Allow interpolation to be configured for data tile sources

src/ol/source/DataTile.js

@@ -34,6 +34,8 @@ import {toPromise} from '../functions.js';
  * @property {boolean} [wrapX=false] Render tiles beyond the antimeridian.
  * @property {number} [transition] Transition time when fading in new tiles (in miliseconds).
  * @property {number} [bandCount=4] Number of bands represented in the data.
+ * @property {boolean} [interpolate=false] Use interpolated values when resampling.  By default,
+ * the nearest neighbor is used when resampling.
  */
 
 /**
@@ -71,6 +73,7 @@ class DataTileSource extends TileSource {
       tilePixelRatio: options.tilePixelRatio,
       wrapX: options.wrapX,
       transition: options.transition,
+      interpolate: options.interpolate,
     });
 
     /**
@@ -90,6 +93,12 @@ class DataTileSource extends TileSource {
      * @type {number}
      */
     this.bandCount = options.bandCount === undefined ? 4 : options.bandCount; // assume RGBA if undefined
+
+    /**
+     * @type {boolean}
+     * @private
+     */
+    this.interpolate_ = !!options.interpolate;
   }
 
   /**

src/ol/source/GeoTIFF.js

@@ -315,6 +315,8 @@ function getMaxForDataType(array) {
  * @property {number} [transition=250] Duration of the opacity transition for rendering.
  * To disable the opacity transition, pass `transition: 0`.
  * @property {boolean} [wrapX=false] Render tiles beyond the tile grid extent.
+ * @property {boolean} [interpolate=true] Use interpolated values when resampling.  By default,
+ * the linear interpolation is used to resample the data.  If false, nearest neighbor is used.
  */
 
 /**
@@ -333,6 +335,7 @@ class GeoTIFFSource extends DataTile {
       projection: null,
       opaque: options.opaque,
       transition: options.transition,
+      interpolate: options.interpolate !== false,
       wrapX: options.wrapX,
     });
 

src/ol/source/Tile.js

@@ -38,6 +38,8 @@ import {scale as scaleSize, toSize} from '../size.js';
  * @property {number} [transition] Transition.
  * @property {string} [key] Key.
  * @property {number|import("../array.js").NearestDirectionFunction} [zDirection=0] ZDirection.
+ * @property {boolean} [interpolate=false] Use interpolated values when resampling.  By default,
+ * the nearest neighbor is used when resampling.
  */
 
 /**
@@ -122,7 +124,10 @@ class TileSource extends Source {
      * @protected
      * @type {import("../Tile.js").Options}
      */
-    this.tileOptions = {transition: options.transition};
+    this.tileOptions = {
+      transition: options.transition,
+      interpolate: options.interpolate,
+    };
 
     /**
      * zDirection hint, read by the renderer. Indicates which resolution should be used

src/ol/source/TileImage.js

@@ -86,6 +86,7 @@ class TileImage extends UrlTile {
       urls: options.urls,
       wrapX: options.wrapX,
       transition: options.transition,
+      interpolate: options.imageSmoothing !== false,
       key: options.key,
       attributionsCollapsible: options.attributionsCollapsible,
       zDirection: options.zDirection,

src/ol/source/UrlTile.js

@@ -26,6 +26,8 @@ import {getUid} from '../util.js';
  * @property {number} [transition] Transition.
  * @property {string} [key] Key.
  * @property {number|import("../array.js").NearestDirectionFunction} [zDirection=0] ZDirection.
+ * @property {boolean} [interpolate=false] Use interpolated values when resampling.  By default,
+ * the nearest neighbor is used when resampling.
  */
 
 /**
@@ -49,6 +51,7 @@ class UrlTile extends TileSource {
       tilePixelRatio: options.tilePixelRatio,
       wrapX: options.wrapX,
       transition: options.transition,
+      interpolate: options.interpolate,
       key: options.key,
       attributionsCollapsible: options.attributionsCollapsible,
       zDirection: options.zDirection,