File Formats
NijiCAD uses its proprietary format (.nijicad) as the standard save format, aiming to fully preserve drawing data and relevant environment information. Additionally, to enable data exchange with external CAD software, it supports reading and writing DXF formats, and reading DWG and JWW formats. Outputting to the JWW format is a consideration for future updates.
1. NijiCAD Format
The drawing file format for NijiCAD.
- The extension is .nijicad.
- Uses JSON format.
Primary Structure
appName
The application name string.
- Fixed as "NijiCAD".
docVer
The version of the .nijicad format as a real value.
- File version checking will be implemented in the future.
dbBlocks
A list of block definitions.
- *Model represents the group of shapes deployed in the drafting area.
- Definitions other than *Model are instantiated as block references.
- Block references can be registered nested within block definitions.
dbImages
A list of image definitions.
- Image names are based on file names.
- Supports png, jpg, and bmp.
- Data is embedded within the .nijicad file.
dbLayers
A list of layer definitions.
- Layer "0" is added by default.
- If the layer name is "Defpoints", it is forcibly set as non-printing.
- Properties include ID, Name, Visibility, Color, Linetype, Transparency, and Printability.
- Linetype scale is currently pending.
dbLayouts
A list of layout definitions.
- Stores print settings.
- Only "Model" is available in v1.0.
dbDocEnv
Document environment variables.
- CLAYER
- CTAB
- DIMSCALE
- LTSCALE
2. DXF Format
A file format intended for exchanging drawing data.
DXF I/O List
| Shape Type | Item | DXF Input | Input Remarks | DXF Output | Output Remarks |
|---|---|---|---|---|---|
| ARC | Arc | ◎ | - | ◎ | - |
| CIRCLE | Circle | ◎ | - | ◎ | - |
| ELLIPSE | Ellipse | ◎ | - | ◎ | - |
| LINE | Line Segment | ◎ | - | ◎ | - |
| PLINE | Polyline | ◎ | - | ◎ | - |
| POINT | Point | ◎ | Replaced by DOT shape | ◎ | Exported as POINT |
| TEXT | Text | ◎ | - | ◎ | Text frames are separated |
| RAY | Ray | ◎ | 2025/10/28 | ◎ | 2025/10/28 |
| XLINE | Construction Line | ◎ | 2025/10/28 | ◎ | 2025/10/28 |
| SOLID | Solid | ◎ | - | ◎ | - |
| HATCH | Hatching | 〇 | SOLID, USER, ANSI31/37 JIS series | ◎ | SOLID, USER, ANSI31/37 JIS series |
| MTEXT | Multiline Text | 〇 | Column formatting is omitted | ◎ | Text frames are separated |
| DIMENSION | Linear Dimension | ◎ | - | ◎ | - |
| DIMENSION | Dimensions other than Linear | △ | Converted to Blocks | - | - |
| SPLINE | Spline | △ | Some splines are converted to Polylines | ◎ | - |
| INSERT | Block Reference | ◎ | - | ◎ | - |
| INSERT | Dynamic Block | △ | Converted to Blocks | 〇 | - |
| INSERT | Array Copy Block | △ | Converted to Blocks | 〇 | - |
| MULTILEADER | Multileader | △ | Converted to Blocks | 〇 | - |
| MULTILEADER | Multileader (with Block) | △ | Block portion is missing | △ | - |
| IMAGE | Image | × | None (frame planned for future) | × | None (frame planned for future) |
DXF Input: Proprietary implementation
DXF Output: Proprietary implementation (2025/10/28) Exported DXF files are verified with Autodesk DWG TrueView. The top priority is ensuring compatibility so that it can be read by any CAD software.
DXF Data Samples
Verification of DXF input uses samples shared on the internet.
🌐 CAD-Material.com (CAD素材.com)
A site providing free, high-quality 2D CAD materials for practical use in architectural design, construction drawings, perspective rendering, and construction planning.
👇 CAD-Material.com | Free Download Site for High-Quality CAD Data
https://cad-freed-rawingsamples.com/
ℹ️ Usage in NijiCAD Open the file and copy-paste the necessary materials. Note that in NijiCAD, Dynamic Blocks and Multileaders are converted to static blocks. If you want to edit the text or shapes, you will need to explode them first.
🌐 Sekouzu.com (施工図ドットコム)
A blog and information site centered on construction drawing expertise and explanations. It also offers CAD data downloads useful for drafting and construction.
👇 Sekouzu.com
ℹ️ Usage in NijiCAD Suitable for use as reference material for learning drawing details and drafting techniques.
🌐 CAD-DATA.com
A CAD data sharing platform where users can share and download diverse CAD data created and posted by other users. Account registration is required.
👇 CAD-DATA.com | CAD Data Sharing Site
ℹ️ Usage in NijiCAD As it is a user-contributed platform, DXF data quality varies. It is impossible to verify all data, and some shapes or drawings may be missing or fail to load.
3. DWG Format
Offers support equivalent to reading the DXF format.
- Supports reading only.
4. JWW Format
The standard file save format for Jw_cad.
- Supports input only.
- Output is not supported (currently under consideration).
- Limited to basic shapes.
- Layers are determined based on naming conventions.
- Layers without shapes are discarded.
- Verification is performed using JWW files included in the installation folder.
- Uses a proprietary implementation.
Supported Shapes
| JWW Data | NijiCAD Shape | Remarks |
|---|---|---|
| Arc | CIRCLE, ARC, ELLIPSE | - |
| Line segment | LINE | - |
| Text | TEXT | - |
Layer Loading Rules
- Prefixes with "Jw_".
- Combines group numbers (0–15) and layer numbers (0–15).
- Non-printing settings append "_NoPlot".
- ByLayer color is determined by the most frequent color used by the shapes within that layer.
- Layers without shapes are discarded.
Example: Jw_0-0 Example: Jw_0-1_NoPlot
5. Update History
| Date | Content |
|---|---|
| 2026/09/21 | Added support for reading/writing DXF and reading DWG. |
| 2025/12/12 | Changes due to the proprietary implementation of DXF output (2025/10/28). |
| 2025/08/21 | Hatch DXF output: SOLID omitted, patterns exploded (to avoid read errors in some CAD software). |
| 2025/08/20 | New |