Added blockdiag liquid style tag

liquid_tags/diag.py

@@ -0,0 +1,177 @@
+"""
+Blockdiag Tag
+---------
+This tag implements a liquid style tag for blockdiag [1].  You can use different
+diagram types like blockdiag, seqdiag, packetdiag etc. [1]
+
+
+[1] http://blockdiag.com/en/blockdiag/
+
+Syntax
+------
+{% blockdiag {
+        <diagramm type> {
+            <CODE>
+        }
+    }
+%}
+
+Examples
+--------
+{% blockdiag {
+        blockdiag {
+          A -> B -> C;
+          B -> D;
+        }
+    }
+%}
+
+
+{% blockdiag {
+        actdiag {
+          A -> B -> C -> D -> E;
+
+          lane {
+            A; C; E;
+          }
+          lane {
+            B; D;
+          }
+        }
+    }
+%}
+
+
+{% blockdiag {
+        packetdiag {
+           0-7: Source Port
+           8-15: Destination Port
+           16-31: Sequence Number
+           32-47: Acknowledgment Number
+        }
+    }
+%}
+
+...
+
+
+Output
+------
+<div class="blockdiag" style="align: center;"><img src="data:image/png;base64,_BASE64_IMAGE DATA_/></div>
+
+"""
+
+import io
+import os
+import sys
+
+import base64
+import re
+from .mdx_liquid_tags import LiquidTags
+
+
+SYNTAX = '{% blockdiag [diagram type] [code] %}'
+DOT_BLOCK_RE = re.compile(r'^\s*(?P<diagram>\w+).*$', re.MULTILINE | re.DOTALL)
+
+_draw_mode = 'PNG'
+_publish_mode = 'PNG'
+
+
+def get_diag(code, command):
+    """ Generate diagramm and return data """
+    import tempfile
+    import shutil
+    code = code + u'\n'
+
+    try:
+        tmpdir = tempfile.mkdtemp()
+        fd, diag_name = tempfile.mkstemp(dir=tmpdir)
+
+        f = os.fdopen(fd, "w")
+        f.write(code.encode('utf-8'))
+        f.close()
+
+        format = _draw_mode.lower()
+        draw_name = diag_name + '.' + format
+
+        saved_argv = sys.argv
+        argv = [diag_name, '-T', format, '-o', draw_name]
+
+        if _draw_mode == 'SVG':
+            argv += ['--ignore-pil']
+
+        # Run command
+        command.main(argv)
+
+        # Read image data from file
+        file_name = diag_name + '.' + _publish_mode.lower()
+
+        with io.open(file_name, 'rb') as f:
+            data = f.read()
+            f.close()
+
+    finally:
+        for file in os.listdir(tmpdir):
+            os.unlink(tmpdir + "/" + file)
+
+        # os.rmdir will fail -> use shutil
+        shutil.rmtree(tmpdir)
+
+    return data
+
+
+def diag(code, command):
+    if command == "blockdiag":                      # blockdiag
+        import blockdiag.command
+        return get_diag(code, blockdiag.command)
+
+    elif command == "diagram":                      # diagram
+        import blockdiag.command
+        return get_diag(code, blockdiag.command)
+
+    elif command == "seqdiag":                      # seqdiag
+        import seqdiag.command
+        return get_diag(code, seqdiag.command)
+
+    elif command == "actdiag":                      # actdiag
+        import actdiag.command
+        return get_diag(code, actdiag.command)
+
+    elif command == "nwdiag":                       # nwdiag
+        import nwdiag.command
+        return get_diag(code, nwdiag.command)
+
+    elif command == "packetdiag":                   # packetdiag
+        import packetdiag.command
+        return get_diag(code, packetdiag.command)
+
+    elif command == "rackdiag":                     # racketdiag
+        import rackdiag.command
+        return get_diag(code, rackdiag.command)
+
+    else:                                           # not found
+        print("No such command %s" % command)
+        return None
+
+
+@LiquidTags.register("blockdiag")
+def blockdiag_parser(preprocessor, tag, markup):
+    """ Blockdiag parser """
+    m = DOT_BLOCK_RE.search(markup)
+    if m:
+        # Get diagram type and code
+        diagram = m.group('diagram').strip()
+        code = markup
+
+        # Run command
+        output = diag(code, diagram)
+
+        if output:
+            # Return Base64 encoded image
+            return '<div class="blockdiag" style="align: center;"><img src="data:image/png;base64,%s"></div>' % base64.b64encode(output)
+    else:
+        raise ValueError('Error processing input. '
+                         'Expected syntax: {0}'.format(SYNTAX))
+
+# This import allows image tag to be a Pelican plugin
+from .liquid_tags import register