fix(thumbnails): public link thumbnails never generated behind compressed proxy

[ThShepard]

Description

This changes the behavior of the thumbnail generation process by not relying on the Content-Length header. Instead thumbnails would generate based on the real size of the image.

Related Issue

• Fixes Error when sharing a directory with images via a public link when gzip compression is enabled for images #3450

Motivation and Context

This change fixes thumbnail generation of publicly shared pictures behind a reverse proxy which is set up for gzip compression of every data type.

How Has This Been Tested?

• test environment: macOS and locally built OpenCloud with reverse proxy
• test case 1: gzip enabled, preview not already generated
• test case 2: gzip disabled, preview not already generated

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation added

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 7 complexity · 0 duplication

Metric	Results
Complexity	7
Duplication	0

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[butonic]

this looks interesting, however I am currently looking into a oush based architecture for the thumbnailer in #3397

I'm not sure this applies there. Could you review that PR and see if it solves your problem?

[ThShepard]

Thanks @butonic, I have tested your implementation locally and the bug is mitigated completely. As this class is deleted completely in your PR, should this one be closed or could this be used as a mitigation until yours is merged?