From 3393de3c5460e0a9411bbcff4d363905b280be3f Mon Sep 17 00:00:00 2001
From: changqing <changqingom@outlook.com>
Date: Tue, 15 Dec 2020 15:38:48 +0800
Subject: [PATCH] Custom circle render example

---
 examples/custom-circle-render.html |  9 ++++
 examples/custom-circle-render.js   | 66 ++++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+)
 create mode 100644 examples/custom-circle-render.html
 create mode 100644 examples/custom-circle-render.js

diff --git a/examples/custom-circle-render.html b/examples/custom-circle-render.html
new file mode 100644
index 0000000000..f0ed7ad7c0
--- /dev/null
+++ b/examples/custom-circle-render.html
@@ -0,0 +1,9 @@
+---
+layout: example.html
+title: Custom Circle Render
+shortdesc: Example of a custom circle render.
+docs: >
+  This example demonstrates the use of 'ol/style/Style' render option function to render circle feature.
+tags: "circle, feature, vector, render, custom"
+---
+<div id="map" class="map"></div>
diff --git a/examples/custom-circle-render.js b/examples/custom-circle-render.js
new file mode 100644
index 0000000000..57c7bf4026
--- /dev/null
+++ b/examples/custom-circle-render.js
@@ -0,0 +1,66 @@
+import Feature from '../src/ol/Feature.js';
+import Map from '../src/ol/Map.js';
+import View from '../src/ol/View.js';
+import {Circle} from '../src/ol/geom.js';
+import {OSM, Vector as VectorSource} from '../src/ol/source.js';
+import {Style} from '../src/ol/style.js';
+import {Tile as TileLayer, Vector as VectorLayer} from '../src/ol/layer.js';
+
+const circleFeature = new Feature({
+  geometry: new Circle([12127398.797692968, 4063894.123105166], 50),
+});
+circleFeature.setStyle(
+  new Style({
+    renderer(coordinate, state) {
+      // eslint-disable-next-line no-console
+      console.log('This circle is rendered by the code below.', Date.now());
+      const [x, y, x1, y1] = coordinate;
+      const ctx = state.context;
+      const dx = x1 - x;
+      const dy = y1 - y;
+      const radius = Math.sqrt(dx * dx + dy * dy);
+
+      const innerRadius = 0;
+      const outerRadius = radius * 1.4;
+
+      const gradient = ctx.createRadialGradient(
+        x,
+        y,
+        innerRadius,
+        x,
+        y,
+        outerRadius
+      );
+      gradient.addColorStop(0, 'rgba(255,0,0,0)');
+      gradient.addColorStop(0.6, 'rgba(255,0,0,0.2)');
+      gradient.addColorStop(1, 'rgba(255,0,0,0.8)');
+      ctx.beginPath();
+      ctx.arc(x, y, radius, 0, 2 * Math.PI, true);
+      ctx.fillStyle = gradient;
+      ctx.fill();
+
+      ctx.arc(x, y, radius, 0, 2 * Math.PI, true);
+      ctx.strokeStyle = 'rgba(255,0,0,1)';
+      ctx.stroke();
+    },
+  })
+);
+
+new Map({
+  layers: [
+    new TileLayer({
+      source: new OSM(),
+      visible: true,
+    }),
+    new VectorLayer({
+      source: new VectorSource({
+        features: [circleFeature],
+      }),
+    }),
+  ],
+  target: 'map',
+  view: new View({
+    center: [12127398.797692968, 4063894.123105166],
+    zoom: 19,
+  }),
+});