Paint System | Qt GUI 6.4.1

- Qt 6.4
- Qt GUI
- Paint System
- Qt 6.4.1 Reference Documentation

# Paint System

Qt's paint system enables painting on screen and print devices using the same API, and is primarily based on the QPainter, QPaintDevice, and QPaintEngine classes.

QPainter is used to perform drawing operations, QPaintDevice is an abstraction of a two-dimensional space that can be painted on using a QPainter, and QPaintEngine provides the interface that the painter uses to draw onto different types of devices. The QPaintEngine class is used internally by QPainter and QPaintDevice, and is hidden from application programmers unless they create their own device type.

The main benefit of this approach is that all painting follows the same painting pipeline making it easy to add support for new features and providing default implementations for unsupported ones.

## Topics

- Classes for Painting
- Paint Devices and Backends
- Drawing and Filling
- Coordinate System
- Reading and Writing Image Files

## Classes for Painting

These classes provide support for painting onto a paint device.

QBitmap | Monochrome (1-bit depth) pixmaps
QBrush | Defines the fill pattern of shapes drawn by QPainter
QColor | Colors based on RGB, HSV or CMYK values
QColorSpace | Color space abstraction
QColorTransform | Transformation between color spaces
QColormap | Maps device independent QColors to device dependent pixel values
QConicalGradient | Used in combination with QBrush to specify a conical gradient brush
QGenericMatrix | Template class that represents a NxM transformation matrix with N columns and M rows
QGradient | Used in combination with QBrush to specify gradient fills
QIconEngine | Abstract base class for QIcon renderers
QImageReader | Format independent interface for reading images from files or other devices
QImageWriter | Format independent interface for writing images to files or other devices
QLine | Two-dimensional vector using integer precision
QLineF | Two-dimensional vector using floating point precision
QLinearGradient | Used in combination with QBrush to specify a linear gradient brush
QMargins | Defines the four margins of a rectangle
QMarginsF | Defines the four margins of a rectangle
QPageRanges | Represents a collection of page ranges
QPagedPaintDevice | Represents a paint device that supports multiple pages
QPaintDevice | The base class of objects that can be painted on with QPainter
QPen | Defines how a QPainter should draw lines and outlines of shapes
QPixmap | Off-screen image representation that can be used as a paint device
QRadialGradient | Used in combination with QBrush to specify a radial gradient brush
QRect | Defines a rectangle in the plane using integer precision
QRectF | Defines a finite rectangle in the plane using floating point precision
QRgba64 | Struct contains a 64-bit RGB color
QRgbaFloat | Struct contains a four part RGBA floating-point color
QSize | Defines the size of a two-dimensional object using integer point precision
QSizeF | Defines the size of a two-dimensional object using floating point precision
QStylePainter | Convenience class for drawing QStyle elements inside a widget
QVector2D | Represents a vector or vertex in 2D space