QOpenGLWidget - A painter can also be opened on a QOpenGLWidget.

QPainter will render widgets using a QBackingStore.

QWidget - A baseclass for pre-Qt Quick user interface classes.

QPainter will primarily use the software rasterizer to draw to QBackingStore instances.

QBackingStore - A backbuffer for top-level windows.

QPainter will use hardware accellerated OpenGL calls to draw to QOpenGLPaintDevice instances.

QOpenGLPaintDevice - A paint device to render to the current OpenGL (ES) 2.0 context.

QPainter will primarily use the software rasterizer to draw to QPixmap instances.

QPixmap - A image representation suited for display on screen.

QPainter will use the software rasterizer to draw to QImage instances.

QImage - A hardware-independent image representation with direct pixel access.

The most important rendering targets for QPainter are:

Drawing and Filling - Explains how QPainter performs filling and outlining of vector shapes.

Coordinate System - Explains how QPainter's coordinate system works.

Paint System - Overview over the QPainter classes and architecture.

Its strength over the OpenGL paint engine is its high quality when antialiasing is enabled, and a complete feature set. The raster paint engine is Qt’s software rasterizer, and is used when drawing on a QImage or QWidget.

The software rasterizer and the OpenGL (ES) 2.0 back-ends are the two most important QPaintEngine implementations. The actual drawing happens in the QPaintDevice's QPaintEngine.

QPainter provides API for drawing vector graphics, text and images onto different surfaces, or QPaintDevice instances, such as QImage, QOpenGLPaintDevice, QWidget, and QPrinter. Qt 5's graphics capabilities also includes support for printing, as well as the loading and saving of various image formats. Graphics in Qt 5 is primarily done either through the imperative QPainter API, or through Qt’s declarative UI language, Qt Quick, and its scene graph back-end.

Open source vector graphics library