Question

Pretty simple question.

I’ve got some Polygons and GroundOverlays defined in KML. Is there a way to specify that they should be clickable, and (in Google Earth, at least) pop up an info balloon or similar when they are clicked?

Similarly, is it possible to give polygons/GroundOverlays any sort of mouseover behavior? e.g. change the icon or color when moused over?

Answer 1

Yes. Giving the Placemark a name and description will make it a clickable object in Google Earth and will open with an info window showing both. You can create rollover/mouseover behavior using stylemaps, here is an example that does both:

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
<Document>
<name>Highlighted Icon</name>
<description>Place your mouse over the icon to see it display the new
      icon</description>
<StyleMap id="exampleStyleMap">
  <Pair>
    <key>normal</key>
    <!-- you could also use a <styleUrl> here instead of inlining -->
    <Style>
      <PolyStyle>
        <color>7dff0000</color>
      </PolyStyle>
    </Style>
  </Pair>
  <Pair>
    <key>highlight</key>
    <!-- you could also use a <styleUrl> here instead of inlining -->
    <Style>
      <PolyStyle>
        <color>7dffffff</color>
      </PolyStyle>
    </Style>
  </Pair>
</StyleMap>

<!-- and now, a Placemark that uses the StyleMap -->
<Placemark>
  <name>Roll over this polygon</name>
  <description>this will show up when clicked</description>
  <visibility>1</visibility>
  <styleUrl>#exampleStyleMap</styleUrl>
  <Polygon>
    <tessellate>1</tessellate>
    <altitudeMode>absolute</altitudeMode>
    <outerBoundaryIs>
      <LinearRing>
        <coordinates>
          -112.3372510731295,36.14888505105317,1784
          -112.3356128688403,36.14781540589019,1784
          -112.3368169371048,36.14658677734382,1784
          -112.3384408457543,36.14762778914076,1784
          -112.3372510731295,36.14888505105317,1784
        </coordinates>
      </LinearRing>
    </outerBoundaryIs>
  </Polygon>
</Placemark>
</Document>
</kml>