Behave like a 3857 tile service when google compatible flag found in COG file

Cargo.toml

@@ -46,6 +46,8 @@ env_logger = "0.11"
 flate2 = "1"
 flume = "0.11"
 futures = "0.3"
+image = "0.25.6"
+imageproc = "0.25.0"
 indoc = "2"
 insta = "1"
 itertools = "0.14"

docs/src/sources-cog-files.md

@@ -57,6 +57,96 @@ cog:
      cog-src2: /path/to/cog2.tif
 ```
 
+## Tile Grid
+
+Generally `COG` file has a custom tile grid which is not aligned to the google 3857 which is default in almost any map client like MapLibre, OpenLayers, etc..
+
+To display the `COG` file the clients needs to know the custom `tile grid` of COG.
+
+To not break the compatiblity of TileJSON spec, martin choose to add a field in `TileJSON` to tell the custom tile grid.
+
+Lile we have a cog source named `rgb_u8`, we could see the custom filed in our `TileJson` by visit `http://your_host:your_port/rgb_u8`.
+
+```json
+{
+  "maxzoom": 3,
+  "minzoom": 0,
+  "tilejson": "3.0.0",
+  "tiles": [
+    "http://localhost:3111/rgb_u8/{z}/{x}/{y}"
+  ],
+  "custom_grid": {   // the custom tile grid added here
+    "extent": [
+      1620750.2508,
+      4271892.7153,
+      1625870.2508,
+      4277012.7153
+    ],
+    "maxZoom": 3,
+    "minZoom": 0,
+    "origin": [
+      1620750.2508,
+      4277012.7153
+    ],
+    "resolutions": [
+      80,
+      40,
+      20,
+      10
+    ],
+    "tileSize": [
+      256,
+      256
+    ]
+  },
+}
+```
+
+A demo about how to load it with `openlayers`.
+
+```js
+import './style.css';
+import { Map, View } from 'ol';
+import TileLayer from 'ol/layer/Tile';
+import OSM from 'ol/source/OSM';
+import XYZ from 'ol/source/XYZ.js';
+
+
+import TileGrid from 'ol/tilegrid/TileGrid.js';
+
+var custom_grid = new TileGrid({
+  extent: [
+    1620750.2508,
+    4271892.7153,
+    1625870.2508,
+    4277012.7153],
+  resolutions: [
+    80,
+    40,
+    20,
+    10],
+  tileSize: [256, 256],
+  origin: [1620750.2508, 4277012.7153]
+});
+
+var source = new XYZ({
+  url: "http://10.1.155.35:3000/rgb_u8/{z}/{x}/{y}", tileGrid: custom_grid
+});
+
+const map = new Map({
+  target: 'map',
+  layers: [
+    new TileLayer({
+      source: source
+    }),
+  ],
+  view: new View({
+    center: [(1620750.2508 + 1625870.2508) / 2, (4271892.7153 + 4277012.7153) / 2],
+    zoom: 14
+  })
+});
+```
+
 ## About COG
 
 [COG](https://cogeo.org/) is just Cloud Optimized GeoTIFF file.

martin-tile-utils/src/lib.rs

@@ -254,6 +254,35 @@ pub fn xyz_to_bbox(zoom: u8, min_x: u32, min_y: u32, max_x: u32, max_y: u32) ->
     [min_lng, min_lat, max_lng, max_lat]
 }
 
+/// Convert min/max XYZ tile coordinates to a bounding box values.
+///
+/// The result is `[min_lng, min_lat, max_lng, max_lat]`
+///
+/// # Panics
+/// Panics if `zoom` is greater than [`MAX_ZOOM`].
+#[must_use]
+pub fn xyz_to_bbox_webmercator(
+    zoom: u8,
+    min_x: u32,
+    min_y: u32,
+    max_x: u32,
+    max_y: u32,
+) -> [f64; 4] {
+    assert!(zoom <= MAX_ZOOM, "zoom {zoom} must be <= {MAX_ZOOM}");
+
+    let tile_length = EARTH_CIRCUMFERENCE / f64::from(1_u32 << zoom);
+
+    let left_down_bbox = tile_bbox(min_x, max_y, tile_length);
+    let right_top_bbox = tile_bbox(max_x, min_y, tile_length);
+
+    [
+        left_down_bbox[0],
+        left_down_bbox[1],
+        right_top_bbox[2],
+        right_top_bbox[3],
+    ]
+}
+
 #[allow(clippy::cast_lossless)]
 fn tile_bbox(x: u32, y: u32, tile_length: f64) -> [f64; 4] {
     let min_x = EARTH_CIRCUMFERENCE * -0.5 + x as f64 * tile_length;

martin/Cargo.toml

@@ -58,7 +58,7 @@ fonts = ["dep:bit-set", "dep:pbf_font_tools"]
 lambda = ["dep:lambda-web"]
 mbtiles = ["dep:mbtiles"]
 pmtiles = ["dep:pmtiles"]
-cog = ["dep:tiff", "dep:png"]
+cog = ["dep:tiff", "dep:png", "dep:image", "dep:imageproc"]
 styles = ["dep:walkdir", "tokio/fs"]
 postgres = ["dep:deadpool-postgres", "dep:json-patch", "dep:postgis", "dep:postgres", "dep:postgres-protocol", "dep:semver", "dep:tokio-postgres-rustls"]
 sprites = ["dep:spreet", "tokio/fs"]
@@ -79,6 +79,8 @@ enum-display.workspace = true
 env_logger.workspace = true
 futures.workspace = true
 itertools.workspace = true
+image = { workspace = true, optional = true }
+imageproc = { workspace = true, optional = true }
 json-patch = { workspace = true, optional = true }
 lambda-web = { workspace = true, optional = true }
 log.workspace = true
@@ -118,6 +120,7 @@ static-files = { workspace = true, optional = true }
 
 [dev-dependencies]
 anyhow.workspace = true
+approx.workspace = true
 criterion.workspace = true
 ctor.workspace = true
 indoc.workspace = true

martin/src/cog/config.rs

@@ -13,6 +13,8 @@ use crate::file_config::{ConfigExtras, FileResult, SourceConfigExtras};
 pub struct CogConfig {
     #[serde(flatten)]
     pub unrecognized: UnrecognizedValues,
+
+    pub force_google: Option<bool>,
 }
 
 impl ConfigExtras for CogConfig {
@@ -23,7 +25,7 @@ impl ConfigExtras for CogConfig {
 
 impl SourceConfigExtras for CogConfig {
     async fn new_sources(&self, id: String, path: PathBuf) -> FileResult<Box<dyn Source>> {
-        let cog = CogSource::new(id, path)?;
+        let cog = CogSource::new(id, path, self.force_google.unwrap_or(true))?;
         Ok(Box::new(cog))
     }
 

martin/src/cog/errors.rs

@@ -44,4 +44,21 @@ pub enum CogError {
 
     #[error("Striped tiff file is not supported, the tiff file is {0}")]
     NotSupportedChunkType(PathBuf),
+
+    #[error("Get origin failed for {0}")]
+    GetOriginFailed(PathBuf),
+
+    #[error("Coord transformation in {0} is invalid")]
+    InvalidGeoInformation(PathBuf, String),
+
+    #[error("Get full resolution failed from file: {0}")]
+    GetFullResolutionFailed(PathBuf),
+
+    #[error("Get extent failed from file: {0}")]
+    GetExtentFailed(PathBuf),
+
+    #[error(
+        "The pixel size of the image {0} is not squared, the x_scale is {1}, the y_scale is {2}"
+    )]
+    NonSquaredImage(PathBuf, f64, f64),
 }