Compile C API (src/c) in libSkiaSharp instead of upstream :core by mattleibow · Pull Request #4131 · mono/SkiaSharp

mattleibow · 2026-06-09T17:57:58Z

Summary

Parent-repo side of the change that compiles SkiaSharp's fork-owned C API shim (externals/skia/src/c/*.cpp) in the libSkiaSharp target on every platform, instead of injecting it into upstream Skia's :core GN target.

The GN graph change lives in the submodule: Move SkiaSharp C API (src/c) out of upstream :core into libSkiaSharp skia#251 (this PR bumps externals/skia to it).
This PR updates the non-GN native builds (Apple xcodeprojs, Tizen makefile) to match, and adds deprecation enforcement where GN can't reach.

See mono/skia#251 for the full motivation (the m148 :fontmgr_fontconfig / SK_FONTMGR_FONTCONFIG_AVAILABLE regression that this architecturally fixes).

Why the non-GN builds need separate changes

libSkiaSharp is produced by three independent build systems:

Build system	Platforms	Compiles `src/c`?
GN (`externals/skia/BUILD.gn`)	Linux, Windows, WASM, Android	now in `skiasharp_build("SkiaSharp")` (mono/skia#251)
Xcode (`*.xcodeproj`)	macOS, iOS, tvOS, Mac Catalyst (reuses the ios project)	listed in `project.pbxproj` Sources
Tizen makefile (`project_def.prop`)	Tizen	listed in `USER_SRCS`

The Apple/Tizen builds compile our shim directly and link a prebuilt libskia.a, so the GN source-list move doesn't propagate to them automatically — they each carry their own copy of the list.

Changes

`externals/skia` submodule

Bumped to Move SkiaSharp C API (src/c) out of upstream :core into libSkiaSharp skia#251: src/c moved into libSkiaSharp; the two dead :core workarounds removed; deprecated-SkPathOps usages in sk_path.cpp fixed; GN warnings/deprecation guardrail added; C API public header list completed.

Apple xcodeprojs — `native/{macos,ios,tvos}/libSkiaSharp/libSkiaSharp.xcodeproj/project.pbxproj`

Added the 40 src/c/*.cpp sources to each project's Sources build phase (previously they came from :core indirectly; now they're explicit, matching the GN move). Covers macOS, iOS, tvOS, and Mac Catalyst (which reuses the ios project via native/maccatalyst/build.cake).
Added OTHER_CFLAGS = -Werror=deprecated-declarations to all four build configurations in each of the three projects. These targets build via xcodebuild (not GN), so the GN-side guardrail doesn't apply — without this, deprecated-API usage only warned and the build still succeeded. They compile only our src/c + src/xamarin shim (upstream Skia is a prebuilt static lib), so the scope is exactly our own sources.

Tizen — `native/tizen/libSkiaSharp/project_def.prop`

Added the src/c/*.cpp sources to USER_SRCS. (Tizen's makefile already builds with -Wall -Wextra -Werror, which is what first caught the deprecated TightBounds usage.)

Deprecation enforcement is now consistent everywhere

Build system	Mechanism
GN (Linux/Windows/WASM/Android)	`:skiasharp_strict` config → `-Werror=deprecated-declarations` (mono/skia#251)
Xcode (macOS/iOS/tvOS/MacCatalyst)	`OTHER_CFLAGS = -Werror=deprecated-declarations` (this PR)
Tizen	existing `-Werror`

Validation

macOS arm64 (native xcodebuild): ARCHIVE SUCCEEDED; real 7.3 MB dylib.
Deprecation guardrail proven on macOS: with the deprecated TightBounds call restored, dotnet cake --target=externals-macos fails (exit 65) with error: 'TightBounds' is deprecated [-Werror,-Wdeprecated-declarations]; with the fix it builds clean.
Linux x64 (Docker): clean; fontconfig regression guard passes (non-empty default typeface).
Tests: SkiaSharp.Tests.Console pass.

Merge order

Merge mono/skia#251 first, then this PR will point at the merged submodule SHA.

github-actions · 2026-06-09T17:58:12Z

📦 Try the packages from this PR

Warning

Do not run these scripts without first reviewing the code in this PR.

Step 1 — Download the packages

bash / macOS / Linux:

curl -fsSL https://raw.githubusercontent.com/mono/SkiaSharp/main/scripts/get-skiasharp-pr.sh | bash -s -- 4131

PowerShell / Windows:

iex "& { $(irm https://raw.githubusercontent.com/mono/SkiaSharp/main/scripts/get-skiasharp-pr.ps1) } 4131"

Step 2 — Add the local NuGet source

dotnet nuget add source ~/.skiasharp/hives/pr-4131/packages --name skiasharp-pr-4131

More options

Option	Description
`--successful-only` / `-SuccessfulOnly`	Only use successful builds
`--force` / `-Force`	Overwrite previously downloaded packages
`--list` / `-List`	List available artifacts without downloading
`--build-id ID` / `-BuildId ID`	Download from a specific build

Or download manually from Azure Pipelines — look for the nuget artifact on the build for this PR.

Remove the source when you're done:

dotnet nuget remove source skiasharp-pr-4131

github-actions · 2026-06-09T18:22:55Z

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Copilot

Pull request overview

This PR aligns the non-GN native build systems (Apple Xcode projects and Tizen makefile) with the upstream GN-graph change that moves SkiaSharp’s fork-owned C API shim (externals/skia/src/c/*.cpp) into the libSkiaSharp target, instead of relying on those sources being compiled via Skia’s upstream :core target.

Changes:

Adds externals/skia/src/c/*.cpp files to the libSkiaSharp Xcode project sources for macOS, iOS (and thus Mac Catalyst via reuse), and tvOS.
Adds -Werror=deprecated-declarations via OTHER_CFLAGS to all Xcode build configurations so deprecation enforcement matches GN/Tizen behavior.
Adds the same src/c/*.cpp list to Tizen’s USER_SRCS so the non-GN Tizen build compiles the shim directly.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

File	Description
native/macos/libSkiaSharp/libSkiaSharp.xcodeproj/project.pbxproj	Adds `src/c` shim sources to the macOS Xcode build and enforces deprecated-declarations as errors.
native/ios/libSkiaSharp/libSkiaSharp.xcodeproj/project.pbxproj	Adds `src/c` shim sources to the iOS (and Mac Catalyst via reuse) Xcode build and enforces deprecated-declarations as errors.
native/tvos/libSkiaSharp/libSkiaSharp.xcodeproj/project.pbxproj	Adds `src/c` shim sources to the tvOS Xcode build and enforces deprecated-declarations as errors.
native/tizen/libSkiaSharp/project_def.prop	Adds `src/c` shim sources to the Tizen makefile’s `USER_SRCS` list.

Follow-up to the mono/skia change that moves the fork-owned C API shim (src/c/*.cpp) out of upstream Skia's :core target and into the libSkiaSharp build, decoupling it from :core's milestone-churning transitive dependencies (which silently dropped SK_FONTMGR_FONTCONFIG_AVAILABLE on Linux in m148). On platforms built via the GN skiasharp_build("SkiaSharp") target (Android, Linux, Windows, WASM) the move is handled entirely in the submodule. But the Apple platforms (macOS, iOS, tvOS) and Tizen build libSkiaSharp from a project file that compiles the managed-interop glue and links the GN-built libskia.a; they relied on src/c being inside :core. Add the src/c/*.cpp sources to: - native/{macos,ios,tvos}/libSkiaSharp/libSkiaSharp.xcodeproj - native/tizen/libSkiaSharp/project_def.prop so every platform compiles the C API into libSkiaSharp itself, consistent with how the src/xamarin glue is already handled. These projects already link -lskottie/-lsksg/-lskresources/-ljsonreader, so no extra linkage is needed. Validated: macOS arm64 (real dylib, full test suite passes) and Linux x64 (real .so with libfontconfig.so.1 dependency and 44 Fc* imports — the m148 regression guard). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The macOS/iOS/tvOS libSkiaSharp targets build via xcodebuild (pbxproj), not GN, so the GN-side deprecation guardrail does not cover them. They compiled the deprecated SkPathOps TightBounds() with only a warning. Add OTHER_CFLAGS = -Werror=deprecated-declarations to every build configuration in the three Apple xcodeprojs so deprecated Skia API usage fails the build on Apple platforms too, matching the GN (:skiasharp_strict) and Tizen (-Werror) builds. These targets compile only our src/c + src/xamarin shim (upstream Skia is linked as a prebuilt static lib), so the scope is exactly our own sources. Bumps externals/skia to pick up the TightBounds fix + GN warnings guardrail. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated no new comments.

github-project-automation Bot added this to SkiaSharp Backlog Jun 9, 2026

mattleibow force-pushed the mattleibow/move-capi-to-libskiasharp branch from d8ec327 to c494443 Compare June 11, 2026 11:18

mattleibow mentioned this pull request Jun 11, 2026

Move SkiaSharp C API (src/c) out of upstream :core into libSkiaSharp mono/skia#251

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mattleibow requested a review from Copilot June 11, 2026 15:14

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mattleibow mentioned this pull request Jun 11, 2026

Build Apple libSkiaSharp/libHarfBuzzSharp from GN; delete all Xcode projects #4147

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mattleibow and others added 4 commits June 13, 2026 00:33

Bump skia submodule: migrate remaining deprecated SkPathOps overloads

bd1573e

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Bump externals/skia: complete C API public header list in GN target

9a9e700

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

mattleibow force-pushed the mattleibow/move-capi-to-libskiasharp branch from f878b64 to 9a9e700 Compare June 12, 2026 22:34

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Compile C API (src/c) in libSkiaSharp instead of upstream :core#4131

Compile C API (src/c) in libSkiaSharp instead of upstream :core#4131
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mattleibow commented Jun 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Why the non-GN builds need separate changes

Changes

externals/skia submodule

Apple xcodeprojs — native/{macos,ios,tvos}/libSkiaSharp/libSkiaSharp.xcodeproj/project.pbxproj

Tizen — native/tizen/libSkiaSharp/project_def.prop

Deprecation enforcement is now consistent everywhere

Validation

Merge order

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📦 Try the packages from this PR

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mattleibow commented Jun 9, 2026 •

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`externals/skia` submodule

Apple xcodeprojs — `native/{macos,ios,tvos}/libSkiaSharp/libSkiaSharp.xcodeproj/project.pbxproj`

Tizen — `native/tizen/libSkiaSharp/project_def.prop`

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