Make tile service GoogleMaps-Compatible when the cog file is GoogleMapsCompatible

martin/src/args/root.rs

@@ -297,8 +297,10 @@ mod tests {
         let err = args.merge_into_config(&mut config, &env);
         assert!(err.is_ok());
         assert_yaml_snapshot!(config, @r#"
+        pmtiles: "../tests/fixtures/cog"
+        mbtiles: "../tests/fixtures/cog"
         cog:
-          - "../tests/fixtures/cog/rgb_u8.tif"
+          - "../tests/fixtures/cog"
           - "../tests/fixtures/cog/rgba_u8_nodata.tiff"
           - "../tests/fixtures/cog/rgba_u8.tif"
         "#);

martin/src/cog/errors.rs

@@ -48,4 +48,7 @@ pub enum CogError {
 
     #[error("Striped tiff file is not supported, the tiff file is {0}")]
     NotSupportedChunkType(PathBuf),
+
+    #[error("Failed to parse GDAL metadata: {0}")]
+    GdalMetadataError(String),
 }

martin/src/cog/mod.rs

@@ -25,6 +25,8 @@ use crate::{
     MartinResult, Source, TileData, UrlQuery,
 };
 
+use regex::Regex;
+
 #[derive(Clone, Debug)]
 pub struct CogSource {
     id: String,
@@ -41,6 +43,8 @@ struct Meta {
     zoom_and_ifd: HashMap<u8, usize>,
     zoom_and_tile_across_down: HashMap<u8, (u32, u32)>,
     nodata: Option<f64>,
+    google_compatible_max_zoom: Option<u8>,
+    google_compatible_min_zoom: Option<u8>,
 }
 
 #[async_trait]
@@ -75,9 +79,14 @@ impl Source for CogSource {
             Decoder::new(tif_file).map_err(|e| CogError::InvalidTiffFile(e, self.path.clone()))?;
         decoder = decoder.with_limits(tiff::decoder::Limits::unlimited());
 
-        let ifd = self.meta.zoom_and_ifd.get(&(xyz.z)).ok_or_else(|| {
+        let actual_zoom = if let Some(google_zoom) = self.meta.google_compatible_max_zoom {
+            self.meta.max_zoom - google_zoom + xyz.z
+        } else {
+            xyz.z
+        };
+        let ifd = self.meta.zoom_and_ifd.get(&(actual_zoom)).ok_or_else(|| {
             CogError::ZoomOutOfRange(
-                xyz.z,
+                actual_zoom,
                 self.path.clone(),
                 self.meta.min_zoom,
                 self.meta.max_zoom,
@@ -216,8 +225,8 @@ impl SourceConfigExtras for CogConfig {
         let meta = get_meta(&path)?;
         let tilejson = tilejson! {
             tiles: vec![],
-            minzoom: meta.min_zoom,
-            maxzoom: meta.max_zoom
+            minzoom: meta.google_compatible_min_zoom.unwrap_or(meta.min_zoom),
+            maxzoom: meta.google_compatible_max_zoom.unwrap_or(meta.max_zoom),
         };
         Ok(Box::new(CogSource {
             id,
@@ -287,6 +296,9 @@ fn get_meta(path: &PathBuf) -> Result<Meta, FileError> {
     } else {
         None
     };
+
+    let (tiling_schema_name, zoom_level) = get_tilling_schema(&mut decoder).unwrap_or((None, None));
+
     let images_ifd = get_images_ifd(&mut decoder);
 
     let mut zoom_and_ifd: HashMap<u8, usize> = HashMap::new();
@@ -315,9 +327,21 @@ fn get_meta(path: &PathBuf) -> Result<Meta, FileError> {
         .keys()
         .max()
         .ok_or_else(|| CogError::NoImagesFound(path.clone()))?;
+
+    let google_compatible_max_zoom =
+        if tiling_schema_name == Some("GoogleMapsCompatible".to_string()) {
+            zoom_level
+        } else {
+            None
+        };
+    let google_compatible_min_zoom =
+        google_compatible_max_zoom.map(|google_max_zoom| google_max_zoom - max_zoom + min_zoom);
+
     Ok(Meta {
         min_zoom: *min_zoom,
         max_zoom: *max_zoom,
+        google_compatible_max_zoom,
+        google_compatible_min_zoom,
         zoom_and_ifd,
         zoom_and_tile_across_down,
         nodata,
@@ -375,3 +399,64 @@ fn get_images_ifd(decoder: &mut Decoder<File>) -> Vec<usize> {
     }
     res
 }
+
+fn get_tilling_schema(
+    decoder: &mut Decoder<File>,
+) -> Result<(Option<String>, Option<u8>), CogError> {
+    let gdal_metadata = decoder
+        .get_tag_ascii_string(Tag::Unknown(42112))
+        .map_err(|e| CogError::TagsNotFound(e, vec![42112], 0, PathBuf::new()))?;
+
+    let mut tiling_schema_name = None;
+    let mut zoom_level = None;
+
+    let re_name = Regex::new(r#"<Item name="NAME" domain="TILING_SCHEME">([^<]+)</Item>"#).unwrap();
+    let re_zoom =
+        Regex::new(r#"<Item name="ZOOM_LEVEL" domain="TILING_SCHEME">([^<]+)</Item>"#).unwrap();
+
+    if let Some(caps) = re_name.captures(&gdal_metadata) {
+        tiling_schema_name = Some(caps[1].to_string());
+    }
+
+    if let Some(caps) = re_zoom.captures(&gdal_metadata) {
+        zoom_level = caps[1].parse().ok();
+    }
+
+    Ok((tiling_schema_name, zoom_level))
+}
+
+#[cfg(test)]
+mod tests {
+    use rstest::rstest;
+
+    #[rstest]
+    #[case("../tests/fixtures/cog/google_compatible.tif", Some("GoogleMapsCompatible".to_string()), Some(14))]
+    #[case("../tests/fixtures/cog/rgba_u8_nodata.tiff", None, None)]
+    fn test_get_gdal_metadata(
+        #[case] path: &str,
+        #[case] expected_tiling_schema_name: Option<String>,
+        #[case] expected_zoom_level: Option<u8>,
+    ) {
+        use std::{fs::File, path::PathBuf};
+
+        use tiff::decoder::Decoder;
+
+        use crate::cog::get_tilling_schema;
+
+        let path = PathBuf::from(path);
+        let tif_file = File::open(&path).expect("Failed to open test fixture file");
+        let mut decoder = Decoder::new(tif_file).expect("Failed to create decoder");
+
+        let (tiling_schema_name, zoom_level) =
+            get_tilling_schema(&mut decoder).expect("Failed to get GDAL metadata");
+
+        assert_eq!(
+            tiling_schema_name, expected_tiling_schema_name,
+            "TILING_SCHEME_NAME value should match the expected value"
+        );
+        assert_eq!(
+            zoom_level, expected_zoom_level,
+            "ZOOM_LEVEL value should match the expected value"
+        );
+    }
+}

tests/expected/auto/catalog_auto.json

@@ -117,6 +117,9 @@
       "description": "One of the example maps that comes with TileMill - a bright & colorful world map that blends retro and high-tech with its folded paper texture and interactive flag tooltips. ",
       "name": "Geography Class"
     },
+    "google_compatible": {
+      "content_type": "image/png"
+    },
     "json": {
       "content_type": "application/json",
       "name": "Dummy json data"

tests/expected/auto/google_compatible.json

@@ -0,0 +1,8 @@
+{
+  "maxzoom": 14,
+  "minzoom": 12,
+  "tilejson": "3.0.0",
+  "tiles": [
+    "http://localhost:3111/google_compatible/{z}/{x}/{y}"
+  ]
+}

tests/expected/auto/save_config.yaml

@@ -258,6 +258,7 @@ cog:
   - tests/fixtures/pmtiles
   - tests/fixtures/cog
   sources:
+    google_compatible: tests/fixtures/cog/google_compatible.tif
     rgb_u8: tests/fixtures/cog/rgb_u8.tif
     rgba_u8: tests/fixtures/cog/rgba_u8.tif
     rgba_u8_nodata: tests/fixtures/cog/rgba_u8_nodata.tiff

tests/test.sh

@@ -296,6 +296,10 @@ test_jsn rgba_u8_nodata       rgba_u8_nodata
 test_png rgba_u8_nodata_0_0_0 rgba_u8_nodata/0/0/0
 test_png rgba_u8_nodata_1_0_0 rgba_u8_nodata/1/0/0
 
+test_jsn google_compatible       google_compatible
+# test_png google_compatible_13_0_0 google_compatible/13/0/0
+# test_png google_compatible_14_0_0 google_compatible/14/0/0
+
 >&2 echo "***** Test server response for table source with empty SRID *****"
 test_pbf points_empty_srid_0_0_0  points_empty_srid/0/0/0