How to get the line height of a QTextBlock?

[therefore]

Windows 7 SP1
MSVS 2010
Qt 4.8.4

Given this code:

#include <QTGui>
 
int main(int argc, char *argv[])
{
    QTextDocument* text_document = new QTextDocument("testing");
    QTextBlock text_block = text_document->begin();
    qDebug() << text_block.text() << text_block.blockFormat().lineHeight()
             << text_block.blockFormat().lineHeightType();
}

#include <QTGui>

int main(int argc, char *argv[])
{
    QTextDocument* text_document = new QTextDocument("testing");
    QTextBlock text_block = text_document->begin();
    qDebug() << text_block.text() << text_block.blockFormat().lineHeight()
             << text_block.blockFormat().lineHeightType();
}

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The console displays:

"testing" 0 0

Question: Why doesn't lineHeight return "the LineHeight property for the paragraph"? The lineHeightType is set for single spacing.

Even trying:

qDebug() << text_block.text() << text_block.layout()->boundingRect().height();

qDebug() << text_block.text() << text_block.layout()->boundingRect().height();

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gives me zero.

[alrawab]

QFontMetrics fm(font);//set to any font =>font.setFamily("Arial"); font.setPointSize(10);
int yCharOffset = 4;
int lineHeight = fm.boundingRect('W').height() + 2 * yCharOffset;
int xCharOffset = 1;
int charWidth = fm.boundingRect('W').width() + 2 * xCharOffset;