Scritp the context
==================

Context objects are accessible from a Python script.

## Load configuration from JSON file

A context configuration can be loaded from a JSON file using the [*load*](../../../argaze.md/#argaze.load) function.

```python
from argaze import load

# Load a context
with load(configuration_filepath) as context:

    while context.is_running():

        # Do something with context
        ...

        # Wait some time eventually
        ...
```

!!! note
    The **with** statement enables context by calling its **enter** method then ensures that its **exit** method is always called at the end.

## Load configuration from dictionary

A context configuration can be loaded from a Python dictionary using the [*from_dict*](../../../argaze.md/#argaze.DataFeatures.from_dict) function.

```python
from argaze import DataFeatures

import my_package

# Set working directory to enable relative file path loading 
DataFeatures.set_working_directory('path/to/folder')

# Edit a dict with context configuration
configuration = {
    "name": "My context",
    "parameter": ...,
    "pipeline": ...
}

# Load a context from a package
with DataFeatures.from_dict(my_package.MyContext, configuration) as context:

    while context.is_running():

        # Do something with context
        ...

        # Wait some time eventually
        ...
```

## Manage context

Check the context or the pipeline type to adapt features.

```python
from argaze import ArFeatures

# Assuming the context is loaded and is running
...

    # Check context type

    # Live processing case: calibration method is available
    if issubclass(type(context), ArFeatures.LiveProcessingContext):
        ...

    # Post processing case: more playback methods are available
    if issubclass(type(context), ArFeatures.PostProcessingContext):
        ...

    # Check pipeline type

    # Screen-based case: only gaze positions are processes
    if issubclass(type(context.pipeline), ArFeatures.ArFrame):
        ...

    # Head-mounted case: camera images also processes
    if issubclass(type(context.pipeline), ArFeatures.ArCamera):
        ...
```

## Display context

The context image can be displayed in low priority to not block pipeline processing.

```python
# Assuming the context is loaded and is running
...

    # Display context if the pipeline is available
    try:

        ... = context.image(wait = False)

    except DataFeatures.SharedObjectBusy:

        pass
```