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use a "smart rounding" algorithm to handle rounding when reducing upm.

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be5invis 2015-08-28 17:41:13 +08:00
parent 7c77c8182d
commit f3ae40b75d
8 changed files with 125 additions and 23 deletions
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74
pass2-smartround.js Normal file
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var fs = require('fs');
var TTFReader = require('node-sfnt').TTFReader;
var TTFWriter = require('node-sfnt').TTFWriter;
var argv = require('yargs').argv;
function toArrayBuffer(buffer) {
var length = buffer.length;
var view = new DataView(new ArrayBuffer(length), 0, length);
for (var i = 0, l = length; i < l; i++) {
view.setUint8(i, buffer[i], false);
}
return view.buffer;
}
function toBuffer(arrayBuffer) {
var length = arrayBuffer.byteLength;
var view = new DataView(arrayBuffer, 0, length);
var buffer = new Buffer(length);
for (var i = 0, l = length; i < l; i++) {
buffer[i] = view.getUint8(i, false);
}
return buffer;
}
var options = {preserveOS2Version: true, preserveXAvgCharWidth: true, writeUnknownTables: true, hinting: true}
function readttf(file) {
var data = fs.readFileSync(file);
var buffer = toArrayBuffer(data);
var ttf = (new TTFReader(options)).read(buffer);
return ttf;
}
function writettf(ttf, file){
var buffer = new TTFWriter(options).write(ttf);
fs.writeFileSync(file, toBuffer(buffer));
}
function mix(a, b, p){ return a + (b - a) * p }
function ratio(l, m, r){
if(l === r) return 0;
return (m - l) / (r - l);
}
function colinear(a, b, c){
return Math.abs(((c.y - a.y) * (b.x - a.x) - (c.x - a.x) * (b.y - a.y))) <= 1e-5
}
var ttf = readttf(argv._[0]);
var targetupm = argv.upm - 0 || 1000;
var upm = ttf.head.unitsPerEm - 0;
var skew = Math.tan(ttf.post.italicAngle / 180 * Math.PI);
for(var j = 0; j < ttf.glyf.length; j++){
var glyph = ttf.glyf[j];
if(glyph.contours && glyph.contours.length > 0) for(var k = 0; k < glyph.contours.length; k++) if(glyph.contours[k].length > 0) {
var c = glyph.contours[k];
for(var l = 0; l < c.length; l++){
c[l].x += skew * c[l].y
}
var xs = c.map(function(p){ return p.x });
var ys = c.map(function(p){ return p.y });
var xmin = Math.min.apply(null, xs);
var xmax = Math.max.apply(null, xs);
var ymin = Math.min.apply(null, ys);
var ymax = Math.max.apply(null, ys);
var rxmin = (upm / targetupm) * Math.round(xmin * targetupm / upm);
var rxmax = (upm / targetupm) * Math.round(xmax * targetupm / upm);
var rymin = (upm / targetupm) * Math.round(ymin * targetupm / upm);
var rymax = (upm / targetupm) * Math.round(ymax * targetupm / upm);
for(var l = 0; l < c.length; l++){
c[l].y = (upm / targetupm) * Math.round(mix(rymin, rymax, ratio(ymin, c[l].y, ymax)) * targetupm / upm)
c[l].x = (upm / targetupm) * Math.round((mix(rxmin, rxmax, ratio(xmin, c[l].x, xmax)) - c[l].y * skew) * targetupm / upm)
}
glyph.contours[k] = c.filter(function(p){ return !p.removable })
}
}
fs.writeFileSync(argv._[1], toBuffer(new TTFWriter(options).write(ttf)));