class

Crowbar::Rules::PNGRule

Inherits Crowbar::Rule < Reference < Object

Structure-preserving rule for Portable Network Graphics (PNG) images. Preserves the 8-byte PNG file signature and valid chunk framing (IHDR, IDAT, IEND, and auxiliary chunks), while mutating header dimensions, bit depths, color types, scanline payloads, or chunk tags, and automatically recalculating 4-byte chunk lengths and CRC32 checksums.

Constants

PNG_SIGNATURE = Bytes[137, 80, 78, 71, 13, 10, 26, 10]

Instance methods

apply(context : Context, buffer : Buffer) : Bool

Applies a structure-preserving transformation to the buffer

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match?(buffer : Buffer) : Bool

Checks whether the buffer matches the format handled by this rule

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parse_chunks(buffer : Buffer) : Array(Chunk)

Parses all valid PNG chunks from the buffer

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Nested types