Compressed property

Controls whether streams in the output PDF are FlateDecode-compressed when SaveAs / Save is called. The post-save compression engine scans the serialised PDF, replaces any uncompressed streams with their zlib-deflated equivalents, and rebuilds the xref table. Already-compressed streams pass through unchanged.

Compressed controls whether the next SaveAs (and family) call applies post-write stream compression. When True — the default — PDFiumVCL serialises the document through PDFium, then runs a pass that replaces any uncompressed content / metadata streams with FlateDecode-compressed equivalents and rewrites the cross-reference table to reflect the new offsets.

When False, output streams are written as-is. The resulting file is typically 2-10× larger but is human-readable when opened in a text editor, which is useful for debugging content streams, comparing two PDF revisions with diff, or feeding the output into a PDF-syntax-aware tool that prefers uncompressed input.

Setting Compressed changes only the behaviour of the next save; the in-memory document is unaffected. A document that was loaded compressed and saved with Compressed := False will decompress on output; a document loaded uncompressed and saved with Compressed := True will compress on output. Round-tripping a fully-compressed document with Compressed := True yields a near-identical file size — the engine recognises pre-compressed streams and does not re-deflate them.

• The setting affects every kind of PDF stream the writer emits: content streams, fonts, embedded files, and XMP metadata.
• Encryption (see Password) and compression are orthogonal — both apply if both are enabled.
• Compression adds a small CPU cost on save but no per-page cost on load, since PDFium decompresses lazily.
• For maximum compatibility with legacy viewers leave Compressed at its default; uncompressed output is allowed by the PDF spec but exercised less frequently.

SaveAs, Save, Active, Password