103 lines
3.2 KiB
Dart
103 lines
3.2 KiB
Dart
import 'dart:async';
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import 'package:flutter/widgets.dart';
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import 'package:http/http.dart' as http;
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/// 底图来源：中文用户用 ESRI，非中文用户用 Google
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enum BaseMapProvider { esri, google }
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class BaseMapConfig {
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const BaseMapConfig({
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required this.provider,
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required this.maxNativeZoom,
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this.urlTemplate,
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this.googleLyr,
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});
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final BaseMapProvider provider;
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/// 原生最大层级：超出后由 flutter_map 用低级别瓦片拉伸，避免整片空白
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final int maxNativeZoom;
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/// ESRI XYZ 模板（WGS84，与设备 GPS 同一坐标系）
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final String? urlTemplate;
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/// Google 瓦片图层：s=纯卫星 / h=地名 / y=卫星+地名
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final String? googleLyr;
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static const BaseMapConfig esri = BaseMapConfig(
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provider: BaseMapProvider.esri,
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maxNativeZoom: 19,
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urlTemplate:
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'https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}',
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);
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/// lyrs=y 让境外用户一张图同时拿到卫星影像 + 英文地名（hl=en）
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static const BaseMapConfig google = BaseMapConfig(
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provider: BaseMapProvider.google,
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maxNativeZoom: 20,
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googleLyr: 'y',
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);
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/// 规则：中文 → ESRI；其余语言 → Google
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static BaseMapConfig of(Locale locale) =>
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locale.languageCode == 'zh' ? esri : google;
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}
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/// Google 瓦片可达性探测：失败后允许定期重试，避免一次探测失败就永久降级
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class GoogleTileAvailability {
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/// 失败后的重试冷却时长：开/关 VPN、切换网络后无需重启 App
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static const Duration retryAfter = Duration(seconds: 30);
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static Future<bool>? _cached;
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static bool? _lastResult;
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static DateTime? _lastFailAt;
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static Future<bool> reachable() {
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final cached = _cached;
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if (cached != null) {
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final failedAt = _lastFailAt;
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final shouldRetry = _lastResult == false &&
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failedAt != null &&
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DateTime.now().difference(failedAt) >= retryAfter;
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// 继续复用同一个 Future 对象，避免 FutureBuilder 因 future 变化而反复重建
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if (!shouldRetry) return cached;
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}
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final future = _probe();
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_cached = future;
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return future;
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}
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/// 手动重试（例如用户点「刷新地图」、App 从后台恢复）
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static void reset() {
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_cached = null;
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_lastResult = null;
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_lastFailAt = null;
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}
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static Future<bool> _probe() async {
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final sw = Stopwatch()..start();
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bool ok;
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try {
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final res = await http
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.get(Uri.parse('https://mt0.google.com/vt/lyrs=s&hl=en&x=1&y=0&z=1'))
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.timeout(const Duration(seconds: 3));
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ok = res.statusCode == 200 && res.bodyBytes.isNotEmpty;
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debugPrint(
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'🗺️ [BaseMap] Google 探测: http=${res.statusCode} '
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'bytes=${res.bodyBytes.length} ${sw.elapsedMilliseconds}ms '
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'→ ${ok ? '可用，英文底图用 Google' : '不可用，回退 ESRI'}',
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);
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} catch (e) {
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ok = false;
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debugPrint(
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'🗺️ [BaseMap] Google 探测异常: ${e.runtimeType} '
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'${sw.elapsedMilliseconds}ms → 回退 ESRI',
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);
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}
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_lastResult = ok;
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_lastFailAt = ok ? null : DateTime.now();
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return ok;
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}
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}
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