TextBackend.h File Reference

#include <cstddef>
#include <optional>
#include <ostream>
#include "donner/base/Path.h"
#include "donner/svg/core/FontVariant.h"
#include "donner/svg/core/TextOrientation.h"
#include "donner/svg/resources/FontManager.h"

Include dependency graph for TextBackend.h:

This graph shows which files directly or indirectly include this file:

Classes
struct	donner::svg::FontVMetrics
	Font vertical metrics in font design units (unscaled). More...
struct	donner::svg::UnderlineMetrics
	Line decoration positioning metrics in font design units. More...
struct	donner::svg::SubSuperMetrics
	Sub/superscript Y offsets from the OS/2 table, in font design units. More...
class	donner::svg::TextBackend
	Abstract font backend for text rendering operations. More...
struct	donner::svg::TextBackend::BitmapGlyph
	Bitmap glyph data from color fonts (CBDT/CBLC). More...
struct	donner::svg::TextBackend::BitmapGlyphMetrics
	Validated bitmap cost and placement metadata; not an authentication or cache identity token. More...
struct	donner::svg::TextBackend::ShapedGlyph
	A single shaped glyph with advance and cluster info. More...
struct	donner::svg::TextBackend::ShapedRun
	Result of shaping a text range. More...
struct	donner::svg::TextBackend::ShapingContext
	A byte range of the span text that surrounds a shaped range. More...
struct	donner::svg::TextBackend::ShapingContext::Detected
struct	donner::svg::TextBackend::ShapingContext::WorkBudget
	Shared admission for all primary/fallback calls while preparing contextual fragments. More...

Namespaces
namespace	donner
	Top-level Donner namespace, which is split into different sub-namespaces such as donner::svg and donner::css.
namespace	donner::svg
	Donner SVG library, which can load, manipulate and render SVG files.

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Class Documentation

donner::svg::FontVMetrics

struct donner::svg::FontVMetrics

Font vertical metrics in font design units (unscaled).

Class Members
int	ascent = 0	Positive, above baseline.
int	descent = 0	Negative, below baseline.
int	lineGap = 0	Extra spacing between lines. x-height in design units, from OS/2 sxHeight or the lowercase x glyph's top bearing. Zero means neither metric is available.
int	unitsPerEm = 0	Number of design units in one em, or zero when unavailable.
int	xHeight = 0

donner::svg::UnderlineMetrics

struct donner::svg::UnderlineMetrics

Line decoration positioning metrics in font design units.

Class Members
double	position = 0	Signed offset from baseline in font design units (negative = below).
double	thickness = 0	Stroke thickness in font design units.

donner::svg::SubSuperMetrics

struct donner::svg::SubSuperMetrics

Sub/superscript Y offsets from the OS/2 table, in font design units.

Class Members
int	subscriptYOffset = 0
int	superscriptYOffset = 0

donner::svg::TextBackend::BitmapGlyph

struct donner::svg::TextBackend::BitmapGlyph

Bitmap glyph data from color fonts (CBDT/CBLC).

Class Members
double	bearingX = 0	Horizontal offset from glyph origin.
double	bearingY = 0	Vertical offset from baseline (positive = up).
int	height = 0	Bitmap height in pixels.
vector< uint8_t >	rgbaPixels	RGBA pixel data (premultiplied alpha).
double	scale = 1.0	Scale factor to apply.
int	width = 0	Bitmap width in pixels.

donner::svg::TextBackend::ShapedRun

struct donner::svg::TextBackend::ShapedRun

Result of shaping a text range.

Class Members
optional< bool >	backward	Known source-group progression; absent when a backend leaves it implicit in its clusters.
vector< ShapedGlyph >	glyphs

donner::svg::TextBackend::ShapingContext

struct donner::svg::TextBackend::ShapingContext

A byte range of the span text that surrounds a shaped range.

Class Members
size_t	byteLength = 0	Length of the context. Backend-defined shaping properties detected for the whole context.
size_t	byteOffset = 0	Start of the context within the span text.
Detected	detected	Filled on first use, so the ranges of one context detect its properties once.
optional< bool >	rightToLeft	Resolved horizontal embedding parity; overrides every guessed shaping direction.
bool	suppressOptionalSubstitutions = false	Analysis-only shaping suppresses optional substitutions to propose emergency boundaries.
bool	suppressRligForAnalysis = false	Analysis-only rlig comparison for font-dependent lam-alef candidate groups.
WorkBudget *	work = nullptr	Aliases a planner-owned budget alive through all synchronous fragment shaping calls.

donner::svg::TextBackend::ShapingContext::Detected

struct donner::svg::TextBackend::ShapingContext::Detected

Class Members
uint32_t	direction = 0	Backend direction value.
const void *	language = nullptr	Backend language value.
uint32_t	script = 0	Backend script value.
bool	valid = false	Whether the fields below have been filled.
bool	vertical = false	Whether the context is shaped vertically.