ref: 4a69412b4fa92677903ca5d7c3c6e2bd188af4ab
parent: 59bc47d5e4b48489646c27e9b50529683fd17963
author: Paul Lalonde <plalonde@acm.org>
date: Sun Jan 19 20:29:09 EST 2025
Anti-alias/filter fonts from truetypefs This makes TrueType fonts actually usable and attractive.
--- a/sys/man/4/truetypefs
+++ b/sys/man/4/truetypefs
@@ -29,6 +29,8 @@
is a
.IR font (6)
file generated for GNU Unifont at a size of 16.
+The generated fonts are supersampled to generate filtered 8 bit fonts instead of the
+1 bit fonts libttf generates.
.SH EXAMPLES
Use size 16 GNU Unifont for
@@ -48,3 +50,8 @@
.SH HISTORY
.I Truetypefs
first appeared in 9front (October, 2018).
+.SH BUGS
+The filtering generates blurry fonts for small point sizes.
+At small point sizes it is better to use a specialty bitmapped font.
+
+The filtering should happen natively in libttf, not in its dependents.
--- a/sys/src/cmd/truetypefs.c
+++ b/sys/src/cmd/truetypefs.c
@@ -126,10 +126,9 @@
}
static void
-blit(uchar *t, int x, int y, int tstride, uchar *s, int w, int h)
+blit8(uchar *t, int x, int y, int tstride, uchar *s, int w, int h)
{int tx, ty, sx, sy;
- u16int b;
uchar *tp, *sp;
if(y < 0) y = 0;
@@ -137,26 +136,81 @@
sp = s;
for(sy = 0; sy < h; sy++, ty++){tx = x;
- tp = t + ty * tstride + (tx >> 3);
- b = 0;
- for(sx = 0; sx < w; sx += 8){- b |= *sp++ << 8 - (tx & 7);
- *tp++ |= b >> 8;
- b <<= 8;
+ tp = t + ty * tstride + (tx);
+ for(sx = 0; sx < w; sx ++){+ *tp++ = *sp++;
}
- *tp |= b >> 8;
}
}
+// Allocate an 8bpp bitmap. We can remove this if we update libttf to support 8 bit bitmaps.
+static TTBitmap *
+newbitmap8(int w, int h, int depth)
+{+ TTBitmap *b;
+ if(!(depth == 1 || depth == 8)) {+ return nil;
+ }
+ b = mallocz(sizeof(TTBitmap), 1);
+ if(b == nil) return nil;
+ b->width = w;
+ b->height = h;
+ switch (depth) {+ case 1:
+ b->stride = (w + 7) >> 3;
+ break;
+ case 8:
+ b->stride = w;
+ break;
+ }
+
+ b->bit = mallocz(b->stride * h, 1);
+ if(b->bit == nil){+ free(b);
+ return nil;
+ }
+ return b;
+}
+
static void
+freebitmap8(TTBitmap *b) {+ if(b == nil) return;
+ free(b->bit);
+ free(b);
+}
+
+
+TTBitmap *
+scaledown(TTBitmap *b)
+{+ TTBitmap *a;
+ int i, j;
+ int scale;
+
+ scale = 8;
+ a = newbitmap8((b->width + 7)>>3 , (b->height +7)>>3, 8);
+ if(a == nil) sysfatal("ttfnewbitmap: %r");+ for(j = 0; j < b->height; j++)
+ for(i = 0; i < b->width; i++){+ if((b->bit[j * b->stride + (i>>3)] >> 7 - (i & 7) & 1) != 0)
+ a->bit[j/scale * a->stride + i/scale]++;
+ if(j % scale == scale - 1 && i % scale == scale - 1)
+ a->bit[j/scale * a->stride + i/scale] = ((a->bit[j/scale * a->stride + i/scale] * 255 + scale * scale / 2) / (scale * scale));
+ }
+ return a;
+}
+
+static void
compilesub(TFont *f, TSubfont *s)
{int n, i, w, x, h, g, sz;
char *d, *p;
- TTGlyph **gs;
- TTFont *t;
+ TTGlyph **gs, *gts;
+ TTFont *t, *tscaled;
+ TTBitmap *scaleddown;
t = f->ttf;
+ tscaled = ttfscale(t, t->ppem * 8, 0);
n = s->end - s->start + 1;
gs = emalloc9p(sizeof(TTGlyph *) * n);
w = 0;
@@ -166,20 +220,22 @@
g = 0;
else
g = ttffindchar(t, s->start + i);
- if((gs[i] = ttfgetglyph(t, g, 1)) == nil && g != 0)
- gs[i] = ttfgetglyph(t, 0, 1);
+ if((gs[i] = ttfgetglyph(tscaled, g, 1)) == nil && g != 0)
+ gs[i] = ttfgetglyph(tscaled, 0, 1);
assert(gs[i] != nil);
- w += gs[i]->width;
+ w += (gs[i]->width + 7)>>3;
}
- sz = 5 * 12 + (w+7>>3) * h + 3 * 12 + (n + 1) * 6;
+ sz = 5 * 12 + w * h + 3 * 12 + (n + 1) * 6;
d = emalloc(sz);
- p = d + sprint(d, "%11s %11d %11d %11d %11d ", "k1", 0, 0, w, h);
+ p = d + sprint(d, "%11s %11d %11d %11d %11d ", "k8", 0, 0, w, h);
x = 0;
for(i = 0; i < n; i++){- blit((uchar*)p, x, t->ascentpx - gs[i]->ymaxpx, w+7>>3, gs[i]->bit, gs[i]->width, gs[i]->height);
- x += gs[i]->width;
+ scaleddown = scaledown(gs[i]);
+ blit8((uchar*)p, x, t->ascentpx - ((gs[i]->ymaxpx+7)>>3), w, scaleddown->bit, scaleddown->width, scaleddown->height);
+ x += scaleddown->width;
+ freebitmap8(scaleddown);
}
- p += (w+7>>3) * h;
+ p += w * h;
p += sprint(p, "%11d %11d %11d ", n, h, t->ascentpx);
x = 0;
for(i = 0; i < n; i++){@@ -187,12 +243,12 @@
*p++ = x >> 8;
*p++ = 0;
*p++ = h;
- *p++ = gs[i]->xminpx;
+ *p++ = (gs[i]->xminpx+7)>>3;
if(gs[i]->advanceWidthpx != 0)
- *p++ = gs[i]->advanceWidthpx;
+ *p++ = (gs[i]->advanceWidthpx + 7)>>3; // Already at the right scale from when we grabbed it from gts
else
- *p++ = gs[i]->width;
- x += gs[i]->width;
+ *p++ = (gs[i]->width+7)>>3;
+ x += (gs[i]->width+7)>>3;
}
*p++ = x;
*p = x >> 8;
@@ -200,7 +256,7 @@
s->ndata = sz;
for(i = 0; i < n; i++)
ttfputglyph(gs[i]);
- free(gs);
+ free(gs);
}
--
⑨