shaped

type Line struct {

	// Source is the input source corresponding to the line contents,
	// derived from the original Lines Source. The style information for
	// each Run is embedded here.
	Source rich.Text

	// SourceRange is the range of runes in the original [Lines.Source] that
	// are represented in this line.
	SourceRange textpos.Range

	// Runs are the shaped [Run] elements.
	Runs []Run

	// Offset specifies the relative offset from the Lines Position
	// determining where to render the line in a target render image.
	// This is the baseline position (not the upper left: see Bounds for that).
	Offset math32.Vector2

	// Bounds is the bounding box for the Line of rendered text,
	// relative to the baseline rendering position (excluding any contribution
	// of Offset). This is centered at the baseline and the upper left
	// typically has a negative Y. Use Size() method to get the size
	// and ToRect() to get an [image.Rectangle]. This is based on the output
	// LineBounds, not the actual GlyphBounds.
	Bounds math32.Box2

	// Selections specifies region(s) of runes within this line that are selected,
	// and will be rendered with the [Lines.SelectionColor] background,
	// replacing any other background color that might have been specified.
	Selections []textpos.Range

	// Highlights specifies region(s) of runes within this line that are highlighted,
	// and will be rendered with the [Lines.HighlightColor] background,
	// replacing any other background color that might have been specified.
	Highlights []textpos.Range
}

type Lines struct {

	// Source is the original input source that generated this set of lines.
	// Each Line has its own set of spans that describes the Line contents.
	Source rich.Text

	// Lines are the shaped lines.
	Lines []Line

	// Offset is an optional offset to add to the position given when rendering.
	Offset math32.Vector2

	// Bounds is the bounding box for the entire set of rendered text,
	// relative to a rendering Position (and excluding any contribution
	// of Offset). Use Size() method to get the size and ToRect() to get
	// an [image.Rectangle].
	Bounds math32.Box2

	// FontSize is the [rich.Context] StandardSize from the Context used
	// at the time of shaping. Actual lines can be larger depending on font
	// styling parameters.
	FontSize float32

	// LineHeight is the line height used at the time of shaping.
	LineHeight float32

	// Truncated indicates whether any lines were truncated.
	Truncated bool

	// Direction is the default text rendering direction from the Context.
	Direction rich.Directions

	// Links holds any hyperlinks within shaped text.
	Links []rich.Hyperlink

	// Color is the default fill color to use for inking text.
	Color color.Color

	// SelectionColor is the color to use for rendering selected regions.
	SelectionColor image.Image

	// HighlightColor is the color to use for rendering highlighted regions.
	HighlightColor image.Image
}

type Math struct {
	Path *ppath.Path
	BBox math32.Box2
}

type Run interface {

	// AsBase returns the base type with relevant shaped text information.
	AsBase() *RunBase

	// LineBounds returns the Line-level Bounds for given Run as rect bounding box.
	LineBounds() math32.Box2

	// Runes returns our rune range in original source using textpos.Range.
	Runes() textpos.Range

	// Advance returns the total distance to advance in going from one run to the next.
	Advance() float32

	// RuneBounds returns the maximal line-bounds level bounding box for given rune index.
	RuneBounds(ri int) math32.Box2

	// RuneAtPoint returns the rune index in Lines source, at given rendered location,
	// based on given starting location for rendering. If the point is out of the
	// line bounds, the nearest point is returned (e.g., start of line based on Y coordinate).
	RuneAtPoint(src rich.Text, pt math32.Vector2, start math32.Vector2) int

	// SetGlyphXAdvance sets the x advance on all glyphs to given value:
	// for monospaced case.
	SetGlyphXAdvance(adv fixed.Int26_6)
}

type RunBase struct {

	// Font is the [text.Font] compact encoding of the font to use for rendering.
	Font text.Font

	// MaxBounds are the maximal line-level bounds for this run, suitable for region
	// rendering and mouse interaction detection.
	MaxBounds math32.Box2

	// Decoration are the decorations from the style to apply to this run.
	Decoration rich.Decorations

	// Math holds the output of Math formatting via the tex package.
	Math Math

	// FillColor is the color to use for glyph fill (i.e., the standard "ink" color).
	// Will only be non-nil if set for this run; Otherwise use default.
	FillColor image.Image

	// StrokeColor is the color to use for glyph outline stroking, if non-nil.
	StrokeColor image.Image

	// Background is the color to use for the background region, if non-nil.
	Background image.Image
}

type Shaper interface {

	// Shape turns given input spans into [Runs] of rendered text,
	// using given context needed for complete styling.
	// The results are only valid until the next call to Shape or WrapParagraph:
	// use slices.Clone if needed longer than that.
	// This is called under a mutex lock, so it is safe for parallel use.
	Shape(tx rich.Text, tsty *text.Style, rts *rich.Settings) []Run

	// WrapLines performs line wrapping and shaping on the given rich text source,
	// using the given style information, where the [rich.Style] provides the default
	// style information reflecting the contents of the source (e.g., the default family,
	// weight, etc), for use in computing the default line height. Paragraphs are extracted
	// first using standard newline markers, assumed to coincide with separate spans in the
	// source text, and wrapped separately. For horizontal text, the Lines will render with
	// a position offset at the upper left corner of the overall bounding box of the text.
	// This is called under a mutex lock, so it is safe for parallel use.
	WrapLines(tx rich.Text, defSty *rich.Style, tsty *text.Style, rts *rich.Settings, size math32.Vector2) *Lines

	// FontFamilies returns a list of available font family names on this system.
	FontList() []fonts.Info
}