QSize

QSize is a simple value type in the Qt framework that represents a two-dimensional size using integer width and height components. It is defined in the QtCore module and is widely used to describe the size of widgets, images, and layout targets. A QSize object stores its dimensions as integers and provides accessors width() and height(), as well as mutators to set these values. Constructors include a default constructor that creates a null size and a constructor that takes width and height.

QSize integrates with other Qt geometry types such as QRect and QPoint and is commonly used in layout calculations and painting code. It is a lightweight, copyable type that is typically passed by value. For common operations, QSize offers methods for scaling: scaled() returns a new QSize scaled to a specified width and height with an optional aspect-ratio mode; scale() modifies the object in place. Equality and inequality operators compare sizes component-wise.

For floating-point needs, Qt provides QSizeF, which uses double precision. Conversions between QSize and QSizeF are supported. In practice, QSize is used to express widget sizes, pixmap dimensions, and other integer-based measurements in user interfaces. It is not intended to represent positions; coordinates are handled by QPoint or QPointF.

Limitations: QSize uses integer components, so fractional results are truncated when scaling. It is primarily a size descriptor, not a position descriptor.