Module documentation.

Corona binding to stb_truetype, from Sean Barrett's stb.

To use the plugin, add the following in build.settings:

plugins = {
  ["plugin.truetype"] = { publisherId = "com.xibalbastudios" }

On Android, the AssetReader plugin may also be included to improve file-reading support:

plugins = {
  ["plugin.truetype"] = { publisherId = "com.xibalbastudios" },
  ["plugin.AssetReader"] = { publisherId = "com.xibalbastudios" }

A require("plugin.AssetReader") will then install support. (Down the road, this will ideally be automatic.)

A sample project is available here.

The Bytes type—specified in various functions and methods—may be any object that implements ByteReader, including strings.

This plugin is designed to be called safely from other Lua processes.

Adapted from stb_truetype.h:

This library processes TrueType files:

    parse files
    extract glyph metrics
    extract glyph shapes
    render glyphs to one-channel bitmaps with antialiasing (box filter)

Some important concepts to understand to use this library:

     Characters are defined by Unicode codepoints, e.g. 65 is
     uppercase A, 231 is lowercase c with a cedilla, 0x7e30 is
     the hiragana for "ma".

     A visual character shape (every codepoint is rendered as
     some glyph).

  Glyph index
     A font-specific integer ID representing a glyph.

     Glyph shapes are defined relative to a baseline, which is the
     bottom of uppercase characters. Characters extend both above
     and below the baseline.

  Current Point
     As you draw text to the screen, you keep track of a "current point"
     which is the origin of each character. The current point's vertical
     position is the baseline. Even "baked fonts" use this model.

  Vertical Font Metrics
     The vertical qualities of the font, used to vertically position
     and space the characters. See docs for FontInfo:GetFontVMetrics.

  Font Size in Pixels or Points
     The preferred interface for specifying font sizes in stb_truetype
     is to specify how tall the font's vertical extent should be in pixels.
     If that sounds good enough, skip the next paragraph.

     Most font APIs instead use "points", which are a common typographic
     measurement for describing font size, defined as 72 points per inch.
     stb_truetype provides a point API for compatibility. However, true
     "per inch" conventions don't make much sense on computer displays
     since different monitors have different number of pixels per inch.
     For example, Windows traditionally uses a convention that there are
     96 pixels per inch, thus making 'inch' measurements have nothing to
     do with inches, and thus effectively defining a point to be 1.333
     pixels. Additionally, the TrueType font data provides an explicit
     scale factor to scale a given font's glyphs to points, but the
     author has observed that this scale factor is often wrong for
     non-commercial fonts, thus making fonts scaled in points according
     to the TrueType spec incoherently sized in practice.



- Use the functions with Subpixel at the end to allow your characters
  to have subpixel positioning. Since the font is anti-aliased, not
  hinted, this is very import for quality. (This is not possible with
  baked fonts.)

- Kerning is now supported, and if you're supporting subpixel rendering
  then kerning is worth using to give your text a polished look.


- Convert Unicode codepoints to glyph indexes and operate on the glyphs;
  if you don't do this, stb_truetype is forced to do the conversion on
  every call.

- There are a lot of memory allocations. We should modify it to take
  a temp buffer and allocate from the temp buffer (without freeing),
  should help performance a lot.

This software is dual-licensed to the public domain and under the following license: you are granted a perpetual, irrevocable license to copy, modify, publish, and distribute this file as you see fit.


truetype Free functions used to create and prepare some font objects.


CharArray Class used intermediately by Packings, representing an array of packed characters.
FontInfo Class that represents font info.
Packing Class that represents a truetype packing context.
RectArray Class used intermediately by Packings, representing an array of rectangles.
Shape Representation of a glyph's shape as a series of contours.
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