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▲
These classes provide support for painting onto a paint device.
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QBitmap: The QBitmap class provides monochrome (1-bit depth) pixmaps.
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QBrush: The QBrush class defines the fill pattern of shapes drawn by QPainter.
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QColor: The QColor class provides colors based on RGB, HSV or CMYK values.
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QColorSpace: The QColorSpace class provides a color space abstraction.
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QColorTransform: The QColorTransform class is a transformation between color spaces.
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QConicalGradient: The QConicalGradient class is used in combination with QBrush to specify a conical gradient brush.
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QFont: The QFont class specifies a query for a font used for drawing text.
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QFontMetrics: The QFontMetrics class provides font metrics information.
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QFontMetricsF: The QFontMetricsF class provides font metrics information.
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QGenericMatrix: The QGenericMatrix class is a template class that represents a NxM transformation matrix with N columns and M rows.
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QGradient: The QGradient class is used in combination with QBrush to specify gradient fills.
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QIcon: The QIcon class provides scalable icons in different modes and states.
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QIconEngine: The QIconEngine class provides an abstract base class for QIcon renderers.
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QImage: The QImage class provides a hardware-independent image representation that allows direct access to the pixel data, and can be used as a paint device.
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QImageReader: The QImageReader class provides a format independent interface for reading images from files or other devices.
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QImageWriter: The QImageWriter class provides a format independent interface for writing images to files or other devices.
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QLine: The QLine class provides a two-dimensional vector using integer precision.
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QLineF: The QLineF class provides a two-dimensional vector using floating point precision.
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QLinearGradient: The QLinearGradient class is used in combination with QBrush to specify a linear gradient brush.
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QMargins: The QMargins class defines the four margins of a rectangle.
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QMarginsF: The QMarginsF class defines the four margins of a rectangle.
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QPageRanges: The QPageRanges class represents a collection of page ranges.
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QPagedPaintDevice: The QPagedPaintDevice class represents a paint device that supports multiple pages.
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QPaintDevice: The QPaintDevice class is the base class of objects that can be painted on with QPainter.
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QPaintEngine: The QPaintEngine class provides an abstract definition of how QPainter draws to a given device on a given platform.
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QPainter: The QPainter class performs low-level painting on widgets and other paint devices.
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QPainterPath: The QPainterPath class provides a container for painting operations, enabling graphical shapes to be constructed and reused.
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QPainterPathStroker: The QPainterPathStroker class is used to generate fillable outlines for a given painter path.
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QPdfWriter: The QPdfWriter class is a class to generate PDFs that can be used as a paint device.
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QPen: The QPen class defines how a QPainter should draw lines and outlines of shapes.
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QPixmap: The QPixmap class is an off-screen image representation that can be used as a paint device.
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QPoint: The QPoint class defines a point in the plane using integer precision.
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QPointF: The QPointF class defines a point in the plane using floating point precision.
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QPolygon: The QPolygon class provides a list of points using integer precision.
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QPolygonF: The QPolygonF class provides a list of points using floating point precision.
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QRadialGradient: The QRadialGradient class is used in combination with QBrush to specify a radial gradient brush.
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QRect: The QRect class defines a rectangle in the plane using integer precision.
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QRectF: The QRectF class defines a finite rectangle in the plane using floating point precision.
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QRegion: The QRegion class specifies a clip region for a painter.
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QRgba64: The QRgba64 struct contains a 64-bit RGB color.
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QRgbaFloat: The QRgbaFloat struct contains a four part RGBA floating-point color.
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QSize: The QSize class defines the size of a two-dimensional object using integer point precision.
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QSizeF: The QSizeF class defines the size of a two-dimensional object using floating point precision.
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QSupportedWritingSystems: The QSupportedWritingSystems class is used when registering fonts with the internal Qt fontdatabase.
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QTransform: The QTransform class specifies 2D transformations of a coordinate system.
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QVector2D: The QVector2D class represents a vector or vertex in 2D space.