Resizable Split Map Panes

Comparing layers

This example allows comparison of two layers with resizable map panes using the Split.js library.

TypeScript

function initMap(): void {
  const mapOptions = {
    center: { lat: 44.5250489, lng: -110.83819 },
    zoom: 18,
    scaleControl: false,
    streetViewControl: false
  };

  // instantiate the map on the left with control positioning
  mapLeft = new google.maps.Map(
    document.getElementById("map-left") as HTMLElement,
    {
      ...mapOptions,
      mapTypeId: "satellite",
      tilt: 0, // at high zoom levels we need to maintain the same projection
      fullscreenControlOptions: {
        position: google.maps.ControlPosition.LEFT_BOTTOM
      },
      mapTypeControlOptions: {
        position: google.maps.ControlPosition.LEFT_TOP
      },
      zoomControlOptions: {
        position: google.maps.ControlPosition.LEFT_BOTTOM
      }
    }
  );

  // instantiate the map on the right with control positioning
  mapRight = new google.maps.Map(
    document.getElementById("map-right") as HTMLElement,
    {
      ...mapOptions,
      fullscreenControlOptions: {
        position: google.maps.ControlPosition.RIGHT_BOTTOM
      },
      mapTypeControlOptions: {
        position: google.maps.ControlPosition.RIGHT_TOP
      },
      zoomControlOptions: {
        position: google.maps.ControlPosition.RIGHT_BOTTOM
      }
    }
  );

  // helper function to keep maps in sync
  function sync(...maps: google.maps.Map[]) {
    let center: google.maps.LatLng, zoom: number;

    function update(changedMap) {
      maps.forEach(m => {
        if (m === changedMap) {
          return;
        }
        m.setCenter(center);
        m.setZoom(zoom);
      });
    }

    maps.forEach(m => {
      m.addListener("bounds_changed", () => {
        const changedCenter = m.getCenter();
        const changedZoom = m.getZoom();

        if (changedCenter !== center || changedZoom !== zoom) {
          center = changedCenter;
          zoom = changedZoom;
          update(m);
        }
      });
    });
  }

  sync(mapLeft, mapRight);

  function handleContainerResize() {
    const width = (document.getElementById("container") as HTMLElement)
      .offsetWidth;
    (document.getElementById(
      "map-left"
    ) as HTMLElement).style.width = `${width}px`;
    (document.getElementById(
      "map-right"
    ) as HTMLElement).style.width = `${width}px`;
  }

  // trigger to set map container size since using absolute
  handleContainerResize();
  // add event listener
  window.addEventListener("resize", handleContainerResize);

  //@ts-ignore
  Split(["#left", "#right"], {
    sizes: [50, 50]
  });
}
index.ts

Note: Read the guide on using TypeScript and Google Maps.

JavaScript

let mapLeft, mapRight;

function initMap() {
  const mapOptions = {
    center: { lat: 44.5250489, lng: -110.83819 },
    zoom: 18,
    scaleControl: false,
    streetViewControl: false
  };
  // instantiate the map on the left with control positioning
  mapLeft = new google.maps.Map(document.getElementById("map-left"), {
    ...mapOptions,
    mapTypeId: "satellite",
    tilt: 0,
    fullscreenControlOptions: {
      position: google.maps.ControlPosition.LEFT_BOTTOM
    },
    mapTypeControlOptions: {
      position: google.maps.ControlPosition.LEFT_TOP
    },
    zoomControlOptions: {
      position: google.maps.ControlPosition.LEFT_BOTTOM
    }
  });
  // instantiate the map on the right with control positioning
  mapRight = new google.maps.Map(document.getElementById("map-right"), {
    ...mapOptions,
    fullscreenControlOptions: {
      position: google.maps.ControlPosition.RIGHT_BOTTOM
    },
    mapTypeControlOptions: {
      position: google.maps.ControlPosition.RIGHT_TOP
    },
    zoomControlOptions: {
      position: google.maps.ControlPosition.RIGHT_BOTTOM
    }
  });

  // helper function to keep maps in sync
  function sync(...maps) {
    let center, zoom;

    function update(changedMap) {
      maps.forEach(m => {
        if (m === changedMap) {
          return;
        }
        m.setCenter(center);
        m.setZoom(zoom);
      });
    }
    maps.forEach(m => {
      m.addListener("bounds_changed", () => {
        const changedCenter = m.getCenter();
        const changedZoom = m.getZoom();

        if (changedCenter !== center || changedZoom !== zoom) {
          center = changedCenter;
          zoom = changedZoom;
          update(m);
        }
      });
    });
  }
  sync(mapLeft, mapRight);

  function handleContainerResize() {
    const width = document.getElementById("container").offsetWidth;
    document.getElementById("map-left").style.width = `${width}px`;
    document.getElementById("map-right").style.width = `${width}px`;
  }
  // trigger to set map container size since using absolute
  handleContainerResize();
  // add event listener
  window.addEventListener("resize", handleContainerResize);
  //@ts-ignore
  Split(["#left", "#right"], {
    sizes: [50, 50]
  });
}
index.js

Note: The JavaScript is compiled from the TypeScript snippet.

CSS

/* Always set the map height explicitly to define the size of the div
       * element that contains the map. */
#map {
  height: 100%;
}

/* Optional: Makes the sample page fill the window. */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

#container,
#left,
#right,
.map,
.gutter {
  height: 100%;
}

#left,
#right,
.gutter {
  float: left;
  position: relative;
  overflow: hidden;
}

#map-left {
  position: absolute;
  left: 0;
  top: 0;
}

#map-right {
  position: absolute;
  right: 0;
  top: 0;
}

.gutter {
  background-color: #eee;
  background-repeat: no-repeat;
  background-position: 50%;
}

.gutter.gutter-horizontal {
  cursor: col-resize;
  background-image: url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAeCAYAAADkftS9AAAAIklEQVQoU2M4c+bMfxAGAgYYmwGrIIiDjrELjpo5aiZeMwF+yNnOs5KSvgAAAABJRU5ErkJggg==");
}
style.css

HTML

<!DOCTYPE html>
<html>
  <head>
    <title>Split Map Panes</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/split.js/1.5.11/split.min.js"></script>
    <script
      src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initMap&libraries=&v=weekly"
      defer
    ></script>
    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script src="./app.js"></script>
  </head>
  <body>
    <div id="container">
      <div id="left">
        <div id="map-left" class="map"></div>
      </div>
      <div id="right">
        <div id="map-right" class="map"></div>
      </div>
    </div>
  </body>
</html>
sample.html

All

<!DOCTYPE html>
<html>
  <head>
    <title>Split Map Panes</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/split.js/1.5.11/split.min.js"></script>
    <script
      src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initMap&libraries=&v=weekly"
      defer
    ></script>
    <style type="text/css">
      /* Always set the map height explicitly to define the size of the div
       * element that contains the map. */
      #map {
        height: 100%;
      }

      /* Optional: Makes the sample page fill the window. */
      html,
      body {
        height: 100%;
        margin: 0;
        padding: 0;
      }

      #container,
      #left,
      #right,
      .map,
      .gutter {
        height: 100%;
      }

      #left,
      #right,
      .gutter {
        float: left;
        position: relative;
        overflow: hidden;
      }

      #map-left {
        position: absolute;
        left: 0;
        top: 0;
      }

      #map-right {
        position: absolute;
        right: 0;
        top: 0;
      }

      .gutter {
        background-color: #eee;
        background-repeat: no-repeat;
        background-position: 50%;
      }

      .gutter.gutter-horizontal {
        cursor: col-resize;
        background-image: url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAeCAYAAADkftS9AAAAIklEQVQoU2M4c+bMfxAGAgYYmwGrIIiDjrELjpo5aiZeMwF+yNnOs5KSvgAAAABJRU5ErkJggg==");
      }
    </style>
    <script>
      "use strict";

      let mapLeft, mapRight;

      function initMap() {
        const mapOptions = {
          center: {
            lat: 44.5250489,
            lng: -110.83819
          },
          zoom: 18,
          scaleControl: false,
          streetViewControl: false
        }; // instantiate the map on the left with control positioning

        mapLeft = new google.maps.Map(document.getElementById("map-left"), {
          ...mapOptions,
          mapTypeId: "satellite",
          tilt: 0,
          fullscreenControlOptions: {
            position: google.maps.ControlPosition.LEFT_BOTTOM
          },
          mapTypeControlOptions: {
            position: google.maps.ControlPosition.LEFT_TOP
          },
          zoomControlOptions: {
            position: google.maps.ControlPosition.LEFT_BOTTOM
          }
        }); // instantiate the map on the right with control positioning

        mapRight = new google.maps.Map(document.getElementById("map-right"), {
          ...mapOptions,
          fullscreenControlOptions: {
            position: google.maps.ControlPosition.RIGHT_BOTTOM
          },
          mapTypeControlOptions: {
            position: google.maps.ControlPosition.RIGHT_TOP
          },
          zoomControlOptions: {
            position: google.maps.ControlPosition.RIGHT_BOTTOM
          }
        }); // helper function to keep maps in sync

        function sync(...maps) {
          let center, zoom;

          function update(changedMap) {
            maps.forEach(m => {
              if (m === changedMap) {
                return;
              }

              m.setCenter(center);
              m.setZoom(zoom);
            });
          }

          maps.forEach(m => {
            m.addListener("bounds_changed", () => {
              const changedCenter = m.getCenter();
              const changedZoom = m.getZoom();

              if (changedCenter !== center || changedZoom !== zoom) {
                center = changedCenter;
                zoom = changedZoom;
                update(m);
              }
            });
          });
        }

        sync(mapLeft, mapRight);

        function handleContainerResize() {
          const width = document.getElementById("container").offsetWidth;
          document.getElementById("map-left").style.width = `${width}px`;
          document.getElementById("map-right").style.width = `${width}px`;
        } // trigger to set map container size since using absolute

        handleContainerResize(); // add event listener

        window.addEventListener("resize", handleContainerResize); //@ts-ignore

        Split(["#left", "#right"], {
          sizes: [50, 50]
        });
      }
    </script>
  </head>
  <body>
    <div id="container">
      <div id="left">
        <div id="map-left" class="map"></div>
      </div>
      <div id="right">
        <div id="map-right" class="map"></div>
      </div>
    </div>
  </body>
</html>
inline.html

"use strict"; let mapLeft, mapRight; function initMap() { const mapOptions = { center: { lat: 44.5250489, lng: -110.83819 }, zoom: 18, scaleControl: false, streetViewControl: false }; // instantiate the map on the left with control positioning mapLeft = new google.maps.Map(document.getElementById("map-left"), { ...mapOptions, mapTypeId: "satellite", tilt: 0, fullscreenControlOptions: { position: google.maps.ControlPosition.LEFT_BOTTOM }, mapTypeControlOptions: { position: google.maps.ControlPosition.LEFT_TOP }, zoomControlOptions: { position: google.maps.ControlPosition.LEFT_BOTTOM } }); // instantiate the map on the right with control positioning mapRight = new google.maps.Map(document.getElementById("map-right"), { ...mapOptions, fullscreenControlOptions: { position: google.maps.ControlPosition.RIGHT_BOTTOM }, mapTypeControlOptions: { position: google.maps.ControlPosition.RIGHT_TOP }, zoomControlOptions: { position: google.maps.ControlPosition.RIGHT_BOTTOM } }); // helper function to keep maps in sync function sync(...maps) { let center, zoom; function update(changedMap) { maps.forEach(m => { if (m === changedMap) { return; } m.setCenter(center); m.setZoom(zoom); }); } maps.forEach(m => { m.addListener("bounds_changed", () => { const changedCenter = m.getCenter(); const changedZoom = m.getZoom(); if (changedCenter !== center || changedZoom !== zoom) { center = changedCenter; zoom = changedZoom; update(m); } }); }); } sync(mapLeft, mapRight); function handleContainerResize() { const width = document.getElementById("container").offsetWidth; document.getElementById("map-left").style.width = `${width}px`; document.getElementById("map-right").style.width = `${width}px`; } // trigger to set map container size since using absolute handleContainerResize(); // add event listener window.addEventListener("resize", handleContainerResize); //@ts-ignore Split(["#left", "#right"], { sizes: [50, 50] }); }

/* Always set the map height explicitly to define the size of the div * element that contains the map. */ #map { height: 100%; } /* Optional: Makes the sample page fill the window. */ html, body { height: 100%; margin: 0; padding: 0; } #container, #left, #right, .map, .gutter { height: 100%; } #left, #right, .gutter { float: left; position: relative; overflow: hidden; } #map-left { position: absolute; left: 0; top: 0; } #map-right { position: absolute; right: 0; top: 0; } .gutter { background-color: #eee; background-repeat: no-repeat; background-position: 50%; } .gutter.gutter-horizontal { cursor: col-resize; background-image: url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAeCAYAAADkftS9AAAAIklEQVQoU2M4c+bMfxAGAgYYmwGrIIiDjrELjpo5aiZeMwF+yNnOs5KSvgAAAABJRU5ErkJggg=="); }

<!DOCTYPE html> <html> <head> <title>Split Map Panes</title> <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/split.js/1.5.11/split.min.js"></script> <script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyBIwzALxUPNbatRBj3Xi1Uhp0fFzwWNBkE&callback=initMap&libraries=&v=weekly" defer ></script> <!-- jsFiddle will insert css and js --> </head> <body> <div id="container"> <div id="left"> <div id="map-left" class="map"></div> </div> <div id="right"> <div id="map-right" class="map"></div> </div> </div> </body> </html>

Create a starter application from sample

A skeleton starter application using TypeScript, Webpack, and Babel can be generated from this sample using one of the methods below.

Run Locally

Node.js is required to run this sample locally. Follow these instructions to install Node.js and NPM.

npm i -g '@googlemaps/js-samples'
googlemaps-js-samples init split-map-panes DESTINATION_FOLDER

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Run in Cloud Shell

Click the start button in the Cloud Shell tutorial.