get_computed_values() method to access computed axis ranges (#5552)

[Khanz9664]

Link to issue

#5552 - [FEATURE]: Access values calculated / derived by plotly.js as part of plotting

Closes #5552

Description of change

This PR introduces the initial implementation of get_computed_values() to expose computed values derived by Plotly.js.

Key aspects of this implementation:

• Provides a filtered interface over full_figure_for_development() to return only requested computed values
• Uses a simple startswith approach to identify axis keys (e.g., xaxis, yaxis, xaxis2)
• Converts extracted ranges to lists to ensure JSON-serializable output
• Includes validation for the include parameter and early return for empty input

Demo

import plotly.graph_objects as go

Create a sample figure

fig = go.Figure(go.Scatter(x=[1, 2, 3], y=[10, 20, 30]))

Retrieve computed values (e.g., autoranged axis limits)

computed = fig.get_computed_values(include=["axis_ranges"])
print(computed)

Output:

{'axis_ranges': {'xaxis': [...], 'yaxis': [...]}}

Testing strategy

Added a comprehensive test suite in tests/test_core/test_update_objects/test_get_computed_values.py:

• Basic Extraction: Verified basic range extraction for standard plots.
• Multi-Axis Support: Verified correct identification and extraction for complex layouts (e.g., xaxis2, yaxis2).
• Input Validation: Verified that invalid include types or unsupported keys raise descriptive ValueError exceptions.
• Serialization Safety: Verified that ranges are correctly converted to lists regardless of source format.
• Early Exit: Verified that empty include input returns immediately without triggering rendering

Note: Tests use mocking for the Kaleido rendering engine to ensure environment-agnostic reliability during CI.

Additional information (optional)

This is a Phase 1 (MVP) implementation intended to establish the API structure. Future work can extend this method to support:

• tick_values, margins, and box_stats.
• Direct communication with FigureWidget backends to bypass Kaleido entirely in live notebook environments.

Guidelines

• I have reviewed the pull request guidelines and the Code of Conduct and confirm that this PR follows them.
• I have added an entry to the changelog if needed (not required for documentation PRs).