Archived:Calculating text width in Qt

Article Metadata

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Tested with

Devices(s): Nokia 5800 XpressMusic

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Compatibility

Platform(s): S60 3rd Edition, FP1, FP2
S60 5th Edition

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Platform Security

Capabilities: )

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Article

Keywords: QFontMetrics, QFont

Created: tepaa (29 Apr 2009)

Last edited: hamishwillee (15 Feb 2012)

Overview

This code snippets shows how to use the QFont and QFontMetrics classes to draw a string into the center of the screen and to get the string height and width in pixels.

Preconditions

• Install Nokia Qt SDK

Source code

• This source code centers the text and sets the text colour.

void QMyWidget::paintEvent(QPaintEvent*)
    {
    QPainter painter(this);
 
    // Create font
    QFont f("Helvetica",20);
    // Set current font
    painter.setFont(f);
    // Set font color
    painter.setPen(Qt::white);
    // Get QFontMetrics reference
    QFontMetrics fm = painter.fontMetrics();
 
    QString text = "helloworld";
 
    // Calculate text center position into the screen using QFontMetrics class
    QPoint center = QPoint( ( width()-fm.width(text))/2,
                            ( height() - fm.height())/2 );
 
    // QFontMetrics::width() gives calculated text width with current QFont in QPainter
    // QFontMetrics::height() gives text height
 
    painter.drawText(center,text);
    }

Postconditions

The text is centered on the screen.

The code example can be found at File:HelloworldNew.zip