Exclude CJK characters from default font build, reducing bundle size …

…by ~2.8MB

scripts/build-font.js

@@ -11,10 +11,12 @@
  * this script transforms it into a .ts file so it can be easily imported
  * into KiCanvas
  *
- * Note: Newstroke is *huge*, nearly 3MB! It's currently the single largest
- * part of KiCanvas's bundle. This is largely due to the CJK character set,
- * so it may make sense to split it into a separate file that's loaded
- * on demand.
+ * Note: Newstroke is *huge*, nearly 3MB! This is massive compared to the rest
+ * of KiCanvas, so we have to do some optimization. The vast bulk of Newstroke
+ * is the extended CJK character set (Unicode 0x4E00-0x9FFF). There aren't a lot
+ * of open source schematics/boards that use those characters so this script
+ * removes them, reducing the size from ~3MB to ~200kB. In the future, it
+ * should be possible to separately load those symbols when needed.
  *
  */
 
@@ -33,7 +35,10 @@ const preamble = `/* Generated from third-party ${INFILE} for KiCanvas.\nSee bel
 const license_str = src.slice(0, src.lastIndexOf("*/", first_bracket) + 2);
 const glyph_array_str = src.slice(first_bracket + 1, src.lastIndexOf("}") - 1);
 
-const glyphs = eval(`[${glyph_array_str}]`);
+const all_glyphs = eval(`[${glyph_array_str}]`);
+// Note: This is where the CJK characters are excluded.
+const glyphs = all_glyphs.slice(0, 0x4e00);
+const excluded_count = all_glyphs.length - glyphs.length;
 const glyph_set = new Set(glyphs);
 const glyph_map = new Map();
 
@@ -56,7 +61,7 @@ for (const [glyph, count] of glyph_map) {
 
 const repeated_glyphs_def_str = repeated_glyph_defs.join(", ");
 
-const out_glyphs = glyphs.map((glyph) => {
+const out_glyphs = glyphs.map((glyph, index) => {
     if (repeated_glyphs.has(glyph)) {
         return repeated_glyphs.get(glyph);
     } else {
@@ -66,7 +71,9 @@ const out_glyphs = glyphs.map((glyph) => {
 
 const out_glyph_array_str = out_glyphs.join(",\n");
 
-console.log(`${glyphs.length} total glyphs, ${glyph_set.size} unique`);
+console.log(
+    `${glyphs.length} total glyphs, ${glyph_set.size} unique, ${excluded_count} excluded`,
+);
 
 const code = `export const shared_glyphs = [${repeated_glyphs_def_str}];\n\nexport const glyph_data: (string|number|undefined)[]  = [${out_glyph_array_str}\n];\n`;
 const header = `${preamble}\n\n${license_str}`;