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Plugin hooks (#351)

* Add doc page for plugins
* Add htmlcov to gitignore.
* Schemadef was missing from setup.py.
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ssteinbach committed Oct 25, 2018
1 parent 3cb1135 commit 6727d215dcfb1386bf4432e608f99d68168159b2
@@ -5,10 +5,11 @@ dist*
*.egg-info
.coverage
.DS_store
htmlcov
# Pycharm metadata
.idea/
# These files are generated, don't put them into source control
docs/api
.tox
.tox
@@ -43,11 +43,12 @@ Tutorials
tutorials/otio-file-format-specification
tutorials/otio-timeline-structure
tutorials/time-ranges
tutorials/versioning-schemas
tutorials/wrapping-otio
tutorials/write-an-adapter
tutorials/write-a-media-linker
tutorials/write-a-hookscript
tutorials/write-a-schemadef
tutorials/versioning-schemas
tutorials/wrapping-otio
Use Cases
------------
@@ -0,0 +1,80 @@
# Writing a Hook Script
OpenTimelineIO Hook Scripts are plugins that run at predefined points during the execution of various OTIO functions, for example after an adapter has read a file into memory but before the media linker has run.
To write a new hook script, you create a python source file that defines a
a function named ``hook_function`` with signature:
``hook_function :: otio.schema.Timeline, Dict => otio.schema.Timeline``
The first argument is the timeline to process, and the second one is a dictionary of arguments that can be passed to it. Only one hook function can be defined per python file.
For example:
```python
def hook_function(tl, arg_dict):
for cl in tl.each_clip():
cl.metadata['example_hook_function_was_here'] = True
return tl
```
This will insert some extra metadata into each clip.
This plugin can then be registered with the system by configuring a plugin manifest.
## Registering Your Hook Script
To create a new OTIO hook script, you need to create a file myhooks.py. Then add a manifest that points at that python file:
```
{
"OTIO_SCHEMA" : "PluginManifest.1",
"hook_scripts" : [
{
"OTIO_SCHEMA" : "HookScript.1",
"name" : "example hook",
"execution_scope" : "in process",
"filepath" : "example.py"
}
],
"hooks" : {
"pre_adapter_write" : ["example hook"],
"post_adapter_read" : []
}
}
```
The ``hook_scripts`` section will register the plugin with the system, and the ``hooks`` section will attach the scripts to hooks.
Then you need to add this manifest to your `$OTIO_PLUGIN_MANIFEST_PATH` environment variable (which is "`:`" separated). You may also define media linkers and adapters via the same manifest.
## Running a Hook Script
If you would like to call a hook script from a plugin, the hooks need not be one of the ones that otio pre-defines. You can have a plugin adapter or media linker, for example, that defines its own hooks and calls your own custom studio specific hook scripts. To run a hook script from your custom code, you can call:
``otio.hooks.run("some_hook", some_timeline, optional_argument_dict)``
This will call the ``some_hook`` hook script and pass in ``some_timeline`` and ``optional_argument_dict``.
## Order of Hook Scripts
To query which hook scripts are attached to a given hook, you can call:
```
import opentimelineio as otio
hook_list = otio.hooks.scripts_attached_to("some_hook")
```
Note that ``hook_list`` will be in order of execution. You can rearrange this list, or edit it to change which scripts will run (or not run) and in which order.
To Edit the order, change the order in the list:
```
hook_list[0], hook_list[2] = hook_list[2], hook_list[0]
print hook_list # ['c','b','a']
```
Now c will run, then b, then a.
To delete a function the list:
```
del hook_list[1]
```
@@ -39,7 +39,9 @@
schema,
schemadef,
plugins,
media_linker,
adapters,
hooks,
algorithms,
test_utils,
console,
@@ -32,6 +32,7 @@
core,
plugins,
media_linker,
hooks,
)
@@ -134,6 +135,9 @@ def read_from_file(
**adapter_argument_map
)
# @TODO: pass arguments through?
result = hooks.run("post_adapter_read", result)
if media_linker_name and (
media_linker_name != media_linker.MediaLinkingPolicy.DoNotLinkMedia
):
@@ -143,6 +147,9 @@ def read_from_file(
media_linker_argument_map
)
# @TODO: pass arguments through?
result = hooks.run("post_media_linker", result)
return result
def write_to_file(self, input_otio, filepath, **adapter_argument_map):
@@ -152,6 +159,9 @@ def write_to_file(self, input_otio, filepath, **adapter_argument_map):
a trivial file object wrapper.
"""
# @TODO: pass arguments through?
input_otio = hooks.run("pre_adapter_write", input_otio)
if (
not self.has_feature("write_to_file") and
self.has_feature("write_to_string")
@@ -183,6 +193,9 @@ def read_from_string(
**adapter_argument_map
)
# @TODO: pass arguments through?
result = hooks.run("post_adapter_read", result)
if media_linker_name and (
media_linker_name != media_linker.MediaLinkingPolicy.DoNotLinkMedia
):
@@ -192,11 +205,18 @@ def read_from_string(
media_linker_argument_map
)
# @TODO: pass arguments through?
# @TODO: Should this run *ONLY* if the media linker ran?
result = hooks.run("post_media_linker", result)
return result
def write_to_string(self, input_otio, **adapter_argument_map):
"""Call the write_to_string function on this adapter."""
# @TODO: pass arguments through?
input_otio = hooks.run("pre_adapter_write", input_otio)
return self._execute_function(
"write_to_string",
input_otio=input_otio,
@@ -22,5 +22,10 @@
"filepath" : "cmx_3600.py",
"suffixes" : ["edl"]
}
]
],
"hooks": {
"post_adapter_read" : [],
"post_media_linker" : [],
"pre_adapter_write" : []
}
}
@@ -0,0 +1,174 @@
#
# Copyright 2018 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.
#
from . import (
plugins,
core,
)
__doc__ = """
HookScripts are plugins that run at defined points ("Hooks").
They expose a hook_function with signature:
hook_function :: otio.schema.Timeline, Dict -> otio.schema.Timeline
Both hook scripts and the hooks they attach to are defined in the plugin
manifest.
You can attach multiple hook scripts to a hook. They will be executed in list
order, first to last.
They are defined by the manifests HookScripts and hooks areas.
>>>
{
"OTIO_SCHEMA" : "PluginManifest.1",
"hook_scripts" : [
{
"OTIO_SCHEMA" : "HookScript.1",
"name" : "example hook",
"execution_scope" : "in process",
"filepath" : "example.py"
}
],
"hooks" : {
"pre_adapter_write" : ["example hook"],
"post_adapter_read" : []
}
}
The 'hook_scripts' area loads the python modules with the 'hook_function's to
call in them. The 'hooks' area defines the hooks (and any associated
scripts). You can further query and modify these from python.
>>> import opentimelineio as otio
... hook_list = otio.hooks.scripts_attached_to("some_hook") # -> ['a','b','c']
...
... # to run the hook scripts:
... otio.hooks.run("some_hook", some_timeline, optional_argument_dict)
This will pass (some_timeline, optional_argument_dict) to 'a', which will
a new timeline that will get passed into 'b' with optional_argument_dict,
etc.
To Edit the order, change the order in the list:
>>> hook_list[0], hook_list[2] = hook_list[2], hook_list[0]
... print hook_list # ['c','b','a']
Now c will run, then b, then a.
To delete a function the list:
>>> del hook_list[1]
"""
@core.register_type
class HookScript(plugins.PythonPlugin):
_serializable_label = "HookScript.1"
def __init__(
self,
name=None,
execution_scope=None,
filepath=None,
):
"""HookScript plugin constructor."""
plugins.PythonPlugin.__init__(self, name, execution_scope, filepath)
def run(self, in_timeline, argument_map={}):
"""Run the hook_function associated with this plugin."""
# @TODO: should in_timeline be passed in place? or should a copy be
# made?
return self._execute_function(
"hook_function",
in_timeline=in_timeline,
argument_map=argument_map
)
def __str__(self):
return "HookScript({}, {}, {})".format(
repr(self.name),
repr(self.execution_scope),
repr(self.filepath)
)
def __repr__(self):
return (
"otio.hooks.HookScript("
"name={}, "
"execution_scope={}, "
"filepath={}"
")".format(
repr(self.name),
repr(self.execution_scope),
repr(self.filepath)
)
)
def names():
"""Return a list of all the registered hooks."""
return plugins.ActiveManifest().hooks.keys()
def available_hookscript_names():
"""Return the names of HookScripts that have been registered."""
return [hs.name for hs in plugins.ActiveManifest().hook_scripts]
def available_hookscripts():
"""Return the HookScripts objects that have been registered."""
return plugins.ActiveManifest().hook_scripts
def scripts_attached_to(hook):
"""Return an editable list of all the hook scriptss that are attached to
the specified hook, in execution order. Changing this list will change the
order that scripts run in, and deleting a script will remove it from
executing
"""
# @TODO: Should this return a copy?
return plugins.ActiveManifest().hooks[hook]
def run(hook, tl, extra_args=None):
"""Run all the scripts associated with hook, passing in tl and extra_args.
Will return the return value of the last hook script.
If no hookscripts are defined, returns tl.
"""
hook_scripts = plugins.ActiveManifest().hooks[hook]
for name in hook_scripts:
hs = plugins.ActiveManifest().from_name(name, "hook_scripts")
tl = hs.run(tl, extra_args)
return tl
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