zola/components/imageproc/src/lib.rs

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#[macro_use]
extern crate lazy_static;
extern crate regex;
extern crate image;
extern crate rayon;
extern crate twox_hash;
extern crate utils;
extern crate errors;
use std::path::{Path, PathBuf};
use std::hash::{Hash, Hasher};
use std::collections::HashMap;
use std::collections::hash_map::Entry as HEntry;
use std::fs::{self, File};
use regex::Regex;
use image::{GenericImage, FilterType};
use image::jpeg::JPEGEncoder;
use rayon::prelude::*;
use twox_hash::XxHash;
use utils::fs as ufs;
use errors::{Result, ResultExt};
static RESIZED_SUBDIR: &'static str = "_resized_images";
lazy_static!{
pub static ref RESIZED_FILENAME: Regex = Regex::new(r#"([0-9a-f]{16})([0-9a-f]{2})[.]jpg"#).unwrap();
}
/// Describes the precise kind of a resize operation
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ResizeOp {
/// A simple scale operation that doesn't take aspect ratio into account
Scale(u32, u32),
/// Scales the image to a specified width with height computed such that aspect ratio is preserved
FitWidth(u32),
/// Scales the image to a specified height with width computed such that aspect ratio is preserved
FitHeight(u32),
/// Scales the image such that it fits within the specified width and height preserving aspect ratio.
/// Either dimension may end up being smaller, but never larger than specified.
Fit(u32, u32),
/// Scales the image such that it fills the specified width and height. Output will always have the exact dimensions specified.
/// The part of the image that doesn't fit in the thumbnail due to differing aspect ratio will be cropped away, if any.
Fill(u32, u32),
}
impl ResizeOp {
pub fn from_args(op: &str, width: Option<u32>, height: Option<u32>) -> Result<ResizeOp> {
use ResizeOp::*;
// Validate args:
match op {
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"fit_width" => if width.is_none() { return Err(format!("op=\"fit_width\" requires a `width` argument").into()) },
"fit_height" => if height.is_none() { return Err(format!("op=\"fit_height\" requires a `height` argument").into()) },
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"scale" | "fit" | "fill" => if width.is_none() || height.is_none() {
return Err(format!("op={} requires a `width` and `height` argument", op).into())
},
_ => return Err(format!("Invalid image resize operation: {}", op).into())
};
Ok(match op {
"scale" => Scale(width.unwrap(), height.unwrap()),
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"fit_width" => FitWidth(width.unwrap()),
"fit_height" => FitHeight(height.unwrap()),
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"fit" => Fit(width.unwrap(), height.unwrap()),
"fill" => Fill(width.unwrap(), height.unwrap()),
_ => unreachable!(),
})
}
pub fn width(self) -> Option<u32> {
use ResizeOp::*;
match self {
Scale(w, _) => Some(w),
FitWidth(w) => Some(w),
FitHeight(_) => None,
Fit(w, _) => Some(w),
Fill(w, _) => Some(w),
}
}
pub fn height(self) -> Option<u32> {
use ResizeOp::*;
match self {
Scale(_, h) => Some(h),
FitWidth(_) => None,
FitHeight(h) => Some(h),
Fit(_, h) => Some(h),
Fill(_, h) => Some(h),
}
}
}
impl From<ResizeOp> for u8 {
fn from(op: ResizeOp) -> u8 {
use ResizeOp::*;
match op {
Scale(_, _) => 1,
FitWidth(_) => 2,
FitHeight(_) => 3,
Fit(_, _) => 4,
Fill(_, _) => 5,
}
}
}
impl Hash for ResizeOp {
fn hash<H: Hasher>(&self, hasher: &mut H) {
hasher.write_u8(u8::from(*self));
if let Some(w) = self.width() { hasher.write_u32(w); }
if let Some(h) = self.height() { hasher.write_u32(h); }
}
}
/// Holds all data needed to perform a resize operation
#[derive(Debug, PartialEq, Eq)]
pub struct ImageOp {
source: String,
op: ResizeOp,
quality: u8,
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/// Hash of the above parameters
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hash: u64,
/// If there is a hash collision with another ImageOp, this contains a sequential ID > 1
/// identifying the collision in the order as encountered (which is essentially random).
/// Therefore, ImageOps with collisions (ie. collision_id > 0) are always considered out of date.
collision_id: u32,
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}
impl ImageOp {
pub fn new(source: String, op: ResizeOp, quality: u8) -> ImageOp {
let mut hasher = XxHash::with_seed(0);
hasher.write(source.as_ref());
op.hash(&mut hasher);
hasher.write_u8(quality);
let hash = hasher.finish();
ImageOp { source, op, quality, hash, collision_id: 0 }
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}
pub fn from_args(source: String, op: &str, width: Option<u32>, height: Option<u32>, quality: u8) -> Result<ImageOp> {
let op = ResizeOp::from_args(op, width, height)?;
Ok(Self::new(source, op, quality))
}
fn perform(&self, content_path: &Path, target_path: &Path) -> Result<()> {
use ResizeOp::*;
let src_path = content_path.join(&self.source);
if !ufs::file_stale(&src_path, target_path) {
return Ok(())
}
let mut img = image::open(&src_path)?;
let (img_w, img_h) = img.dimensions();
const RESIZE_FILTER: FilterType = FilterType::Gaussian;
const RATIO_EPSILLION: f32 = 0.1;
let img = match self.op {
Scale(w, h) => img.resize_exact(w, h, RESIZE_FILTER),
FitWidth(w) => img.resize(w, u32::max_value(), RESIZE_FILTER),
FitHeight(h) => img.resize(u32::max_value(), h, RESIZE_FILTER),
Fit(w, h) => img.resize(w, h, RESIZE_FILTER),
Fill(w, h) => {
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let factor_w = img_w as f32 / w as f32;
let factor_h = img_h as f32 / h as f32;
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if (factor_w - factor_h).abs() <= RATIO_EPSILLION {
// If the horizontal and vertical factor is very similar, that means the aspect is similar enough
// that there's not much point in cropping, so just perform a simple scale in this case.
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img.resize_exact(w, h, RESIZE_FILTER)
} else {
// We perform the fill such that a crop is performed first and then resize_exact can be used,
// which should be cheaper than resizing and then cropping (smaller number of pixels to resize).
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let (crop_w, crop_h) = if factor_w < factor_h {
(img_w, (factor_w * h as f32).round() as u32)
} else {
((factor_h * w as f32).round() as u32, img_h)
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};
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let (offset_w, offset_h) = if factor_w < factor_h {
(0, (img_h - crop_h) / 2)
} else {
((img_w - crop_w) / 2, 0)
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};
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img.crop(offset_w, offset_h, crop_w, crop_h).resize_exact(w, h, RESIZE_FILTER)
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}
},
};
let mut f = File::create(target_path)?;
let mut enc = JPEGEncoder::new_with_quality(&mut f, self.quality);
let (img_w, img_h) = img.dimensions();
enc.encode(&img.raw_pixels(), img_w, img_h, img.color())?;
Ok(())
}
}
/// A strcture into which image operations can be enqueued and then performed.
/// All output is written in a subdirectory in `static_path`,
/// taking care of file stale status based on timestamps and possible hash collisions.
#[derive(Debug)]
pub struct Processor {
content_path: PathBuf,
resized_path: PathBuf,
resized_url: String,
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/// A map of a ImageOps by their stored hash.
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/// Note that this cannot be a HashSet, because hashset handles collisions and we don't want that,
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/// we need to be aware of and handle collisions ourselves.
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img_ops: HashMap<u64, ImageOp>,
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/// Hash collisions go here:
img_ops_collisions: Vec<ImageOp>,
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}
impl Processor {
pub fn new(content_path: PathBuf, static_path: &Path, base_url: &str) -> Processor {
Processor {
content_path,
resized_path: static_path.join(RESIZED_SUBDIR),
resized_url: Self::resized_url(base_url),
img_ops: HashMap::new(),
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img_ops_collisions: Vec::new(),
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}
}
fn resized_url(base_url: &str) -> String {
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if base_url.ends_with('/') {
format!("{}{}", base_url, RESIZED_SUBDIR)
} else {
format!("{}/{}", base_url, RESIZED_SUBDIR)
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}
}
pub fn set_base_url(&mut self, base_url: &str) {
self.resized_url = Self::resized_url(base_url);
}
pub fn source_exists(&self, source: &str) -> bool {
self.content_path.join(source).exists()
}
pub fn num_img_ops(&self) -> usize {
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self.img_ops.len() + self.img_ops_collisions.len()
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}
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fn insert_with_collisions(&mut self, mut img_op: ImageOp) -> u32 {
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match self.img_ops.entry(img_op.hash) {
HEntry::Occupied(entry) => if *entry.get() == img_op { return 0; },
HEntry::Vacant(entry) => {
entry.insert(img_op);
return 0;
},
}
// If we get here, that means a hash collision.
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// This is detected when there is an ImageOp with the same hash in the `img_ops` map but which is not equal to this one.
// To deal with this, all collisions get a (random) sequential ID number.
// First try to look up this ImageOp in `img_ops_collisions`, maybe we've already seen the same ImageOp.
// At the same time, count IDs to figure out the next free one.
// Start with the ID of 2, because we'll need to use 1 for the ImageOp already present in the map:
let mut collision_id = 2;
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for op in self.img_ops_collisions.iter().filter(|op| op.hash == img_op.hash) {
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if *op == img_op {
// This is a colliding ImageOp, but we've already seen an equal one (not just by hash, but by content too),
// so just return its ID:
return collision_id;
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} else {
collision_id += 1;
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}
}
// If we get here, that means this is a new colliding ImageOp and `collision_id` is the next free ID
if collision_id == 2 {
// This is the first collision found with this hash, update the ID of the matching ImageOp in the map.
self.img_ops.get_mut(&img_op.hash).unwrap().collision_id = 1;
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}
img_op.collision_id = collision_id;
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self.img_ops_collisions.push(img_op);
collision_id
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}
fn op_filename(hash: u64, collision_id: u32) -> String {
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// Please keep this in sync with RESIZED_FILENAME
assert!(collision_id < 256, "Unexpectedly large number of collisions: {}", collision_id);
format!("{:016x}{:02x}.jpg", hash, collision_id)
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}
fn op_url(&self, hash: u64, collision_id: u32) -> String {
format!("{}/{}", &self.resized_url, Self::op_filename(hash, collision_id))
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}
pub fn insert(&mut self, img_op: ImageOp) -> String {
let hash = img_op.hash;
let collision_id = self.insert_with_collisions(img_op);
self.op_url(hash, collision_id)
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}
pub fn prune(&self) -> Result<()> {
ufs::ensure_directory_exists(&self.resized_path)?;
let entries = fs::read_dir(&self.resized_path)?;
for entry in entries {
let entry_path = entry?.path();
if entry_path.is_file() {
let filename = entry_path.file_name().unwrap().to_string_lossy();
if let Some(capts) = RESIZED_FILENAME.captures(filename.as_ref()) {
let hash = u64::from_str_radix(capts.get(1).unwrap().as_str(), 16).unwrap();
let collision_id = u32::from_str_radix(capts.get(2).unwrap().as_str(), 16).unwrap();
if collision_id > 0 || !self.img_ops.contains_key(&hash) {
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fs::remove_file(&entry_path)?;
}
}
}
}
Ok(())
}
pub fn do_process(&mut self) -> Result<()> {
self.img_ops.par_iter().map(|(hash, op)| {
let target = self.resized_path.join(Self::op_filename(*hash, op.collision_id));
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op.perform(&self.content_path, &target)
.chain_err(|| format!("Failed to process image: {}", op.source))
})
.fold(|| Ok(()), Result::and)
.reduce(|| Ok(()), Result::and)
}
}
/// Looks at file's extension and returns whether it's a supported image format
pub fn file_is_img<P: AsRef<Path>>(p: P) -> bool {
p.as_ref().extension().and_then(|s| s.to_str()).map(|ext| {
match ext.to_lowercase().as_str() {
"jpg" | "jpeg" => true,
"png" => true,
"gif" => true,
"bmp" => true,
_ => false,
}
}).unwrap_or(false)
}