Merge remote-tracking branch 'origin/feature/17'

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/__init__.py

@@ -4,5 +4,6 @@ from . import _filters, _ffmpeg, _run
 from ._filters import *
 from ._ffmpeg import *
 from ._run import *
+from ._view import *
 
-__all__ = _filters.__all__ + _ffmpeg.__all__ + _run.__all__
+__all__ = _filters.__all__ + _ffmpeg.__all__ + _run.__all__ + _view.__all__

ffmpeg/_view.py

@@ -0,0 +1,86 @@
+from __future__ import unicode_literals
+
+from builtins import str
+from .dag import get_outgoing_edges
+from ._run import topo_sort
+import os
+import tempfile
+
+from ffmpeg.nodes import (
+    FilterNode,
+    get_stream_spec_nodes,
+    InputNode,
+    OutputNode,
+    Stream,
+    stream_operator,
+)
+
+
+_RIGHT_ARROW = '\u2192'
+
+
+def _get_node_color(node):
+    if isinstance(node, InputNode):
+        color = '#99cc00'
+    elif isinstance(node, OutputNode):
+        color = '#99ccff'
+    elif isinstance(node, FilterNode):
+        color = '#ffcc00'
+    else:
+        color = None
+    return color
+
+
+@stream_operator()
+def view(stream_spec, **kwargs):
+    try:
+        import graphviz
+    except ImportError:
+        raise ImportError('failed to import graphviz; please make sure graphviz is installed (e.g. `pip install '
+            'graphviz`)')
+
+    filename = kwargs.pop('filename', None)
+    show_labels = kwargs.pop('show_labels', True)
+    if filename is None:
+        filename = tempfile.mktemp()
+
+    nodes = get_stream_spec_nodes(stream_spec)
+
+    sorted_nodes, outgoing_edge_maps = topo_sort(nodes)
+    graph = graphviz.Digraph()
+    graph.attr(rankdir='LR')
+    if len(list(kwargs.keys())) != 0:
+        raise ValueError('Invalid kwargs key(s): {}'.format(', '.join(list(kwargs.keys()))))
+
+    for node in sorted_nodes:
+        color = _get_node_color(node)
+
+        graph.node(str(hash(node)), node.short_repr, 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 = {}
+            up_label = edge.upstream_label
+            down_label = edge.downstream_label
+            if show_labels and (up_label is not None or down_label is not None):
+                if up_label is None:
+                    up_label = ''
+                if down_label is None:
+                    down_label = ''
+                if up_label != '' and down_label != '':
+                    middle = ' {} '.format(_RIGHT_ARROW)
+                else:
+                    middle = ''
+                kwargs['label'] = '{}  {}  {}'.format(up_label, middle, down_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(filename)
+
+    return stream_spec
+
+
+__all__ = [
+    'view',
+]