How to get maximum Font Size in Qt to fit text into Widget

Article Metadata

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Tested with

Devices(s): Emulator / desktop / device

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Compatibility

Platform(s): All Qt Supported

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Article

Keywords: QWidget, QFont, QFontMetrics

Created: Avis (30 Nov 2010)

Last edited: hamishwillee (11 Oct 2012)

Basic Idea

This article shows how you can calculate the maximum font size of text in a QWidget using the font attributes QFont and QFontMetrics. See also Archived:Calculating text width in Qt

And here is contrary task: set font size to maximally fit into widget's size. Simple loop will help.

// Function gets aFont with initialized Font Family, and aText - which size is calculated
void TextWidget::calcFontSize(const QString aText, QFont& aFont)
{
    // get widget's width
    int wd_width = size().width(); 
    // get widget's height
    int wd_hgt = size().height(); 
    int fontPointSize;
    // calculating loop
    for (int i = 0; i < 200; i++)
    {
        aFont.setPointSize(i);
        // create FontMetrics for resized font
        QFontMetrics fm(aFont);
        // get text width for current font size
        int x = fm.width(aText);
        // get text height for current font size
        int y = fm.height();
        // check if text fits widget
        if ((x > wd_width) || (y > wd_hgt))
        {
            // saving maximum possible size of font
            fontPointSize = i-1;
            break;
        }
    }
    aFont.setPointSize(fontPointSize);
    // as a result - we get already resized aFont
}

--Avis 8:29, 30 November 2010 (UTC)