细节层次控制

控制地图的视觉细节层次;

<!DOCTYPE html>
<html lang="en">
<head>
    <title>细节层次控制</title>
    <meta property="og:description" content="控制地图的视觉细节层次" />
    <meta charset='utf-8'>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel='stylesheet' href='https://unpkg.com/maplibre-gl@5.5.0/dist/maplibre-gl.css' />
    <script src='https://unpkg.com/maplibre-gl@5.5.0/dist/maplibre-gl.js'></script>
    <style>
        body { margin: 0; padding: 0; }
        html, body, #map { height: 100%; }
        .map-overlay {
            font: 12px/20px 'Helvetica Neue', Arial, Helvetica, sans-serif;
            position: absolute;
            width: 220px;
            top: 0;
            left: 0;
            padding: 10px;
        }
        .map-overlay .map-overlay-inner {
            background-color: #fff;
            box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
            border-radius: 3px;
            padding: 10px;
            margin-bottom: 10px;
        }
        .map-overlay-inner fieldset {
            border: none;
            padding: 0;
            margin: 0 0 10px;
        }
        .map-overlay-inner label {
            display: block;
            margin: 0 0 5px;
        }
        .map-overlay-inner input {
            width: 100%;
        }
        .info {
            font-size: 11px;
            font-style: italic;
            margin-top: 8px;
            color: #666;
        }
    </style>
</head>
<body>
<div id="map"></div>
<div class="map-overlay">
    <div class="map-overlay-inner">
        <fieldset>
            <label for="level">地图细节层次 (LOD)</label>
            <input id="level" type="range" min="0" max="1" step="0.01" value="1">
        </fieldset>
        <fieldset>
            <label for="lod-toggle">启用LOD控制</label>
            <input id="lod-toggle" type="checkbox" checked>
        </fieldset>
        <div class="info">
            降低LOD值可提升性能，尤其在低端设备上。
        </div>
    </div>
</div>
<script>
    // 创建MapLibre地图
    const map = new maplibregl.Map({
        container: 'map',
        style: 'https://api.maptiler.com/maps/streets/style.json?key=get_your_own_OpIi9ZULNHzrESv6T2vL',
        center: [-74.50, 40], // 起始位置
        zoom: 10 // 起始缩放级别
    });

    // 设置LOD级别
    function setLOD(level) {
        if (!map || !map.setLOD) return;
        map.setLOD(level);
    }

    // 获取控制元素
    const levelInput = document.getElementById('level');
    const lodToggle = document.getElementById('lod-toggle');

    // 添加事件监听器处理滑动条更改
    levelInput.addEventListener('input', function() {
        // 只有在LOD控制启用时设置LOD级别
        if (lodToggle.checked) {
            setLOD(parseFloat(levelInput.value));
        }
    });

    // 添加事件监听器处理复选框更改
    lodToggle.addEventListener('change', function() {
        if (lodToggle.checked) {
            // 启用LOD控制
            setLOD(parseFloat(levelInput.value));
            levelInput.disabled = false;
        } else {
            // 禁用LOD控制（设置为最大值1.0）
            setLOD(1.0);
            levelInput.disabled = true;
        }
    });

    // 地图加载后设置初始LOD值
    map.on('load', function() {
        if (lodToggle.checked) {
            setLOD(parseFloat(levelInput.value));
        }
    });

    // 添加导航控件
    map.addControl(new maplibregl.NavigationControl());
</script>
</body>
</html>