Added pygal generation tag to liquid tags

Generate SVG graphs using PyGal

liquid_tags/pygalcharts.py

@@ -0,0 +1,164 @@
+"""
+pygal Tag
+---------
+This implements a Liquid-style pygal tag for Pelican. JSON is used for the data,
+and you can pass a bunch of pygal's 'config' items through as-is
+
+[1] http://www.pygal.org/
+
+Syntax
+------
+{% pygal
+    {
+        <graph data>
+    }
+%}
+
+Examples
+--------
+{%
+	pygal {
+		"type": "bar",
+		"title": "Test Chart",
+		"x-labels" : {"from": 2002, "to": 2013},
+		"data" : [
+		{"title": "Firefox",
+		 "values": [null, null, 0, 16.6,   25,   31, 36.4, 45.5, 46.3, 42.8, 37.1]},
+		 {"title": "Chrome",
+		 "values": [null, null, null, null, null, null,    0,  3.9, 10.8, 23.8, 35.3]},
+		 {"title": "IE",
+		 "values": [85.8, 84.6, 84.7, 74.5,   66, 58.6, 54.7, 44.8, 36.2, 26.6, 20.1]},
+		 {"title": "Others",
+		 "values": [14.2, 15.4, 15.3,  8.9,    9, 10.4,  8.9,  5.8,  6.7,  6.8,  7.5]}
+		]
+	}
+%}
+
+{%
+	pygal {
+		"type": "pie",
+		"half_pie": true,
+		"title": "Browser usage in February 2012 (in %)",
+		"data" : [
+		{"title": "IE",
+		 "values": 19.5},
+		 {"title": "Firefox",
+		 "values": 36.6},
+		 {"title": "Chrome",
+		 "values": 36.3},
+		 {"title": "Safari",
+		 "values": 4.5},
+		 {"title": "Opera",
+		 "values": 2.3}
+		]
+	}
+%}
+
+{%
+	pygal {
+		"type": "pie",
+			"config": {
+			"show_legend": false,
+			"print_values": true,
+			"show_y_labels": true
+		},
+		"title": "Browser usage in February 2012 (in %)",
+		"data" : [
+		{"title": "IE",
+		 "values": 19.5},
+		 {"title": "Firefox",
+		 "values": 36.6},
+		 {"title": "Chrome",
+		 "values": 36.3},
+		 {"title": "Safari",
+		 "values": 4.5},
+		 {"title": "Opera",
+		 "values": 2.3}
+		]
+	}
+%}
+
+
+
+...
+
+
+Output
+------
+<<div class="pygal" style="text-align: center;"><embed type="image/svg+xml" src=SVG_MARKUP_EMBEDDED style="max-width:1000px"/></div>
+
+"""
+
+import base64
+import re
+from json import loads
+from .mdx_liquid_tags import LiquidTags
+
+SYNTAX = '{% pygal (data) %}'
+DOT_BLOCK_RE = re.compile(r'^\s*\{\s*(?P<code>.*\})\s*\}$', re.MULTILINE | re.DOTALL)
+
+
+def run_pygal(data, options=[], format='svg'):
+    """ Runs pygal programs and returns image data
+    """
+    import pygal
+
+    chart_title = data.get('title', None)
+    chart_type = data.get('type', '').lower()
+    # Config options are pretty much proxied straight through from the JSON dict into the object
+    config = pygal.Config()
+    config_dict = data.get('config', {})
+    for key in config_dict.keys():
+        setattr(config, key, config_dict[key])
+
+    if chart_type == 'bar':
+        chart = pygal.HorizontalBar(config) if data.get('horizontal', False) else pygal.Bar(config)
+    elif chart_type == 'line':
+        chart = pygal.Line(config)
+    elif chart_type == 'pie':
+        ir=data.get('inner_radius', 0.0)
+        hp=data.get('half_pie', False)
+        chart = pygal.Pie(config, inner_radius=ir, half_pie=hp)
+    else:
+        print('undefined or unknown chart type')
+
+    if chart is not None:
+        chart.title = data.get('title', None)
+        # Do labels (if present)
+        label_data = data.get('x-labels', None)
+        if isinstance(label_data, list):
+            # use list
+            chart.x_labels = label_data
+        elif isinstance(label_data, dict):
+            # use a range
+            range_from = label_data.get('from', 0)
+            range_to = label_data.get('to', 0)
+            chart.x_labels = map(str, range(range_from, range_to))
+        # insert data
+        for data_set in data.get('data', []):
+            title = data_set.get('title', None)
+            values = data_set.get('values', None)
+            chart.add(title, values)
+        # now render
+        result = chart.render_data_uri()
+    else:
+        result = None
+    return result
+
+@LiquidTags.register('pygal')
+def pygal_parser(preprocessor, tag, markup):
+    """ Simple pygal parser """
+    # Find JSON payload
+    data = loads(markup)
+    if tag == 'pygal' and data is not None:
+        # Run generation of chart
+        output = run_pygal(data)
+        # Return embedded SVG image
+        return '<div class="pygal" style="text-align: center;"><embed type="image/svg+xml" src=%s style="max-width:1000px"/></div>' % output
+
+    else:
+        raise ValueError('Error processing input. \nExpected syntax: {0}'.format(SYNTAX))
+
+#----------------------------------------------------------------------
+# This import allows image tag to be a Pelican plugin
+from .liquid_tags import register