Return SVG string when path not specified. Closes #39.

leather/chart.py

@@ -234,7 +234,7 @@ def to_svg_group(self, width, height):
 
         return root_group
 
-    def to_svg(self, path, width=None, height=None):
+    def to_svg(self, path=None, width=None, height=None):
         """
         Render this chart to an SVG document.
 
@@ -243,7 +243,8 @@ def to_svg(self, path, width=None, height=None):
         as though they were pixels.
 
         :param path:
-            Filepath or file-like object to write to.
+            Filepath or file-like object to write to. If not specified then
+            the SVG will be returned as a string.
         :param width:
             The output width, in SVG user units.
         :param height:
@@ -262,26 +263,26 @@ def to_svg(self, path, width=None, height=None):
         group = self.to_svg_group(width, height)
         root.append(group)
 
+        svg_text = svg.stringify(root)
         close = True
 
-        try:
-            if hasattr(path, 'write'):
-                f = path
-                close = False
-            else:
-                dirpath = os.path.dirname(path)
-
-                if dirpath and not os.path.exists(dirpath):
-                    os.makedirs(dirpath)
+        if path:
+            try:
+                if hasattr(path, 'write'):
+                    f = path
+                    close = False
+                else:
+                    dirpath = os.path.dirname(path)
 
-                f = open(path, 'w')
+                    if dirpath and not os.path.exists(dirpath):
+                        os.makedirs(dirpath)
 
-            f.write(svg.HEADER)
+                    f = open(path, 'w')
 
-            if six.PY3:
-                f.write(ET.tostring(root, encoding='unicode'))
-            else:
-                f.write(ET.tostring(root, encoding='utf-8'))
-        finally:
-            if close and f is not None:
-                f.close()
+                f.write(svg.HEADER)
+                f.write(svg_text)
+            finally:
+                if close and f is not None:
+                    f.close()
+        else:
+            return svg_text

leather/grid.py

@@ -23,7 +23,7 @@ def add_chart(self, chart):
         """
         self._charts.append(chart)
 
-    def to_svg(self, path, width=None, height=None):
+    def to_svg(self, path=None, width=None, height=None):
         """
         Render the grid to an SVG.
         """
@@ -61,23 +61,26 @@ def to_svg(self, path, width=None, height=None):
 
             root.append(group)
 
+        svg_text = svg.stringify(root)
         close = True
 
-        try:
-            if hasattr(path, 'write'):
-                f = path
-                close = False
-            else:
-                dirpath = os.path.dirname(path)
-
-                if dirpath and not os.path.exists(dirpath):
-                    os.makedirs(dirpath)
-
-                f = open(path, 'w')
-
-            f.write(svg.HEADER)
-            f.write(ET.tostring(root, encoding='unicode'))
-            f.close()
-        finally:
-            if close and f is not None:
-                f.close()
+        if path:
+            try:
+                if hasattr(path, 'write'):
+                    f = path
+                    close = False
+                else:
+                    dirpath = os.path.dirname(path)
+
+                    if dirpath and not os.path.exists(dirpath):
+                        os.makedirs(dirpath)
+
+                    f = open(path, 'w')
+
+                f.write(svg.HEADER)
+                f.write(svg_text)
+            finally:
+                if close and f is not None:
+                    f.close()
+        else:
+            return svg_text

leather/svg.py

@@ -4,9 +4,33 @@
 Helpers for working with SVG.
 """
 
+import xml.etree.ElementTree as ET
+
+import six
+
 HEADER = '<?xml version="1.0" standalone="no"?>\n' + \
     '<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"\n' + \
     '"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">\n'
 
+
+def stringify(root):
+    """
+    Convert an SVG XML tree to a unicode string.
+    """
+    if six.PY3:
+        return ET.tostring(root, encoding='unicode')
+    else:
+        return ET.tostring(root, encoding='utf-8')
+
+def save(f, root):
+    """
+    Save an SVG XML tree to a file.
+    """
+    f.write(HEADER)
+    f.write(stringify(root))
+
 def translate(x, y):
+    """
+    Generate an SVG transform statement representing a simple translation.
+    """
     return 'translate(%i %i)' % (x, y)

tests/utils.py

@@ -6,7 +6,6 @@
     import unittest
 
 from lxml import etree
-import six
 
 
 class XMLTest(unittest.TestCase):
@@ -17,10 +16,7 @@ def render_chart(self, chart):
         """
         Verify the column names in the given table match what is expected.
         """
-        output = six.StringIO()
-        chart.to_svg(output)
-        text = output.getvalue()
-
+        text = chart.to_svg()
         text = text.replace(' xmlns="http://www.w3.org/2000/svg"', '')
 
         return etree.fromstring(text)
@@ -29,6 +25,6 @@ def assertElementCount(self, svg, selector, count):
         series = svg.cssselect(selector)
         self.assertEqual(len(series), count)
 
-    def assertTickLabels(self, svg, orient, cmp):
+    def assertTickLabels(self, svg, orient, compare):
         ticks = [t.text for t in svg.cssselect('.%s .tick text' % orient)]
-        self.assertSequenceEqual(ticks, cmp)
+        self.assertSequenceEqual(ticks, compare)