Improve (and greatly complicate) CMap generation for TrueType fonts.

We now detect ranges of glyphs mapped contiguously and use {begin,end}cidrange
for them, and also bunch together multiple characters and ranges in each
{begin,end}cid{char,range} pair.

git-svn-id: svn://svn.tartarus.org/sgt/halibut@7263 cda61777-01e9-0310-a592-d414129be87e

diff --git a/bk_pdf.c b/bk_pdf.c
index 23408ee..d69e833 100644 (file)
--- a/bk_pdf.c
+++ b/bk_pdf.c
@@ -196,6 +196,10 @@ void pdf_backend(paragraph *sourceform, keywordlist *keywords,
        if (fe->font->info->filetype == TRUETYPE) {
            object *cidfont = new_object(&olist);
            object *cmap = new_object(&olist);
+           unsigned short ranges[256];
+           unsigned startidx, nranges, nchars;
+           int start;
+
            objtext(font, "/Subtype/Type0\n/Encoding ");
            objtext(cmap, "<</Type/CMap\n/CMapName/");
            objtext(cmap, fe->name);
@@ -219,20 +223,74 @@ void pdf_backend(paragraph *sourceform, keywordlist *keywords,
            objstream(cmap, " def/CMapType 0 def/WMode 0 def\n");
            objstream(cmap, "1 begincodespacerange<00><FF>"
                      "endcodespacerange\n");
+           start = -1; nranges = nchars = 0;
            for (i = 0; i < 256; i++) {
-               char buf[20];
+               unsigned idx;
+
+               ranges[i] = 0;
                if (fe->vector[i] == NOGLYPH)
                    continue;
-               objstream(cmap, "1 begincidchar");
-               sprintf(buf, "<%02X>", i);
+               idx = sfnt_glyphtoindex(fe->font->info->fontfile,
+                                       fe->vector[i]);
+               if (start >= 0 && idx - startidx == i - start) {
+                   if (ranges[start] == 1) {
+                       nranges++; nchars--;
+                   }
+                   ranges[start] = i - start + 1;
+               } else {
+                   ranges[i] = 1;
+                   start = i;
+                   startidx = idx;
+                   nchars++;
+               }
+           }
+           i = 0;
+           while (nranges) {
+               unsigned blk = nranges > 100 ? 100 : nranges;
+               nranges -= blk;
+               sprintf(buf, "%u ", blk);
                objstream(cmap, buf);
-               sprintf(buf, "%hu", sfnt_glyphtoindex(fe->font->info->fontfile,
-                                                     fe->vector[i]));
+               objstream(cmap, "begincidrange\n");
+               while (blk) {
+                   if (ranges[i] > 1) {
+                       sprintf(buf, "<%02X>", i);
+                       objstream(cmap, buf);
+                       sprintf(buf, "<%02X>", i + ranges[i] - 1);
+                       objstream(cmap, buf);
+                       sprintf(buf, "%hu\n",
+                               sfnt_glyphtoindex(fe->font->info->fontfile,
+                                                 fe->vector[i]));
+                       objstream(cmap, buf);
+                       blk--;
+                   }
+                   i++;
+               }
+               objstream(cmap, "endcidrange\n");
+           }
+           i = 0;
+           while (nchars) {
+               unsigned blk = nchars > 100 ? 100 : nchars;
+               nchars -= blk;
+               sprintf(buf, "%u ", blk);
                objstream(cmap, buf);
-               objstream(cmap, " endcidchar\n");
+               objstream(cmap, "begincidchar\n");
+               while (blk) {
+                   if (ranges[i] == 1) {
+                       sprintf(buf, "<%02X>", i);
+                       objstream(cmap, buf);
+                       sprintf(buf, "%hu\n",
+                               sfnt_glyphtoindex(fe->font->info->fontfile,
+                                                 fe->vector[i]));
+                       objstream(cmap, buf);
+                       blk--;
+                   }
+                   i++;
+               }
+               objstream(cmap, "endcidchar\n");
            }
            objstream(cmap, "endcmap CMapName currentdict /CMap "
                      "defineresource pop end end\n%%EndResource\n%%EOF\n");
+
            objref(font, cmap);
            objtext(font, "\n/DescendantFonts[");
            objref(font, cidfont);