PeachPDF

PeachDrawing.Text

TypefaceMetrics Class

The vertical dimensions of a Typeface, in design units: whole numbers on the grid the font was drawn on, UnitsPerEm of them to the em.

public sealed class TypefaceMetrics

Inheritance System.Object → TypefaceMetrics

Remarks

Nothing here depends on a text size. To get a length at a size, multiply by the size and divide by UnitsPerEm. Distances above the baseline are positive, and a descent is a positive length below it in every font that follows the specification; a font that records a descent with the wrong sign is reported as it is.

Two sets of line dimensions are given because platforms disagree about which one text is laid out with. CellAscent, CellDescent and LineSpacing are the rectangle Windows draws a line of text in, derived from the OS/2 Windows metrics unless the font asks for its typographic metrics; in that case the typographic line gap is folded into the cell ascent, so the cell can be taller than NormalLineAscent. NormalLineAscent, NormalLineDescent and NormalLineGap are what browsers use for CSS line-height: normal: the hhea triple, or the OS/2 typographic triple when the font sets its USE_TYPO_METRICS bit and records typographic metrics at all.

Properties
CapHeight	The height of a flat capital letter above the baseline. A font that does not record it (an `OS/2` table older than version 2) reports its CellAscent, which is the fallback CSS Values 4 prescribes for the `cap` unit.
CellAscent	The height of the line cell above the baseline.
CellDescent	The depth of the line cell below the baseline.
FirstCharIndex	The lowest character code the font’s `OS/2` table says it covers; a symbol font’s codes are offset by its high byte.
HasMeasuredXHeight	Whether XHeight is the font’s own figure and not an estimate.
HasSerifs	Whether the font’s `OS/2` family class is one of the serif classes, 1 to 7. A font that says nothing, or is a sans serif, a script or a symbol font, reports false.
IsFixedPitch	Whether every glyph advances by the same width (the `post` table’s `isFixedPitch`, the authoritative signal, unlike PANOSE).
IsItalicStyle	Whether the `OS/2` selection flags mark the face italic. This is the font’s own claim: IsItalic is the answer to use for choosing a face.
IsSymbolic	Whether the font’s character map is a symbol one (a `cmap` subtable for platform 3, encoding 0), whose codes are in the private range starting at FirstCharIndex and not Unicode.
ItalicAngle	The angle of italic strokes in degrees counter-clockwise from vertical, so negative for a slope to the right (the `post` table).
LineSpacing	The distance from one baseline to the next when lines are set solid: the cell plus any external leading, which is none when the font asks for its typographic metrics.
NormalLineAscent	The height above the baseline that CSS `line-height: normal` uses.
NormalLineDescent	The depth below the baseline that CSS `line-height: normal` uses.
NormalLineGap	The gap between lines that CSS `line-height: normal` adds to the ascent and descent, never negative.
StrikeoutPosition	The position of the strikeout stroke relative to the baseline (the `OS/2` table).
StrikeoutThickness	The thickness of the strikeout stroke.
UnderlinePosition	The position of the top of the underline stroke relative to the baseline, negative below it (the `post` table).
UnderlineThickness	The thickness of the underline stroke, which a poorly authored font may give as 0.
UnitsPerEm	The number of design units to the em square (the `head` table’s `unitsPerEm`).
XHeight	The height of a lower-case letter without an ascender above the baseline. A font that does not record it reports 66 percent of its CellAscent, and HasMeasuredXHeight says so.
XMax	The right edge of the box that holds every glyph.
XMin	The left edge of the box that holds every glyph (the `head` table’s `xMin`).
YMax	The top edge of the box that holds every glyph.
YMin	The bottom edge of the box that holds every glyph.