tiles: make the internal tile extent of vector tiles configurable

xtraplatform-tiles/src/main/java/de/ii/xtraplatform/tiles/app/FeatureEncoderMVT.java

@@ -60,13 +60,12 @@ public FeatureEncoderMVT(TileGenerationContext encodingContext) {
     super(encodingContext);
     this.parameters = encodingContext.getParameters();
     this.tile = encodingContext.getCoordinates();
-    this.tileEncoder = new VectorTileEncoder(tile.getTileMatrixSet().getTileExtent());
+    final int tileExtent = parameters.getTileExtentOrDefault(tile.getTileMatrixSet());
+    this.tileEncoder = new VectorTileEncoder(tileExtent);
     this.affineTransformation = createTransformNativeToTile();
     this.tileset = encodingContext.getTileset();
     this.tilePrecisionModel =
-        new PrecisionModel(
-            (double) tile.getTileMatrixSet().getTileExtent()
-                / (double) tile.getTileMatrixSet().getTileSize());
+        new PrecisionModel((double) tileExtent / (double) tile.getTileMatrixSet().getTileSize());
     this.geometryFactoryTile = new GeometryFactory(tilePrecisionModel);
     this.geometryFactoryWorld = new GeometryFactory();
 

xtraplatform-tiles/src/main/java/de/ii/xtraplatform/tiles/app/TileBuilderDefault.java

@@ -258,7 +258,9 @@ private FeatureQuery getFeatureQuery(
             .limit(tileset.getFeatureLimit())
             .offset(0)
             .crs(tile.getTileMatrixSet().getCrs())
-            .maxAllowableOffset(getMaxAllowableOffset(tile, nativeCrs));
+            .maxAllowableOffset(
+                getMaxAllowableOffset(
+                    tile, nativeCrs, tileset.getTileExtentOrDefault(tile.getTileMatrixSet())));
 
     if (tileset.getFilters().containsKey(tile.getTileMatrixSet().getId())) {
       tileset.getFilters().get(tile.getTileMatrixSet().getId()).stream()
@@ -310,10 +312,10 @@ private FeatureQuery getFeatureQuery(
     return queryBuilder.build();
   }
 
-  public double getMaxAllowableOffset(TileCoordinates tile, EpsgCrs nativeCrs) {
+  public double getMaxAllowableOffset(TileCoordinates tile, EpsgCrs nativeCrs, int tileExtent) {
     double maxAllowableOffsetTileMatrixSet =
         tile.getTileMatrixSet()
-            .getMaxAllowableOffset(tile.getLevel(), tile.getRow(), tile.getCol());
+            .getMaxAllowableOffset(tile.getLevel(), tile.getRow(), tile.getCol(), tileExtent);
     Unit<?> tmsCrsUnit = crsInfo.getUnit(tile.getTileMatrixSet().getCrs());
     Unit<?> nativeCrsUnit = crsInfo.getUnit(nativeCrs);
     if (tmsCrsUnit.equals(nativeCrsUnit)) {

xtraplatform-tiles/src/main/java/de/ii/xtraplatform/tiles/app/TileBuilderPgisAsMvt.java

@@ -290,27 +290,24 @@ private String queryToSql(
             .map(FeatureSchema::getName);
 
     String filter = filtersToSql(providerId, tileset, schema, tms.getId(), level);
-    int buffer = (tms.getTileExtent() / tms.getTileSize()) * TileBuilder.BUFFER_SIZE_FORMAL;
+    int tileExtent = tileset.getTileExtentOrDefault(tms);
+    // the buffer is in the units of the internal coordinate system, so it has to be derived from
+    // the tile extent to stay proportional to the tile
+    int buffer = (tileExtent / tms.getTileSize()) * TileBuilder.BUFFER_SIZE_FORMAL;
 
     String bounds = "bounds AS (SELECT %1$s AS geom, %2$s::box2d AS b2d)";
     String mvtgeom =
         String.format(
             "mvtgeom AS (SELECT ST_AsMVTGeom(ST_Transform(A.%1$s, %%3$s), bounds.b2d, %6$d, %7$d) AS geom, %2$s FROM %3$s A, bounds WHERE (%5$s AND ST_Intersects(A.%1$s, ST_Transform(bounds.geom, %4$s))))",
-            geomColumn,
-            attrColumns,
-            table,
-            nativeCrs.getCode(),
-            filter,
-            tms.getTileExtent(),
-            buffer);
+            geomColumn, attrColumns, table, nativeCrs.getCode(), filter, tileExtent, buffer);
 
     String template =
         String.format(
             "WITH\n%s,\n%s\nSELECT ST_AsMVT(mvtgeom.*, '%s', %d, 'geom'%s) FROM mvtgeom",
             bounds,
             mvtgeom,
             schema.getName(),
-            tms.getTileExtent(),
+            tileExtent,
             idProperty.map(id -> ", '" + id + "'").orElse(""));
 
     queryTemplates.put(key, template);

xtraplatform-tiles/src/main/java/de/ii/xtraplatform/tiles/app/TileEncoderMvt.java

@@ -43,10 +43,14 @@ public byte[] empty(TileMatrixSetBase tms) {
   public byte[] combine(
       TileQuery tile, TileProviderFeaturesData data, ChainedTileProvider tileProvider)
       throws IOException {
-    TilesetFeatures combinedTileset = data.getTilesets().get(tile.getTileset());
+    TilesetFeatures combinedTileset =
+        data.getTilesets().get(tile.getTileset()).mergeDefaults(data.getTilesetDefaults());
     List<String> tilesets =
         getLayerTilesets(data, combinedTileset, tile.getGenerationParametersTransient());
-    VectorTileEncoder encoder = new VectorTileEncoder(tile.getTileMatrixSet().getTileExtent());
+    // the layers of the source tilesets are decoded to a normalized coordinate space, so a source
+    // tileset with a different tile extent is rescaled to the tile extent of the combined tileset
+    VectorTileEncoder encoder =
+        new VectorTileEncoder(combinedTileset.getTileExtentOrDefault(tile.getTileMatrixSet()));
     VectorTileDecoder decoder = new VectorTileDecoder();
 
     for (String tileset : tilesets) {

xtraplatform-tiles/src/main/java/de/ii/xtraplatform/tiles/domain/TileGenerationOptions.java

@@ -9,6 +9,7 @@
 
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import javax.annotation.Nullable;
 
 public interface TileGenerationOptions {
@@ -97,4 +98,30 @@ public interface TileGenerationOptions {
    * @since v4.3
    */
   List<String> getProfiles();
+
+  /**
+   * @langEn The width and height of a tile in the internal coordinate system that is used for the
+   *     coordinates in a vector tile. A higher value increases the geometric precision of the tiles
+   *     and reduces the simplification of the geometries, but it also increases the size of the
+   *     tiles. The value should be a power of 2. Renderers typically restrict the internal
+   *     precision, MapLibre for example normalizes all coordinates to a value of `8192`, so higher
+   *     values have no effect in such clients. Changing the value invalidates the content of
+   *     existing tile caches, the tiles have to be seeded again.
+   * @langDe Die Breite und Höhe einer Kachel in dem internen Koordinatensystem, das für die
+   *     Koordinaten in einer Vector Tile verwendet wird. Ein höherer Wert erhöht die geometrische
+   *     Genauigkeit der Kacheln und reduziert die Vereinfachung der Geometrien, erhöht aber auch
+   *     die Größe der Kacheln. Der Wert sollte eine Zweierpotenz sein. Renderer beschränken die
+   *     interne Genauigkeit üblicherweise, MapLibre normalisiert zum Beispiel alle Koordinaten auf
+   *     einen Wert von `8192`, höhere Werte haben in solchen Clients daher keinen Effekt. Eine
+   *     Änderung des Werts invalidiert den Inhalt bestehender Tile-Caches, die Kacheln müssen
+   *     erneut geseedet werden.
+   * @default 4096
+   * @since v4.9
+   */
+  @Nullable
+  Integer getTileExtent();
+
+  default int getTileExtentOrDefault(TileMatrixSetBase tileMatrixSet) {
+    return Objects.isNull(getTileExtent()) ? tileMatrixSet.getTileExtent() : getTileExtent();
+  }
 }

xtraplatform-tiles/src/main/java/de/ii/xtraplatform/tiles/domain/TileMatrixSet.java

@@ -151,8 +151,24 @@ default int getRows(int level) {
    *     scheme
    */
   default double getMaxAllowableOffset(int level, int row, int col) {
+    return getMaxAllowableOffset(level, row, col, getTileExtent());
+  }
+
+  /**
+   * determine the Douglas-Peucker distance parameter for a tile that uses a tile extent that
+   * differs from the tile extent of the tiling scheme
+   *
+   * @param level the zoom level
+   * @param row the row
+   * @param col the column
+   * @param tileExtent the width/height of the tile in its internal coordinate system
+   * @return the distance in the units of measure of the coordinate references system of the tiling
+   *     scheme
+   */
+  @Override
+  default double getMaxAllowableOffset(int level, int row, int col, int tileExtent) {
     BoundingBox bbox = getBoundingBox();
-    return (bbox.getXmax() - bbox.getXmin()) / getCols(level) / getTileExtent();
+    return (bbox.getXmax() - bbox.getXmin()) / getCols(level) / tileExtent;
   }
 
   /**

xtraplatform-tiles/src/main/java/de/ii/xtraplatform/tiles/domain/TileMatrixSetBase.java

@@ -31,5 +31,7 @@ public interface TileMatrixSetBase {
 
   double getMaxAllowableOffset(int level, int row, int col);
 
+  double getMaxAllowableOffset(int level, int row, int col, int tileExtent);
+
   int getTmsRow(int level, int row);
 }

xtraplatform-tiles/src/main/java/de/ii/xtraplatform/tiles/domain/TilesetFeatures.java

@@ -69,6 +69,11 @@ public interface TilesetFeatures
   @Override
   Boolean getSparse();
 
+  @DocIgnore
+  @Nullable
+  @Override
+  Integer getTileExtent();
+
   @DocIgnore
   @Override
   Map<String, List<LevelTransformation>> getTransformations();
@@ -157,6 +162,9 @@ default TilesetFeatures mergeDefaults(TilesetFeaturesDefaults defaults) {
     if (Objects.isNull(this.getSparse()) && Objects.nonNull(defaults.getSparse())) {
       withDefaults.sparse(defaults.getSparse());
     }
+    if (Objects.isNull(this.getTileExtent()) && Objects.nonNull(defaults.getTileExtent())) {
+      withDefaults.tileExtent(defaults.getTileExtent());
+    }
 
     return withDefaults.build();
   }