The QSize class defines the size of a two-dimensional object using integer point precision.| doc.qt.io
The QMargins class defines the four margins of a rectangle.| doc.qt.io
The QSizeF class defines the size of a two-dimensional object using floating point precision.| doc.qt.io
The header file includes Qt fundamental type declarations.| doc.qt.io
The Qt namespace contains miscellaneous identifiers used throughout the Qt library.| doc.qt.io