diff options
Diffstat (limited to 'src/renderer.rs')
| -rw-r--r-- | src/renderer.rs | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/src/renderer.rs b/src/renderer.rs new file mode 100644 index 0000000..14dfb6f --- /dev/null +++ b/src/renderer.rs @@ -0,0 +1,189 @@ +use std::{fs, mem, path::Path}; + +use color_eyre::eyre::{bail, Result}; +use image::{ImageBuffer, Luma, Pixel, Rgba, RgbaImage}; +use nalgebra::{vector, Vector2}; +use num_traits::identities::Zero; + +use super::{ + gpx::Coordinates, + layer::{self, TileLayer}, +}; + +pub type HeatCounter = TileLayer<Luma<u32>>; + +pub type HeatMap = TileLayer<Rgba<u8>>; + +/// Returns (a - b)**2, but ensures that no underflow happens (if b > a). +fn diff_squared(a: u64, b: u64) -> u64 { + if a > b { + (a - b).pow(2) + } else { + (b - a).pow(2) + } +} + +fn render_circle<P: Pixel>(layer: &mut TileLayer<P>, center: (u64, u64), radius: u64, pixel: P) { + let x_lower = center.0.saturating_sub(radius); + let x_upper = (layer.width() - 1).min(center.0 + radius); + let y_lower = center.1.saturating_sub(radius); + let y_upper = (layer.height() - 1).min(center.1 + radius); + + for x in x_lower..=x_upper { + for y in y_lower..=y_upper { + if diff_squared(center.0, x) + diff_squared(center.1, y) <= radius * radius { + *layer.get_pixel_mut(x, y) = pixel; + } + } + } +} + +fn render_line<P: Pixel>( + layer: &mut TileLayer<P>, + start: (u64, u64), + end: (u64, u64), + thickness: u64, + pixel: P, +) { + use imageproc::point::Point; + + if start == end { + return; + } + + fn unsigned_add(a: Vector2<u64>, b: Vector2<i32>) -> Vector2<u64> { + let x = if b[0] < 0 { + a[0] - b[0].abs() as u64 + } else { + a[0] + b[0] as u64 + }; + let y = if b[1] < 0 { + a[1] - b[0].abs() as u64 + } else { + a[1] + b[1] as u64 + }; + vector![x, y] + } + + let r = vector![end.0 as f64, end.1 as f64] - vector![start.0 as f64, start.1 as f64]; + let r = r.normalize(); + let normal = vector![r[1], -r[0]]; + + let start = vector![start.0, start.1]; + let end = vector![end.0, end.1]; + + let displacement = normal * thickness as f64; + let displacement = displacement.map(|x| x as i32); + let polygon = [ + unsigned_add(start, displacement), + unsigned_add(end, displacement), + unsigned_add(end, -displacement), + unsigned_add(start, -displacement), + ]; + let min_x = polygon.iter().map(|p| p[0]).min().unwrap(); + let min_y = polygon.iter().map(|p| p[1]).min().unwrap(); + let max_x = polygon.iter().map(|p| p[0]).max().unwrap(); + let max_y = polygon.iter().map(|p| p[1]).max().unwrap(); + + let mut overlay = ImageBuffer::<P, Vec<P::Subpixel>>::new( + (max_x - min_x).try_into().unwrap(), + (max_y - min_y).try_into().unwrap(), + ); + let adjusted_poly = polygon + .into_iter() + .map(|p| Point::new((p[0] - min_x) as i32, (p[1] - min_y) as i32)) + .collect::<Vec<_>>(); + imageproc::drawing::draw_polygon_mut(&mut overlay, &adjusted_poly, pixel); + + for (x, y, pixel) in overlay.enumerate_pixels() { + if pixel.channels()[0] > Zero::zero() { + *layer.get_pixel_mut(u64::from(x) + min_x, u64::from(y) + min_y) = *pixel; + } + } +} + +fn merge_heat_counter(base: &mut HeatCounter, overlay: &HeatCounter) { + for (x, y, source) in overlay.enumerate_pixels() { + let target = base.get_pixel_mut(x, y); + target[0] += source[0]; + } +} + +fn colorize_tile(tile: &ImageBuffer<Luma<u32>, Vec<u32>>, max: u32) -> RgbaImage { + let gradient = colorgrad::turbo(); + let mut result = ImageBuffer::from_pixel(tile.width(), tile.height(), [0, 0, 0, 0].into()); + for (x, y, pixel) in tile.enumerate_pixels() { + if pixel[0] > 0 { + let alpha = pixel[0] as f64 / max as f64; + let color = gradient.at(alpha); + let target = result.get_pixel_mut(x, y); + *target = color.to_rgba8().into(); + } + } + result +} + +pub fn colorize_heatcounter(layer: &HeatCounter) -> HeatMap { + let max = layer.pixels().map(|l| l.0[0]).max().unwrap_or_default(); + let mut result = TileLayer::from_pixel(layer.width(), layer.height(), [0, 0, 0, 0].into()); + if max == 0 { + return result; + } + for (tile_x, tile_y, tile) in layer.enumerate_tiles() { + let colorized = colorize_tile(&tile, max); + *result.tile_mut(tile_x, tile_y) = colorized; + } + result +} + +/// Lazily colorizes a [`HeatCounter`] by colorizing it tile-by-tile and saving a tile before +/// rendering the next one. +/// +/// This has a way lower memory usage than [`colorize_heatcounter`]. +pub fn lazy_colorization<P: AsRef<Path>>(layer: &HeatCounter, base_dir: P) -> Result<()> { + let base_dir = base_dir.as_ref(); + let max = layer.pixels().map(|l| l.0[0]).max().unwrap_or_default(); + if max == 0 { + return Ok(()); + } + for (tile_x, tile_y, tile) in layer.enumerate_tiles() { + let colorized = colorize_tile(&tile, max); + let folder = base_dir.join(&tile_x.to_string()); + let metadata = folder.metadata(); + match metadata { + Err(_) => fs::create_dir(&folder)?, + Ok(m) if !m.is_dir() => bail!("Output path is not a directory"), + _ => {} + } + let file = folder.join(&format!("{tile_y}.png")); + layer::compress_png(&colorized, file)?; + } + Ok(()) +} + +/// Renders the heat counter for the given zoom level and track points. +pub fn render_heatcounter(zoom: u32, tracks: &[Vec<Coordinates>]) -> HeatCounter { + let size = 256 * 2u64.pow(zoom); + + let mut heatcounter = TileLayer::from_pixel(size, size, [0].into()); + + for track in tracks { + let mut layer = TileLayer::from_pixel(size, size, [0].into()); + + let points = track + .iter() + .map(|coords| coords.web_mercator(zoom)) + .collect::<Vec<_>>(); + + for point in points.iter() { + render_circle(&mut layer, *point, 10, [1].into()); + } + + for (a, b) in points.iter().zip(points.iter().skip(1)) { + render_line(&mut layer, *a, *b, 10, [1].into()); + } + + merge_heat_counter(&mut heatcounter, &layer); + } + heatcounter +} |