Bug 2028886 - Restrict use of graphite on worker threads a=dsmith (53c34800) · Commits · The Tor Project / Applications / Tor Browser

gfx/thebes/gfxFont.cpp

+24 −20

Original line number	Diff line number	Diff line
		@@ -1528,11 +1528,12 @@ tainted_boolean_hint gfxFont::SpaceMayParticipateInShaping(
		}
		}

		if (FontCanSupportGraphite()) {
		if (gfxPlatform::GetPlatform()->UseGraphiteShaping()) {
		// Note that Graphite shaping is only available on the main thread.
		// `UseGraphiteShaping` will always be false in workers.
		if (gfxPlatform::GetPlatform()->UseGraphiteShaping() &&
		FontCanSupportGraphite()) {
		return mFontEntry->HasGraphiteSpaceContextuals();
		}
		}

		// We record the presence of space-dependent features in the font entry
		// so that subsequent instantiations for the same font face won't
		@@ -1566,6 +1567,9 @@ tainted_boolean_hint gfxFont::SpaceMayParticipateInShaping(
		}

		bool gfxFont::SupportsFeature(Script aScript, uint32_t aFeatureTag) {
		// mGraphiteShaper may be observed non-null on a worker thread, but workers
		// shape via harfbuzz regardless, because graphite shaping is only available
		// on the main thread.
		if (mGraphiteShaper && gfxPlatform::GetPlatform()->UseGraphiteShaping()) {
		return GetFontEntry()->SupportsGraphiteFeature(aFeatureTag);
		}
		@@ -3448,9 +3452,10 @@ bool gfxFont::ShapeText(DrawTarget* aDrawTarget, const char16_t* aText,
		// XXX Currently, we do all vertical shaping through harfbuzz.
		// Vertical graphite support may be wanted as a future enhancement.
		// XXX Graphite shaping currently only supported on the main thread!
		// Worker-thread shaping (offscreen canvas) will always go via harfbuzz.
		if (FontCanSupportGraphite() && !aVertical && NS_IsMainThread()) {
		if (gfxPlatform::GetPlatform()->UseGraphiteShaping()) {
		// On workers (offscreen canvas), `UseGraphiteShaping` always returns false,
		// and shaping uses harfbuzz.
		if (gfxPlatform::GetPlatform()->UseGraphiteShaping() &&
		FontCanSupportGraphite() && !aVertical) {
		gfxGraphiteShaper* shaper = mGraphiteShaper;
		if (!shaper) {
		shaper = new gfxGraphiteShaper(this);
		@@ -3466,7 +3471,6 @@ bool gfxFont::ShapeText(DrawTarget* aDrawTarget, const char16_t* aText,
		return true;
		}
		}
		}

		gfxHarfBuzzShaper* shaper = GetHarfBuzzShaper();
		if (shaper &&

gfx/thebes/gfxFontEntry.cpp

+5 −6

Original line number	Diff line number	Diff line
		@@ -571,13 +571,10 @@ gfxFontEntry::GetGrSandboxAdvanceCallbackHandle() {
		}

		tainted_opaque_gr<gr_face*> gfxFontEntry::GetGrFace() {
		if (!mGrFaceInitialized) {
		// When possible, the below code will use WASM as a sandboxing mechanism.
		// At this time the wasm sandbox does not support threads.
		// If Thebes is updated to make callst to the sandbox on multiple threaads,
		// we need to make sure the underlying sandbox supports threading.
		MOZ_ASSERT(NS_IsMainThread());
		// Graphite shaping is only available on the main thread.
		MOZ_RELEASE_ASSERT(NS_IsMainThread());

		if (!mGrFaceInitialized) {
		mSandboxData = new GrSandboxData();

		auto p_faceOps = mSandboxData->sandbox.malloc_in_sandbox<gr_face_ops>();
		@@ -646,6 +643,8 @@ bool gfxFontEntry::HasFontTable(uint32_t aTableTag) {
		}

		tainted_boolean_hint gfxFontEntry::HasGraphiteSpaceContextuals() {
		// Graphite shaping is only available on the main thread.
		MOZ_RELEASE_ASSERT(NS_IsMainThread());
		LazyFlag flag = mHasGraphiteSpaceContextuals;
		if (flag == LazyFlag::Uninitialized) {
		auto face = GetGrFace();

gfx/thebes/gfxPlatform.cpp

+3 −1

Original line number	Diff line number	Diff line
		@@ -1852,7 +1852,9 @@ uint32_t gfxPlatform::WordCacheMaxEntries() {
		}

		bool gfxPlatform::UseGraphiteShaping() {
		return StaticPrefs::gfx_font_rendering_graphite_enabled();
		// Graphite shaping is only available on the main thread.
		return StaticPrefs::gfx_font_rendering_graphite_enabled() &&
		NS_IsMainThread();
		}

		bool gfxPlatform::IsFontFormatSupported(