feat(pdf): add configurable PDF compression level support

[Neko1313]

SUMMARY

Added support for configurable PDF compression levels in Superset. The changes include:

• New configuration variable PDF_COMPRESSION_LEVEL in config.py with four compression levels: "NONE", "FAST", "MEDIUM", "SLOW" (defaults to "MEDIUM")
• Passing this parameter through bootstrap data to the frontend
• Using the compression parameter in the downloadAsPdf function to improve performance and file size optimization
• Updated TypeScript BootstrapData interface to support the new field

This allows administrators to configure the balance between PDF generation speed and file size based on system requirements and user needs.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

No visual changes - this is an internal performance optimization for PDF generation.

TESTING INSTRUCTIONS

1. Run Superset with different PDF_COMPRESSION_LEVEL values in config.py
2. Try exporting dashboards or charts to PDF
3. Verify that PDFs are generated correctly
4. Compare file sizes and generation speed with different compression levels:
   • PDF_COMPRESSION_LEVEL = "NONE" - fastest generation, largest file size
   • PDF_COMPRESSION_LEVEL = "FAST" - fast generation, medium file size
   • PDF_COMPRESSION_LEVEL = "MEDIUM" - moderate speed, good compression
   • PDF_COMPRESSION_LEVEL = "SLOW" - slower generation, best compression
5. Ensure bootstrap data contains the correct pdf_compression_level value
6. Test that the compression parameter is properly passed to the PDF generation library

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

Additional Notes:

• Changes are backward compatible - if the variable is not set, the default value is used
• No database migration required for this feature
• TypeScript typing updated to support the new field
• Configuration follows existing Superset patterns for PDF-related settings

[korbit-ai]

Review by Korbit AI

Korbit automatically attempts to detect when you fix issues in new commits.

Category	Issue	Status
	Default PDF compression too aggressive ▹ view	✅ Fix detected

Files scanned

​

File Path	Reviewed
superset-frontend/src/utils/downloadAsPdf.ts	✅
superset-frontend/src/types/bootstrapTypes.ts	✅
superset/views/base.py	✅
superset/config.py	✅

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[github-actions]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.91%. Comparing base (76d897e) to head (ca90cbf).
⚠️ Report is 2586 commits behind head on master.

Additional details and impacted files

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- Hits        46114    31260    -14854     
+ Misses      28017    10979    -17038     
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Flag	Coverage Δ
hive	46.29% <100.00%> (-2.86%)	⬇️
javascript	?
mysql	70.94% <100.00%> (?)
postgres	70.99% <100.00%> (?)
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sqlite	70.58% <100.00%> (?)
unit	100.00% <ø> (+42.36%)	⬆️

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[rusackas]

re-running CI 🤞

[Quatters]

Great feature, thank you!

[Neko1313]

@rusackas Will you make a confirmation please?

[rusackas]

re-running CI. Ping me again (here or on Superset Slack) if it passes

[rusackas]

LGTM, but adding @sadpandajoe / @eschutho in case they have concerns for.... certain hosted SaaS services built around Superset ;)