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鐵人賽 神助攻 HERE Technologies

HERE API Example - 顯示 KML 資料

KML (Keyhole Markup Language,鎖孔標記語言) 是一種檔案格式,用於存儲地理資料相關內容,採用標記結構,含有嵌套的元素和屬性。由 Google 旗下的 Keyhole 公司發展並維護,用來表達地理標記。

本範例取得 土石流潛勢溪流基本資料 KML 資料,採用內建的 KML 分析器載入資料並顯示於 HERE 地圖,當用戶點擊顯示於地圖上的土石流潛勢溪流形狀時,將顯示出溪流的名稱。

HTML

<!DOCTYPE html>
<html>
  <head>
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=yes">
    <meta http-equiv="Content-type" content="text/html;charset=UTF-8">
    <meta name="description" content="Parse a KML file and display the data on a map">
    <link rel="stylesheet" type="text/css" href="https://js.api.here.com/v3/3.1/mapsjs-ui.css" />
    <script type="text/javascript" src="https://js.api.here.com/v3/3.1/mapsjs-core.js"></script>
    <script type="text/javascript" src="https://js.api.here.com/v3/3.1/mapsjs-service.js"></script>
    <script type="text/javascript" src="https://js.api.here.com/v3/3.1/mapsjs-ui.js"></script>
    <script type="text/javascript" src="https://js.api.here.com/v3/3.1/mapsjs-mapevents.js"></script>
    <script type="text/javascript" src="https://js.api.here.com/v3/3.1/mapsjs-data.js"></script>
    <link rel="stylesheet" type="text/css" href="../template.css" />
    <link rel="stylesheet" type="text/css" href="demo.css" />
    <script type="text/javascript" src='../test-credentials.js'></script>     
    <style type="text/css">
      .log {
        position: absolute;
        top: 5px;
        left: 5px;
        height: 150px;
        width: 250px;
        overflow: scroll;
        background: white;
        margin: 0;
        padding: 0;
        list-style: none;
        font-size: 12px;
      }
      .log-entry {
        padding: 5px;
        border-bottom: 1px solid #d0d9e9;
      }
      .log-entry:nth-child(odd) {
          background-color: #e1e7f1;
      }
    </style>
  </head>
  <body>   
    <div id="map"></div>
    <script type="text/javascript" src='demo.js'></script>
  </body>
</html>

JavaScript

function renderKML(map) {
  // 建立 reader object 解析 KML 檔案
  reader = new H.data.kml.Reader('https://246.swcb.gov.tw/download/Debris.kml');
  reader.addEventListener("statechange", function(evt){
    if (evt.state === H.data.AbstractReader.State.READY) {
      // 從 reader object 取得 KML layer 並加到 map 中
      map.addLayer(reader.getLayer());
      reader.getLayer().getProvider().addEventListener("tap", (evt) => {
        logEvent(evt.target.getData().name)
      });
    }
    if (evt.state === H.data.AbstractReader.State.ERROR) {
      logEvent('KML 解析錯誤')
    }
  });

  reader.parse();
}

// Step 1: 初始化 platform
var platform = new H.service.Platform({
  apikey: window.apikey
});
var defaultLayers = platform.createDefaultLayers();

// Step 2: 初始化 map
var map = new H.Map(document.getElementById('map'), defaultLayers.vector.normal.map, {
  zoom: 8,
  center: {lat: 23, lng: 120},
  pixelRatio: window.devicePixelRatio || 1
});
// 建立 resize 監聽器
window.addEventListener('resize', () => map.getViewPort().resize());

// Step 3: 建立互動式地圖
var behavior = new H.mapevents.Behavior(new H.mapevents.MapEvents(map));

// Step 4: 建立預設 UI 元件
var ui = H.ui.UI.createDefault(map, defaultLayers);

// Step 5: 建立自訂的日誌記錄工具
var logContainer = document.createElement('ul');
logContainer.className ='log';
logContainer.innerHTML = '<li class="log-entry">嘗試點擊地圖</li>';
map.getElement().appendChild(logContainer);

function logEvent(str) {
  var entry = document.createElement('li');
  entry.className = 'log-entry';
  entry.textContent = str;
  logContainer.insertBefore(entry, logContainer.firstChild);
}

// Step 6: 主要邏輯
renderKML(map);

CSS

#map {
    width: 95%;
    height: 450px;
    background: grey;
}

#panel {
    width: 100%;
    height: 400px;
}

執行結果
https://ithelp.ithome.com.tw/upload/images/20200919/20012621O9j4VKlC59.jpg

參考文章
Display KML Data


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