1 files changed, 115 insertions, 22 deletions

diff --git a/src/renderer/tilehunt.rs b/src/renderer/tilehunt.rs
index 55b30af..9081523 100644
--- a/src/renderer/tilehunt.rs
+++ b/src/renderer/tilehunt.rs
@@ -4,30 +4,76 @@
 //!
 //! Note that is version of "tile hunt" is a bit silly, as the tile size changes with the zoom
 //! level. For a better version, the "tile hunt size" should be fixed to a given zoom.
+use std::cmp::Ordering;
+
 use color_eyre::eyre::Result;
 use crossbeam_channel::Sender;
-use fnv::FnvHashSet;
+use fnv::{FnvHashMap, FnvHashSet};
+use image::RgbaImage;
+use imageproc::{drawing::draw_filled_rect_mut, rect::Rect};
+use rayon::iter::{IntoParallelIterator, ParallelIterator};
 
 use super::{
     super::{
         gpx::Coordinates,
-        layer::{TILE_HEIGHT, TILE_WIDTH},
+        layer::{self, TILE_HEIGHT, TILE_WIDTH},
     },
     RenderedTile,
 };
 
+fn render_squares(grid: u32, inner: Vec<(u8, u8)>) -> Result<Vec<u8>> {
+    // We re-use the tiny PNG if possible
+    static FULL_TILE: &[u8] = include_bytes!("tile-marked.png");
+    if grid == 1 && !inner.is_empty() {
+        return Ok(FULL_TILE.to_vec());
+    }
+    let mut base =
+        RgbaImage::from_pixel(TILE_WIDTH as u32, TILE_HEIGHT as u32, [0, 0, 0, 0].into());
+    let patch_size = TILE_WIDTH as u32 / grid;
+
+    for (patch_x, patch_y) in inner {
+        draw_filled_rect_mut(
+            &mut base,
+            Rect::at(
+                patch_x as i32 * patch_size as i32,
+                patch_y as i32 * patch_size as i32,
+            )
+            .of_size(patch_size, patch_size),
+            [0, 255, 0, 128].into(),
+        );
+    }
+
+    layer::compress_png_as_bytes(&base)
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct Renderer;
+pub struct Renderer(u32);
+
+impl Renderer {
+    pub fn new(hunter_zoom: u32) -> Self {
+        Renderer(hunter_zoom)
+    }
+
+    #[inline]
+    pub fn hunter_zoom(&self) -> u32 {
+        self.0
+    }
+}
 
 impl super::Renderer for Renderer {
-    type Prepared = FnvHashSet<(u64, u64)>;
+    type Prepared = (u32, FnvHashMap<(u64, u64), Vec<(u8, u8)>>);
 
-    fn prepare(zoom: u32, tracks: &[Vec<Coordinates>], tick: Sender<()>) -> Result<Self::Prepared> {
+    fn prepare(
+        &self,
+        zoom: u32,
+        tracks: &[Vec<Coordinates>],
+        tick: Sender<()>,
+    ) -> Result<Self::Prepared> {
         let mut marked = FnvHashSet::default();
 
         for track in tracks {
             for point in track {
-                let merc = point.web_mercator(zoom);
+                let merc = point.web_mercator(self.hunter_zoom());
                 let tile_x = merc.0 / TILE_WIDTH;
                 let tile_y = merc.1 / TILE_HEIGHT;
                 marked.insert((tile_x, tile_y));
@@ -36,25 +82,72 @@ impl super::Renderer for Renderer {
             tick.send(()).unwrap();
         }
 
-        Ok(marked)
-    }
+        let scale = i32::try_from(zoom).unwrap() - i32::try_from(self.hunter_zoom()).unwrap();
+        let grid = if scale >= 0 {
+            1
+        } else {
+            2u64.pow(scale.abs().min(8) as u32)
+        };
+
+        let mut result = FnvHashMap::<(u64, u64), Vec<(u8, u8)>>::default();
 
-    fn colorize(layer: Self::Prepared, tx: Sender<RenderedTile>) -> Result<()> {
-        // The tile is hand-crafted to be very small. See
-        // <https://www.mjt.me.uk/posts/smallest-png/> for a reference, and of course the actual
-        // PNG specification <http://www.libpng.org/pub/png/spec/1.2/PNG-Contents.html>.
-        static IMAGE_DATA: &[u8] = include_bytes!("tile-marked.png");
-        for (tile_x, tile_y) in layer {
-            tx.send(RenderedTile {
-                x: tile_x,
-                y: tile_y,
-                data: IMAGE_DATA.to_vec(),
-            })?;
+        for (tile_x, tile_y) in marked {
+            match scale.cmp(&0) {
+                Ordering::Equal =>
+                // The current zoom level is the same as the hunter level, so the tiles have a 1:1
+                // mapping
+                {
+                    result.entry((tile_x, tile_y)).or_default().push((0u8, 0u8))
+                }
+                Ordering::Less =>
+                // In this case we are "zoomed out" further than the hunter level, so a marked tile
+                // has to be scaled down and we need to figure out where in the "big tile" our
+                // marked tile is
+                {
+                    result
+                        .entry((tile_x / grid, tile_y / grid))
+                        .or_default()
+                        .push((
+                            (tile_x % grid).try_into().unwrap(),
+                            (tile_y % grid).try_into().unwrap(),
+                        ))
+                }
+                Ordering::Greater => {
+                    // In this case, we are zoomed in more than the hunter level. Each marked tile
+                    // expands to multiple tiles.
+                    let multiplier = 2u64.pow(scale as u32);
+                    for dx in 0..multiplier {
+                        for dy in 0..multiplier {
+                            result
+                                .entry((tile_x * multiplier + dx, tile_y * multiplier + dy))
+                                .or_default()
+                                .push((0u8, 0u8));
+                        }
+                    }
+                }
+            }
         }
-        Ok(())
+
+        Ok((grid.try_into().unwrap(), result))
+    }
+
+    fn colorize(&self, layer: Self::Prepared, tx: Sender<RenderedTile>) -> Result<()> {
+        let grid = layer.0;
+        layer
+            .1
+            .into_par_iter()
+            .try_for_each_with(tx, |tx, ((tile_x, tile_y), inner)| {
+                let data = render_squares(grid, inner)?;
+                tx.send(RenderedTile {
+                    x: tile_x,
+                    y: tile_y,
+                    data,
+                })?;
+                Ok(())
+            })
     }
 
-    fn tile_count(layer: &Self::Prepared) -> Result<u64> {
-        Ok(layer.len().try_into().unwrap())
+    fn tile_count(&self, layer: &Self::Prepared) -> Result<u64> {
+        Ok(layer.1.len().try_into().unwrap())
     }
 }