QFontMetrics::boundingRect is two times slower than QPainter::drawText

Dmitriano

In my app I draw a table with 1000+ strings from beforeRendering() haldler:

void LightGrid::beforeRendering()
{
    const QSize window_size = window()->size();
    QOpenGLPaintDevice device(window_size);
    QPainter painter(&device);
    ...
    //Measure the strings with QFontMetrics::boundingRect
    //Draw the strings with QPainter::drawText
}

MSVC 2017 profiler shows that QFontMetrics::boundingRect is two times slower than QPainter::drawText in my app.

Is there a way to replace QFontMetrics::boundingRect with something that works faster?

My QT version is 5.15.0, OS: Windows 10

Christian Ehrlicher

Since those two functions do completely different things - no. But the Qt source code is freely available so you can take a look if you can improve it's performance.

Unsolved QFontMetrics::boundingRect is two times slower than QPainter::drawText