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use crate::sections::PsdCursor;
use thiserror::Error;
/// Bytes representing the string "8BPS".
pub const EXPECTED_PSD_SIGNATURE: [u8; 4] = [56, 66, 80, 83];
/// Bytes representing the number 1
const EXPECTED_VERSION: [u8; 2] = [0, 1];
/// Bytes representing the Reserved section of the header
const EXPECTED_RESERVED: [u8; 6] = [0; 6];
/// The FileHeaderSection comes from the first 26 bytes in the PSD file.
///
/// We don't store information that isn't useful.
///
/// For example, after validating the PSD signature we won't store it since it is always the
/// same value.
///
/// # [Adobe Docs](https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/)
///
/// The file header contains the basic properties of the image.
///
///
/// | Length | Description |
/// |--------|------------------------------------------------------------------------------------------------------------------------------------------------------|
/// | 4 | Signature: always equal to '8BPS' . Do not try to read the file if the signature does not match this value. |
/// | 2 | Version: always equal to 1. Do not try to read the file if the version does not match this value.<br> (**PSB** version is 2.) |
/// | 6 | Reserved: must be zero. |
/// | 2 | The number of channels in the image, including any alpha channels. Supported range is 1 to 56. |
/// | 4 | The height of the image in pixels. Supported range is 1 to 30,000.<br> (**PSB** max of 300,000.) |
/// | 4 | The width of the image in pixels. Supported range is 1 to 30,000.<br> (**PSB** max of 300,000) |
/// | 2 | Depth: the number of bits per channel. Supported values are 1, 8, 16 and 32. |
/// | 2 | The color mode of the file. Supported values are: Bitmap = 0; Grayscale = 1; Indexed = 2; RGB = 3; CMYK = 4; Multichannel = 7; Duotone = 8; Lab = 9. |
#[derive(Debug)]
pub struct FileHeaderSection {
pub(in crate) version: PsdVersion,
pub(in crate) channel_count: ChannelCount,
pub(in crate) width: PsdWidth,
pub(in crate) height: PsdHeight,
pub(in crate) depth: PsdDepth,
pub(in crate) color_mode: ColorMode,
}
/// Represents an malformed file section header
#[derive(Debug, PartialEq, Error)]
pub enum FileHeaderSectionError {
#[error("A file section header is comprised of 26 bytes, you provided {length} bytes.")]
IncorrectLength { length: usize },
#[error(
r#"The first four bytes (indices 0-3) of a PSD must always equal [56, 66, 80, 83],
which in string form is '8BPS'."#
)]
InvalidSignature {},
#[error(
r#"Bytes 5 and 6 (indices 4-5) must always be [0, 1], Representing a PSD version of 1."#
)]
InvalidVersion {},
#[error(r#"Bytes 7-12 (indices 6-11) must be zeroes"#)]
InvalidReserved {},
#[error("Invalid channel count: {channel_count}. Must be 1 <= channel count <= 56")]
ChannelCountOutOfRange { channel_count: u8 },
#[error("Invalid width: {width}. Must be 1 <= width <= 30,000")]
WidthOutOfRange { width: u32 },
#[error("Invalid height: {height}. Must be 1 <= height <= 30,000")]
HeightOutOfRange { height: u32 },
#[error("Depth {depth} is invalid. Must be 1, 8, 16 or 32")]
InvalidDepth { depth: u8 },
#[error("Invalid color mode {color_mode}. Must be 0, 1, 2, 3, 4, 7, 8 or 9")]
InvalidColorMode { color_mode: u8 },
}
impl FileHeaderSection {
/// Create a FileSectionHeader from the first 26 bytes of a PSD
///
/// TODO: Accept a ColorModeSection along with the bytes so that we can add
/// any ColorModeSection data to the ColorMode if necessary. Rename this method
/// to "new" in the process.
pub fn from_bytes(bytes: &[u8]) -> Result<FileHeaderSection, FileHeaderSectionError> {
let mut cursor = PsdCursor::new(bytes);
// File header section must be 26 bytes long
if bytes.len() != 26 {
return Err(FileHeaderSectionError::IncorrectLength {
length: bytes.len(),
}
);
}
// First four bytes must be '8BPS'
let signature = cursor.read_4();
if signature != EXPECTED_PSD_SIGNATURE {
return Err(FileHeaderSectionError::InvalidSignature {});
}
// The next 2 bytes represent the version
let version = cursor.read_2();
if version != EXPECTED_VERSION {
return Err(FileHeaderSectionError::InvalidVersion {});
}
// The next 6 bytes are reserved and should always be 0
let reserved = cursor.read_6();
if reserved != EXPECTED_RESERVED {
return Err(FileHeaderSectionError::InvalidReserved {});
}
// The next 2 bytes represent the channel count
let channel_count = cursor.read_u16() as u8;
let channel_count = ChannelCount::new(channel_count)
.ok_or(FileHeaderSectionError::ChannelCountOutOfRange { channel_count })?;
// 4 bytes for the height
let height = cursor.read_u32();
let height =
PsdHeight::new(height).ok_or(FileHeaderSectionError::HeightOutOfRange { height })?;
// 4 bytes for the width
let width = cursor.read_u32();
let width =
PsdWidth::new(width).ok_or(FileHeaderSectionError::WidthOutOfRange { width })?;
// 2 bytes for depth
let depth = cursor.read_2()[1];
let depth = PsdDepth::new(depth).ok_or(FileHeaderSectionError::InvalidDepth { depth })?;
// 2 bytes for color mode
let color_mode = cursor.read_2()[1];
let color_mode = ColorMode::new(color_mode)
.ok_or(FileHeaderSectionError::InvalidColorMode { color_mode })?;
let file_header_section = FileHeaderSection {
version: PsdVersion::One,
channel_count,
width,
height,
depth,
color_mode,
};
Ok(file_header_section)
}
}
/// # [Adobe Docs](https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/)
///
/// Version: always equal to 1. Do not try to read the file if the version does not match this value. (**PSB** version is 2.)
///
/// via: https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/
#[derive(Debug)]
pub enum PsdVersion {
/// Regular PSD (Not a PSB)
One,
}
/// # [Adobe Docs](https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/)
///
/// The number of channels in the image, including any alpha channels. Supported range is 1 to 56.
///
/// via: https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/
#[derive(Debug)]
pub struct ChannelCount(u8);
impl ChannelCount {
/// Create a new ChannelCount
pub fn new(channel_count: u8) -> Option<ChannelCount> {
if channel_count < 1 || channel_count > 56 {
return None;
}
Some(ChannelCount(channel_count))
}
/// Return the channel count
pub fn count(&self) -> u8 {
self.0
}
}
/// # [Adobe Docs](https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/)
///
/// The height of the image in pixels. Supported range is 1 to 30,000.
/// (**PSB** max of 300,000.)
///
/// via: https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/
#[derive(Debug)]
pub struct PsdHeight(pub(in crate) u32);
impl PsdHeight {
/// Create a new PsdHeight
pub fn new(height: u32) -> Option<PsdHeight> {
if height < 1 || height > 30000 {
return None;
}
Some(PsdHeight(height))
}
}
/// # [Adobe Docs](https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/)
///
/// The width of the image in pixels. Supported range is 1 to 30,000.
/// (*PSB** max of 300,000)
///
/// via: https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/
#[derive(Debug, Clone, Copy)]
pub struct PsdWidth(pub(in crate) u32);
impl PsdWidth {
/// Create a new PsdWidth
pub fn new(width: u32) -> Option<PsdWidth> {
if width < 1 || width > 30000 {
return None;
}
Some(PsdWidth(width))
}
}
/// # [Adobe Docs](https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/)
///
/// Depth: the number of bits per channel. Supported values are 1, 8, 16 and 32.
///
/// via: https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
#[allow(missing_docs)]
pub enum PsdDepth {
One = 1,
Eight = 8,
Sixteen = 16,
ThirtyTwo = 32,
}
impl PsdDepth {
/// Create a new PsdDepth
pub fn new(depth: u8) -> Option<PsdDepth> {
match depth {
1 => Some(PsdDepth::One),
8 => Some(PsdDepth::Eight),
16 => Some(PsdDepth::Sixteen),
32 => Some(PsdDepth::ThirtyTwo),
_ => None,
}
}
}
/// # [Adobe Docs](https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/)
///
/// The color mode of the file. Supported values are: Bitmap = 0; Grayscale = 1; Indexed = 2; RGB = 3; CMYK = 4; Multichannel = 7; Duotone = 8; Lab = 9.
///
/// via: https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
#[allow(missing_docs)]
pub enum ColorMode {
Bitmap = 0,
Grayscale = 1,
// TODO: Indexed(Vec<u8>)
// Where the vector is the data from the color mode data section
Indexed = 2,
Rgb = 3,
Cmyk = 4,
Multichannel = 7,
// TODO: DuoTone(Vec<u8>)
// Where the vector is the data from the color mode data section.
Duotone = 8,
Lab = 9,
}
impl ColorMode {
/// Create a new ColorMode
pub fn new(color_mode: u8) -> Option<ColorMode> {
match color_mode {
0 => Some(ColorMode::Bitmap),
1 => Some(ColorMode::Grayscale),
2 => Some(ColorMode::Indexed),
3 => Some(ColorMode::Rgb),
4 => Some(ColorMode::Cmyk),
7 => Some(ColorMode::Multichannel),
8 => Some(ColorMode::Duotone),
9 => Some(ColorMode::Lab),
_ => None,
}
}
}
#[cfg(test)]
mod tests {
use super::*;
// Valid:
// >= 1, <= 56
#[test]
fn valid_channel_count() {
for channel_count in 1..=56 {
assert!(ChannelCount::new(channel_count).is_some());
}
}
// Invalid:
// < 1, > 56
#[test]
fn invalid_channel_count() {
assert!(ChannelCount::new(0).is_none());
assert!(ChannelCount::new(57).is_none());
}
// We're passing in 25 bytes even though we're supposed to pass in 26 bytes
#[test]
fn incorrect_file_header_section_length() {
let too_short = [0; 25];
match error_from_bytes(&too_short) {
FileHeaderSectionError::IncorrectLength { length } => assert_eq!(length, 25),
_ => panic!("Should have returned incorrect length error"),
};
}
#[test]
fn first_four_bytes_incorrect() {
let bytes = make_bytes();
let error = error_from_bytes(&bytes);
match error {
FileHeaderSectionError::InvalidSignature {} => {}
_ => panic!("Should have returned invalid signature error"),
};
}
#[test]
fn version_incorrect() {
let mut bytes = make_bytes();
bytes[0..4].copy_from_slice(&EXPECTED_PSD_SIGNATURE);
match error_from_bytes(&bytes) {
FileHeaderSectionError::InvalidVersion {} => {}
_ => panic!("Should have returned invalid version error"),
};
}
#[test]
fn invalid_reserved_section() {
let mut bytes = make_bytes();
bytes[0..4].copy_from_slice(&EXPECTED_PSD_SIGNATURE);
bytes[4..6].copy_from_slice(&EXPECTED_VERSION);
match error_from_bytes(&bytes) {
FileHeaderSectionError::InvalidReserved {} => {}
_ => panic!("Should have returned reserved section error"),
};
}
fn error_from_bytes(bytes: &[u8]) -> FileHeaderSectionError {
FileHeaderSection::from_bytes(&bytes).expect_err("error")
}
// [0, 1, 2, ..., 25]
fn make_bytes() -> [u8; 26] {
let mut bytes = [0; 26];
for i in 0..26 {
bytes[i] = i as u8;
}
bytes
}
}