draft: style rendering

Cargo.toml

@@ -52,6 +52,7 @@ itertools = "0.14"
 json-patch = "4"
 lambda-web = { version = "0.2.1", features = ["actix4"] }
 log = "0.4"
+maplibre_native = "0.1.1"
 martin-tile-utils = { path = "./martin-tile-utils", version = "0.6.0" }
 mbtiles = { path = "./mbtiles", version = "0.12.0" }
 md5 = "0.7.0"

docs/src/config-file.md

@@ -232,7 +232,6 @@ fonts:
   - /path/to/font_dir
 
 # Publish MapLibre style files
-# In the future, the style files will be used for the server-side rendering as well
 styles:
    paths:
      # publish all *.json files in this directory

docs/src/sources-styles.md

@@ -7,6 +7,7 @@ To edit these styles, we recommend using <https://maputnik.github.io/editor/>.
 ### API
 
 Martin can serve [MapLibre Style Spec](https://maplibre.org/maplibre-style-spec/).
+
 Currently, Martin will use any valid [`JSON`](https://json.org) file as a style,
 but in the future, we may optimise Martin which may result in additional restrictions.
 
@@ -21,5 +22,4 @@ A restart of Martin is required to see new styles.
 
 ### Server-side raster tile rendering
 
-This is not implemented yet, but there is a plan to add it.
-Please see <https://github.com/maplibre/martin/issues/978> for more information.
+TODO, document

martin/Cargo.toml

@@ -60,6 +60,7 @@ mbtiles = ["dep:mbtiles"]
 pmtiles = ["dep:pmtiles"]
 cog = ["dep:tiff", "dep:png"]
 styles = ["dep:walkdir", "tokio/fs"]
+styles_rendering = ["styles", "dep:maplibre_native"]
 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"]
 bless-tests = []
@@ -82,6 +83,7 @@ itertools.workspace = true
 json-patch = { workspace = true, optional = true }
 lambda-web = { workspace = true, optional = true }
 log.workspace = true
+maplibre_native = { workspace = true, optional = true }
 martin-tile-utils.workspace = true
 mbtiles = { workspace = true, optional = true }
 moka.workspace = true

martin/src/srv/server.rs

@@ -129,6 +129,8 @@ pub fn router(cfg: &mut web::ServiceConfig, #[allow(unused_variables)] usr_cfg:
 
     #[cfg(feature = "styles")]
     cfg.service(crate::srv::styles::get_style_json);
+    #[cfg(feature = "styles_rendering")]
+    cfg.service(crate::srv::styles::get_style_rendered);
 
     #[cfg(feature = "webui")]
     {

martin/src/srv/styles.rs

@@ -43,3 +43,36 @@ async fn get_style_json(path: Path<StyleRequest>, styles: Data<StyleSources>) ->
         }
     }
 }
+
+#[cfg(feature = "styles_rendering")]
+#[derive(Deserialize, Debug)]
+struct StyleRenderRequest {
+    style_id: String,
+    z: u8,
+    x: u32,
+    y: u32,
+}
+
+#[cfg(feature = "styles_rendering")]
+#[route("/style/{style_id}/{z}/{x}/{y}.png", method = "GET")]
+async fn get_style_rendered(
+    path: Path<StyleRenderRequest>,
+    styles: Data<StyleSources>,
+) -> HttpResponse {
+    let style_id = &path.style_id;
+    let Some(style_path) = styles.style_json_path(style_id) else {
+        return HttpResponse::NotFound()
+            .content_type(ContentType::plaintext())
+            .body("No such style exists");
+    };
+    let xyz = martin_tile_utils::TileCoord {
+        z: path.z,
+        x: path.x,
+        y: path.y,
+    };
+    log::trace!("Rendering style {style_id} ({style_path:?}) at {xyz}");
+
+    HttpResponse::Ok()
+        .content_type(ContentType.png())
+        .body(styles.render(path, xyz))
+}

martin/src/styles/mod.rs

@@ -6,6 +6,7 @@ use std::fmt::Debug;
 use std::path::{Path, PathBuf};
 
 use crate::config::UnrecognizedValues;
+
 use crate::file_config::{ConfigExtras, FileConfigEnum, FileError, FileResult};
 
 #[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq)]
@@ -96,6 +97,23 @@ impl StyleSources {
         Some(item.path.clone())
     }
 
+    // assumptions:
+    // - martin is not an interacive renderer (think 60fps, embedded)
+    // - We are not rendering the same tile all the time (instead, it is cached)
+    //
+    // For now, we only use a static renderer which is optimized for our kind of usage
+    // In the future, we may consider adding support for smarter rendering including a pool of renderers.
+    #[cfg(feature = "styles_rendering")]
+    pub fn render(
+        &self,
+        path: &Path,
+        zxy: martin_tile_utils::TileCoord,
+    ) -> StyleResult<Vec<u8>, Error> {
+        let mut map = maplibre_native::ImageRendererOptions::new().build_static_renderer();
+        map.set_style_path(path);
+        Ok(map.render_static(zxy.z, zxy.x, zxy.y))
+    }
+
     /// an external representation of the internal catalog
     #[must_use]
     pub fn get_catalog(&self) -> StyleCatalog {
@@ -187,6 +205,7 @@ mod tests {
     use crate::file_config::FileConfigSrc;
 
     use super::*;
+
     #[test]
     fn test_add_single_source() {
         use std::fs::File;