An object with methods for projecting geographical coordinates of the world onto a flat surface (and back). See Map projection.
具有将世界地理坐标投影到平面（和背面）上的方法的对象。请参见贴图投影。
Methods
| Method | Returns | Description |
|---|---|---|
project(<LatLng> latlng) |
Point |
Projects geographical coordinates into a 2D point. Only accepts actual L.LatLng instances, not arrays.
将地理坐标投影到二维点中。只接受实际的L.LatLng实例，不接受数组。 |
unproject(<Point> point) |
LatLng |
The inverse of project. Projects a 2D point into a geographical location. Only accepts actual L.Point instances, not arrays.
Note that the projection instances do not inherit from Leaflet’s 项目的倒数。将二维点投影到地理位置。只接受实际的L.Point实例，不接受数组。请注意，投影实例不是从Leaflet的Class对象继承的，并且不能实例化。此外，新类不能从它们继承，方法也不能用include函数添加到它们中。 |
Properties
| Property | Type | Description |
|---|---|---|
bounds |
Bounds |
The bounds (specified in CRS units) where the projection is valid
投影有效的边界（以CRS单位指定） |
Defined projections
Leaflet comes with a set of already defined Projections out of the box:
Leaflet 附带一组现成的已定义投影：
| Projection | Description |
|---|---|
L.Projection.LonLat |
Equirectangular, or Plate Carree projection — the most simple projection, mostly used by GIS enthusiasts. Directly maps x as longitude, and y as latitude. Also suitable for flat worlds, e.g. game maps. Used by the EPSG:4326 and Simple CRS.
等矩形投影，或平板卡瑞投影-最简单的投影，主要由GIS爱好者使用。直接将x映射为经度，将y映射为纬度。也适用于平面世界，例如游戏地图。EPSG:4326和简单CRS使用。 |
L.Projection.Mercator |
Elliptical Mercator projection — more complex than Spherical Mercator. Assumes that Earth is an ellipsoid. Used by the EPSG:3395 CRS.
椭圆墨卡托投影-比球面墨卡托更复杂。假设地球是一个椭球体。EPSG使用：3395 CRS。 |
L.Projection.SphericalMercator |
Spherical Mercator projection — the most common projection for online maps, used by almost all free and commercial tile providers. Assumes that Earth is a sphere. Used by the EPSG:3857 CRS.
球面墨卡托投影-在线地图最常见的投影，几乎所有免费和商业瓷砖供应商都使用。假设地球是一个球体。EPSG使用：3857 CRS。 |