add commands framework

1 files changed, 89 insertions, 0 deletions

diff --git a/lib/commands.py b/lib/commands.py
new file mode 100644
index 00000000..ec62d716
--- /dev/null
+++ b/lib/commands.py
@@ -0,0 +1,89 @@
+import inkex
+import cubicsuperpath
+
+from .svg import apply_transforms
+from .svg.tags import SVG_USE_TAG, SVG_SYMBOL_TAG, CONNECTION_START, CONNECTION_END, XLINK_HREF
+
+
+class Command(object):
+    def __init__(self, connector):
+        self.connector = connector
+        self.svg = self.connector.getroottree().getroot()
+
+        self.parse_command()
+
+    def get_node_by_url(self, url):
+        # url will be #path12345.  Find the object at the other end.
+
+        if url is None:
+            raise ValueError("url is None")
+
+        if not url.startswith('#'):
+            raise ValueError("invalid connection url: %s" % url)
+
+        id = url[1:]
+
+        try:
+            return self.svg.xpath(".//*[@id='%s']" % id)[0]
+        except (IndexError, AttributeError):
+            raise ValueError("could not find node by url %s" % id)
+
+    def parse_connector_path(self):
+        path = cubicsuperpath.parsePath(self.connector.get('d'))
+        return apply_transforms(path, self.connector)
+
+    def parse_command(self):
+        path = self.parse_connector_path()
+
+        neighbors = [
+            (self.get_node_by_url(self.connector.get(CONNECTION_START)), path[0][0][1]),
+            (self.get_node_by_url(self.connector.get(CONNECTION_END)), path[0][-1][1])
+        ]
+
+        if neighbors[0][0].tag != SVG_USE_TAG:
+            neighbors.reverse()
+
+        if neighbors[0][0].tag != SVG_USE_TAG:
+            raise ValueError("connector does not point to a use tag")
+
+        self.symbol = self.get_node_by_url(neighbors[0][0].get(XLINK_HREF))
+
+        if self.symbol.tag != SVG_SYMBOL_TAG:
+            raise ValueError("use points to non-symbol")
+
+        self.command = self.symbol.get('id')
+
+        if self.command.startswith('inkstitch_'):
+            self.command = self.command[10:]
+        else:
+            raise ValueError("symbol is not an Ink/Stitch command")
+
+        self.target = neighbors[1][0]
+        self.target_point = neighbors[1][1]
+
+    def __repr__(self):
+        return "Command('%s', %s)" % (self.command, self.target_point)
+
+def find_commands(node):
+    """Find the symbols this node is connected to and return them as Commands"""
+
+    # find all paths that have this object as a connection
+    xpath = ".//*[@inkscape:connection-start='#%(id)s' or @inkscape:connection-end='#%(id)s']" % dict(id=node.get('id'))
+    connectors = node.getroottree().getroot().xpath(xpath, namespaces=inkex.NSS)
+
+    # try to turn them into commands
+    commands = []
+    for connector in connectors:
+        try:
+            commands.append(Command(connector))
+        except ValueError:
+            import sys
+            import traceback
+            print >> sys.stderr, "not a Command:", connector.get('id'), traceback.format_exc()
+            # Parsing the connector failed, meaning it's not actually an Ink/Stitch command.
+            pass
+
+    return commands
+
+def is_command(node):
+    return CONNECTION_START in node.attrib or CONNECTION_END in node.attrib