GlyphHinter Class

Namespace: Meziantou.Framework.Fonts
Assembly: Meziantou.Framework.Fonts.dll
Package: Meziantou.Framework.Fonts 1.0.9
Source: GlyphHinter.cs
Available in package assets: net10.0net11.0

Decodes the outlines of the glyphs of a font fitted to the pixel grid of a size: hinted outlines are sharper at small sizes, where an exactly scaled outline puts its edges across pixels.

public sealed class GlyphHinter : IDisposable

Remarks

The outlines are given in font units, like those of FontFace.DecodeOutline: multiplied by the size divided by FontFace.UnitsPerEm, their hinted coordinates are on the pixel grid, with the origin of the glyph at a whole pixel. The y axis goes up.

GlyphHinting.Full runs the TrueType instructions of the font (OpenType specification, "TrueType Instructions"), with the version 40 interpreter of FreeType hinting for black and white pixels (FT_LOAD_TARGET_MONO) as the reference. A font program or a control value program that breaks a rule of the specification makes the font unhinted; instructions of a glyph that break one make that glyph unhinted. The work of the programs is bounded: each run charges every instruction to a GlyphBudget, and the stack, the storage area, the control values, the functions and the twilight zone are sized from the font and rented from the allocator.

A hinter keeps the state of the programs of the font at its size: it is used by one operation at a time, and must be disposed to give its storage back to the allocator.

Implements

IDisposable

Properties

Name	Description
Hinting	Gets how the outlines are hinted: the mode asked for, or `GlyphHinting.Light` when `GlyphHinting.Full` was asked for a font whose instructions cannot be run.
Size	Gets the size the outlines are hinted for, in pixels per em.

Hinting

GlyphHinter.cs

Gets how the outlines are hinted: the mode asked for, or GlyphHinting.Light when GlyphHinting.Full was asked for a font whose instructions cannot be run.

public GlyphHinting Hinting { get; }

Property value

GlyphHinting

Size

GlyphHinter.cs

Gets the size the outlines are hinted for, in pixels per em.

public double Size { get; }

Property value

double

Methods

Name	Description
Create(FontFace, double, GlyphHinting, GlyphScratch, FontAllocator)	Creates a hinter for a font at a size: with `GlyphHinting.Full`, runs the font program and the control value program.
DecodeOutline(int, OutlineSink, GlyphScratch, GlyphBudget)	Decodes the hinted outline of a glyph into a sink, in font units, and gives its advance.
Dispose()	Gives back the storage of the state of the instructions.

Create(FontFace, double, GlyphHinting, GlyphScratch, FontAllocator)

GlyphHinter.cs

Creates a hinter for a font at a size: with GlyphHinting.Full, runs the font program and the control value program.

public static GlyphHinter Create(FontFace face, double size, GlyphHinting hinting, GlyphScratch scratch, FontAllocator allocator)

Parameters

face FontFace: The font.
size double: The size, in pixels per em.
hinting GlyphHinting: How the outlines are hinted.
scratch GlyphScratch: The working storage of the glyphs the hinter measures to find the alignment zones of the font.
allocator FontAllocator: The storage of the state of the TrueType instructions.

Returns

GlyphHinter

Exceptions

ArgumentOutOfRangeException: size is not a positive finite number, or hinting is not a defined value.
InvalidFontException: The data of the font is malformed.
FontResourceLimitException: A program of the font exceeds the complexity limit, or its storage exceeds the allocation limit.

DecodeOutline(int, OutlineSink, GlyphScratch, GlyphBudget)

GlyphHinter.cs

Decodes the hinted outline of a glyph into a sink, in font units, and gives its advance.

public double DecodeOutline(int glyphId, OutlineSink sink, GlyphScratch scratch, ref GlyphBudget budget)

Parameters

glyphId int: The glyph.
sink OutlineSink: The sink.
scratch GlyphScratch: The working storage of the outline.
budget GlyphBudget: The budget of the glyph, which its instructions are charged to.

Returns

double The advance of the glyph, in pixels: a whole number with GlyphHinting.Full, the advance of the font scaled to the size otherwise.

Exceptions

ObjectDisposedException: The hinter is disposed.
InvalidFontException: The data of the glyph is malformed.
FontResourceLimitException: The glyph exceeds the complexity limit or the allocation limit.

Dispose()

GlyphHinter.cs

Gives back the storage of the state of the instructions.

public void Dispose()