dwXSize

dwXSize is a field name used in several Windows API structures to store the horizontal size component of a two-dimensional size. The prefix dw indicates a DWORD, a 32-bit unsigned integer, and the X denotes the horizontal axis, with Size describing the magnitude. Because it is a field rather than a function or type, its exact meaning depends on the structure in which it appears.

In practice, dwXSize is used alongside a corresponding Y-sized field to describe width and height. The units and coordinate system are defined by the API structure: axes may be measured in pixels, device units, or another unit defined by the context. For example, some graphics or imaging structures represent image dimensions in pixels, while others might use logical or device-dependent units.

As with all DWORD fields, dwXSize is 32 bits wide and unsigned; when structures are serialized for storage or inter-process communication, the value’s byte order follows the platform’s endianness conventions.

If you encounter dwXSize, consult the documentation for the specific structure to determine the units, permissible ranges, and how it relates to other size fields. It is not a standalone API; rather it is a data member used within APIs that describe two-dimensional sizes.

See also: dwYSize, DWORD, SIZE (cx, cy), and related two-dimensional size representations in Windows API.