[Feature] Add svg and gif support for DocC image(SR-15311)

[Kyle-Ye]

Feature/SR-15311

Summary

Swift-DocC currently ignores SVG and GIF files.

This PR add support for recognizing them as images in the same we do for JPEG, JPG, and PNG files.

Testing

Steps:

1. Download sample project developer.apple.com/documentation/xcode/slothcreator_building_docc_documentation_in_xcode
2. Download a svg file and a gif file and drag them to the Package's Sources/SlothCreator/SlothCreator.docc/Resources folder
3. Replace the content in SlothCreator.tutorial

@Image(source: slothcreator-intro.png, alt: "An illustration of ... tutorials.")

to

@Image(source: xx.svg, alt: "An illustration of ... tutorials.")

@Image(source: xx.gif, alt: "An illustration of ... tutorials.")

4. Build documentation to verify.

Checklist

Make sure you check off the following items. If they cannot be completed, provide a reason.

• Added tests
• Ran the ./bin/test script and it succeeded
• Updated documentation if necessary

[Kyle-Ye]

Which one should we use for gif's MIME type? "image/gif" or "application/octet-stream"

"image/gif" in https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types

"application/octet-stream" in FileRequestHandlerTests.swift

swift-docc/Tests/SwiftDocCUtilitiesTests/PreviewServer/RequestHandler/FileRequestHandlerTests.swift

Lines 73 to 81 in ff972f1

	// default font type
	try verifyAsset(root: tempDir.url, path: "/fonts/test.ttf", body: "ttf", type: "application/octet-stream")
	try verifyAsset(root: tempDir.url, path: "/images/image.png", body: "png", type: "image/png")
	try verifyAsset(root: tempDir.url, path: "/images/image.gif", body: "gif", type: "application/octet-stream")
	// default image type
	try verifyAsset(root: tempDir.url, path: "/images/image.jpg", body: "jpg", type: "image/jpeg")
	try verifyAsset(root: tempDir.url, path: "/images/logo.svg", body: "svg", type: "image/svg+xml")
	try verifyAsset(root: tempDir.url, path: "/img/image.png", body: "png", type: "image/png")
	try verifyAsset(root: tempDir.url, path: "/img/image.gif", body: "gif", type: "application/octet-stream")

[d-ronnqvist]

Which one should we use for gif's MIME type? "image/gif" or "application/octet-stream"

"image/gif" in https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types

"application/octet-stream" in FileRequestHandlerTests.swift

Thanks for opening this PR.

This test should verify that the MIME type is “image/gif”. The “application/octet-stream” value is a general binary data file or an unknown file type but “image/gif” is more precise here.

The rest of these changes look good to me.

[Kyle-Ye]

Which one should we use for gif's MIME type? "image/gif" or "application/octet-stream"
"image/gif" in developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types
"application/octet-stream" in FileRequestHandlerTests.swift

Thanks for opening this PR.

This test should verify that the MIME type is “image/gif”. The “application/octet-stream” value is a general binary data file or an unknown file type but “image/gif” is more precise here.

The rest of these changes look good to me.

Change “application/octet-stream” to "image/gif" and pass the test. Any other suggestion?

[Kyle-Ye]

@swift-ci Please smoke test

[d-ronnqvist]

@swift-ci test

[d-ronnqvist]

Thanks, this looks good to me. I will merge this after the CI passes.

[Kyle-Ye]

The Linux test fail seem to a Swift bug on the development branch.
The test machine is running on ubuntu1604 with 2021-10-18 snapshot
And I can reproduce it on my server on ubuntu2004 with 2021-10-18 snapshot
Also I rebased the branch to make the history more readable. Can you please test it again after the bug is fixed.

[Kyle-Ye]

It seems to be a bug on Swift Complier on Linux. And the CI Test on swift-markdown is missing, so we did not find it early.

Also the 2021-10-05 snapshot of swift is working both on Linux and macOS.(For the success of building swift-markdown)

Bug created at https://bugs.swift.org/browse/SR-15362

[d-ronnqvist]

@swift-ci test

[Kyle-Ye]

The bug has been fixed on the main branch of Swift, but the latest snapshot has not updated yet.

Can we merge it as it pass the macOS Platform test or do we need wait until there is a new snapshot released and pass the Linux Platform test?

[franklinsch]

A successful build on macOS and Linux are required to merge, so we'll wait for the fix for https://bugs.swift.org/browse/SR-15362 to land in a toolchain.

[Kyle-Ye]

A successful build on macOS and Linux are required to merge, so we'll wait for the fix for bugs.swift.org/browse/SR-15362 to land in a toolchain.

The new toolchain is landed, could you please make the ci-bots to test again?

[franklinsch]

@swift-ci please test

[franklinsch]

@swift-ci please test

[d-ronnqvist]

@swift-ci please test

[d-ronnqvist]

@swift-ci please test