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truetype.c
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truetype.c
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#include "truetype.h"
#include "cstdint.h"
#include "bits.h"
#include "memory.h"
#include "std.h"
typedef char tl_tt__check_size32[sizeof(int32_t)==4 ? 1 : -1];
typedef char tl_tt__check_size16[sizeof(int16_t)==2 ? 1 : -1];
#define STBTT_malloc(x,u) memalloc(x)
#define STBTT_free(x,u) memfree(x)
#define STBTT_assert(x) assert(x)
#define STBTT_strlen(x) strlen(x)
#define STBTT_memcpy memcpy
#define STBTT_memset memset
// #define your own STBTT_sort() to override this to avoid qsort
#ifndef STBTT_sort
#include <stdlib.h>
#define STBTT_sort(data,num_items,item_size,compare_func) qsort(data,num_items,item_size,compare_func)
#endif
// #define your own STBTT_ifloor/STBTT_iceil() to avoid math.h
#ifndef STBTT_ifloor
#include <math.h>
#define STBTT_ifloor(x) ((int) floor(x))
#define STBTT_iceil(x) ((int) ceil(x))
#endif
// #define your own functions "STBTT_malloc" / "STBTT_free" to avoid malloc.h
#ifndef STBTT_malloc
#include <malloc.h>
#define STBTT_malloc(x,u) malloc(x)
#define STBTT_free(x,u) free(x)
#endif
#ifndef STBTT_assert
#include <assert.h>
#define STBTT_assert(x) assert(x)
#endif
#ifndef STBTT_strlen
#include <string.h>
#define STBTT_strlen(x) strlen(x)
#endif
#ifndef STBTT_memcpy
#include <memory.h>
#define STBTT_memcpy memcpy
#define STBTT_memset memset
#endif
//////////////////////////////////////////////////////////////////////////
//
// accessors to parse data from file
//
// on platforms that don't allow misaligned reads, if we want to allow
// truetype fonts that aren't padded to alignment, define ALLOW_UNALIGNED_TRUETYPE
#define ttBYTE(p) (* (uint8_t *) (p))
#define ttCHAR(p) (* (int8_t *) (p))
#define ttFixed(p) ttLONG(p)
#define ttUSHORT(p) tl_read_be16(p)
#define ttSHORT(p) ((int16_t)tl_read_be16(p))
#define ttULONG(p) tl_read_be32(p)
#define ttLONG(p) ((int32_t)tl_read_be32(p))
#define tl_tt_tag4(p,c0,c1,c2,c3) ((p)[0] == (c0) && (p)[1] == (c1) && (p)[2] == (c2) && (p)[3] == (c3))
#define tl_tt_tag(p,str) tl_tt_tag4(p,str[0],str[1],str[2],str[3])
static int tl_tt__isfont(const uint8_t *font)
{
// check the version number
if (tl_tt_tag(font, "1")) return 1; // TrueType 1
if (tl_tt_tag(font, "typ1")) return 1; // TrueType with type 1 font -- we don't support this!
if (tl_tt_tag(font, "OTTO")) return 1; // OpenType with CFF
if (tl_tt_tag4(font, 0,1,0,0)) return 1; // OpenType 1.0
return 0;
}
// @OPTIMIZE: binary search
static uint32_t tl_tt__find_table(uint8_t *data, uint32_t fontstart, char *tag)
{
int32_t num_tables = ttUSHORT(data+fontstart+4);
uint32_t tabledir = fontstart + 12;
int32_t i;
for (i=0; i < num_tables; ++i) {
uint32_t loc = tabledir + 16*i;
if (tl_tt_tag(data+loc+0, tag))
return ttULONG(data+loc+8);
}
return 0;
}
int tl_tt_GetFontOffsetForIndex(const unsigned char *font_collection, int index)
{
// if it's just a font, there's only one valid index
if (tl_tt__isfont(font_collection))
return index == 0 ? 0 : -1;
// check if it's a TTC
if (tl_tt_tag(font_collection, "ttcf")) {
// version 1?
if (ttULONG(font_collection+4) == 0x00010000 || ttULONG(font_collection+4) == 0x00020000) {
int32_t n = ttLONG(font_collection+8);
if (index >= n)
return -1;
return ttULONG(font_collection+12+index*14);
}
}
return -1;
}
int tl_tt_InitFont(tl_tt_fontinfo *info, const unsigned char *data2, int fontstart)
{
uint8_t *data = (uint8_t *) data2;
uint32_t cmap, t;
int32_t i,numTables;
info->data = data;
info->fontstart = fontstart;
cmap = tl_tt__find_table(data, fontstart, "cmap");
info->loca = tl_tt__find_table(data, fontstart, "loca");
info->head = tl_tt__find_table(data, fontstart, "head");
info->glyf = tl_tt__find_table(data, fontstart, "glyf");
info->hhea = tl_tt__find_table(data, fontstart, "hhea");
info->hmtx = tl_tt__find_table(data, fontstart, "hmtx");
if (!cmap || !info->loca || !info->head || !info->glyf || !info->hhea || !info->hmtx)
return 0;
t = tl_tt__find_table(data, fontstart, "maxp");
if (t)
info->numGlyphs = ttUSHORT(data+t+4);
else
info->numGlyphs = 0xffff;
// 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; i < numTables; ++i) {
uint32_t encoding_record = cmap + 4 + 8 * i;
// find an encoding we understand:
switch(ttUSHORT(data+encoding_record)) {
case STBTT_PLATFORM_ID_MICROSOFT:
switch (ttUSHORT(data+encoding_record+2)) {
case STBTT_MS_EID_UNICODE_BMP:
case STBTT_MS_EID_UNICODE_FULL:
// MS/Unicode
info->index_map = cmap + ttULONG(data+encoding_record+4);
break;
}
break;
}
}
if (info->index_map == 0)
return 0;
info->indexToLocFormat = ttUSHORT(data+info->head + 50);
return 1;
}
int tl_tt_FindGlyphIndex(const tl_tt_fontinfo *info, int unicode_codepoint)
{
uint8_t *data = info->data;
uint32_t index_map = info->index_map;
uint16_t format = ttUSHORT(data + index_map + 0);
if (format == 0) { // apple byte encoding
int32_t bytes = ttUSHORT(data + index_map + 2);
if (unicode_codepoint < bytes-6)
return ttBYTE(data + index_map + 6 + unicode_codepoint);
return 0;
} else if (format == 6) {
uint32_t first = ttUSHORT(data + index_map + 6);
uint32_t count = ttUSHORT(data + index_map + 8);
if ((uint32_t) unicode_codepoint >= first && (uint32_t) unicode_codepoint < first+count)
return ttUSHORT(data + index_map + 10 + (unicode_codepoint - first)*2);
return 0;
} else if (format == 2) {
STBTT_assert(0); // @TODO: high-byte mapping for japanese/chinese/korean
return 0;
} else if (format == 4) { // standard mapping for windows fonts: binary search collection of ranges
uint16_t segcount = ttUSHORT(data+index_map+6) >> 1;
uint16_t searchRange = ttUSHORT(data+index_map+8) >> 1;
uint16_t entrySelector = ttUSHORT(data+index_map+10);
uint16_t rangeShift = ttUSHORT(data+index_map+12) >> 1;
uint16_t item, offset, start, end;
// do a binary search of the segments
uint32_t endCount = index_map + 14;
uint32_t search = endCount;
if (unicode_codepoint > 0xffff)
return 0;
// they lie from endCount .. endCount + segCount
// but searchRange is the nearest power of two, so...
if (unicode_codepoint >= ttUSHORT(data + search + rangeShift*2))
search += rangeShift*2;
// now decrement to bias correctly to find smallest
search -= 2;
while (entrySelector) {
searchRange >>= 1;
start = ttUSHORT(data + search + 2 + segcount*2 + 2);
end = ttUSHORT(data + search + 2);
start = ttUSHORT(data + search + searchRange*2 + segcount*2 + 2);
end = ttUSHORT(data + search + searchRange*2);
if (unicode_codepoint > end)
search += searchRange*2;
--entrySelector;
}
search += 2;
item = (uint16_t) ((search - endCount) >> 1);
STBTT_assert(unicode_codepoint <= ttUSHORT(data + endCount + 2*item));
start = ttUSHORT(data + index_map + 14 + segcount*2 + 2 + 2*item);
end = ttUSHORT(data + index_map + 14 + 2 + 2*item);
if (unicode_codepoint < start)
return 0;
offset = ttUSHORT(data + index_map + 14 + segcount*6 + 2 + 2*item);
if (offset == 0)
return unicode_codepoint + ttSHORT(data + index_map + 14 + segcount*4 + 2 + 2*item);
return ttUSHORT(data + offset + (unicode_codepoint-start)*2 + index_map + 14 + segcount*6 + 2 + 2*item);
} else if (format == 12) {
uint16_t ngroups = ttUSHORT(data+index_map+6);
int32_t low,high;
//uint16_t g = 0;
low = 0; high = (int32_t)ngroups;
// Binary search the right group.
while (low <= high) {
int32_t mid = low + ((high-low) >> 1); // rounds down, so low <= mid < high
uint32_t start_char = ttULONG(data+index_map+16+mid*12);
uint32_t end_char = ttULONG(data+index_map+16+mid*12+4);
if ((uint32_t) unicode_codepoint < start_char)
high = mid-1;
else if ((uint32_t) unicode_codepoint > end_char)
low = mid+1;
else {
uint32_t start_glyph = ttULONG(data+index_map+16+mid*12+8);
return start_glyph + unicode_codepoint-start_char;
}
}
return 0; // not found
}
// @TODO
STBTT_assert(0);
return 0;
}
int tl_tt_GetCodepointShape(const tl_tt_fontinfo *info, int unicode_codepoint, tl_tt_vertex **vertices)
{
return tl_tt_GetGlyphShape(info, tl_tt_FindGlyphIndex(info, unicode_codepoint), vertices);
}
static void tl_tt_setvertex(tl_tt_vertex *v, uint8_t type, int16_t x, int16_t y, int16_t cx, int16_t cy)
{
v->type = type;
v->x = x;
v->y = y;
v->cx = cx;
v->cy = cy;
}
static int tl_tt__GetGlyfOffset(const tl_tt_fontinfo *info, int glyph_index)
{
int g1,g2;
if (glyph_index >= info->numGlyphs) return -1; // glyph index out of range
if (info->indexToLocFormat >= 2) return -1; // unknown index->glyph map format
if (info->indexToLocFormat == 0) {
g1 = info->glyf + ttUSHORT(info->data + info->loca + glyph_index * 2) * 2;
g2 = info->glyf + ttUSHORT(info->data + info->loca + glyph_index * 2 + 2) * 2;
} else {
g1 = info->glyf + ttULONG (info->data + info->loca + glyph_index * 4);
g2 = info->glyf + ttULONG (info->data + info->loca + glyph_index * 4 + 4);
}
return g1==g2 ? -1 : g1; // if length is 0, return -1
}
int tl_tt_GetGlyphBox(const tl_tt_fontinfo *info, int glyph_index, int *x0, int *y0, int *x1, int *y1)
{
int g = tl_tt__GetGlyfOffset(info, glyph_index);
if (g < 0) return 0;
if (x0) *x0 = ttSHORT(info->data + g + 2);
if (y0) *y0 = ttSHORT(info->data + g + 4);
if (x1) *x1 = ttSHORT(info->data + g + 6);
if (y1) *y1 = ttSHORT(info->data + g + 8);
return 1;
}
int tl_tt_GetCodepointBox(const tl_tt_fontinfo *info, int codepoint, int *x0, int *y0, int *x1, int *y1)
{
return tl_tt_GetGlyphBox(info, tl_tt_FindGlyphIndex(info,codepoint), x0,y0,x1,y1);
}
int tl_tt_GetGlyphShape(const tl_tt_fontinfo *info, int glyph_index, tl_tt_vertex **pvertices)
{
int16_t numberOfContours;
uint8_t *endPtsOfContours;
uint8_t *data = info->data;
tl_tt_vertex *vertices=0;
int num_vertices=0;
int g = tl_tt__GetGlyfOffset(info, glyph_index);
*pvertices = NULL;
if (g < 0) return 0;
numberOfContours = ttSHORT(data + g);
if (numberOfContours > 0) {
uint8_t flags=0,flagcount;
int32_t ins, i,j=0,m,n, next_move, was_off=0, off;
int16_t x,y,cx,cy,sx,sy;
uint8_t *points;
endPtsOfContours = (data + g + 10);
ins = ttUSHORT(data + g + 10 + numberOfContours * 2);
points = data + g + 10 + numberOfContours * 2 + 2 + ins;
n = 1+ttUSHORT(endPtsOfContours + numberOfContours*2-2);
m = n + numberOfContours; // a loose bound on how many vertices we might need
vertices = (tl_tt_vertex *) STBTT_malloc(m * sizeof(vertices[0]), info->userdata);
if (vertices == 0)
return 0;
next_move = 0;
flagcount=0;
// 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
off = m - n; // starting offset for uninterpreted data, regardless of how m ends up being calculated
// first load flags
for (i=0; i < n; ++i) {
if (flagcount == 0) {
flags = *points++;
if (flags & 8)
flagcount = *points++;
} else
--flagcount;
vertices[off+i].type = flags;
}
// now load x coordinates
x=0;
for (i=0; i < n; ++i) {
flags = vertices[off+i].type;
if (flags & 2) {
int16_t dx = *points++;
x += (flags & 16) ? dx : -dx; // ???
} else {
if (!(flags & 16)) {
x = x + (int16_t) (points[0]*256 + points[1]);
points += 2;
}
}
vertices[off+i].x = x;
}
// now load y coordinates
y=0;
for (i=0; i < n; ++i) {
flags = vertices[off+i].type;
if (flags & 4) {
int16_t dy = *points++;
y += (flags & 32) ? dy : -dy; // ???
} else {
if (!(flags & 32)) {
y = y + (int16_t) (points[0]*256 + points[1]);
points += 2;
}
}
vertices[off+i].y = y;
}
// now convert them to our format
num_vertices=0;
sx = sy = cx = cy = 0;
for (i=0; i < n; ++i) {
flags = vertices[off+i].type;
x = (int16_t) vertices[off+i].x;
y = (int16_t) vertices[off+i].y;
if (next_move == i) {
// when we get to the end, we have to close the shape explicitly
if (i != 0) {
if (was_off)
tl_tt_setvertex(&vertices[num_vertices++], STBTT_vcurve,sx,sy,cx,cy);
else
tl_tt_setvertex(&vertices[num_vertices++], STBTT_vline,sx,sy,0,0);
}
// now start the new one
tl_tt_setvertex(&vertices[num_vertices++], STBTT_vmove,x,y,0,0);
next_move = 1 + ttUSHORT(endPtsOfContours+j*2);
++j;
was_off = 0;
sx = x;
sy = y;
} else {
if (!(flags & 1)) { // if it's a curve
if (was_off) // two off-curve control points in a row means interpolate an on-curve midpoint
tl_tt_setvertex(&vertices[num_vertices++], STBTT_vcurve, (cx+x)>>1, (cy+y)>>1, cx, cy);
cx = x;
cy = y;
was_off = 1;
} else {
if (was_off)
tl_tt_setvertex(&vertices[num_vertices++], STBTT_vcurve, x,y, cx, cy);
else
tl_tt_setvertex(&vertices[num_vertices++], STBTT_vline, x,y,0,0);
was_off = 0;
}
}
}
if (i != 0) {
if (was_off)
tl_tt_setvertex(&vertices[num_vertices++], STBTT_vcurve,sx,sy,cx,cy);
else
tl_tt_setvertex(&vertices[num_vertices++], STBTT_vline,sx,sy,0,0);
}
} else if (numberOfContours == -1) {
// Compound shapes.
int more = 1;
uint8_t *comp = data + g + 10;
num_vertices = 0;
vertices = 0;
while (more) {
uint16_t flags, gidx;
int comp_num_verts = 0, i;
tl_tt_vertex *comp_verts = 0, *tmp = 0;
float mtx[6] = {1,0,0,1,0,0}, m, n;
flags = ttSHORT(comp); comp+=2;
gidx = ttSHORT(comp); comp+=2;
if (flags & 2) { // XY values
if (flags & 1) { // shorts
mtx[4] = ttSHORT(comp); comp+=2;
mtx[5] = ttSHORT(comp); comp+=2;
} else {
mtx[4] = ttCHAR(comp); comp+=1;
mtx[5] = ttCHAR(comp); comp+=1;
}
}
else {
// @TODO handle matching point
STBTT_assert(0);
}
if (flags & (1<<3)) { // WE_HAVE_A_SCALE
mtx[0] = mtx[3] = ttSHORT(comp)/16384.0f; comp+=2;
mtx[1] = mtx[2] = 0;
} else if (flags & (1<<6)) { // WE_HAVE_AN_X_AND_YSCALE
mtx[0] = ttSHORT(comp)/16384.0f; comp+=2;
mtx[1] = mtx[2] = 0;
mtx[3] = ttSHORT(comp)/16384.0f; comp+=2;
} else if (flags & (1<<7)) { // WE_HAVE_A_TWO_BY_TWO
mtx[0] = ttSHORT(comp)/16384.0f; comp+=2;
mtx[1] = ttSHORT(comp)/16384.0f; comp+=2;
mtx[2] = ttSHORT(comp)/16384.0f; comp+=2;
mtx[3] = ttSHORT(comp)/16384.0f; comp+=2;
}
// Find transformation scales.
m = (float) sqrt(mtx[0]*mtx[0] + mtx[1]*mtx[1]);
n = (float) sqrt(mtx[2]*mtx[2] + mtx[3]*mtx[3]);
// Get indexed glyph.
comp_num_verts = tl_tt_GetGlyphShape(info, gidx, &comp_verts);
if (comp_num_verts > 0) {
// Transform vertices.
for (i = 0; i < comp_num_verts; ++i) {
tl_tt_vertex* v = &comp_verts[i];
tl_tt_vertex_type x,y;
x=v->x; y=v->y;
v->x = (tl_tt_vertex_type)(m * (mtx[0]*x + mtx[2]*y + mtx[4]));
v->y = (tl_tt_vertex_type)(n * (mtx[1]*x + mtx[3]*y + mtx[5]));
x=v->cx; y=v->cy;
v->cx = (tl_tt_vertex_type)(m * (mtx[0]*x + mtx[2]*y + mtx[4]));
v->cy = (tl_tt_vertex_type)(n * (mtx[1]*x + mtx[3]*y + mtx[5]));
}
// Append vertices.
tmp = (tl_tt_vertex*)STBTT_malloc((num_vertices+comp_num_verts)*sizeof(tl_tt_vertex), info->userdata);
if (!tmp) {
if (vertices) STBTT_free(vertices, info->userdata);
if (comp_verts) STBTT_free(comp_verts, info->userdata);
return 0;
}
if (num_vertices > 0) memcpy(tmp, vertices, num_vertices*sizeof(tl_tt_vertex));
memcpy(tmp+num_vertices, comp_verts, comp_num_verts*sizeof(tl_tt_vertex));
if (vertices) STBTT_free(vertices, info->userdata);
vertices = tmp;
STBTT_free(comp_verts, info->userdata);
num_vertices += comp_num_verts;
}
// More components ?
more = flags & (1<<5);
}
} else if (numberOfContours < 0) {
// @TODO other compound variations?
STBTT_assert(0);
} else {
// numberOfCounters == 0, do nothing
}
*pvertices = vertices;
return num_vertices;
}
void tl_tt_GetGlyphHMetrics(const tl_tt_fontinfo *info, int glyph_index, int *advanceWidth, int *leftSideBearing)
{
uint16_t numOfLongHorMetrics = ttUSHORT(info->data+info->hhea + 34);
if (glyph_index < numOfLongHorMetrics) {
if (advanceWidth) *advanceWidth = ttSHORT(info->data + info->hmtx + 4*glyph_index);
if (leftSideBearing) *leftSideBearing = ttSHORT(info->data + info->hmtx + 4*glyph_index + 2);
} else {
if (advanceWidth) *advanceWidth = ttSHORT(info->data + info->hmtx + 4*(numOfLongHorMetrics-1));
if (leftSideBearing) *leftSideBearing = ttSHORT(info->data + info->hmtx + 4*numOfLongHorMetrics + 2*(glyph_index - numOfLongHorMetrics));
}
}
int tl_tt_GetGlyphKernAdvance(const tl_tt_fontinfo *info, int glyph1, int glyph2)
{
TL_UNUSED(info); TL_UNUSED(glyph1); TL_UNUSED(glyph2);
return 0;
}
int tl_tt_GetCodepointKernAdvance(const tl_tt_fontinfo *info, int ch1, int ch2)
{
TL_UNUSED(info); TL_UNUSED(ch1); TL_UNUSED(ch2);
return 0;
}
void tl_tt_GetCodepointHMetrics(const tl_tt_fontinfo *info, int codepoint, int *advanceWidth, int *leftSideBearing)
{
tl_tt_GetGlyphHMetrics(info, tl_tt_FindGlyphIndex(info,codepoint), advanceWidth, leftSideBearing);
}
void tl_tt_GetFontVMetrics(const tl_tt_fontinfo *info, int *ascent, int *descent, int *lineGap)
{
if (ascent ) *ascent = ttSHORT(info->data+info->hhea + 4);
if (descent) *descent = ttSHORT(info->data+info->hhea + 6);
if (lineGap) *lineGap = ttSHORT(info->data+info->hhea + 8);
}
float tl_tt_ScaleForPixelHeight(const tl_tt_fontinfo *info, float height)
{
int fheight = ttSHORT(info->data + info->hhea + 4) - ttSHORT(info->data + info->hhea + 6);
return (float) height / fheight;
}
void tl_tt_FreeShape(const tl_tt_fontinfo *info, tl_tt_vertex *v)
{
TL_UNUSED(info);
STBTT_free(v, info->userdata);
}
//////////////////////////////////////////////////////////////////////////////
//
// antialiasing software rasterizer
//
void tl_tt_GetGlyphBitmapBox(const tl_tt_fontinfo *font, int glyph, float scale_x, float scale_y, int *ix0, int *iy0, int *ix1, int *iy1)
{
int x0,y0,x1,y1;
if (!tl_tt_GetGlyphBox(font, glyph, &x0,&y0,&x1,&y1))
x0=y0=x1=y1=0; // e.g. space character
// now move to integral bboxes (treating pixels as little squares, what pixels get touched)?
if (ix0) *ix0 = STBTT_ifloor(x0 * scale_x);
if (iy0) *iy0 = -STBTT_iceil (y1 * scale_y);
if (ix1) *ix1 = STBTT_iceil (x1 * scale_x);
if (iy1) *iy1 = -STBTT_ifloor(y0 * scale_y);
}
void tl_tt_GetCodepointBitmapBox(const tl_tt_fontinfo *font, int codepoint, float scale_x, float scale_y, int *ix0, int *iy0, int *ix1, int *iy1)
{
tl_tt_GetGlyphBitmapBox(font, tl_tt_FindGlyphIndex(font,codepoint), scale_x, scale_y, ix0,iy0,ix1,iy1);
}
typedef struct tl_tt__edge {
float x0,y0, x1,y1;
int invert;
} tl_tt__edge;
typedef struct tl_tt__active_edge
{
int x,dx;
float ey;
struct tl_tt__active_edge *next;
int valid;
} tl_tt__active_edge;
#define FIXSHIFT 10
#define FIX (1 << FIXSHIFT)
#define FIXMASK (FIX-1)
static tl_tt__active_edge *new_active(tl_tt__edge *e, int off_x, float start_point, void *userdata)
{
TL_UNUSED(userdata);
tl_tt__active_edge *z = (tl_tt__active_edge *) STBTT_malloc(sizeof(*z), userdata); // @TODO: make a pool of these!!!
float dxdy = (e->x1 - e->x0) / (e->y1 - e->y0);
STBTT_assert(e->y0 <= start_point);
if (!z) return z;
// round dx down to avoid going too far
if (dxdy < 0)
z->dx = -STBTT_ifloor(FIX * -dxdy);
else
z->dx = STBTT_ifloor(FIX * dxdy);
z->x = STBTT_ifloor(FIX * (e->x0 + dxdy * (start_point - e->y0)));
z->x -= off_x * FIX;
z->ey = e->y1;
z->next = 0;
z->valid = e->invert ? 1 : -1;
return z;
}
// note: this routine clips fills that extend off the edges... ideally this
// wouldn't happen, but it could happen if the truetype glyph bounding boxes
// are wrong, or if the user supplies a too-small bitmap
static void tl_tt__fill_active_edges(unsigned char *scanline, int len, tl_tt__active_edge *e, int max_weight)
{
// non-zero winding fill
int x0=0, w=0;
while (e) {
if (w == 0) {
// if we're currently at zero, we need to record the edge start point
x0 = e->x; w += e->valid;
} else {
int x1 = e->x; w += e->valid;
// if we went to zero, we need to draw
if (w == 0) {
int i = x0 >> FIXSHIFT;
int j = x1 >> FIXSHIFT;
if (i < len && j >= 0) {
if (i == j) {
// x0,x1 are the same pixel, so compute combined coverage
scanline[i] = scanline[i] + (uint8_t) ((x1 - x0) * max_weight >> FIXSHIFT);
} else {
if (i >= 0) // add antialiasing for x0
scanline[i] = scanline[i] + (uint8_t) (((FIX - (x0 & FIXMASK)) * max_weight) >> FIXSHIFT);
else
i = -1; // clip
if (j < len) // add antialiasing for x1
scanline[j] = scanline[j] + (uint8_t) (((x1 & FIXMASK) * max_weight) >> FIXSHIFT);
else
j = len; // clip
for (++i; i < j; ++i) // fill pixels between x0 and x1
scanline[i] = scanline[i] + (uint8_t) max_weight;
}
}
}
}
e = e->next;
}
}
static void tl_tt__rasterize_sorted_edges(tl_image *result, tl_tt__edge *e, int n, int vsubsample, int off_x, int off_y, void *userdata)
{
tl_tt__active_edge *active = NULL;
int y;
uint32_t j = 0;
int max_weight = (255 / vsubsample); // weight per vertical scanline
int s; // vertical subsample index
unsigned char scanline_data[512], *scanline;
if (result->w > 512)
scanline = (unsigned char *) STBTT_malloc(result->w, userdata);
else
scanline = scanline_data;
y = off_y * vsubsample;
e[n].y0 = (off_y + result->h) * (float) vsubsample + 1;
while (j < result->h) {
STBTT_memset(scanline, 0, result->w);
for (s=0; s < vsubsample; ++s) {
// find center of pixel for this scanline
float scan_y = y + 0.5f;
tl_tt__active_edge **step = &active;
// update all active edges;
// remove all active edges that terminate before the center of this scanline
while (*step) {
tl_tt__active_edge * z = *step;
if (z->ey <= scan_y) {
*step = z->next; // delete from list
STBTT_assert(z->valid);
z->valid = 0;
STBTT_free(z, userdata);
} else {
z->x += z->dx; // advance to position for current scanline
step = &((*step)->next); // advance through list
}
}
// resort the list if needed
for(;;) {
int changed=0;
step = &active;
while (*step && (*step)->next) {
if ((*step)->x > (*step)->next->x) {
tl_tt__active_edge *t = *step;
tl_tt__active_edge *q = t->next;
t->next = q->next;
q->next = t;
*step = q;
changed = 1;
}
step = &(*step)->next;
}
if (!changed) break;
}
// insert all edges that start before the center of this scanline -- omit ones that also end on this scanline
while (e->y0 <= scan_y) {
if (e->y1 > scan_y) {
tl_tt__active_edge *z = new_active(e, off_x, scan_y, userdata);
// find insertion point
if (active == NULL)
active = z;
else if (z->x < active->x) {
// insert at front
z->next = active;
active = z;
} else {
// find thing to insert AFTER
tl_tt__active_edge *p = active;
while (p->next && p->next->x < z->x)
p = p->next;
// at this point, p->next->x is NOT < z->x
z->next = p->next;
p->next = z;
}
}
++e;
}
// now process all active edges in XOR fashion
if (active)
tl_tt__fill_active_edges(scanline, result->w, active, max_weight);
++y;
}
STBTT_memcpy(result->pixels + j * result->pitch, scanline, result->w);
++j;
}
while (active) {
tl_tt__active_edge *z = active;
active = active->next;
STBTT_free(z, userdata);
}
if (scanline != scanline_data)
STBTT_free(scanline, userdata);
}
static int tl_tt__edge_compare(const void *p, const void *q)
{
tl_tt__edge *a = (tl_tt__edge *) p;
tl_tt__edge *b = (tl_tt__edge *) q;
if (a->y0 < b->y0) return -1;
if (a->y0 > b->y0) return 1;
return 0;
}
typedef struct
{
float x,y;
} tl_tt__point;
static void tl_tt__rasterize(tl_image *result, tl_tt__point *pts, int *wcount, int windings, float scale_x, float scale_y, int off_x, int off_y, int invert, void *userdata)
{
float y_scale_inv = invert ? -scale_y : scale_y;
tl_tt__edge *e;
int n,i,j,k,m;
int vsubsample = result->h < 8 ? 15 : 5;
// vsubsample should divide 255 evenly; otherwise we won't reach full opacity
// now we have to blow out the windings into explicit edge lists
n = 0;
for (i=0; i < windings; ++i)
n += wcount[i];
e = (tl_tt__edge *) STBTT_malloc(sizeof(*e) * (n+1), userdata); // add an extra one as a sentinel
if (e == 0) return;
n = 0;
m=0;
for (i=0; i < windings; ++i) {
tl_tt__point *p = pts + m;
m += wcount[i];
j = wcount[i]-1;
for (k=0; k < wcount[i]; j=k++) {
int a=k,b=j;
// skip the edge if horizontal
if (p[j].y == p[k].y)
continue;
// add edge from j to k to the list
e[n].invert = 0;
if (invert ? p[j].y > p[k].y : p[j].y < p[k].y) {
e[n].invert = 1;
a=j,b=k;
}
e[n].x0 = p[a].x * scale_x;
e[n].y0 = p[a].y * y_scale_inv * vsubsample;
e[n].x1 = p[b].x * scale_x;
e[n].y1 = p[b].y * y_scale_inv * vsubsample;
++n;
}
}
// now sort the edges by their highest point (should snap to integer, and then by x)
STBTT_sort(e, n, sizeof(e[0]), tl_tt__edge_compare);
// now, traverse the scanlines and find the intersections on each scanline, use xor winding rule
tl_tt__rasterize_sorted_edges(result, e, n, vsubsample, off_x, off_y, userdata);
STBTT_free(e, userdata);
}
static void tl_tt__add_point(tl_tt__point *points, int n, float x, float y)
{
if (!points) return; // during first pass, it's unallocated
points[n].x = x;
points[n].y = y;
}
// tesselate until threshhold p is happy... @TODO warped to compensate for non-linear stretching
static int tl_tt__tesselate_curve(tl_tt__point *points, int *num_points, float x0, float y0, float x1, float y1, float x2, float y2, float objspace_flatness_squared, int n)
{
// midpoint
float mx = (x0 + 2*x1 + x2)/4;
float my = (y0 + 2*y1 + y2)/4;
// versus directly drawn line
float dx = (x0+x2)/2 - mx;
float dy = (y0+y2)/2 - my;
if (n > 16) // 65536 segments on one curve better be enough!
return 1;
if (dx*dx+dy*dy > objspace_flatness_squared) { // half-pixel error allowed... need to be smaller if AA
tl_tt__tesselate_curve(points, num_points, x0,y0, (x0+x1)/2.0f,(y0+y1)/2.0f, mx,my, objspace_flatness_squared,n+1);
tl_tt__tesselate_curve(points, num_points, mx,my, (x1+x2)/2.0f,(y1+y2)/2.0f, x2,y2, objspace_flatness_squared,n+1);
} else {
tl_tt__add_point(points, *num_points,x2,y2);
*num_points = *num_points+1;
}
return 1;
}
// returns number of contours
tl_tt__point *tl_tt_FlattenCurves(tl_tt_vertex *vertices, int num_verts, float objspace_flatness, int **contour_lengths, int *num_contours, void *userdata)
{
TL_UNUSED(userdata);
tl_tt__point *points=0;
int num_points=0;
float objspace_flatness_squared = objspace_flatness * objspace_flatness;
int i,n=0,start=0, pass;
// count how many "moves" there are to get the contour count
for (i=0; i < num_verts; ++i)
if (vertices[i].type == STBTT_vmove)
++n;
*num_contours = n;
if (n == 0) return 0;
*contour_lengths = (int *) STBTT_malloc(sizeof(**contour_lengths) * n, userdata);
if (*contour_lengths == 0) {
*num_contours = 0;
return 0;
}
// make two passes through the points so we don't need to realloc
for (pass=0; pass < 2; ++pass) {
float x=0,y=0;
if (pass == 1) {
points = (tl_tt__point *) STBTT_malloc(num_points * sizeof(points[0]), userdata);
if (points == NULL) goto error;
}
num_points = 0;
n= -1;
for (i=0; i < num_verts; ++i) {
switch (vertices[i].type) {
case STBTT_vmove:
// start the next contour
if (n >= 0)
(*contour_lengths)[n] = num_points - start;
++n;
start = num_points;
x = vertices[i].x, y = vertices[i].y;
tl_tt__add_point(points, num_points++, x,y);
break;
case STBTT_vline:
x = vertices[i].x, y = vertices[i].y;
tl_tt__add_point(points, num_points++, x, y);
break;
case STBTT_vcurve:
tl_tt__tesselate_curve(points, &num_points, x,y,
vertices[i].cx, vertices[i].cy,
vertices[i].x, vertices[i].y,
objspace_flatness_squared, 0);
x = vertices[i].x, y = vertices[i].y;
break;
}
}
(*contour_lengths)[n] = num_points - start;
}
return points;
error:
STBTT_free(points, userdata);
STBTT_free(*contour_lengths, userdata);
*contour_lengths = 0;
*num_contours = 0;
return NULL;
}
void tl_tt_Rasterize(tl_image *result, float flatness_in_pixels, tl_tt_vertex *vertices, int num_verts, float scale_x, float scale_y, int x_off, int y_off, int invert, void *userdata)
{
TL_UNUSED(userdata);
float scale = scale_x > scale_y ? scale_y : scale_x;
int winding_count, *winding_lengths;
tl_tt__point *windings = tl_tt_FlattenCurves(vertices, num_verts, flatness_in_pixels / scale, &winding_lengths, &winding_count, userdata);
if (windings) {
tl_tt__rasterize(result, windings, winding_lengths, winding_count, scale_x, scale_y, x_off, y_off, invert, userdata);
STBTT_free(winding_lengths, userdata);
STBTT_free(windings, userdata);
}
}
void tl_tt_FreeBitmap(unsigned char *bitmap, void *userdata)
{
TL_UNUSED(userdata);
STBTT_free(bitmap, userdata);
}
tl_image tl_tt_GetGlyphBitmap(const tl_tt_fontinfo *info, float scale_x, float scale_y, int glyph, int *xoff, int *yoff)
{
int ix0,iy0,ix1,iy1;
tl_image gbm;
tl_tt_vertex *vertices;
int num_verts = tl_tt_GetGlyphShape(info, glyph, &vertices);
gbm.w = 0;
gbm.h = 0;
gbm.bpp = 1;
gbm.pitch = 0;
gbm.pixels = NULL; // in case we error
if (scale_x == 0) scale_x = scale_y;
if (scale_y == 0) {
if (scale_x == 0) return gbm;
scale_y = scale_x;
}
tl_tt_GetGlyphBitmapBox(info, glyph, scale_x, scale_y, &ix0,&iy0,&ix1,&iy1);
// now we get the size
gbm.w = (ix1 - ix0);
gbm.h = (iy1 - iy0);
gbm.pitch = gbm.w;
if (xoff ) *xoff = ix0;
if (yoff ) *yoff = iy0;
if (gbm.w && gbm.h) {
gbm.pixels = (unsigned char *) STBTT_malloc(gbm.w * gbm.h, info->userdata);
if (gbm.pixels) {
tl_tt_Rasterize(&gbm, 0.35f, vertices, num_verts, scale_x, scale_y, ix0, iy0, 1, info->userdata);
}
}
STBTT_free(vertices, info->userdata);
return gbm;
}