105 lines
3 KiB
Rust
105 lines
3 KiB
Rust
use std::convert::TryInto;
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use bytemuck::cast_slice;
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use crate::consts::{QOI_HEADER_SIZE, QOI_MAGIC, QOI_PIXELS_MAX};
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use crate::encoded_size_limit;
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use crate::error::{Error, Result};
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use crate::types::{Channels, ColorSpace};
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use crate::utils::unlikely;
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#[derive(Copy, Clone, Debug, PartialEq, Eq)]
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pub struct Header {
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pub width: u32,
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pub height: u32,
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pub channels: Channels,
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pub colorspace: ColorSpace,
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}
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impl Default for Header {
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#[inline]
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fn default() -> Self {
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Self {
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width: 1,
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height: 1,
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channels: Channels::default(),
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colorspace: ColorSpace::default(),
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}
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}
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}
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impl Header {
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#[inline]
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pub const fn try_new(
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width: u32, height: u32, channels: Channels, colorspace: ColorSpace,
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) -> Result<Self> {
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if unlikely(height == 0 || width == 0) {
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return Err(Error::EmptyImage { width, height });
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} else if unlikely((width as usize).saturating_mul(height as usize) > QOI_PIXELS_MAX) {
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return Err(Error::ImageTooLarge { width, height });
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}
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Ok(Self { width, height, channels, colorspace })
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}
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#[inline]
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pub const fn with_channels(mut self, channels: Channels) -> Self {
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self.channels = channels;
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self
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}
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#[inline]
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pub const fn with_colorspace(mut self, colorspace: ColorSpace) -> Self {
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self.colorspace = colorspace;
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self
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}
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#[inline]
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pub const fn encoded_size() -> usize {
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QOI_HEADER_SIZE
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}
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#[inline]
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pub(crate) fn encode(&self) -> [u8; QOI_HEADER_SIZE] {
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let mut out = [0; QOI_HEADER_SIZE];
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out[..4].copy_from_slice(&QOI_MAGIC.to_be_bytes());
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out[4..8].copy_from_slice(&self.width.to_be_bytes());
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out[8..12].copy_from_slice(&self.height.to_be_bytes());
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out[12] = self.channels.into();
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out[13] = self.colorspace.into();
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out
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}
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#[inline]
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pub(crate) fn decode(data: impl AsRef<[u8]>) -> Result<Self> {
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let data = data.as_ref();
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if unlikely(data.len() < QOI_HEADER_SIZE) {
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return Err(Error::InputBufferTooSmall { size: data.len(), required: QOI_HEADER_SIZE });
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}
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let v = cast_slice::<_, [u8; 4]>(&data[..12]);
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let magic = u32::from_be_bytes(v[0]);
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let width = u32::from_be_bytes(v[1]);
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let height = u32::from_be_bytes(v[2]);
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let channels = data[12].try_into()?;
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let colorspace = data[13].try_into()?;
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if unlikely(magic != QOI_MAGIC) {
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return Err(Error::InvalidMagic { magic });
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}
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Self::try_new(width, height, channels, colorspace)
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}
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#[inline]
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pub const fn n_pixels(&self) -> usize {
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(self.width as usize).saturating_mul(self.height as usize)
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}
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#[inline]
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pub const fn n_bytes(&self) -> usize {
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self.n_pixels() * self.channels.as_u8() as usize
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}
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#[inline]
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pub fn encoded_size_limit(&self) -> usize {
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encoded_size_limit(self.width, self.height, self.channels)
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}
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}
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