ref: fb96a050f8a9d5f23da3557ba89251ffb73889bf
dir: /sys/src/libttf/scan.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ttf.h>
#include "impl.h"
typedef struct Scan Scan;
typedef struct TTLine TTLine;
enum {
LINEBLOCK = 32,
PTBLOCK = 64,
};
struct TTLine {
int x0, y0;
int x1, y1;
int link;
u8int dir;
};
struct Scan {
enum {
DROPOUTS = 1,
STUBDET = 2,
SMART = 4,
} flags;
TTGlyph *g;
TTLine *lines;
int nlines;
int *hpts, *vpts;
int nhpts, nvpts;
int *hscanl, *vscanl;
u8int *bit;
int width, height;
int stride;
};
static void
dobezier(Scan *s, TTPoint p, TTPoint q, TTPoint r)
{
vlong m, n;
TTLine *l;
m = (vlong)(q.x - p.x) * (r.y - p.y) - (vlong)(q.y - p.y) * (r.x - p.x);
n = (vlong)(r.x - p.x) * (r.x - p.x) + (vlong)(r.y - p.y) * (r.y - p.y);
if(m * m > 4 * n){
dobezier(s, p, (TTPoint){(p.x+q.x+1)/2, (p.y+q.y+1)/2, 0}, (TTPoint){(p.x+2*q.x+r.x+2)/4, (p.y+2*q.y+r.y+2)/4, 0});
dobezier(s, (TTPoint){(p.x+2*q.x+r.x+2)/4, (p.y+2*q.y+r.y+2)/4, 0}, (TTPoint){(r.x+q.x+1)/2, (r.y+q.y+1)/2, 0}, r);
return;
}
if((s->nlines & LINEBLOCK - 1) == 0)
s->lines = realloc(s->lines, sizeof(TTLine) * (s->nlines + LINEBLOCK));
l = &s->lines[s->nlines++];
if(p.y < r.y){
l->x0 = p.x;
l->y0 = p.y;
l->x1 = r.x;
l->y1 = r.y;
l->dir = 0;
}else{
l->x0 = r.x;
l->y0 = r.y;
l->x1 = p.x;
l->y1 = p.y;
l->dir = 1;
}
l->link = -1;
}
static int
hlinecmp(void *va, void *vb)
{
TTLine *a, *b;
a = va;
b = vb;
if(a->y0 < b->y0) return -1;
if(a->y0 > b->y0) return 1;
return 0;
}
static int
vlinecmp(void *va, void *vb)
{
TTLine *a, *b;
a = va;
b = vb;
if(a->x0 < b->x0) return -1;
if(a->x0 > b->x0) return 1;
return 0;
}
static int
intcmp(void *va, void *vb)
{
int a, b;
a = *(int*)va;
b = *(int*)vb;
return (a>b) - (a<b);
}
static void
hprep(Scan *s)
{
int i, j, x, y;
TTLine *l;
int watch, act, *p;
qsort(s->lines, s->nlines, sizeof(TTLine), hlinecmp);
s->hscanl = calloc(sizeof(int), (s->height + 1));
act = -1;
watch = 0;
p = &act;
for(i = 0; i < s->height; i++){
y = 64 * i + 32;
for(; watch < s->nlines && s->lines[watch].y0 <= y; watch++){
if(s->lines[watch].y1 <= y || s->lines[watch].y0 == s->lines[watch].y1)
continue;
s->lines[watch].link = -1;
*p = watch;
p = &s->lines[watch].link;
}
s->hscanl[i] = s->nhpts;
p = &act;
while(j = *p, j >= 0){
l = &s->lines[j];
if(l->y1 <= y){
j = l->link;
l->link = -1;
*p = j;
continue;
}
x = l->x0 + ttfvrounddiv((vlong)(y - l->y0)*(l->x1 - l->x0), l->y1 - l->y0);
if((s->nhpts & PTBLOCK - 1) == 0)
s->hpts = realloc(s->hpts, (s->nhpts + PTBLOCK) * sizeof(int));
s->hpts[s->nhpts++] = x << 1 | l->dir;
p = &l->link;
}
qsort(s->hpts + s->hscanl[i], s->nhpts - s->hscanl[i], sizeof(int), intcmp);
}
s->hscanl[i] = s->nhpts;
}
static int
iswhite(Scan *s, int x, int y)
{
return (s->bit[(s->height - 1 - y) * s->stride + (x>>3)] >> 7-(x&7) & 1)==0;
}
static void
pixel(Scan *s, int x, int y)
{
assert(x >= 0 && x < s->width && y >= 0 && y < s->height);
s->bit[(s->height - 1 - y) * s->stride + (x>>3)] |= (1<<7-(x&7));
}
static int
intersectsh(Scan *s, int x, int y)
{
int a, b, c, vc, v;
a = s->hscanl[y];
b = s->hscanl[y+1]-1;
v = x * 64 + 32;
if(a > b || s->hpts[a]>>1 > v + 64 || s->hpts[b]>>1 < v) return 0;
while(a <= b){
c = (a + b) / 2;
vc = s->hpts[c]>>1;
if(vc < v)
a = c + 1;
else if(vc > v + 64)
b = c - 1;
else
return 1;
}
return 0;
}
static int
intersectsv(Scan *s, int x, int y)
{
int a, b, c, vc, v;
a = s->vscanl[x];
b = s->vscanl[x+1]-1;
v = y * 64 + 32;
if(a > b || s->vpts[a]>>1 > v + 64 || s->vpts[b]>>1 < v) return 0;
while(a <= b){
c = (a + b) / 2;
vc = s->vpts[c]>>1;
if(vc < v)
a = c + 1;
else if(vc > v + 64)
b = c - 1;
else
return 1;
}
return 0;
}
static void
hscan(Scan *s)
{
int i, j, k, e;
int wind, match, seen, x;
for(i = 0; i < s->height; i++){
e = s->hscanl[i+1];
k = s->hscanl[i];
if(k == e) continue;
wind = 0;
for(j = 0; j < s->width; j++){
x = 64 * j + 32;
match = 0;
seen = 0;
while(k < e && (s->hpts[k] >> 1) <= x){
wind += (s->hpts[k] & 1) * 2 - 1;
seen |= 1<<(s->hpts[k] & 1);
if((s->hpts[k] >> 1) == x)
match++;
k++;
}
if(match || wind)
pixel(s, j, i);
else if((s->flags & DROPOUTS) != 0 && seen == 3 && j > 0 && iswhite(s, j-1, i)){
if((s->flags & STUBDET) == 0){
pixel(s, j-1, i);
continue;
}
if(i <= 0 || i > s->height - 1 || j <= 0 || j > s->width - 1)
continue;
if(!intersectsv(s, j-1, i-1) && !intersectsh(s, j-1, i-1) && !intersectsv(s, j, i-1) || !intersectsv(s, j-1, i) && !intersectsh(s, j-1, i+1) && !intersectsv(s, j, i))
continue;
pixel(s, j-1, i);
}
}
}
}
static void
vprep(Scan *s)
{
int i, j, x, y;
TTLine *l;
int watch, act, *p;
for(i = 0; i < s->nlines; i++){
l = &s->lines[i];
if(l->x0 > l->x1){
x = l->x0, l->x0 = l->x1, l->x1 = x;
x = l->y0, l->y0 = l->y1, l->y1 = x;
l->dir ^= 1;
}
}
qsort(s->lines, s->nlines, sizeof(TTLine), vlinecmp);
s->vscanl = calloc(sizeof(int), (s->width + 1));
act = -1;
watch = 0;
p = &act;
for(i = 0; i < s->width; i++){
x = 64 * i + 32;
for(; watch < s->nlines && s->lines[watch].x0 <= x; watch++){
if(s->lines[watch].x1 <= x || s->lines[watch].x0 == s->lines[watch].x1)
continue;
s->lines[watch].link = -1;
*p = watch;
p = &s->lines[watch].link;
}
s->vscanl[i] = s->nvpts;
p = &act;
while(j = *p, j >= 0){
l = &s->lines[j];
if(l->x1 <= x){
j = l->link;
l->link = -1;
*p = j;
continue;
}
y = l->y0 + ttfvrounddiv((vlong)(x - l->x0) * (l->y1 - l->y0), l->x1 - l->x0);
if((s->nvpts & PTBLOCK - 1) == 0)
s->vpts = realloc(s->vpts, (s->nvpts + PTBLOCK) * sizeof(int));
s->vpts[s->nvpts++] = y << 1 | l->dir;
p = &l->link;
}
qsort(s->vpts + s->vscanl[i], s->nvpts - s->vscanl[i], sizeof(int), intcmp);
}
s->vscanl[i] = s->nvpts;
}
static void
vscan(Scan *s)
{
int i, j, k, e;
int seen, y;
for(i = 0; i < s->width; i++){
e = s->vscanl[i+1];
k = s->vscanl[i];
if(k == e) continue;
for(j = 0; j < s->height; j++){
y = 64 * j + 32;
seen = 0;
while(k < e && (s->vpts[k] >> 1) <= y){
seen |= 1<<(s->vpts[k] & 1);
k++;
}
if(seen == 3 && j > 0 && iswhite(s, i, j-1) && iswhite(s, i, j)){
if((s->flags & STUBDET) == 0){
pixel(s, i, j-1);
continue;
}
if(i <= 0 || i > s->width - 1 || j <= 0 || j > s->height - 1)
continue;
if(!intersectsv(s, i-1, j-1) & !intersectsh(s, i-1, j-1) & !intersectsh(s, i-1, j) | !intersectsv(s, i+1, j-1) & !intersectsh(s, i, j-1) & !intersectsh(s, i, j))
continue;
pixel(s, i, j-1);
}
}
}
}
void
ttfscan(TTGlyph *g)
{
int i, j, c;
TTPoint p, q, r;
Scan s;
memset(&s, 0, sizeof(s));
s.g = g;
s.flags = 0;
c = g->font->scanctrl;
if((c & 1<<8) != 0 && g->font->ppem <= (c & 0xff))
s.flags |= DROPOUTS;
if((c & 1<<11) != 0 && g->font->ppem > (c & 0xff))
s.flags &= ~DROPOUTS;
if((c & 3<<12) != 0)
s.flags &= ~DROPOUTS;
if((s.flags & DROPOUTS) != 0)
switch(g->font->scantype){
case 0: break;
case 1: s.flags |= STUBDET; break;
case 2: case 3: case 6: case 7: s.flags &= ~DROPOUTS; break;
case 4: s.flags |= SMART; break;
case 5: s.flags |= SMART | STUBDET; break;
}
// s.width = (g->pt[g->npt - 1].x + 63) / 64;
// s.height = g->font->ascentpx + g->font->descentpx;
s.width = -g->xminpx + g->xmaxpx;
s.height = -g->yminpx + g->ymaxpx;
s.stride = s.width + 7 >> 3;
s.bit = mallocz(s.height * s.stride, 1);
assert(s.bit != nil);
for(i = 0; i < g->npt; i++){
g->pt[i].x -= g->xminpx * 64;
g->pt[i].y -= g->yminpx * 64;
// g->pt[i].y += g->font->descentpx * 64;
}
for(i = 0; i < g->ncon; i++){
if(g->confst[i] + 1 >= g->confst[i+1]) continue;
p = g->pt[g->confst[i]];
assert((p.flags & 1) != 0);
for(j = g->confst[i]; j++ < g->confst[i+1]; ){
if(j < g->confst[i+1] && (g->pt[j].flags & 1) == 0)
q = g->pt[j++];
else
q = p;
if(j >= g->confst[i+1])
r = g->pt[g->confst[i]];
else{
r = g->pt[j];
if((g->pt[j].flags & 1) == 0){
r.x = (r.x + q.x) / 2;
r.y = (r.y + q.y) / 2;
}
}
dobezier(&s, p, q, r);
p = r;
if(j < g->confst[i+1] && (g->pt[j].flags & 1) == 0)
j--;
}
}
hprep(&s);
if((s.flags & DROPOUTS) != 0)
vprep(&s);
hscan(&s);
if((s.flags & DROPOUTS) != 0)
vscan(&s);
free(s.hpts);
free(s.vpts);
free(s.hscanl);
free(s.vscanl);
free(s.lines);
g->bit = s.bit;
g->width = s.width;
g->height = s.height;
g->stride = s.stride;
}
int
ttfgetcontour(TTGlyph *g, int i, float **fp, int *np)
{
float offy, scale;
float *nf;
int n, j;
TTPoint p, q, r;
if((uint)i >= g->ncon)
return 0;
if(g->confst[i]+1 >= g->confst[i+1]){
if(np != nil)
*np = 0;
if(fp != nil)
*fp = malloc(0);
return g->ncon - i;
}
if(g->bit != nil){
scale = 1.0f / 64;
offy = g->yminpx;
}else{
scale = 1.0f * g->font->ppem / g->font->u->emsize;
offy = 0;
}
p = g->pt[g->confst[i]];
n = 1;
if(fp != nil){
*fp = malloc(2 * sizeof(float));
if(*fp == nil) return -1;
(*fp)[0] = p.x * scale;
(*fp)[1] = p.y * scale + offy;
}
assert((p.flags & 1) != 0);
for(j = g->confst[i]; j++ < g->confst[i+1]; ){
if(j < g->confst[i+1] && (g->pt[j].flags & 1) == 0)
q = g->pt[j++];
else
q = p;
if(j >= g->confst[i+1])
r = g->pt[g->confst[i]];
else{
r = g->pt[j];
if((g->pt[j].flags & 1) == 0){
r.x = (r.x + q.x) / 2;
r.y = (r.y + q.y) / 2;
}
}
if(fp != nil){
nf = realloc(*fp, sizeof(float) * 2 * (n + 2));
if(nf == nil){
free(*fp);
return -1;
}
*fp = nf;
nf[2*n] = q.x * scale;
nf[2*n+1] = q.y * scale + offy;
nf[2*n+2] = r.x * scale;
nf[2*n+3] = r.y * scale + offy;
}
p = r;
n += 2;
if(j < g->confst[i+1] && (g->pt[j].flags & 1) == 0)
j--;
}
if(np != nil)
*np = n;
return g->ncon - i;
}