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Comments: mirror upstream imgui.cpp/.h, imgui_internal.h, widgets/draw/tables/demo and imstb_* comments (comment-only, code tokens unchanged)
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4DBug
2026-10-14 10:23:55 -05:00
parent e502866075
commit 95fdf94912
14 changed files with 30451 additions and 7887 deletions
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imstb_truetype.lua
+374 -54
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@@ -1,6 +1,164 @@
--- Dear ImGui
-- This is a Lua port of original `imstb_truetype.h`
-- [DEAR IMGUI]
-- This is a slightly modified version of stb_truetype.h 1.26.
-- Mostly fixing for compiler and static analyzer warnings.
-- Grep for [DEAR IMGUI] to find the changes.
-- stb_truetype.h - v1.26 - public domain
-- authored from 2009-2021 by Sean Barrett / RAD Game Tools
--
-- =======================================================================
--
-- NO SECURITY GUARANTEE -- DO NOT USE THIS ON UNTRUSTED FONT FILES
--
-- This library does no range checking of the offsets found in the file,
-- meaning an attacker can use it to read arbitrary memory.
--
-- =======================================================================
--
-- This library processes TrueType files:
-- parse files
-- extract glyph metrics
-- extract glyph shapes
-- render glyphs to one-channel bitmaps with antialiasing (box filter)
--
-- Todo:
-- non-MS cmaps
-- crashproof on bad data
-- hinting? (no longer patented)
-- cleartype-style AA?
-- optimize: build edge-list directly from curves
-- optimize: rasterize directly from curves?
--
-- ADDITIONAL CONTRIBUTORS
--
-- Mikko Mononen: compound shape support, more cmap formats
-- Tor Andersson: kerning, subpixel rendering
-- Dougall Johnson: OpenType / Type 2 font handling
-- Daniel Ribeiro Maciel: basic GPOS-based kerning
--
-- Misc other:
-- Ryan Gordon
-- Simon Glass
-- github:IntellectualKitty
-- Imanol Celaya
-- Daniel Ribeiro Maciel
--
-- Bug/warning reports/fixes:
-- "Zer" on mollyrocket Fabian "ryg" Giesen github:NiLuJe
-- Cass Everitt Martins Mozeiko github:aloucks
-- stoiko (Haemimont Games) Cap Petschulat github:oyvindjam
-- Brian Hook Omar Cornut github:vassvik
-- Walter van Niftrik Ryan Griege
-- David Gow Peter LaValle
-- David Given Sergey Popov
-- Ivan-Assen Ivanov Giumo X. Clanjor
-- Anthony Pesch Higor Euripedes
-- Johan Duparc Thomas Fields
-- Hou Qiming Derek Vinyard
-- Rob Loach Cort Stratton
-- Kenney Phillis Jr. Brian Costabile
-- Ken Voskuil (kaesve)
--
-- USAGE
--
-- "Load" a font file from a memory buffer (you have to keep the buffer loaded)
-- stbtt_InitFont()
-- stbtt_GetFontOffsetForIndex() -- indexing for TTC font collections
--
-- Character advance/positioning
-- stbtt_GetFontVMetrics()
--
-- Starting with version 1.06, the rasterizer was replaced with a new,
-- faster and generally-more-precise rasterizer. The new rasterizer more
-- accurately measures pixel coverage for anti-aliasing, except in the case
-- where multiple shapes overlap, in which case it overestimates the AA pixel
-- coverage. Thus, anti-aliasing of intersecting shapes may look wrong.
-- (This port only implements the new rasterizer.)
--
-- ADDITIONAL DOCUMENTATION
--
-- Some important concepts to understand to use this library:
--
-- Codepoint
-- 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".
--
-- Glyph
-- A visual character shape (every codepoint is rendered as
-- some glyph)
--
-- Glyph index
-- A font-specific integer ID representing a glyph
--
-- Baseline
-- 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 stbtt_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.
--
-- DETAILED USAGE:
--
-- Scale:
-- Select how high you want the font to be, in pixels.
-- Call ScaleForPixelHeight to compute a scale factor SF that will be
-- used by all other functions.
--
-- Current point:
-- Set the current point where the first character will appear. The
-- first character could extend left of the current point; this is font
-- dependent. You can either choose a current point that is the leftmost
-- point and hope, or add some padding, or check the bounding box or
-- left-side-bearing of the first character to be displayed and set
-- the current point based on that.
--
-- Displaying a character:
-- Compute the bounding box of the character. It will contain signed values
-- relative to <current_point, baseline>. I.e. if it returns x0,y0,x1,y1,
-- then the character should be displayed in the rectangle from
-- <current_point+SF*x0, baseline+SF*y0> to <current_point+SF*x1,baseline+SF*y1).
--
-- Advancing for the next character:
-- Call GlyphHMetrics, and compute 'current_point += SF * advance'.
--
--
-- ADVANCED USAGE
--
-- Quality:
--
-- - 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.)
--
-- Performance:
--
-- - 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.
--
-- NOTES
--
-- The system uses the raw data found in the .ttf file without changing it
-- and without building auxiliary data structures. This is a bit inefficient
-- on little-endian systems (the data is big-endian), but assuming you're
-- caching the bitmaps or glyph shapes this shouldn't be a big deal.
--- STBTT_RASTERIZER_VERSION == 2
local stbtt_fontinfo
@@ -21,7 +179,7 @@ local stbtt_FindGlyphIndex
local STBTT_MAX_OVERSAMPLE = 8
--- @enum STBTT_PLATFORM_ID
local STBTT_PLATFORM_ID = {
local STBTT_PLATFORM_ID = { -- platformID
UNICODE = 0,
MAC = 1,
ISO = 2,
@@ -29,7 +187,7 @@ local STBTT_PLATFORM_ID = {
}
--- @enum STBTT_MS_EID
local STBTT_MS_EID = {
local STBTT_MS_EID = { -- encodingID for STBTT_PLATFORM_ID_MICROSOFT
SYMBOL = 0,
UNICODE_BMP = 1,
SHIFTJIS = 2,
@@ -75,6 +233,7 @@ local stbtt_int8 = ImS8
local stbtt_uint8 = ImU8
local unsigned_char = stbtt_uint8
-- private structure
--- @class stbtt__buf
--- @field data? table # 1-based byte table
--- @field offset int # Every access to `data` will be offset by this
@@ -93,6 +252,8 @@ local function stbtt__buf(initial_offset)
}
end
-- The following structure is defined publicly so you can declare one on
-- the stack or as a global or etc, but you should treat it as opaque.
--- @class stbtt_fontinfo
--- @field userdata any
--- @field data table # pointer to .ttf file
@@ -283,6 +444,7 @@ local function stbtt__new_active(e, off_x, start_point)
return z
end
-- @TODO: don't expose this structure
--- @class stbtt__bitmap
--- @field w int
--- @field h int
@@ -496,7 +658,7 @@ end
-------------------------------------
-------------------------------------
---
--- Accessors to parse data from file
--- accessors to parse data from file
---
---
@@ -535,14 +697,16 @@ local function stbtt_tag4(p, c0, c1, c2, c3, offset) offset = offset or 0; retur
local function stbtt_tag(p, str, offset) local c0, c1, c2, c3 = string.byte(str, 1, 4); return stbtt_tag4(p, c0, c1, c2, c3, offset) end
local function stbtt__isfont(font)
if stbtt_tag4(font, 49, 0, 0, 0) then return true end
if stbtt_tag(font, "typ1") then return true end
if stbtt_tag(font, "OTTO") then return true end
if stbtt_tag4(font, 0, 1, 0, 0) then return true end
if stbtt_tag(font, "true") then return true end
-- check the version number
if stbtt_tag4(font, 49, 0, 0, 0) then return true end -- TrueType 1
if stbtt_tag(font, "typ1") then return true end -- TrueType with type 1 font -- we don't support this!
if stbtt_tag(font, "OTTO") then return true end -- OpenType with CFF
if stbtt_tag4(font, 0, 1, 0, 0) then return true end -- OpenType 1.0
if stbtt_tag(font, "true") then return true end -- Apple specification for TrueType fonts
return false
end
-- @OPTIMIZE: binary search
local function stbtt__find_table(data, font_start, tag)
local num_tables = ttUSHORT(data, font_start + 4)
local tabledir = font_start + 12
@@ -556,11 +720,14 @@ local function stbtt__find_table(data, font_start, tag)
end
local function stbtt_GetFontOffsetForIndex_internal(font_collection, index)
-- if it's just a font, there's only one valid index
if stbtt__isfont(font_collection) then
if index == 0 then return 0 else return -1 end
end
-- check if it's a TTC
if stbtt_tag(font_collection, "ttcf") then
-- version 1?
if ttULONG(font_collection, 4) == 0x00010000 or ttULONG(font_collection, 4) == 0x00020000 then
local n = ttLONG(font_collection, 8)
if index >= n then
@@ -598,23 +765,25 @@ local function stbtt_InitFont_internal(info, data, fontstart)
info.fontstart = fontstart
info.cff = stbtt__new_buf(nil, 0)
cmap = stbtt__find_table(data, fontstart, "cmap")
info.loca = stbtt__find_table(data, fontstart, "loca")
info.head = stbtt__find_table(data, fontstart, "head")
info.glyf = stbtt__find_table(data, fontstart, "glyf")
info.hhea = stbtt__find_table(data, fontstart, "hhea")
info.hmtx = stbtt__find_table(data, fontstart, "hmtx")
info.kern = stbtt__find_table(data, fontstart, "kern")
info.gpos = stbtt__find_table(data, fontstart, "GPOS")
cmap = stbtt__find_table(data, fontstart, "cmap") -- required
info.loca = stbtt__find_table(data, fontstart, "loca") -- required
info.head = stbtt__find_table(data, fontstart, "head") -- required
info.glyf = stbtt__find_table(data, fontstart, "glyf") -- required
info.hhea = stbtt__find_table(data, fontstart, "hhea") -- required
info.hmtx = stbtt__find_table(data, fontstart, "hmtx") -- required
info.kern = stbtt__find_table(data, fontstart, "kern") -- not required
info.gpos = stbtt__find_table(data, fontstart, "GPOS") -- not required
if (cmap == 0 or info.head == 0 or info.hhea == 0 or info.hmtx == 0) then
return false
end
if info.glyf ~= 0 then
-- required for truetype
if info.loca == 0 then
return false
end
else
-- initialization for CFF / Type2 fonts (OTF)
local cff = stbtt__find_table(data, fontstart, "CFF ")
if cff == 0 then
return false
@@ -623,14 +792,16 @@ local function stbtt_InitFont_internal(info, data, fontstart)
info.fontdicts = stbtt__new_buf(nil, 0)
info.fdselect = stbtt__new_buf(nil, 0)
info.cff = stbtt__new_buf(data, 64 * 1024 * 1024, cff) -- TODO: this should use size from table
-- @TODO this should use size from table (not 512MB)
info.cff = stbtt__new_buf(data, 64 * 1024 * 1024, cff) -- PORT: 64MB here instead of 512MB
local b = info.cff
-- read the header
stbtt__buf_skip(b, 2)
stbtt__buf_seek(b, stbtt__buf_get8(b))
stbtt__buf_seek(b, stbtt__buf_get8(b)) -- hdrsize
-- TODO: the name INDEX could list multiple fonts, but we just use the first one.
-- @TODO the name INDEX could list multiple fonts,
-- but we just use the first one.
stbtt__cff_get_index(b) -- name INDEX
local topdictidx = stbtt__cff_get_index(b)
local topdict = stbtt__cff_index_get(topdictidx, 0)
@@ -643,6 +814,7 @@ local function stbtt_InitFont_internal(info, data, fontstart)
local fdselectoff = stbtt__dict_get_ints(topdict, bit32.bor(0x100, 37), 1)
info.subrs = stbtt__get_subrs(b, topdict)
-- we only support Type 2 charstrings
if cstype[1] ~= 2 then
return false
end
@@ -651,6 +823,7 @@ local function stbtt_InitFont_internal(info, data, fontstart)
end
if fdarrayoff[1] ~= 0 then
-- looks like a CID font
if fdselectoff[1] == 0 then
return false
end
@@ -673,19 +846,26 @@ local function stbtt_InitFont_internal(info, data, fontstart)
info.svg = -1
-- find a cmap encoding table we understand *now* to avoid searching
-- later. (todo: could make this installable)
-- the same regardless of glyph.
numTables = ttUSHORT(data, cmap + 2)
info.index_map = 0
for i = 0, numTables - 1 do
local encoding_record = cmap + 4 + 8 * i
-- find an encoding we understand:
local platform_id = ttUSHORT(data, encoding_record)
if platform_id == STBTT_PLATFORM_ID.MICROSOFT then
local ms_eid = ttUSHORT(data, encoding_record + 2)
if ms_eid == STBTT_MS_EID.UNICODE_BMP or ms_eid == STBTT_MS_EID.UNICODE_FULL then
-- MS/Unicode
info.index_map = cmap + ttULONG(data, encoding_record + 4)
end
elseif platform_id == STBTT_PLATFORM_ID.UNICODE then
-- Mac/iOS has these
-- all the encodingIDs are unicode, so we don't bother to check it
info.index_map = cmap + ttULONG(data, encoding_record + 4)
end
end
@@ -697,6 +877,11 @@ local function stbtt_InitFont_internal(info, data, fontstart)
return true
end
-- If you're going to perform multiple operations on the same character
-- and you want a speed-up, call this function with the character you're
-- going to process, then use glyph-based functions instead of the
-- codepoint-based functions.
-- Returns 0 if the character codepoint is not defined in the font.
--- @param info stbtt_fontinfo
--- @param unicode_codepoint int
function stbtt_FindGlyphIndex(info, unicode_codepoint)
@@ -704,7 +889,7 @@ function stbtt_FindGlyphIndex(info, unicode_codepoint)
local index_map = info.index_map
local format = ttUSHORT(data, index_map + 0)
if format == 0 then
if format == 0 then -- apple byte encoding
local bytes = ttUSHORT(data, index_map + 2)
if unicode_codepoint < bytes - 6 then
return ttBYTE(data, index_map + 6 + unicode_codepoint)
@@ -718,14 +903,15 @@ function stbtt_FindGlyphIndex(info, unicode_codepoint)
end
return 0
elseif format == 2 then
STBTT_assert(false) -- TODO: high-byte mapping for japanese/chinese/korean
STBTT_assert(false) -- @TODO: high-byte mapping for japanese/chinese/korean
return 0
elseif format == 4 then
elseif format == 4 then -- standard mapping for windows fonts: binary search collection of ranges
local segcount = bit32.rshift(ttUSHORT(data, index_map + 6), 1)
local searchRange = bit32.rshift(ttUSHORT(data, index_map + 8), 1)
local entrySelector = ttUSHORT(data, index_map + 10)
local rangeShift = bit32.rshift(ttUSHORT(data, index_map + 12), 1)
-- do a binary search of the segments
local endCount = index_map + 14
local search = endCount
@@ -733,10 +919,13 @@ function stbtt_FindGlyphIndex(info, unicode_codepoint)
return 0
end
-- they lie from endCount .. endCount + segCount
-- but searchRange is the nearest power of two, so...
if unicode_codepoint >= ttUSHORT(data, search + rangeShift * 2) then
search = search + rangeShift * 2
end
-- now decrement to bias correctly to find smallest
search = search - 2
while entrySelector ~= 0 do
searchRange = bit32.rshift(searchRange, 1)
@@ -768,8 +957,9 @@ function stbtt_FindGlyphIndex(info, unicode_codepoint)
local ngroups = ttULONG(data, index_map + 12)
local low = 0
local high = ngroups
-- Binary search the right group.
while low < high do
local mid = low + bit32.rshift(high - low, 1)
local mid = low + bit32.rshift(high - low, 1) -- rounds down, so low <= mid < high
local start_char = ttULONG(data, index_map + 16 + mid * 12)
local end_char = ttULONG(data, index_map + 16 + mid * 12 + 4)
if unicode_codepoint < start_char then
@@ -785,10 +975,10 @@ function stbtt_FindGlyphIndex(info, unicode_codepoint)
end
end
end
return 0
return 0 -- not found
end
-- TODO:
-- @TODO
STBTT_assert(false)
return 0
end
@@ -810,8 +1000,8 @@ end
local function stbtt__GetGlyfOffset(info, glyph_index)
STBTT_assert(info.cff.size == 0)
if glyph_index >= info.numGlyphs then return -1 end
if info.indexToLocFormat >= 2 then return -1 end
if glyph_index >= info.numGlyphs then return -1 end -- glyph index out of range
if info.indexToLocFormat >= 2 then return -1 end -- unknown index->glyph map format
local g1, g2
if info.indexToLocFormat == 0 then
@@ -822,9 +1012,10 @@ local function stbtt__GetGlyfOffset(info, glyph_index)
g2 = info.glyf + ttULONG(info.data, info.loca + glyph_index * 4 + 4)
end
if g1 == g2 then return -1 else return g1 end
if g1 == g2 then return -1 else return g1 end -- if length is 0, return -1
end
-- Gets the bounding box of the visible part of the glyph, in unscaled coordinates
--- @return integer, integer?, integer?, integer?, integer?
local function stbtt_GetGlyphBox(info, glyph_index)
local n, x0, y0, x1, y1
@@ -896,7 +1087,7 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
local points = (endPtsOfContours + numberOfContours * 2 + 2 + ins) + 1 -- 1-based idx
local n = 1 + ttUSHORT(data, endPtsOfContours + numberOfContours * 2 - 2)
local m = n + 2 * numberOfContours
local m = n + 2 * numberOfContours -- a loose bound on how many vertices we might need
vertices = {}
for i = 1, m do vertices[i] = stbtt_vertex() end
@@ -907,7 +1098,11 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
local next_move = 0
local flagcount = 0
local off = m - n
-- in first pass, we load uninterpreted data into the allocated array
-- above, shifted to the end of the array so we won't overwrite it when
-- we create our final data starting from the front
local off = m - n -- starting offset for uninterpreted data, regardless of how m ends up being calculated
-- first load flags
local flags = 0
@@ -934,7 +1129,7 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
if bit32.band(flags, 2) ~= 0 then
local dx = data[points]
points = points + 1
if bit32.band(flags, 16) ~= 0 then
if bit32.band(flags, 16) ~= 0 then -- ???
x = x + dx
else
x = x - dx
@@ -956,7 +1151,7 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
if bit32.band(flags, 4) ~= 0 then
local dy = data[points]
points = points + 1
if bit32.band(flags, 32) ~= 0 then
if bit32.band(flags, 32) ~= 0 then -- ???
y = y + dy
else
y = y - dy
@@ -987,15 +1182,19 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
-- now start the new one
start_off = (bit32.band(flags, 1) == 0)
if start_off then
-- if we start off with an off-curve point, then when we need to find a point on the curve
-- where we can start, and we need to save some state for when we wraparound.
scx = x
scy = y
if bit32.band(vertices[off + i + 1].type, 1) == 0 then
-- next point is also a curve point, so interpolate an on-point curve
sx = bit32.rshift(x + stbtt_int32(vertices[off + i + 1].x), 1)
sy = bit32.rshift(y + stbtt_int32(vertices[off + i + 1].y), 1)
else
-- otherwise just use the next point as our start point
sx = stbtt_int32(vertices[off + i + 1].x)
sy = stbtt_int32(vertices[off + i + 1].y)
i = i + 1
i = i + 1 -- we're using point i+1 as the starting point, so skip it
end
else
sx = x
@@ -1007,8 +1206,8 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
next_move = 1 + ttUSHORT(data, endPtsOfContours + j * 2)
j = j + 1
else
if bit32.band(flags, 1) == 0 then
if was_off then
if bit32.band(flags, 1) == 0 then -- if it's a curve
if was_off then -- two off-curve control points in a row means interpolate an on-curve midpoint
stbtt_setvertex(vertices[num_vertices + 1], STBTT_VTX.CURVE, bit32.rshift(cx + x, 1), bit32.rshift(cy + y, 1), cx, cy)
num_vertices = num_vertices + 1
end
@@ -1032,6 +1231,7 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
num_vertices = stbtt__close_shape(vertices, num_vertices, was_off, start_off, sx, sy, scx, scy, cx, cy)
elseif numberOfContours < 0 then
-- Compound shapes.
local more = 1
local comp = g + 10
num_vertices = 0
@@ -1047,8 +1247,8 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
flags = ttSHORT(data, comp) comp = comp + 2
gidx = ttSHORT(data, comp) comp = comp + 2
if bit32.band(flags, 2) ~= 0 then
if bit32.band(flags, 1) ~= 0 then
if bit32.band(flags, 2) ~= 0 then -- XY values
if bit32.band(flags, 1) ~= 0 then -- shorts
mtx[5] = ttSHORT(data, comp) comp = comp + 2
mtx[6] = ttSHORT(data, comp) comp = comp + 2
else
@@ -1056,7 +1256,7 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
mtx[6] = ttCHAR(data, comp) comp = comp + 1
end
else
-- TODO: handle matching point
-- @TODO handle matching point
STBTT_assert(false)
end
@@ -1083,11 +1283,14 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
mtx[4] = ttSHORT(data, comp) / 16384.0 comp = comp + 2
end
-- Find transformation scales.
m = STBTT_sqrt(mtx[1] * mtx[1] + mtx[2] * mtx[2])
n = STBTT_sqrt(mtx[3] * mtx[3] + mtx[4] * mtx[4])
-- Get indexed glyph.
comp_num_vertices, comp_verts = stbtt_GetGlyphShape(info, gidx)
if comp_num_vertices > 0 then
-- Transform vertices.
for i = 1, comp_num_vertices do
local v = comp_verts[i]
local x = v.x
@@ -1100,6 +1303,7 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
v.cy = stbtt_int16(n * (mtx[2] * x + mtx[4] * y + mtx[6]))
end
-- Append vertices.
if num_vertices == 0 then -- LUA: No malloc
vertices = comp_verts
else
@@ -1111,6 +1315,7 @@ local function stbtt__GetGlyphShapeTT(info, glyph_index)
num_vertices = num_vertices + comp_num_vertices
end
-- More components ?
more = bit32.band(flags, bit32.lshift(1, 5))
end
end
@@ -1266,7 +1471,7 @@ local function stbtt__run_charstring(info, glyph_index, c)
clear_stack = 1
b0 = stbtt__buf_get8(b)
-- TODO: implement hinting
-- @TODO implement hinting
if b0 == 0x13 or b0 == 0x14 then -- hintmask or cntrmask
if in_header then
maskbits = maskbits + trunc(sp / 2) -- implicit "vstem"
@@ -1415,6 +1620,8 @@ local function stbtt__run_charstring(info, glyph_index, c)
elseif b0 == 0x0C then -- two-byte escape
local b1 = stbtt__buf_get8(b)
-- @TODO These "flex" implementations ignore the flex-depth and resolution,
-- and always draw beziers.
if b1 == 0x22 then -- hflex
if sp < 7 then return STBTT__CSERR("hflex stack") end
local dx1 = s[0]
@@ -1547,6 +1754,15 @@ function stbtt__GetGlyphInfoT2(info, glyph_index)
return ((r ~= 0) and c.num_vertices or 0), x0, y0, x1, y1
end
-- returns # of vertices and fills *vertices with the pointer to them
-- these are expressed in "unscaled" coordinates
--
-- The shape is a series of contours. Each one starts with
-- a STBTT_moveto, then consists of a series of mixed
-- STBTT_lineto and STBTT_curveto segments. A lineto
-- draws a line from previous endpoint to its x,y; a curveto
-- draws a quadratic bezier from previous endpoint to
-- its x,y, using cx,cy as the bezier control point.
--- @param info stbtt_fontinfo
--- @param glyph_index int
function stbtt_GetGlyphShape(info, glyph_index)
@@ -1557,6 +1773,9 @@ function stbtt_GetGlyphShape(info, glyph_index)
end
end
-- leftSideBearing is the offset from the current horizontal position to the left edge of the character
-- advanceWidth is the offset from the current horizontal position to the next horizontal position
-- these are expressed in unscaled coordinates
--- @param info stbtt_fontinfo
--- @param glyph_index int
function stbtt_GetGlyphHMetrics(info, glyph_index)
@@ -1574,6 +1793,12 @@ function stbtt_GetGlyphHMetrics(info, glyph_index)
return advanceWidth, leftSideBearing
end
-- ascent is the coordinate above the baseline the font extends; descent
-- is the coordinate below the baseline the font extends (i.e. it is typically negative)
-- lineGap is the spacing between one row's descent and the next row's ascent...
-- so you should advance the vertical position by "ascent - descent + lineGap"
-- these are expressed in unscaled coordinates, so you must multiply by
-- the scale factor for a given size
--- @param info stbtt_fontinfo
function stbtt_GetFontVMetrics(info)
local ascent = ttSHORT(info.data, info.hhea + 4)
@@ -1583,6 +1808,12 @@ function stbtt_GetFontVMetrics(info)
return ascent, descent, lineGap
end
-- computes a scale factor to produce a font whose "height" is 'pixels' tall.
-- Height is measured as the distance from the highest ascender to the lowest
-- descender; in other words, it's equivalent to calling stbtt_GetFontVMetrics
-- and computing:
-- scale = pixels / (ascent - descent)
-- so if you prefer to measure height by the ascent only, use a similar calculation.
--- @param info stbtt_fontinfo
--- @param height float
function stbtt_ScaleForPixelHeight(info, height)
@@ -1593,10 +1824,12 @@ end
------------------------------------
------------------------------------
---
--- Antialiasing software rasterizer
--- antialiasing software rasterizer
---
---
-- same as stbtt_GetGlyphBitmapBox, but you can specify a subpixel
-- shift for the character
--- @param font stbtt_fontinfo
--- @param glyph int
--- @param scale_x float
@@ -1624,6 +1857,11 @@ function stbtt_GetGlyphBitmapBoxSubpixel(font, glyph, scale_x, scale_y, shift_x,
return ix0, iy0, ix1, iy1
end
-- get the bbox of the bitmap centered around the glyph origin; so the
-- bitmap width is ix1-ix0, height is iy1-iy0, and location to place
-- the bitmap top left is (leftSideBearing*scale,iy0).
-- (Note that the bitmap uses y-increases-down, but the shape uses
-- y-increases-up, so GlyphBitmapBox and GlyphBox are inverted.)
--- @param font stbtt_fontinfo
--- @param glyph int
--- @param scale_x float
@@ -1646,6 +1884,8 @@ end
--- stbtt_MakeGlyphBitmap
--- stbtt_GetGlyphBitmapSubpixel
-- the edge passed in here does not cross the vertical line at x or the vertical line at x+1
-- (i.e. it has already been clipped to those)
--- @param scanline float[]
--- @param x int
--- @param e stbtt__active_edge
@@ -1687,7 +1927,7 @@ local function stbtt__handle_clipped_edge(scanline, x, e, x0, y0, x1, y1)
-- do nothing
else
STBTT_assert(x0 >= x and x0 <= x + 1 and x1 >= x and x1 <= x + 1)
scanline[x] = scanline[x] + e.direction * (y1 - y0) * (1 - ((x0 - x) + (x1 - x)) / 2)
scanline[x] = scanline[x] + e.direction * (y1 - y0) * (1 - ((x0 - x) + (x1 - x)) / 2) -- coverage = 1 - average x position
end
end
@@ -1725,6 +1965,7 @@ local function stbtt__fill_active_edges_new(scanline, scanline_fill, len, e, y_t
while e do
-- brute force every pixel
-- compute intersection points with top & bottom
STBTT_assert(e.ey >= y_top)
@@ -1768,8 +2009,8 @@ local function stbtt__fill_active_edges_new(scanline, scanline_fill, len, e, y_t
if x_top >= 0 and x_bottom >= 0 and x_top < len and x_bottom < len then
-- from here on, we don't have to range check x values
if trunc(x_top) == trunc(x_bottom) then
-- simple case, only spans one pixel
local height
-- simple case, only spans one pixel
local x = trunc(x_top)
height = (sy1 - sy0) * e.direction
STBTT_assert(x >= 0 and x < len)
@@ -1801,8 +2042,25 @@ local function stbtt__fill_active_edges_new(scanline, scanline_fill, len, e, y_t
-- compute intersection with y axis at x2
y_final = y_top + dy * (x2 - x0)
-- x1 x_top x2 x_bottom
-- y_top +------|-----+------------+------------+--------|---+------------+
-- | | | | | |
-- | | | | | |
-- sy0 | Txxxxx|............|............|............|............|
-- y_crossing | *xxxxx.......|............|............|............|
-- | | xxxxx..|............|............|............|
-- | | /- xx*xxxx........|............|............|
-- | | dy < | xxxxxx..|............|............|
-- y_final | | \- | xx*xxx.........|............|
-- sy1 | | | | xxxxxB...|............|
-- | | | | | |
-- | | | | | |
-- y_bottom +------------+------------+------------+------------+------------+
--
-- goal is to measure the area covered by '.' in each pixel
-- if x2 is right at the right edge of x1, y_crossing can blow up, github #1057
-- TODO: maybe test against sy1 rather than y_bottom?
-- @TODO: maybe test against sy1 rather than y_bottom?
if y_crossing > y_bottom then
y_crossing = y_bottom
end
@@ -1824,6 +2082,16 @@ local function stbtt__fill_active_edges_new(scanline, scanline_fill, len, e, y_t
end
end
-- in second pixel, area covered by line segment found in first pixel
-- is always a rectangle 1 wide * the height of that line segment; this
-- is exactly what the variable 'area' stores. it also gets a contribution
-- from the line segment within it. the THIRD pixel will get the first
-- pixel's rectangle contribution, the second pixel's rectangle contribution,
-- and its own contribution. the 'own contribution' is the same in every pixel except
-- the leftmost and rightmost, a trapezoid that slides down in each pixel.
-- the second pixel's contribution to the third pixel will be the
-- rectangle 1 wide times the height change in the second pixel, which is dy.
step = sign * dy * 1 -- dy is dy/dx, change in y for every 1 change in x,
-- which multiplied by 1-pixel-width is how much pixel area changes for each step in x
-- so the area advances by 'step' every time
@@ -1843,7 +2111,27 @@ local function stbtt__fill_active_edges_new(scanline, scanline_fill, len, e, y_t
scanline_fill[x2 + 1] = scanline_fill[x2 + 1] + sign * (sy1 - sy0)
end
else
-- if edge goes outside of box we're drawing, we require
-- clipping logic. since this does not match the intended use
-- of this library, we use a different, very slow brute
-- force implementation
-- note though that this does happen some of the time because
-- x_top and x_bottom can be extrapolated at the top & bottom of
-- the shape and actually lie outside the bounding box
for x = 0, len - 1 do
-- cases:
--
-- there can be up to two intersections with the pixel. any intersection
-- with left or right edges can be handled by splitting into two (or three)
-- regions. intersections with top & bottom do not necessitate case-wise logic.
--
-- the old way of doing this found the intersections with the left & right edges,
-- then used some simple logic to produce up to three segments in sorted order
-- from top-to-bottom. however, this had a problem: if an x edge was epsilon
-- across the x border, then the corresponding y position might not be distinct
-- from the other y segment, and it might ignored as an empty segment. to avoid
-- that, we need to explicitly produce segments based on x positions.
-- rename variables to clearly-defined pairs
local y0 = y_top
local x1 = x
@@ -1887,6 +2175,7 @@ local function stbtt__fill_active_edges_new(scanline, scanline_fill, len, e, y_t
end
end
-- directly AA rasterize edges w/o supersampling
--- @param result stbtt__bitmap
--- @param e stbtt__edge
--- @param n int
@@ -1914,28 +2203,33 @@ local function stbtt__rasterize_sorted_edges(result, e, n, vsubsample, off_x, of
for i = 0, result.w - 1 do scanline[i] = 0 end
for i = 0, result.w do scanline2[i] = 0 end
-- update all active edges;
-- remove all active edges that terminate before the top of this scanline
local prev = nil
local curr = active
while curr do
local next = curr.next
if curr.ey <= scan_y_top then
if prev then prev.next = next
if prev then prev.next = next -- delete from list
else active = next end
curr.direction = 0
else
prev = curr
prev = curr -- advance through list
end
curr = next
end
-- insert all edges that start before the bottom of this scanline
local edge = e[p]
while edge.y0 <= scan_y_bottom do
if edge.y0 ~= edge.y1 then
local z = stbtt__new_active(edge, off_x, scan_y_top)
if j == 0 and off_y ~= 0 and z.ey < scan_y_top then
-- this can happen due to subpixel positioning and some kind of fp rounding error i think
z.ey = scan_y_top
end
STBTT_assert(z.ey >= scan_y_top)
STBTT_assert(z.ey >= scan_y_top) -- if we get really unlucky a tiny bit of an edge can be out of bounds
-- insert at front
z.next = active
active = z
end
@@ -1943,6 +2237,7 @@ local function stbtt__rasterize_sorted_edges(result, e, n, vsubsample, off_x, of
edge = e[p]
end
-- now process all active edges
if active then
stbtt__fill_active_edges_new(scanline, scanline2, result.w, active, scan_y_top)
end
@@ -1961,10 +2256,11 @@ local function stbtt__rasterize_sorted_edges(result, e, n, vsubsample, off_x, of
end
end
-- advance all the edges
step = active
while step do
step.fx = step.fx + step.fdx
step = step.next
step.fx = step.fx + step.fdx -- advance to position for current scanline
step = step.next -- advance through list
end
y = y + 1
@@ -1999,6 +2295,7 @@ end
local function stbtt__rasterize(result, pts, wcount, windings, scale_x, scale_y, shift_x, shift_y, off_x, off_y, invert)
local y_scale_inv = (invert) and -scale_y or scale_y
local vsubsample = 1 -- STBTT_RASTERIZER_VERSION == 2
-- vsubsample should divide 255 evenly; otherwise we won't reach full opacity
-- now we have to blow out the windings into explicit edge lists
local n = 0
@@ -2066,8 +2363,7 @@ local function stbtt__add_point(points, n, x, y)
points[n + 1].y = y
end
-- tessellate until threshold p is happy...
-- TODO: warped to compensate for non-linear stretching
-- tessellate until threshold p is happy... @TODO warped to compensate for non-linear stretching
--- @param points? stbtt__point[]
--- @param num_points int
--- @param x0 float
@@ -2116,7 +2412,7 @@ end
--- @param n int
--- @return int num_points # updated num_points passed in
local function stbtt__tesselate_cubic(points, num_points, x0, y0, x1, y1, x2, y2, x3, y3, objspace_flatness_squared, n)
-- TODO: this "flatness" calculation is just made-up nonsense that seems to work well enough
-- @TODO this "flatness" calculation is just made-up nonsense that seems to work well enough
local dx0 = x1 - x0
local dy0 = y1 - y0
local dx1 = x2 - x1
@@ -2159,6 +2455,7 @@ local function stbtt__tesselate_cubic(points, num_points, x0, y0, x1, y1, x2, y2
return num_points
end
-- returns number of contours
--- @param vertices stbtt_vertex[]
--- @param num_verts int
--- @param objspace_flatness float
@@ -2235,6 +2532,7 @@ local function stbtt_FlattenCurves(vertices, num_verts, objspace_flatness)
return points, num_contours, contour_lengths
end
-- rasterize a shape with quadratic beziers into a bitmap
--- @param result stbtt__bitmap
--- @param flatness_in_pixels float
--- @param vertices stbtt_vertex[]
@@ -2258,6 +2556,11 @@ local function stbtt_Rasterize(result, flatness_in_pixels, vertices, num_verts,
end
end
-- renders the glyph into storage you pass in for the bitmap,
-- in the form of 'output', with row spacing of 'out_stride' bytes. the bitmap
-- is clipped to out_w/out_h bytes. Call stbtt_GetGlyphBitmapBox to get the
-- width and height and positioning info for it first. You can also specify
-- a subpixel shift for the character.
--- @param info stbtt_fontinfo
--- @param output unsigned_char[]
--- @param out_w int
@@ -2286,7 +2589,7 @@ end
-----------------
-----------------
---
--- Bitmap baking
--- bitmap baking
---
---
@@ -2298,7 +2601,7 @@ end
---------------------------
---------------------------
---
--- Bitmap baking / packing
--- bitmap baking / packing
---
---
@@ -2380,9 +2683,16 @@ local function stbtt__oversample_shift(oversample)
if oversample == 0 then
return 0.0
end
-- The prefilter is a box filter of width "oversample",
-- which shifts phase by (oversample - 1)/2 pixels in
-- oversampled space. We want to shift in the opposite
-- direction to counter this.
return -(oversample - 1) / (2.0 * oversample)
end
-- same as stbtt_MakeGlyphBitmapSubpixel, but prefiltering
-- is performed. Returns (sub_x, sub_y).
--- @param info stbtt_fontinfo
--- @param output unsigned_char[]
--- @param out_w int
@@ -2415,7 +2725,7 @@ end
-------------------
-------------------
---
--- SDF computation
--- sdf computation
---
---
@@ -2441,10 +2751,20 @@ end
--- stbtt__matchpair
--- stbtt__matches
-- Each .ttf/.ttc file may have more than one font. Each font has a sequential
-- index number starting from 0. Call this function to get the font offset for
-- a given index; it returns -1 if the index is out of range. A regular .ttf
-- file will only define one font and it always be at offset 0, so it will
-- return '0' for index 0, and -1 for all other indices.
--- @param data table
--- @param index int
function stbtt_GetFontOffsetForIndex(data, index) return stbtt_GetFontOffsetForIndex_internal(data, index) end
-- Given an offset into the file that defines a font, this function builds
-- the necessary cached info for the rest of the system. You must allocate
-- the stbtt_fontinfo yourself (see stbtt_fontinfo()), and stbtt_InitFont will fill it out. You don't
-- need to do anything special to free it, because the contents are pure
-- value data with no additional data structures. Returns false on failure.
--- @param info stbtt_fontinfo
--- @param data table
--- @param offset int