95 lines
1.7 KiB
Rust
95 lines
1.7 KiB
Rust
//! QuickDraw PICT format run length encoded data.
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use crate::{bin::*, err::*};
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/// Read run-length encoded data.
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pub fn read<T>(b: &[u8], pitch: usize) -> ResultS<(Vec<T>, usize)>
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where T: ReadRleData
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{
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let mut p = 0;
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let mut o = Vec::with_capacity(pitch);
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let sz = if pitch > 250 {
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(usize::from(u16b(b)) + 2, p += 2).0
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} else {
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(usize::from(b[0]) + 1, p += 1).0
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};
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while p < sz {
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let szf = b[p];
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let cmp = szf & 0x80 != 0;
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let len = usize::from(if cmp {!szf + 2} else {szf + 1});
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p += 1;
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o.reserve(len);
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T::read_rle_data(b, &mut p, cmp, len, &mut o);
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}
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if o.len() == pitch {
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Ok((o, p))
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} else {
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Err(err_msg("incorrect size for compressed scanline"))
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}
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}
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pub trait ReadRleData: Sized
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{
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// Read a sequence of packed RLE data.
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fn read_rle_data(b: &[u8],
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p: &mut usize,
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cmp: bool,
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len: usize,
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out: &mut Vec<Self>);
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}
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impl ReadRleData for u16
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{
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fn read_rle_data(b: &[u8],
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p: &mut usize,
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cmp: bool,
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len: usize,
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out: &mut Vec<Self>)
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{
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if cmp {
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let d = u16b(&b[*p..*p + 2]);
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*p += 2;
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for _ in 0..len {
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out.push(d);
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}
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} else {
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for _ in 0..len {
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let d = u16b(&b[*p..*p + 2]);
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*p += 2;
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out.push(d);
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}
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}
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}
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}
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impl ReadRleData for u8
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{
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fn read_rle_data(b: &[u8],
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p: &mut usize,
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cmp: bool,
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len: usize,
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out: &mut Vec<Self>)
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{
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if cmp {
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let d = b[*p];
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*p += 1;
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for _ in 0..len {
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out.push(d);
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}
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} else {
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for _ in 0..len {
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let d = b[*p];
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*p += 1;
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out.push(d);
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}
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}
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}
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}
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// EOF
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