Overview
ISO/IEC 8651-4:1995 specifies the C language binding for the Graphical Kernel System (GKS), a language-independent nucleus for interactive computer graphics (see ISO/IEC 7942-1:1994). This part defines how GKS concepts map into C: header files, type definitions, function and macro identifiers, memory and error handling, and compatibility mechanisms so GKS programs in C are portable and interoperable across implementations.
Key topics
- C language binding: rules for embedding the GKS nucleus in C, including naming conventions, function identifiers and macro policies.
- Header files: standardized headers (notably gks.h and gks_compat.h) to provide the required API and a compatibility layer with earlier editions.
- Type mapping: mapping GKS data types to C types, with environment-, implementation- and implementation-independent type definitions.
- Function vs macro usage: guidance on which GKS operations are provided as functions or macros in C bindings.
- Memory management: conventions for functions that return simple lists and complex data structures; annex material describes allocation and deallocation patterns.
- Error handling: standard error codes, C-specific error behavior, and support for application-supplied error handlers.
- Colour models and storage conventions: representations for colour, colour characteristics, and standardized storage of multi-dimensional arrays (2×3 and 3×3 matrices, conics, colour arrays).
- Compatibility: differences from the 1991 edition and a compatibility layer to ease migration.
Applications and who uses it
ISO/IEC 8651-4:1995 is valuable for:
- Graphics library implementers who need a standard, portable API for exposing GKS functionality to C programs.
- Application developers in CAD, scientific visualization, technical drawing, and charting who require a stable, portable graphics interface.
- Tool vendors and middleware authors creating cross-platform visualization tools or translators between graphics systems.
- Researchers and educators working with legacy GKS systems or teaching standardized graphics APIs.
Benefits include portability, interoperability, and a consistent C interface for industry and academic projects that rely on the established GKS model.
Related standards
- ISO/IEC 7942-1:1994 (GKS language-independent nucleus) - the core GKS specification that 8651-4 maps into C.
- Other parts of ISO/IEC 8651 (language bindings) - for bindings to other programming languages and compatibility across environments.
Keywords: ISO/IEC 8651-4:1995, GKS C binding, Graphical Kernel System, gks.h, gks_compat.h, computer graphics standard, C graphics API.