Validated, allocation-bounded index for one sfnt font. More...

#include "donner/base/fonts/SfntUtils.h"

Classes
struct	TableRecord
	A table location validated against the original font byte span. More...
struct	GlyphOutlineComplexity
	Allocation and CPU-work ceiling proved for one glyph outline. More...

Public Member Functions
	SfntFont (SfntFont &&) noexcept
SfntFont &	operator= (SfntFont &&) noexcept
	SfntFont (const SfntFont &)=delete
SfntFont &	operator= (const SfntFont &)=delete
std::optional< std::span< const uint8_t > >	findTable (std::span< const uint8_t > data, std::string_view tag) const
	Find a validated table in `data`.
bool	hasTable (std::string_view tag) const
	Return true when the validated directory contains `tag`.
size_t	numTables () const
	Number of validated directory entries.
size_t	numGlyphs () const
	Number of glyphs with retained outline bounds, or zero when validation was unavailable.
std::optional< GlyphOutlineComplexity >	glyphOutlineComplexity (size_t glyphIndex) const
	Return the validation-time outline bound for a glyph.
size_t	retainedBytes () const
	Exact dynamic bytes retained by the sorted directory and outline indexes.

Static Public Member Functions
static std::optional< SfntFont >	Validate (std::span< const uint8_t > data, const SfntValidationOptions &options={}, SfntValidationMetrics *metrics=nullptr)
	Validate and index `data`.

Detailed Description

Validated, allocation-bounded index for one sfnt font.

Table records are sorted once, making lookup O(log T). TrueType glyf fonts also retain a validated loca index and are accepted only when every compound dependency is acyclic, at most kMaximumCompoundGlyphDepth frames deep, and within the expanded vertex and outline-work caps. The work model includes repeated and shared descendants, simple point decoding, component transforms, and stb_truetype's repeated prefix copies.

CFF and non-variable CFF2 outlines also receive bounded CharString validation. CFF tables must still be consumed by an exact-span parser such as FreeType; stb_truetype's CFF parser uses a synthetic 512 MiB span and must not be initialized for untrusted CFF fonts.

Class Documentation

◆ donner::fonts::SfntFont::TableRecord

struct donner::fonts::SfntFont::TableRecord

A table location validated against the original font byte span.

Class Members
uint32_t	length = 0
uint32_t	offset = 0
uint32_t	tag = 0

◆ donner::fonts::SfntFont::GlyphOutlineComplexity

struct donner::fonts::SfntFont::GlyphOutlineComplexity

Allocation and CPU-work ceiling proved for one glyph outline.

Class Members
uint32_t	maximumVertices = 0
uint32_t	work = 0

Member Function Documentation

◆ findTable()

std::optional< std::span< const uint8_t > > donner::fonts::SfntFont::findTable	(	std::span< const uint8_t >	data,
		std::string_view	tag ) const

Find a validated table in data.

data must be the same immutable byte stream passed to Validate.

Parameters

data	Original sfnt byte stream.
tag	Four-byte table tag.

Returns: A bounded table span, or std::nullopt when absent.

◆ Validate()

std::optional< SfntFont > donner::fonts::SfntFont::Validate	(	std::span< const uint8_t >	data,
		const SfntValidationOptions &	options = {},
		SfntValidationMetrics *	metrics = nullptr )

static

Validate and index data.

Parameters

data	Complete sfnt byte stream.

Returns: A cached index on success, or std::nullopt for malformed or over-limit input.

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

donner/base/fonts/SfntUtils.h

Classes

Public Member Functions