coreldraw_cdr.ksy

CDR (CorelDRAW drawing) format specification for Kaitai Struct

What it is

Formal specifications for the CorelDRAW .cdr format in Kaitai Struct YAML (.ksy), a declarative language for describing binary formats.

If you are interested in...

• what graphic objects (paths, polygons, rectangles, ellipses, embedded images) the CDR document contains,
• how do they look like (i.e. the geometry data associated with them: path points, rectangle side lengths and so on),
• what fill and outline styles the objects use (solid colors, gradients),
• what transformation matrix is applied on each object,

... and more, Kaitai Struct can make all this data accessible to you given the .ksy specifications from this repository.

How to use

Use the bin/cdr-unpk Bash script to preprocess the .cdr file so that you can read all CDR versions (especially the new ones) without having to worry about what version of the CDR format the .cdr file in front of you is using. The usage is the following:

bin/cdr-unpk example.cdr

It creates example.cdr.unpk in the same directory where example.cdr is. The example.cdr.unpk file needs to be interpreted by cdr_unpk.ksy (which imports coreldraw_cdr.ksy and file_streams.ksy under the hood).

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To understand why applying the coreldraw_cdr.ksy Kaitai Struct specification to real-world .cdr files is complicated, you need to have a basic overview of CDR format versions:

• X3 (13.0) and older: directly the RIFF-based chunk structure that coreldraw_cdr.ksy understands;
• X4 (14.0) and X5 (15.0): a ZIP archive, the coreldraw_cdr.ksy spec can only recognize the content/riffData.cdr file inside it;
• X6 (16.0) or later: also a ZIP archive, but the entrypoint is content/root.dat which needs to read external chunk payloads from content/data/*.dat files.

The need for accessing external streams in CDR X6+ files was a problem, because to be able to use visualizers available for Kaitai Struct (e.g. ksv, Web IDE), the entire parsed byte stream needs to be contained in a single file and the top-level type in the main .ksy spec must not have any parameters. That's why the bin/cdr-unpk script was created - it extracts the necessary streams from the given .cdr file and dumps them into a .unpk file in a custom auxiliary format described in cdr_unpk.ksy.

Standalone use of coreldraw_cdr.ksy from your application

There is a branch unpack-zip-yourself available when you want to use the Kaitai Struct parser generated from coreldraw_cdr.ksy in your application. It makes the integration easier, because it provides you a top-level parameter where you pass a list of KaitaiStream objects for each external data stream in X6+ files (in the order specified in content/dataFileList.dat file of X6+ .cdr ZIP archives):

params:
  - id: streams
    type: io[]

For pre-X6 .cdr files, just pass an empty list.

You should be able to understand how to find the data streams in the ZIP archive by looking into bin/cdr-unpk, or you can look into libcdr.

Manual standalone use of coreldraw_cdr.ksy (no support for external streams)

By default, the coreldraw_cdr.ksy spec is expected to be imported from cdr_unpk.ksy and not used by itself. However, if you don't want to preprocess .cdr files by bin/cdr-unpk, you can manually edit coreldraw_cdr.ksy to disable support for external streams (comment out sections /meta/imports, /params and /types/chunk_wrapper/instances/body_external).

Such a coreldraw_cdr.ksy specification can be used directly on the .cdr file for pre-X4 files (will work great), or on content/riffData.cdr if it's inside the ZIP archive of CDR X4/X5 files. For X6 and later it's technically possible to use it on content/root.dat itself too, but you won't get too deep into the file because it uses external streams for most chunks (so it probably won't be very useful).