual bool mightRender (const QString &text) const =0
 
virtual void textMargins (const QFont &font, const QString &text, double &left, double &right, double &top, double &bottom) const =0
 
virtual void draw (QPainter *painter, const QRectF &rect, int flags, const QString &text) const =0
 

Protected Member Functions

 QwtTextEngine ()
 Constructor.
 

Detailed Description

Abstract base class for rendering text strings.

A text engine is responsible for rendering texts for a specific text format. They are used by QwtText to render a text.

QwtPlainTextEngine and QwtRichTextEngine are part of the Qwt library. The implementation of QwtMathMLTextEngine uses code from the Qt solution package. Because of license implications it is built into a separate library.

See Also
QwtText::setTextEngine()

Member Function Documentation

virtual void QwtTextEngine::draw ( QPainter *  painter,
const QRectF &  rect,
int  flags,
const QString &  text 
) const
pure virtual

Draw the text in a clipping rectangle

Parameters
painterPainter
rectClipping rectangle
flagsBitwise OR of the flags like in for QPainter::drawText()
textText to be rendered

Implemented in QwtRichTextEngine, QwtPlainTextEngine, and QwtMathMLTextEngine.

virtual double QwtTextEngine::heightForWidth ( const QFont &  font,
int  flags,
const QString &  text,
double  width 
) const
pure virtual

Find the height for a given width

Parameters
fontFont of the text
flagsBitwise OR of the flags used like in QPainter::drawText
textText to be rendered
widthWidth
Returns
Calculated height

Implemented in QwtRichTextEngine, QwtPlainTextEngine, and QwtMathMLTextEngine.

virtual bool QwtTextEngine::mightRender ( const QString &  text) const
pure virtual

Test if a string can be rendered by this text engine

Parameters
textText to be tested
Returns
true, if it can be rendered

Implemented in QwtRichTextEngine, QwtPlainTextEngine, and QwtMathMLTextEngine.

virtual void QwtTextEngine::textMargins ( const QFont &  font,
const QString &  text,
double &  left,
double &  right,
double &  top,
double &  bottom 
) const
pure virtual

Return margins around the texts

The textSize might include margins around the text, like QFontMetrics::descent(). In situations where texts need to be aligned in detail, knowing these margins might improve the layout calculations.

Parameters
fontFont of the text
textText to be rendered
leftReturn value for the left margin
rightReturn value for the right margin
topReturn value for the top margin
bottomReturn value for the bottom margin

Implemented in QwtRichTextEngine, QwtPlainTextEngine, and QwtMathMLTextEngine.

virtual QSizeF QwtTextEngine::textSize ( const QFont &  font,
int  flags,
const QString &  text 
) const
pure virtual

Returns the size, that is needed to render text

Parameters
fontFont of the text
flagsBitwise OR of the flags like in for QPainter::drawText
textText to be rendered
Returns
Calculated size

Implemented in QwtRichTextEngine, QwtPlainTextEngine, and QwtMathMLTextEngine.