File I/O

yucad reads and writes AutoCAD DXF (round-trip fidelity with AutoCAD itself) and its own native .yuc container. The file extension selects the format.

CadFileOpen(dwg, hWin, "in.dxf");     // or in.yuc
CadFileSaveAs(dwg, hWin, "out.dxf");  // or out.yuc

Formats by extension

The native .yuc format

A versioned binary container. It keeps the drawing at full AutoCAD fidelity (the body is the validated DXF serialization) while adding what DXF can't carry:

• App-data — the per-entity park / way strings (CadEntityPutParkData) and extended-data blobs, restored on load.
• Embedded preview — a thumbnail so CadExtractImage returns a preview of a .yuc file without re-rendering it.
• Single versioned file — future revisions extend it without breaking older readers.

Use .yuc for your application's own working files (fastest, loss-less for yucad-specific data); export .dxf for interchange with other CAD tools.

What the reader & writer cover

• Entities — line, ray, xline, circle, arc, ellipse (full & partial), polyline / lwpolyline with bulges, rational spline, point, text with alignment, mtext, hatch (solid + real pattern), dimensions incl. 4-point angular, leader, insert/block, 3DFACE, raster image reference.
• Tables & styles — layers (colour, linetype, lineweight, on/off/frozen), custom linetypes with dash patterns, text styles, dimension styles.
• Attributes — per-entity linetype (group 6), lineweight (370), linetype scale (48) and true colour (420).
• Header variables — the drawing settings AutoCAD expects so the file opens clean.
• Layouts & viewports — paper-space layout with plot settings and floating viewports, written in AutoCAD's shape (active layout content in ENTITIES flagged paper-space; LAYOUT objects with plot settings).
• XDATA — extended entity data is preserved through a read/write round-trip.

Raster images

CadAddImage references an external raster file; the DXF carries the IMAGE entity plus the IMAGEDEF/IMAGEDEF_REACTOR objects AutoCAD needs. Formats the underlying image loader already handles include JPG, PNG, BMP, GIF, ICO and SVG.