1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
|
//! Lazy tiled image.
//!
//! This supports OSM-style "tiled" images, but not all of the tiles have to be present. If a tile
//! is not present, a default pixel is returned. The tile is allocated with the first call to a
//! mutating operation.
use std::{
fs::File,
io::{BufWriter, Write},
path::Path,
};
use color_eyre::eyre::Result;
use fnv::FnvHashMap;
use image::{
codecs::png::{CompressionType, FilterType, PngEncoder},
ColorType, ImageBuffer, ImageEncoder, Pixel, RgbaImage,
};
use num_traits::Zero;
use rayon::iter::{IntoParallelIterator, ParallelIterator};
/// Height of a single tile.
pub const TILE_HEIGHT: u64 = 256;
/// Width of a single tile.
pub const TILE_WIDTH: u64 = 256;
type TileIndex = (u64, u64);
/// Main "lazy image buffer" struct.
///
/// This lazily allocates a new tile (of size [`TILE_WIDTH`] × [`TILE_HEIGHT`]) for each mutable
/// pixel access. Each tile is pre-filled with the given default pixel.
#[derive(Debug, Clone)]
pub struct TileLayer<P: Pixel> {
tiles: FnvHashMap<TileIndex, ImageBuffer<P, Vec<P::Subpixel>>>,
default_pixel: P,
}
impl<P: Pixel> TileLayer<P> {
/// Construct a new lazy buffer with the given default (background) pixel.
///
/// Note that this does not yet allocate any image tiles.
pub fn from_pixel(pixel: P) -> Self {
TileLayer {
tiles: Default::default(),
default_pixel: pixel,
}
}
/// Iterates over all tiles, together with their indices.
pub fn enumerate_tiles(
&self,
) -> impl Iterator<Item = (u64, u64, &ImageBuffer<P, Vec<P::Subpixel>>)> {
self.tiles.iter().map(|((x, y), t)| (*x, *y, t))
}
/// Returns a mutable reference to the given tile.
///
/// This allocates a new tile if the requested tile does not yet exist.
pub fn tile_mut(&mut self, tile_x: u64, tile_y: u64) -> &mut ImageBuffer<P, Vec<P::Subpixel>> {
self.tiles.entry((tile_x, tile_y)).or_insert_with(|| {
ImageBuffer::from_pixel(TILE_WIDTH as u32, TILE_HEIGHT as u32, self.default_pixel)
})
}
/// Enumerate all pixels that are allocated.
///
/// This provides access to the pixel and its coordinates.
pub fn enumerate_pixels(&self) -> impl Iterator<Item = (u64, u64, &P)> {
self.tiles.iter().flat_map(|((tx, ty), tile)| {
tile.enumerate_pixels().map(move |(x, y, p)| {
(
u64::from(x) + tx * TILE_WIDTH,
u64::from(y) + ty * TILE_HEIGHT,
p,
)
})
})
}
/// Iterate over all pixels that are allocated.
pub fn pixels(&self) -> impl Iterator<Item = &P> {
self.enumerate_pixels().map(|x| x.2)
}
/// Returns the number of allocated tiles.
pub fn tile_count(&self) -> usize {
self.tiles.len()
}
/// Copies the non-zero pixels from `source` to `self`.
///
/// A zero-pixel is identified by comparing all its channels' values with `Zero::zero()`. If
/// any channel is non-zero, the pixel is considered non-zero and is copied.
///
/// The top-left pixel of `source` is copied to `(x, y)`.
///
/// This method is more efficient than copying pixels one by one, as it groups them by tile and
/// only does one tile lookup then.
pub fn blit_nonzero(&mut self, x: u64, y: u64, source: &ImageBuffer<P, Vec<P::Subpixel>>) {
let zero = zero_pixel::<P>();
let source_width = u64::from(source.width());
let source_height = u64::from(source.height());
for tx in x / TILE_WIDTH..=(x + source_width) / TILE_WIDTH {
for ty in y / TILE_HEIGHT..=(y + source_height) / TILE_HEIGHT {
let tile = self.tile_mut(tx, ty);
let offset_x = (tx * TILE_WIDTH).saturating_sub(x);
let offset_y = (ty * TILE_HEIGHT).saturating_sub(y);
let local_min_x = x.saturating_sub(tx * TILE_WIDTH);
let local_min_y = y.saturating_sub(ty * TILE_HEIGHT);
let local_max_x = TILE_WIDTH.min(x + source_width - tx * TILE_WIDTH);
let local_max_y = TILE_HEIGHT.min(y + source_height - ty * TILE_HEIGHT);
// Keep x in the inner loop for better cache locality!
for (y, source_y) in (local_min_y..local_max_y).zip(offset_y..) {
for (x, source_x) in (local_min_x..local_max_x).zip(offset_x..) {
let pixel = source
.get_pixel(source_x.try_into().unwrap(), source_y.try_into().unwrap());
if pixel.channels() != zero.channels() {
*tile.get_pixel_mut(x.try_into().unwrap(), y.try_into().unwrap()) =
*pixel;
}
}
}
}
}
}
}
impl<P> TileLayer<P>
where
P: Pixel + Send,
P::Subpixel: Send,
{
/// Turns this lazy tile layer into a parallelized iterator.
pub fn into_parallel_tiles(
self,
) -> impl ParallelIterator<Item = (u64, u64, ImageBuffer<P, Vec<P::Subpixel>>)> {
IntoParallelIterator::into_par_iter(self.tiles).map(|((x, y), t)| (x, y, t))
}
}
/// Saves the given image buffer to the given path.
pub fn compress_png<P: AsRef<Path>>(image: &RgbaImage, path: P) -> Result<()> {
let outstream = BufWriter::new(File::create(path)?);
compress_png_stream(image, outstream)
}
/// Saves the given image buffer to the given stream.
///
/// Note that this uses the best compression available.
pub fn compress_png_stream<W: Write>(image: &RgbaImage, outstream: W) -> Result<()> {
let encoder =
PngEncoder::new_with_quality(outstream, CompressionType::Best, FilterType::Adaptive);
encoder.write_image(image, image.width(), image.height(), ColorType::Rgba8)?;
Ok(())
}
/// Encodes the given image buffer and returns its data as a vector.
pub fn compress_png_as_bytes(image: &RgbaImage) -> Result<Vec<u8>> {
let mut buffer = Vec::new();
compress_png_stream(image, &mut buffer)?;
Ok(buffer)
}
fn zero_pixel<P: Pixel>() -> P {
let zeroes = vec![Zero::zero(); P::CHANNEL_COUNT as usize];
*P::from_slice(&zeroes)
}
|
