Extended Static-Images Endpoint (#619)

* extended staticmap capabilities

* added allowRemoteMarkerIcons configuration option and restricted fetching of remote marker icons only when option is set to true;
asynchronously load all available icons in a settings object on server startup;
replaced fs.existsSync() call in serve_rendered when drawing marker icons with a check against available icons settings object;

* updated documentation for linecap parameter in staticmaps endpoint;
added linejoin parameter to staticmaps endpoint;

* added capability of staticmap endpoint to draw multiple paths

docs/config.rst

@@ -14,6 +14,7 @@ Example:
         "root": "",
         "fonts": "fonts",
         "sprites": "sprites",
+        "icons": "icons",
         "styles": "styles",
         "mbtiles": ""
       },
@@ -31,6 +32,7 @@ Example:
       "serveAllFonts": false,
       "serveAllStyles": false,
       "serveStaticMaps": true,
+      "allowRemoteMarkerIcons": true,
       "tileMargin": 0
     },
     "styles": {
@@ -141,6 +143,13 @@ Optional string to be rendered into the raster tiles (and static maps) as waterm
 Can be used for hard-coding attributions etc. (can also be specified per-style).
 Not used by default.
 
+``allowRemoteMarkerIcons``
+--------------
+
+Allows the rendering of marker icons fetched via http(s) hyperlinks.
+For security reasons only allow this if you can control the origins from where the markers are fetched!
+Default is to disallow fetching of icons from remote sources.
+
 ``styles``
 ==========
 

docs/endpoints.rst

@@ -38,15 +38,41 @@ Static images
   * ``path`` - comma-separated ``lng,lat``, pipe-separated pairs
 
     * e.g. ``5.9,45.8|5.9,47.8|10.5,47.8|10.5,45.8|5.9,45.8``
+    * can be provided multiple times
 
-  * ``latlng`` - indicates the ``path`` coordinates are in ``lat,lng`` order rather than the usual ``lng,lat``
+  * ``latlng`` - indicates coordinates are in ``lat,lng`` order rather than the usual ``lng,lat``
   * ``fill`` - color to use as the fill (e.g. ``red``, ``rgba(255,255,255,0.5)``, ``#0000ff``)
   * ``stroke`` - color of the path stroke
   * ``width`` - width of the stroke
+  * ``linecap`` - rendering style for the start and end points of the path
+  * ``linejoin`` - rendering style for overlapping segments of the path with differing directions
+  * ``border`` - color of the optional border path stroke
+  * ``borderwidth`` - width of the border stroke (default 10% of width)
+  * ``marker`` - Marker in format ``lng,lat|iconPath|option|option|...``
+
+    * Will be rendered with the bottom center at the provided location
+    * ``lng,lat`` and ``iconPath`` are mandatory and icons won't be rendered without them
+    * ``iconPath`` is either a link to an image served via http(s) or a path to a file relative to the configured icon path
+    * ``option`` must adhere to the format ``optionName:optionValue`` and supports the following names
+
+      * ``scale`` - Factor to scale image by
+
+        * e.g. ``0.5`` - Scales the image to half it's original size
+
+      * ``offset`` - Image offset as positive or negative pixel value in format ``[offsetX],[offsetY]``
+
+        * scales with ``scale`` parameter since image placement is relative to it's size
+        * e.g. ``2,-4`` - Image will be moved 2 pixel to the right and 4 pixel in the upwards direction from the provided location
+
+    * e.g. ``5.9,45.8|marker-start.svg|scale:0.5|offset:2,-4``
+    * can be provided multiple times
+
   * ``padding`` - "percentage" padding for fitted endpoints (area-based and path autofit)
 
     * value of ``0.1`` means "add 10% size to each side to make sure the area of interest is nicely visible"
 
+  * ``maxzoom`` - Maximum zoom level (only for auto endpoint where zoom level is calculated and not provided)
+
 * You can also use (experimental) ``/styles/{id}/static/raw/...`` endpoints with raw spherical mercator coordinates (EPSG:3857) instead of WGS84.
 
 * The static images are not available in the ``tileserver-gl-light`` version.