🗜️ Support zstd compression algorithm

pyproject.toml

@@ -3,7 +3,12 @@ name = "fig2sketch"
 readme = "README.md"
 requires-python = ">=3.10"
 dynamic = ["version"]
-dependencies = ["Pillow==10.3.0", "fonttools==4.43.0", "appdirs==1.4.4"]
+dependencies = [
+  "Pillow==10.3.0",
+  "fonttools==4.43.0",
+  "appdirs==1.4.4",
+  "zstd==1.5.5.1",
+]
 
 [project.scripts]
 fig2sketch = "fig2sketch:main"

src/figformat/decodefig.py

@@ -21,14 +21,14 @@ def decode(path):
     if header == b"PK":
         fig_zip = zipfile.ZipFile(reader)
 
-    try:
-        import fig_kiwi
+    # try:
+    #     import fig_kiwi
 
-        logging.debug("Using fast (rust) kiwi reader")
-        return fig_kiwi.decode(path, type_converters), fig_zip
+    #     logging.debug("Using fast (rust) kiwi reader")
+    #     return fig_kiwi.decode(path, type_converters), fig_zip
 
-    except ImportError:
-        logging.debug("Falling back to slow (python) kiwi reader")
+    # except ImportError:
+    #     logging.debug("Falling back to slow (python) kiwi reader")
 
     if fig_zip:
         reader = fig_zip.open("canvas.fig")

src/figformat/kiwi.py

@@ -2,6 +2,7 @@
 import ctypes
 from collections import OrderedDict
 import zlib
+import zstd
 import struct
 import io
 import logging
@@ -146,6 +147,10 @@ def decode(reader, type_converters):
     MIN_SUPPORTED_VERSIONS = 15
     MAX_SUPPORTED_VERSION = 25
 
+    # `zstd` data will start with a magic number frame
+    # the value of which is `0xfd2fb528`
+    ZSTD_MAGIC_NUMBER = b"\x28\xb5\x2f\xfd"
+
     header = reader.read(12)
     fig_version = struct.unpack("<I", header[8:12])[0]
     if fig_version < MIN_SUPPORTED_VERSIONS:
@@ -159,10 +164,29 @@ def decode(reader, type_converters):
 
     segment_header = reader.read(4)
     size = struct.unpack("<I", segment_header)[0]
-    data = io.BytesIO(zlib.decompress(reader.read(size), wbits=-15))
-    schema = KiwiSchema(data)
+    compressedSchema = reader.read(size)
+
+    schemaData = b""
+    # Check to see if the first four bytes are the zstd magic number.
+    # If so we need to use zstd to decompress, not zlib
+    if compressedSchema.startswith(ZSTD_MAGIC_NUMBER):
+        schemaData = io.BytesIO(zstd.decompress(compressedSchema))
+    else:
+        schemaData = io.BytesIO(zlib.decompress(compressedSchema, wbits=-15))
+
+    schema = KiwiSchema(schemaData)
 
     segment_header = reader.read(4)
     size = struct.unpack("<I", segment_header)[0]
-    data = io.BytesIO(zlib.decompress(reader.read(size), wbits=-15))
+    compressedData = reader.read(size)
+
+    data = b""
+    # Check to see if the first four bytes are the zstd magic number.
+    # If so we need to use zstd to decompress, not zlib
+
+    if compressedData.startswith(ZSTD_MAGIC_NUMBER):
+        data = io.BytesIO(zstd.decompress(compressedData))
+    else:
+        data = io.BytesIO(zlib.decompress(compressedData, wbits=-15))
+
     return KiwiDecoder(schema, type_converters).decode(data, "Message")