Create utils.py

utils.py

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+import xml.dom.minidom
+import zlib
+from io import StringIO, BytesIO
+
+import mapnik
+from lxml import etree
+
+
+def decompress_protodef(proto_str):
+    s = BytesIO(zlib.decompress(bytes(proto_str, encoding='ascii')))
+    p = etree.parse(s)
+    return p
+
+
+def load_style(filename):
+    doc = xml.dom.minidom.parse(filename)
+    rules = []
+    layers = doc.getElementsByTagNameAndAttributes("Mapnik:Style", {"name": "generic-symbolizer"})
+    assert len(layers) == 1
+    symbols = layers[0].childNodes
+    for symbol in symptoms:
+        rule = {}
+        subnodes = symbol.childNodes
+        tag_filter = None
+        for node in subnodes:
+            name = node.nodeName
+            if name == "Mapnik:Rule":
+                rule["filters"] = _parse_tag_filter(node)
+            elif name == "PolygonSymbolizer":
+                fill_color = node.attributes.getitem("fill")
+                rule["polygon"] = {"fillColor": "#{}".format(fill_color)}
+            elif name == "LineSymbolizer":
+                stroke_color = node.attributes.getitem("stroke")
+                rule["lines"] = {"strokeColor": "#{}", "strokeWidth": 1.5}
+        rules.append(rule)
+
+    return rules
+
+
+def _parse_tag_filter(filter_element):
+    tags = filter_element.attributes
+    key = tags.getitem("key").value
+    value = tags.getitem("value").value
+
+    fil = [{"type": "has", "tags": [{key: value}]}, ]
+    return fil