TextEngineHelpers.h File Reference

Internal helpers for TextEngine layout. Exposed in a header for unit testing. More...

#include <optional>
#include <string_view>
#include <vector>
#include "donner/base/Length.h"
#include "donner/base/SmallVector.h"
#include "donner/svg/components/text/ComputedTextComponent.h"
#include "donner/svg/core/DominantBaseline.h"
#include "donner/svg/core/TextAnchor.h"
#include "donner/svg/text/TextBackend.h"
#include "donner/svg/text/TextLayoutParams.h"
#include "donner/svg/text/TextTypes.h"

Include dependency graph for TextEngineHelpers.h:

Classes
struct	donner::svg::text_engine_detail::ChunkRange
	Byte range within a span representing a shaping chunk. More...
struct	donner::svg::text_engine_detail::ByteIndexMappings
	Index mapping result for a span's text. More...
struct	donner::svg::text_engine_detail::ChunkBoundary
	Text chunk boundary for per-chunk text-anchor adjustment. More...
struct	donner::svg::text_engine_detail::RunPenExtent
	Per-run pen start/end position for textLength calculation. 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.

Functions
double	donner::svg::text_engine_detail::computeBaselineShift (DominantBaseline baseline, const FontVMetrics &vm, float scale)
	Compute baseline shift for a given DominantBaseline/AlignmentBaseline value. Returns a Y offset in pixels (positive = shift up toward ascender).
std::vector< ChunkRange >	donner::svg::text_engine_detail::findChunkRanges (std::string_view spanText, const SmallVector< std::optional< Lengthd >, 1 > &xList, const SmallVector< std::optional< Lengthd >, 1 > &yList)
	Pre-scan span text to find chunk byte boundaries. A new chunk starts when a non-first codepoint has an absolute x or y position.
ByteIndexMappings	donner::svg::text_engine_detail::buildByteIndexMappings (std::string_view spanText)
	Build byte→charIdx and byte→rawCpIdx mappings for a span.
void	donner::svg::text_engine_detail::applyTextLength (std::vector< TextRun > &runs, const components::ComputedTextComponent &text, const std::vector< RunPenExtent > &runExtents, const TextLayoutParams &params, bool vertical, double currentPenX, double currentPenY)
	Apply per-span and global textLength adjustments to positioned runs.
void	donner::svg::text_engine_detail::applyTextAnchor (std::vector< TextRun > &runs, std::vector< ChunkBoundary > &chunkBoundaries, const components::ComputedTextComponent &text, bool vertical)
	Fix up chunk text-anchors and apply per-chunk text-anchor adjustment.
double	donner::svg::text_engine_detail::computeSpanBaselineShiftPx (const TextBackend &backend, const components::ComputedTextComponent::TextSpan &span, FontHandle spanFont, float spanScale, const TextLayoutParams &params)
	Compute per-span baseline-shift in pixels, including OS/2 sub/super metrics and ancestor baseline-shift accumulation.

Detailed Description

Internal helpers for TextEngine layout. Exposed in a header for unit testing.