Add iconUrlFunction option

Test iconUrlFunction option

remove @private

test/spec/ol/format/kml.test.js

@@ -2154,6 +2154,52 @@ describe('ol.format.KML', function () {
           expect(style.getZIndex()).to.be(undefined);
         });
 
+        it("can read a feature's IconStyle and apply an iconUrlFunction", function () {
+          format = new KML({
+            iconUrlFunction: function (href) {
+              return href.replace(/^http:/, 'https:');
+            },
+          });
+          const text =
+            '<kml xmlns="http://earth.google.com/kml/2.2">' +
+            '  <Placemark>' +
+            '    <Style>' +
+            '      <IconStyle>' +
+            '        <Icon>' +
+            '          <href>http://foo.png</href>' +
+            '        </Icon>' +
+            '      </IconStyle>' +
+            '    </Style>' +
+            '  </Placemark>' +
+            '</kml>';
+          const fs = format.readFeatures(text);
+          expect(fs).to.have.length(1);
+          const f = fs[0];
+          expect(f).to.be.an(Feature);
+          const styleFunction = f.getStyleFunction();
+          expect(styleFunction).not.to.be(undefined);
+          const styleArray = styleFunction(f, 0);
+          expect(styleArray).to.be.an(Array);
+          expect(styleArray).to.have.length(1);
+          const style = styleArray[0];
+          expect(style).to.be.an(Style);
+          expect(style.getFill()).to.be(getDefaultFillStyle());
+          expect(style.getStroke()).to.be(getDefaultStrokeStyle());
+          const imageStyle = style.getImage();
+          expect(imageStyle).to.be.an(Icon);
+          expect(new URL(imageStyle.getSrc()).href).to.eql(
+            new URL('https://foo.png').href
+          );
+          expect(imageStyle.getAnchor()).to.be(null);
+          expect(imageStyle.getOrigin()).to.be(null);
+          expect(imageStyle.getRotation()).to.eql(0);
+          expect(imageStyle.getSize()).to.be(null);
+          expect(imageStyle.getScale()).to.be(1);
+          expect(imageStyle.getImage().crossOrigin).to.eql('anonymous');
+          expect(style.getText()).to.be(getDefaultTextStyle());
+          expect(style.getZIndex()).to.be(undefined);
+        });
+
         it("can read a IconStyle's hotspot", function () {
           const text =
             '<kml xmlns="http://earth.google.com/kml/2.2">' +