#18: add initial graph.py

README.md

@@ -64,7 +64,7 @@ overlay_file = ffmpeg.input('overlay.png')
     )
     .overlay(overlay_file.hflip())
     .drawbox(50, 50, 120, 120, color='red', thickness=5)
-    .output(TEST_OUTPUT_FILE)
+    .output('out.mp4')
     .run()
 )
 ```

ffmpeg/graph.py

@@ -0,0 +1,47 @@
+from __future__ import unicode_literals
+
+from .dag import get_outgoing_edges
+from ._run import topo_sort
+import graphviz
+import os
+
+from ffmpeg.nodes import (
+    InputNode,
+    OutputNode,
+    FilterNode,
+    operator,
+)
+
+
+@operator()
+def view(*downstream_nodes, **kwargs):
+    sorted_nodes, outgoing_edge_maps = topo_sort(downstream_nodes)
+    graph = graphviz.Digraph()
+    graph.attr(rankdir='LR')
+    show_labels = kwargs.pop('show_labels', False)
+    if len(kwargs.keys()) != 0:
+        raise ValueError('Invalid kwargs key(s): {}'.format(', '.join(kwargs.keys())))
+
+    for node in sorted_nodes:
+        name = node.name
+        if '_kwargs' in dir(node) and 'filename' in node._kwargs:
+            name = os.path.basename(node._kwargs['filename'])
+        if isinstance(node, InputNode):
+            color = '#99cc00'
+        elif isinstance(node, OutputNode):
+            color = '#99ccff'
+        elif isinstance(node, FilterNode):
+            color = '#ffcc00'
+        else:
+            color = None
+        graph.node(str(hash(node)), name, shape='box', style='filled', fillcolor=color)
+        outgoing_edge_map = outgoing_edge_maps.get(node, {})
+        for edge in get_outgoing_edges(node, outgoing_edge_map):
+            kwargs = {}
+            if show_labels:
+                kwargs['label'] = '{} -> {}'.format(edge.upstream_label, edge.downstream_label)
+            upstream_node_id = str(hash(edge.upstream_node))
+            downstream_node_id = str(hash(edge.downstream_node))
+            graph.edge(upstream_node_id, downstream_node_id, **kwargs)
+
+    graph.view('graph.png')