Public API

The DwgIO package is the supported surface listed here. Everything else (the container reader, the cipher, the checksums, the decompressor, the bit reader and the section parsers under DwgIO.Internal) is internal. It can change in any release and is visible only to the test project through InternalsVisibleTo.

Reading a file (DwgIO)

Type	Use
DwgDocument	Opens a drawing (Open) and gives its version, file and container headers, section catalog, metadata, handle map, object inventory, entities and Diagnostics. ReadSection(name) returns the decompressed bytes of one named section.
DwgReaderOptions	What Open reads: ReadSectionMap, ReadSummaryInfo, ReadMetadata, ReadObjects, ReadEntities (all on by default) and VerifyChecksums (off by default).
DwgException	Thrown for a damaged or truncated file, and by ReadSection for an unknown section name, a document opened without its section map, or a checksum mismatch when VerifyChecksums is on.
DwgUnsupportedVersionException	Thrown when the version is not recognised or its container is not implemented yet (R13 to R2000, R2007). Derives from DwgException.

DwgDocument.Open throws FileNotFoundException when the file does not exist.

Model (DwgIO.Model)

Type	Use
DwgVersionInfo, DwgContainerFamily	The release identified from the version magic (Magic, Release, Year, Family).
DwgFileHeader	The 128-byte prefix shared by every version: Version, MaintenanceVersion, PreviewOffset, Codepage, CodepageName.
DwgContainerHeader	The decrypted header of AutoCAD 2004 and later files: page and section map locations, PageCount, GapCount, StoredCrc32 and HeaderCrcValid.
DwgSectionInfo	One named section: Name, Size, PageCount, MaxPageSize, Compression, Encryption, SectionId.
DwgSummaryInfo	Drawing properties (title, author, keywords, ...), custom properties and the created and modified dates.
DwgAppInfo	The application that saved the drawing.
DwgFileDepList, DwgFileDependency	External files the drawing refers to (fonts, images, references).
DwgPreview, DwgPreviewImageKind	The embedded thumbnail and its format (BMP, PNG or WMF).
DwgHandleMap, DwgHandleMapEntry	The handle to offset index of the object stream; Find(handle) looks up one object.
DwgObjectInfo, DwgHandle	One record of the object stream: offset, size, type code and handle.
DwgEntity, DwgEntityKind	A decoded entity: handle, type, colour, linetype scale and, for LINE, CIRCLE, ARC and POINT, its Geometry.

JSON export (DwgIO.Json)

Type	Use
DwgJsonExporter	Write(document, stream, options) writes an opened DwgDocument to a stream; WriteFile(document, path, options) writes it to a new file.
DwgJsonExportOptions	Indented (default true), IncludeSectionContents (embeds the decompressed bytes of sections as base64; default false) and SectionsToInclude (names of the sections to embed; empty means every readable section). Default holds the default values.

using DwgIO;
using DwgIO.Json;

var doc = DwgDocument.Open("drawing.dwg");
DwgJsonExporter.WriteFile(doc, "drawing.json", DwgJsonExportOptions.Default);

The export has the objects file, version, containerHeader, summaryInfo, appInfo, preview, fileDepList and objects, the numbers pageCount and entityCount, the entities array and the sections array. An object whose data the drawing does not hold is left out.

Diagnostics

The library never writes to the console. Parts of a drawing that could not be decoded are listed in DwgDocument.Diagnostics (section name and message) and the rest of the drawing is still read.

dwgio inspect prints the first three of them.