QPainter painter; painter.begin(this); qreal scale = 1.0 / this->devicePixelRatioCache; painter.scale(scale, scale); I need very high pixel granularity accuracy because in my project, one pixel represents several nanometers for measurement tools. Pixel accuracy is crucial for me. However, with QT QPainter, the coordinates often place the (0,0) point outside the canvas and position (1,1) at the […]