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GZipDecompressString

Function GZipDecompressString( const Data : TBytes) : string

Example​

procedure ScriptEvent(var Value: variant);
var
  Compressed: TBytes;
begin
  Compressed := GZipCompressString('Fictional order 1001');
  Value := GZipDecompressString(Compressed);
end;

Usage​

GZipDecompressString expands gzip bytes and decodes the result as a Velox UTF-16LE Unicode string.

Parameters

NameTypeDescription
DataTBytes, constComplete gzip member whose expanded bytes are expected to be Velox UTF-16LE text.

Returns

The decoded Velox string. Empty input produces an empty byte result in GZipDecompress and therefore an empty string.

Behaviour

Data created by GZipCompressString is intended to round-trip. Gzip data created by common tools usually contains the original file bytes, often UTF-8 or an arbitrary binary format; passing that data here can return incorrect text even when decompression succeeds.

Errors

All gzip, allocation and Unicode-decoding failures propagate. No partial string is returned.

Usage notes

For arbitrary gzip payloads call GZipDecompress and interpret the returned bytes according to the integration's explicit wire format. Do not infer text encoding from the .gz function.

Additional Technical Info​

GZipDecompressString expands gzip bytes with Velox's custom decompressor and decodes the expanded payload through Delphi TEncoding.Unicode. Use it only for gzip data whose payload is UTF-16 little-endian text without a byte-order mark, such as data created by GZipCompressString.

The example round-trips fictional text in memory. It is source-reviewed and is not executed by the documentation workflow.

Implementation

The directly registered function copies the parameter to a local byte array, calls vxCompression.GZipDecompress, then calls TEncoding.Unicode.GetString on the expanded bytes. There is no BOM detection, UTF-8 fallback, content-type check or schema validation.

Edge cases and quirks

  • The function inherits GZipDecompress's no-progress defect: truncated input can cause repeated buffer growth rather than a prompt decompression exception.
  • Expanded size is unlimited and the complete expanded byte array coexists with the resulting managed string.
  • Decoding is explicitly UTF-16LE. No byte-order mark is required or removed as an encoding negotiation mechanism.
  • Binary payloads, UTF-8 payloads and odd or malformed UTF-16 input are outside the intended contract; decoder behaviour must not be used as binary validation.

Side effects

None outside memory allocation.

Performance and concurrency

The compressed bytes, expanded bytes and decoded string can coexist in memory. The call is synchronous and uses local state.

Related entries

External references

Created 2026-07-15