geom

type Matrix struct {
	A, B, C, D, E, F float64
}

type Rect struct {
	X0, Y0, X1, Y1 float64
}

type Tolerance struct {
	// SpaceFrac is the fraction of a font's nominal space advance that a
	// horizontal gap must exceed before an inter-word space is inferred.
	// Below 1.0 because many producers emit slightly tightened spacing.
	SpaceFrac float64

	// WideSpaceFrac is the multiple of nominal space advance above which a gap
	// is treated as column or tab separation rather than a single space.
	WideSpaceFrac float64

	// LineFrac is the fraction of font size that a baseline must shift
	// vertically before a new line is started.
	LineFrac float64

	// ParaFrac is the multiple of line height above which a vertical gap is
	// treated as a paragraph break rather than a line break.
	ParaFrac float64

	// SizeFrac is the ratio between two consecutive lines' dominant type sizes
	// above which they are treated as separate blocks even when the vertical step
	// says otherwise. A heading set at ordinary leading is the case: the step alone
	// cannot see it, and without this the heading fuses into the paragraph below.
	//
	// It is a ratio of larger to smaller, so 1.0 would split on any difference at
	// all and is not a usable setting — OCR output reports the same line of type at
	// sizes differing by a few percent. Zero means the default.
	SizeFrac float64

	// IndentFrac is the number of space widths a line must be indented past its
	// block's own margin, while repeating the indent that block's first line was set
	// with, before it is read as starting a new paragraph.
	//
	// This is the paragraph break that has no vertical evidence: a document setting
	// no space between paragraphs steps down by exactly one line at a boundary, so
	// ParaFrac cannot see it and SizeFrac has nothing to compare. Expressed in space
	// widths rather than points so a footnote and a heading are judged alike. Zero
	// means off, which is a usable setting — the rule is the least certain of the
	// three and a caller who wants only vertical evidence can have it.
	IndentFrac float64

	// IndentMax is the number of space widths beyond which an indent is column or
	// cell placement rather than a paragraph's first line, and is ignored.
	IndentMax float64

	// Epsilon is the absolute tolerance for coordinate comparison in user-space
	// units, absorbing float noise from matrix composition.
	Epsilon float64
}