donner::svg::SystemFontProvider Class Reference

FontFamilyProvider backed by the host operating system's installed fonts. More...

#include "donner/svg/resources/SystemFontProvider.h"

Inheritance diagram for donner::svg::SystemFontProvider:

Public Member Functions
std::vector< FontFamilyInfo >	families () const override
	List the families this provider can supply.
bool	hasFamily (std::string_view family) const override
	Returns true if family is available.
FontFaceAvailability	availability (std::string_view family, const FontFaceRequest &) const override
	Metadata only; the default preserves existing synchronous/system/custom providers.
std::vector< uint8_t >	loadFamilyData (std::string_view family, const FontFaceRequest &request) const override
	Load encoded font-file bytes (sfnt, or WOFF2 in a full-text consumer) for the face of family that best matches request, or an empty vector if the family is unavailable.
Public Member Functions inherited from donner::svg::FontFamilyProvider
virtual FontFaceAdmission	tryAcquireFace (std::string_view, const FontFaceRequest &) const
	Acquire product-wide copy/decode admission without blocking. Does not fetch missing bytes.

Static Public Member Functions
static bool	isSupported ()
	Returns true if this build enumerates real system fonts (i.e. macOS), false for the stub.

Detailed Description

FontFamilyProvider backed by the host operating system's installed fonts.

On macOS this enumerates families via CoreText (CTFontManagerCopyAvailableFontFamilyNames) and materializes a flat sfnt byte stream on demand by reconstructing the font's tables through CoreText (which works even for .ttc/.dfont members). Faces within a family are scored against the requested weight/style/stretch, so bold and italic resolve to the real designed face. All families report FontSource::System.

On non-Apple platforms this is a stub: it enumerates nothing and loads nothing, so the catalog still compiles and behaves (embedded fonts only).

Member Function Documentation

availability()

FontFaceAvailability donner::svg::SystemFontProvider::availability ( std::string_view family, const FontFaceRequest &  ) const

inlineoverridevirtual

Metadata only; the default preserves existing synchronous/system/custom providers.

Reimplemented from donner::svg::FontFamilyProvider.

families()

std::vector< FontFamilyInfo > donner::svg::SystemFontProvider::families ( ) const

overridevirtual

List the families this provider can supply.

Implements donner::svg::FontFamilyProvider.

hasFamily()

bool donner::svg::SystemFontProvider::hasFamily ( std::string_view family ) const

overridevirtual

Returns true if family is available.

Matching must be case-insensitive: callers fold family names when they index them, so a provider that compared case-sensitively would disagree with its own caller about which families exist.

It must also answer in constant or logarithmic time. Text layout asks once per unresolved family per span, and the number of families a provider holds is set by the host rather than by the document, so a linear scan of the provider's list turns one layout into work proportional to spans times families times installed fonts. Providers that enumerate a list should build a folded index alongside it rather than scanning it per call, and must not perform I/O or re-enumerate the underlying font source here.

Parameters

family

Font family name to test.

Returns

True when this provider can supply the family.

Implements donner::svg::FontFamilyProvider.

loadFamilyData()

std::vector< uint8_t > donner::svg::SystemFontProvider::loadFamilyData ( std::string_view family, const FontFaceRequest & request ) const

overridevirtual

Load encoded font-file bytes (sfnt, or WOFF2 in a full-text consumer) for the face of family that best matches request, or an empty vector if the family is unavailable.

Providers that only hold a single file per family return it for every request, which means bold and italic render as regular for those families - see EmbeddedFontProvider.

The returned bytes are suitable for FontManager::loadFontData() when its feature tier supports that format. They are not necessarily raw sfnt and must not be passed directly to an SFNT-only consumer such as an ImGui TTF loader.

A synchronous provider whose load cost grows with the font's size should poll ScopedFontLoadInterruption::Requested and may return an empty vector once it is true.

Parameters

family	Family name to load (case-insensitive).
request	Face within the family to prefer.

Implements donner::svg::FontFamilyProvider.

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The documentation for this class was generated from the following file:

• donner/svg/resources/SystemFontProvider.h