| //! Chunk types and functions |
| #![allow(dead_code)] |
| #![allow(non_upper_case_globals)] |
| |
| pub type ChunkType = [u8; 4]; |
| |
| // -- Critical chunks -- |
| |
| /// Image header |
| pub const IHDR: ChunkType = [b'I', b'H', b'D', b'R']; |
| /// Palette |
| pub const PLTE: ChunkType = [b'P', b'L', b'T', b'E']; |
| /// Image data |
| pub const IDAT: ChunkType = [b'I', b'D', b'A', b'T']; |
| /// Image trailer |
| pub const IEND: ChunkType = [b'I', b'E', b'N', b'D']; |
| |
| // -- Ancillary chunks -- |
| |
| /// Transparency |
| pub const tRNS: ChunkType = [b't', b'R', b'N', b'S']; |
| /// Background colour |
| pub const bKGD: ChunkType = [b'b', b'K', b'G', b'D']; |
| /// Image last-modification time |
| pub const tIME: ChunkType = [b't', b'I', b'M', b'E']; |
| /// Physical pixel dimensions |
| pub const pHYs: ChunkType = [b'p', b'H', b'Y', b's']; |
| |
| // -- Extension chunks -- |
| |
| /// Animation control |
| pub const acTL: ChunkType = [b'a', b'c', b'T', b'L']; |
| /// Frame control |
| pub const fcTL: ChunkType = [b'f', b'c', b'T', b'L']; |
| /// Frame data |
| pub const fdAT: ChunkType = [b'f', b'd', b'A', b'T']; |
| |
| // -- Chunk type determination -- |
| |
| /// Returns true if the chunk is critical. |
| pub fn is_critical(type_: ChunkType) -> bool { |
| type_[0] & 32 == 0 |
| } |
| |
| /// Returns true if the chunk is private. |
| pub fn is_private(type_: ChunkType) -> bool { |
| type_[1] & 32 != 0 |
| } |
| |
| /// Checks whether the reserved bit of the chunk name is set. |
| /// If it is set the chunk name is invalid. |
| pub fn reserved_set(type_: ChunkType) -> bool { |
| type_[2] & 32 != 0 |
| } |
| |
| /// Returns true if the chunk is safe to copy if unknown. |
| pub fn safe_to_copy(type_: ChunkType) -> bool { |
| type_[3] & 32 != 0 |
| } |
