Clip tile layers by extent

src/ol/renderer/canvas/Layer.js

@@ -85,6 +85,39 @@ class CanvasLayerRenderer extends LayerRenderer {
     rotateAtOffset(context, rotation, halfWidth, halfHeight);
   }
 
+  /**
+   * @param {CanvasRenderingContext2D} context Context.
+   * @param {import("../../PluggableMap.js").FrameState} frameState Frame state.
+   * @param {import("../../extent.js").Extent} extent Clip extent.
+   * @protected
+   */
+  clipUnrotated(context, frameState, extent) {
+    const topLeft = getTopLeft(extent);
+    const topRight = getTopRight(extent);
+    const bottomRight = getBottomRight(extent);
+    const bottomLeft = getBottomLeft(extent);
+
+    applyTransform(frameState.coordinateToPixelTransform, topLeft);
+    applyTransform(frameState.coordinateToPixelTransform, topRight);
+    applyTransform(frameState.coordinateToPixelTransform, bottomRight);
+    applyTransform(frameState.coordinateToPixelTransform, bottomLeft);
+
+    const inverted = invertTransform(this.pixelTransform_.slice());
+
+    applyTransform(inverted, topLeft);
+    applyTransform(inverted, topRight);
+    applyTransform(inverted, bottomRight);
+    applyTransform(inverted, bottomLeft);
+
+    context.save();
+    context.beginPath();
+    context.moveTo(Math.round(topLeft[0]), Math.round(topLeft[1]));
+    context.lineTo(Math.round(topRight[0]), Math.round(topRight[1]));
+    context.lineTo(Math.round(bottomRight[0]), Math.round(bottomRight[1]));
+    context.lineTo(Math.round(bottomLeft[0]), Math.round(bottomLeft[1]));
+    context.clip();
+  }
+
   /**
    * @param {import("../../render/EventType.js").default} type Event type.
    * @param {CanvasRenderingContext2D} context Context.

src/ol/renderer/canvas/TileLayer.js

@@ -143,12 +143,10 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
     const tileResolution = tileGrid.getResolution(z);
     let extent = frameState.extent;
 
-    if (layerState.extent !== undefined) {
+    if (layerState.extent) {
       extent = getIntersection(extent, layerState.extent);
     }
 
-    // TODO: clip by layer extent
-
     const tilePixelRatio = tileSource.getTilePixelRatio(pixelRatio);
 
     // desired dimensions of the canvas in pixels
@@ -235,6 +233,10 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
       context.clearRect(0, 0, width, height);
     }
 
+    if (layerState.extent) {
+      this.clipUnrotated(context, frameState, layerState.extent);
+    }
+
     this.preRender(context, frameState, pixelTransform);
 
     this.renderedTiles.length = 0;
@@ -285,6 +287,10 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
 
     this.postRender(context, frameState, pixelTransform);
 
+    if (layerState.extent) {
+      context.restore();
+    }
+
     const opacity = layerState.opacity;
     if (opacity !== canvas.style.opacity) {
       canvas.style.opacity = opacity;