| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/git/checkouts/incubator-teaclave-crates-c8106113f74feefc/ede1f68/image/./src/utils/mod.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>mod.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../image/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../image/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">//! Utilities |
| |
| </span><span class="kw">use </span>num_iter::range_step; |
| <span class="kw">use </span>std::iter::repeat; |
| |
| <span class="attribute">#[inline(always)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>expand_packed<F>(buf: <span class="kw-2">&mut </span>[u8], channels: usize, bit_depth: u8, <span class="kw-2">mut </span>func: F) |
| <span class="kw">where |
| </span>F: FnMut(u8, <span class="kw-2">&mut </span>[u8]), |
| { |
| <span class="kw">let </span>pixels = buf.len() / channels * bit_depth <span class="kw">as </span>usize; |
| <span class="kw">let </span>extra = pixels % <span class="number">8</span>; |
| <span class="kw">let </span>entries = pixels / <span class="number">8 </span>+ <span class="kw">match </span>extra { |
| <span class="number">0 </span>=> <span class="number">0</span>, |
| <span class="kw">_ </span>=> <span class="number">1</span>, |
| }; |
| <span class="kw">let </span>mask = ((<span class="number">1u16 </span><< bit_depth) - <span class="number">1</span>) <span class="kw">as </span>u8; |
| <span class="kw">let </span>i = (<span class="number">0</span>..entries) |
| .rev() <span class="comment">// Reverse iterator |
| </span>.flat_map(|idx| |
| <span class="comment">// This has to be reversed to |
| </span>range_step(<span class="number">0</span>, <span class="number">8</span>, bit_depth) |
| .zip(repeat(idx)) |
| ) |
| .skip(extra); |
| <span class="kw">let </span>channels = channels <span class="kw">as </span>isize; |
| <span class="kw">let </span>j = range_step(buf.len() <span class="kw">as </span>isize - channels, -channels, -channels); |
| <span class="comment">//let j = range_step(0, buf.len(), channels).rev(); // ideal solution; |
| </span><span class="kw">for </span>((shift, i), j) <span class="kw">in </span>i.zip(j) { |
| <span class="kw">let </span>pixel = (buf[i] & (mask << shift)) >> shift; |
| func(pixel, <span class="kw-2">&mut </span>buf[j <span class="kw">as </span>usize..(j + channels) <span class="kw">as </span>usize]) |
| } |
| } |
| |
| <span class="doccomment">/// Expand a buffer of packed 1, 2, or 4 bits integers into u8's. Assumes that |
| /// every `row_size` entries there are padding bits up to the next byte boundry. |
| </span><span class="attribute">#[allow(dead_code)] |
| </span><span class="comment">// When no image formats that use it are enabled |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>expand_bits(bit_depth: u8, row_size: u32, buf: <span class="kw-2">&</span>[u8]) -> Vec<u8> { |
| <span class="comment">// Note: this conversion assumes that the scanlines begin on byte boundaries |
| </span><span class="kw">let </span>mask = (<span class="number">1u8 </span><< bit_depth <span class="kw">as </span>usize) - <span class="number">1</span>; |
| <span class="kw">let </span>scaling_factor = <span class="number">255 </span>/ ((<span class="number">1 </span><< bit_depth <span class="kw">as </span>usize) - <span class="number">1</span>); |
| <span class="kw">let </span>bit_width = row_size * u32::from(bit_depth); |
| <span class="kw">let </span>skip = <span class="kw">if </span>bit_width % <span class="number">8 </span>== <span class="number">0 </span>{ |
| <span class="number">0 |
| </span>} <span class="kw">else </span>{ |
| (<span class="number">8 </span>- bit_width % <span class="number">8</span>) / u32::from(bit_depth) |
| }; |
| <span class="kw">let </span>row_len = row_size + skip; |
| <span class="kw">let </span><span class="kw-2">mut </span>p = Vec::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>i = <span class="number">0</span>; |
| <span class="kw">for </span>v <span class="kw">in </span>buf { |
| <span class="kw">for </span>shift <span class="kw">in </span>num_iter::range_step_inclusive(<span class="number">8i8</span>-(bit_depth <span class="kw">as </span>i8), <span class="number">0</span>, -(bit_depth <span class="kw">as </span>i8)) { |
| <span class="comment">// skip the pixels that can be neglected because scanlines should |
| // start at byte boundaries |
| </span><span class="kw">if </span>i % (row_len <span class="kw">as </span>usize) < (row_size <span class="kw">as </span>usize) { |
| <span class="kw">let </span>pixel = (v & mask << shift <span class="kw">as </span>usize) >> shift <span class="kw">as </span>usize; |
| p.push(pixel * scaling_factor); |
| } |
| i += <span class="number">1</span>; |
| } |
| } |
| p |
| } |
| |
| <span class="doccomment">/// Checks if the provided dimensions would cause an overflow. |
| </span><span class="attribute">#[allow(dead_code)] |
| </span><span class="comment">// When no image formats that use it are enabled |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>check_dimension_overflow(width: u32, height: u32, bytes_per_pixel: u8) -> bool { |
| width <span class="kw">as </span>u64 * height <span class="kw">as </span>u64 > std::u64::MAX / bytes_per_pixel <span class="kw">as </span>u64 |
| } |
| |
| <span class="attribute">#[allow(dead_code)] |
| </span><span class="comment">// When no image formats that use it are enabled |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>vec_u16_into_u8(vec: Vec<u16>) -> Vec<u8> { |
| <span class="comment">// Do this way until we find a way to not alloc/dealloc but get llvm to realloc instead. |
| </span>vec_copy_to_u8(<span class="kw-2">&</span>vec) |
| } |
| |
| <span class="attribute">#[allow(dead_code)] |
| </span><span class="comment">// When no image formats that use it are enabled |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>vec_u32_into_u8(vec: Vec<u32>) -> Vec<u8> { |
| <span class="comment">// Do this way until we find a way to not alloc/dealloc but get llvm to realloc instead. |
| </span>vec_copy_to_u8(<span class="kw-2">&</span>vec) |
| } |
| |
| <span class="attribute">#[allow(dead_code)] |
| </span><span class="comment">// When no image formats that use it are enabled |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>vec_u64_into_u8(vec: Vec<u64>) -> Vec<u8> { |
| <span class="comment">// Do this way until we find a way to not alloc/dealloc but get llvm to realloc instead. |
| </span>vec_copy_to_u8(<span class="kw-2">&</span>vec) |
| } |
| |
| <span class="attribute">#[allow(dead_code)] |
| </span><span class="comment">// When no image formats that use it are enabled |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>vec_copy_to_u8<T>(vec: <span class="kw-2">&</span>[T]) -> Vec<u8> |
| <span class="kw">where |
| </span>T: bytemuck::Pod, |
| { |
| bytemuck::cast_slice(vec).to_owned() |
| } |
| |
| |
| <span class="doccomment">/// A marker struct for __NonExhaustive enums. |
| /// |
| /// This is an empty type that can not be constructed. When an enum contains a tuple variant that |
| /// includes this type the optimizer can statically determined tha the branch is never taken while |
| /// at the same time the matching of the branch is required. |
| /// |
| /// The effect is thus very similar to the actual `#[non_exhaustive]` attribute with no runtime |
| /// costs. Also note that we use a dirty trick to not only hide this type from the doc but make it |
| /// inaccessible. The visibility in this module is pub but the module itself is not and the |
| /// top-level crate never exports the type. |
| </span><span class="attribute">#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)] |
| </span><span class="kw">pub struct </span>NonExhaustiveMarker { |
| <span class="doccomment">/// Allows this crate, and this crate only, to match on the impossibility of this variant. |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) _private: Empty, |
| } |
| |
| <span class="attribute">#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">enum </span>Empty { } |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>clamp<N>(a: N, min: N, max: N) -> N |
| <span class="kw">where |
| </span>N: PartialOrd, |
| { |
| <span class="kw">if </span>a < min { |
| min |
| } <span class="kw">else if </span>a > max { |
| max |
| } <span class="kw">else </span>{ |
| a |
| } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>test { |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>gray_to_luma8_skip() { |
| <span class="kw">let </span>check = |bit_depth, w, from, to| { |
| <span class="macro">assert_eq!</span>( |
| <span class="kw">super</span>::expand_bits(bit_depth, w, from), |
| to); |
| }; |
| <span class="comment">// Bit depth 1, skip is more than half a byte |
| </span>check( |
| <span class="number">1</span>, <span class="number">10</span>, |
| <span class="kw-2">&</span>[<span class="number">0b11110000</span>, <span class="number">0b11000000</span>, <span class="number">0b00001111</span>, <span class="number">0b11000000</span>], |
| <span class="macro">vec!</span>[<span class="number">255</span>, <span class="number">255</span>, <span class="number">255</span>, <span class="number">255</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">255</span>, <span class="number">255</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">255</span>, <span class="number">255</span>, <span class="number">255</span>, <span class="number">255</span>, <span class="number">255</span>, <span class="number">255</span>]); |
| <span class="comment">// Bit depth 2, skip is more than half a byte |
| </span>check( |
| <span class="number">2</span>, <span class="number">5</span>, |
| <span class="kw-2">&</span>[<span class="number">0b11110000</span>, <span class="number">0b11000000</span>, <span class="number">0b00001111</span>, <span class="number">0b11000000</span>], |
| <span class="macro">vec!</span>[<span class="number">255</span>, <span class="number">255</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">255</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">255</span>, <span class="number">255</span>, <span class="number">255</span>]); |
| <span class="comment">// Bit depth 2, skip is 0 |
| </span>check( |
| <span class="number">2</span>, <span class="number">4</span>, |
| <span class="kw-2">&</span>[<span class="number">0b11110000</span>, <span class="number">0b00001111</span>], |
| <span class="macro">vec!</span>[<span class="number">255</span>, <span class="number">255</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">255</span>, <span class="number">255</span>]); |
| <span class="comment">// Bit depth 4, skip is half a byte |
| </span>check( |
| <span class="number">4</span>, <span class="number">1</span>, |
| <span class="kw-2">&</span>[<span class="number">0b11110011</span>, <span class="number">0b00001100</span>], |
| <span class="macro">vec!</span>[<span class="number">255</span>, <span class="number">0</span>]); |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="image" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
