Example RV OTIO reading application plugin (#565)

* Example RV OTIO reading application plugin

contrib/opentimelineio_contrib/application_plugins/rv/example_otio_reader/PACKAGE

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+package: Example OTIO Reader
+author: Robyn Rindge
+organization: Pixar Animation Studios
+contact: opentimelineio@pixar.com
+version: 1.0
+url: http://opentimeline.io
+rv: 4.0.8
+
+modes: 
+  - file: example_otio_reader_plugin.py
+    load: immediate
+  - file: otio_reader.py
+    location: Python
+
+
+description: |
+  <p>
+  Example plugin that can read files supported by otio from within rv. This is
+  meant only as proof of concept.
+  </p>
+  <p>
+  To create the package run:
+  </p>
+  <p>
+  zip example_otio_reader_plugin-1.0.rvpkg PACKAGE example_otio_reader_plugin.py otio_reader.py
+  </p>

contrib/opentimelineio_contrib/application_plugins/rv/example_otio_reader/example_otio_reader_plugin.py

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+"""
+Example plugin showing how otio files can be loaded into an RV context
+"""
+#
+# Copyright 2019 Pixar Animation Studios
+#
+# Licensed under the Apache License, Version 2.0 (the "Apache License")
+# with the following modification; you may not use this file except in
+# compliance with the Apache License and the following modification to it:
+# Section 6. Trademarks. is deleted and replaced with:
+#
+# 6. Trademarks. This License does not grant permission to use the trade
+#    names, trademarks, service marks, or product names of the Licensor
+#    and its affiliates, except as required to comply with Section 4(c) of
+#    the License and to reproduce the content of the NOTICE file.
+#
+# You may obtain a copy of the Apache License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the Apache License with the above modification is
+# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the Apache License for the specific
+# language governing permissions and limitations under the Apache License.
+#
+
+import os
+
+from rv import commands
+from rv import rvtypes
+
+import opentimelineio as otio
+
+import otio_reader
+
+
+class Mode(object):
+    sleeping = 1
+    loading = 2
+    processing = 3
+
+
+class ExampleOTIOReaderPlugin(rvtypes.MinorMode):
+    def __init__(self):
+        super(ExampleOTIOReaderPlugin, self).__init__()
+        self.init("example_otio_reader",
+                  [("incoming-source-path",
+                    self.incoming_source_path,
+                    "Catch otio supported files and return movieproc"),
+                   ("source-group-complete",
+                    self.source_group_complete,
+                    "Expand otio supported files (synchronous load)"),
+                   ("after-progressive-loading",
+                    self.after_progressive_loading,
+                    "Expand otio supported files (asynchronous load)")],
+                  None)
+
+        # Start as sleeping
+        self.mode = Mode.sleeping
+
+    def incoming_source_path(self, event):
+        """
+        Detects if a file supported by otio is being loaded, and replaces
+        it with an empty movie proc containing an otioFile tag. This will be
+        replaced in expand_sources().
+        """
+        event.reject()
+
+        parts = event.contents().split(';')
+        in_path = parts[0]
+        _, ext = os.path.splitext(in_path)
+        if ext:
+            ext = ext[1:]
+
+        if ext in otio.adapters.suffixes_with_defined_adapters(read=True):
+            self.mode = Mode.loading
+            movieproc = 'blank,otioFile={}.movieproc'.format(in_path)
+            event.setReturnContent(movieproc)
+
+    def after_progressive_loading(self, event):
+        """
+        After progress loading event, is used for asynchronous addSource
+        file loading.
+        """
+        event.reject()
+
+        if self.mode != Mode.loading:
+            return
+        self.mode = Mode.processing
+        self.expand_sources()
+
+    def source_group_complete(self, event):
+        """
+        Source group complete event, is used for synchronous addSource
+        file loading.
+        """
+        event.reject()
+        if self.mode == Mode.sleeping:
+            # this plugin isn't doing anything
+            return
+
+        if self.mode == Mode.processing:
+            # already processing otio
+            return
+
+        if commands.loadTotal() > 0:
+            # async load
+            return
+
+        self.mode = Mode.processing
+        self.expand_sources()
+
+    def expand_sources(self):
+        """
+        Expand any movie movieproc otioFile sources.
+        """
+        # disable caching for load speed
+        cache_mode = commands.cacheMode()
+        commands.setCacheMode(commands.CacheOff)
+
+        try:
+            # find sources with a movieproc with an otioFile=foo.otio tag
+            default_inputs, _ = commands.nodeConnections('defaultSequence')
+            for src in commands.nodesOfType('RVSource'):
+                src_group = commands.nodeGroup(src)
+                if src_group not in default_inputs:
+                    # not in default sequence, already processed
+                    continue
+
+                # get the source file name
+                paths = [info['file'] for info in
+                         commands.sourceMediaInfoList(src) if 'file' in info]
+                for info_path in paths:
+                    # Looking for: 'blank,otioFile=/foo.otio.movieproc'
+                    parts = info_path.split("=", 1)
+                    itype = parts[0]
+                    if not itype.startswith('blank,otioFile'):
+                        continue
+                    # remove the .movieproc extension
+                    path, _ = os.path.splitext(parts[1])
+
+                    # remove temp movieproc source from current view, and all
+                    # the default views
+                    _remove_source_from_views(src_group)
+
+                    result = otio_reader.read_otio_file(path)
+                    commands.setViewNode(result)
+                    break
+        finally:
+            # turn cache mode back on and go back to sleep
+            commands.setCacheMode(cache_mode)
+            self.mode = Mode.sleeping
+
+
+def _remove_source_from_views(source_group):
+    """
+    Remove a source group from all views.
+    """
+    for view in commands.viewNodes():
+        view_inputs = commands.nodeConnections(view)[0]
+        if source_group in view_inputs:
+            view_inputs.remove(source_group)
+            commands.setNodeInputs(view, view_inputs)
+
+
+def createMode():
+    return ExampleOTIOReaderPlugin()