fix 代码备注

 /*
  * @Date: 2025-01-22 11:45:30
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-02-08 10:24:25
+ * @LastEditTime: 2025-02-24 13:21:58
  * @FilePath: /map-demo/src/utils/TileCutter.js
  * @Description: 文件描述
  */
@@ -21,27 +21,38 @@ export function TileCutter(imageURL, bounds, zoomLevel) {
 }
 
 
+/**
+ * 将图片切割成瓦片并打包下载
+ * @param {HTMLImageElement} image - 要切割的图片元素
+ * @param {L.LatLngBounds} bounds - 图片边界范围，包含西南角和东北角的经纬度
+ * @param {number} zoomLevel - 地图缩放级别
+ */
 function sliceImageToTiles(image, bounds, zoomLevel) {
+  // 创建画布及上下文
   const canvas = document.createElement("canvas");
   const ctx = canvas.getContext("2d");
 
-  const imgWidth = image.width;
-  const imgHeight = image.height;
+  // 获取原始图片尺寸
+  const imgWidth = image.width;    // 图片原始宽度
+  const imgHeight = image.height;  // 图片原始高度
 
-  const southWest = bounds.getSouthWest();
-  const northEast = bounds.getNorthEast();
+  // 获取边界经纬度
+  const southWest = bounds.getSouthWest();  // 西南角坐标
+  const northEast = bounds.getNorthEast();  // 东北角坐标
 
-  const lonStart = southWest.lng;
-  const latStart = southWest.lat;
-  const lonEnd = northEast.lng;
-  const latEnd = northEast.lat;
+  // 提取边界经纬度值
+  const lonStart = southWest.lng;  // 起始经度
+  const latStart = southWest.lat;  // 起始纬度
+  const lonEnd = northEast.lng;    // 结束经度
+  const latEnd = northEast.lat;    // 结束纬度
 
-  let tileStartX = lonToTileX(lonStart, zoomLevel);
-  let tileEndX = lonToTileX(lonEnd, zoomLevel);
-  let tileStartY = latToTileY(latEnd, zoomLevel); // 取 latEnd 作为起点
-  let tileEndY = latToTileY(latStart, zoomLevel); // 取 latStart 作为终点
+  // 计算瓦片坐标范围
+  let tileStartX = lonToTileX(lonStart, zoomLevel);  // 起始瓦片X坐标
+  let tileEndX = lonToTileX(lonEnd, zoomLevel);      // 结束瓦片X坐标
+  let tileStartY = latToTileY(latEnd, zoomLevel);    // 起始瓦片Y坐标
+  let tileEndY = latToTileY(latStart, zoomLevel);    // 结束瓦片Y坐标
 
-  // 确保 tileStartX <= tileEndX，tileStartY <= tileEndY
+  // 确保瓦片坐标范围正确（起始值小于结束值）
   tileStartX = Math.min(tileStartX, tileEndX);
   tileEndX = Math.max(tileStartX, tileEndX);
   tileStartY = Math.min(tileStartY, tileEndY);
@@ -49,9 +60,11 @@ function sliceImageToTiles(image, bounds, zoomLevel) {
 
   const scaleFactor = 2; // 调高分辨率倍率
 
+  // 设置画布尺寸
   canvas.width = tileSize * scaleFactor;
   canvas.height = tileSize * scaleFactor;
 
+  // 设置画布缩放
   ctx.scale(scaleFactor, scaleFactor);
 
   const zip = new JSZip();  // 创建一个 JSZip 实例，用来打包所有瓦片
@@ -62,26 +75,28 @@ function sliceImageToTiles(image, bounds, zoomLevel) {
   for (let tileX = tileStartX; tileX <= tileEndX; tileX++) {
     for (let tileY = tileStartY; tileY <= tileEndY; tileY++) {
       // 计算当前瓦片的经纬度范围
-      const tileLonStart = tileX * 360 / Math.pow(2, zoomLevel) - 180;
-      const tileLonEnd = (tileX + 1) * 360 / Math.pow(2, zoomLevel) - 180;
-      const tileLatStart = Math.atan(Math.sinh(Math.PI * (1 - 2 * (tileY + 1) / Math.pow(2, zoomLevel)))) * 180 / Math.PI;
-      const tileLatEnd = Math.atan(Math.sinh(Math.PI * (1 - 2 * tileY / Math.pow(2, zoomLevel)))) * 180 / Math.PI;
-
-      // 计算图片在当前瓦片中的位置和尺寸
-      const tileImgX = (lonStart - tileLonStart) / (tileLonEnd - tileLonStart) * tileSize;
-      const tileImgY = (tileLatEnd - latEnd) / (tileLatEnd - tileLatStart) * tileSize;
-      const tileImgWidth = (lonEnd - lonStart) / (tileLonEnd - tileLonStart) * tileSize;
-      const tileImgHeight = (latEnd - latStart) / (tileLatEnd - tileLatStart) * tileSize;
-
+      const tileLonStart = tileX * 360 / Math.pow(2, zoomLevel) - 180;        // 瓦片起始经度
+      const tileLonEnd = (tileX + 1) * 360 / Math.pow(2, zoomLevel) - 180;   // 瓦片结束经度
+      const tileLatStart = Math.atan(Math.sinh(Math.PI * (1 - 2 * (tileY + 1) / Math.pow(2, zoomLevel)))) * 180 / Math.PI;  // 瓦片起始纬度
+      const tileLatEnd = Math.atan(Math.sinh(Math.PI * (1 - 2 * tileY / Math.pow(2, zoomLevel)))) * 180 / Math.PI;          // 瓦片结束纬度
+
+      // 计算图片在当前瓦片中的位置和尺寸（像素坐标）
+      const tileImgX = (lonStart - tileLonStart) / (tileLonEnd - tileLonStart) * tileSize;        // 图片在瓦片中的X坐标
+      const tileImgY = (tileLatEnd - latEnd) / (tileLatEnd - tileLatStart) * tileSize;           // 图片在瓦片中的Y坐标
+      const tileImgWidth = (lonEnd - lonStart) / (tileLonEnd - tileLonStart) * tileSize;         // 图片在瓦片中的宽度
+      const tileImgHeight = (latEnd - latStart) / (tileLatEnd - tileLatStart) * tileSize;        // 图片在瓦片中的高度
+
+      // 清空画布
       ctx.clearRect(0, 0, tileSize * scaleFactor, tileSize * scaleFactor);
 
-      // 根据图片在瓦片中的实际位置和尺寸绘制
+      // 绘制图片到画布
       ctx.drawImage(
         image,
         0, 0, imgWidth, imgHeight, // 源图像区域（使用完整图片）
         tileImgX, tileImgY, tileImgWidth, tileImgHeight // 目标画布区域（保持实际位置和比例）
       );
 
+      // 将画布内容转换为Blob对象
       canvas.toBlob((blob) => {
         if (!blob) {
           console.error("瓦片转换失败！");
@@ -104,6 +119,7 @@ function sliceImageToTiles(image, bounds, zoomLevel) {
     }
   }
 }
+
 // 经纬度转换为瓦片坐标
 function lonToTileX(lon, zoom) {
   return Math.floor(((lon + 180) / 360) * Math.pow(2, zoom));
@@ -127,7 +143,7 @@ function saveTile(blob, filename) {
 // 生成并下载压缩包
 function generateAndDownloadZip(zip, zoomLevel) {
   zip.generateAsync({ type: "blob" }).then((content) => {
-      // 使用 FileSaver.js 下载压缩包
-      saveAs(content, `${zoomLevel}级瓦片切片包.zip`);
+    // 使用 FileSaver.js 下载压缩包
+    saveAs(content, `${zoomLevel}级瓦片切片包.zip`);
   });
 }