[Dev-luatex] Fwd: [poppler] [PATCH] Fixup LaTeX composed characters

Martin Schröder martin at oneiros.de
Fri Mar 25 14:40:09 CET 2011


FYI.
Don't ask me what's the problem with our PDF seems to be...

---------- Forwarded message ----------
From: Tim Brody <tdb2 at ecs.soton.ac.uk>
Date: 2011/3/25
Subject: [poppler] [PATCH] Fixup LaTeX composed characters
To: poppler at lists.freedesktop.org


Hi All,

Attached is a patch to address the previous problem I wrote about with
pdflatex-produced PDFs that contain overlapping-diacritics/accents.

This patch contains:
 - a table of diacritic to Unicode combining character code-points
 - if an overlapping character is detected checks whether the first (in
stream-sequence) character is in the table
 - pops the diacritic off the word
 - appends the diacritic to the character as a Unicode combining character

This does not fix \b{o} or \d{o} because TeX places them on the next line
(so aren't detected as overlapping).

Yes, this is an issue with pdflatex but there are 100,000s of TeX-produced
PDFs for which we don't have source for ...

--
All the best,
Tim.
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-------------- next part --------------
From f4f70a49c42905d1e249a750ec9c68cd469586f8 Mon Sep 17 00:00:00 2001
From: Tim Brody <tdb2 at ecs.soton.ac.uk>
Date: Fri, 25 Mar 2011 13:02:18 +0000
Subject: [PATCH] Turn TeX-style composed characters into Unicode combining characters during text conversion.

---
 poppler/TextOutputDev.cc         |   39 +++++++++++++++++++++++----
 poppler/UnicodeCompEquivTables.h |   54 ++++++++++++++++++++++++++++++++++++++
 poppler/UnicodeTypeTable.cc      |   21 ++++++++++++++
 poppler/UnicodeTypeTable.h       |    2 +
 4 files changed, 110 insertions(+), 6 deletions(-)
 create mode 100644 poppler/UnicodeCompEquivTables.h

diff --git a/poppler/TextOutputDev.cc b/poppler/TextOutputDev.cc
index 13c67c6..b949986 100644
--- a/poppler/TextOutputDev.cc
+++ b/poppler/TextOutputDev.cc
@@ -2161,6 +2161,7 @@ void TextPage::addChar(GfxState *state, double x, double y,
   double x1, y1, w1, h1, dx2, dy2, base, sp, delta;
   GBool overlap;
   int i;
+  Unicode *uc = NULL; // u + combining character
 
   // subtract char and word spacing from the dx,dy values
   sp = state->getCharSpace();
@@ -2236,12 +2237,35 @@ void TextPage::addChar(GfxState *state, double x, double y,
     }
     overlap = fabs(delta) < dupMaxPriDelta * curWord->fontSize &&
               fabs(base - curWord->base) < dupMaxSecDelta * curWord->fontSize;
-    if (overlap || lastCharOverlap ||
-	sp < -minDupBreakOverlap * curWord->fontSize ||
-	sp > minWordBreakSpace * curWord->fontSize ||
-	fabs(base - curWord->base) > 0.5 ||
-	curFontSize != curWord->fontSize) {
-      endWord();
+    // whitespace caused by delta
+    if (sp > minWordBreakSpace * curWord->fontSize) {
+        endWord();
+    }
+    // font size changed
+    else if (curFontSize != curWord->fontSize) {
+        endWord();
+    }
+    // vertical whitespace
+	else if (fabs(base - curWord->base) > 0.5 ) {
+        endWord();
+    }
+    // overlapping characters
+    else if (overlap || lastCharOverlap ||
+            sp < -minDupBreakOverlap * curWord->fontSize ) {
+      // "u => ü, as seen in pdflatex output
+      Unicode uu;
+      if (unicodeCombineEquiv (curWord->text[curWord->len - 1], &uu)) {
+          curWord->len--;
+          curWord->charLen--;
+          overlap = gFalse;
+          uc = (Unicode *) gmallocn (uLen, sizeof (Unicode));
+          memcpy (uc, u, uLen * sizeof (Unicode));
+          uc[uLen++] = uu;
+          u = uc;
+      }
+      else {
+        endWord();
+      }
     }
     lastCharOverlap = overlap;
   } else {
@@ -2293,6 +2317,9 @@ void TextPage::addChar(GfxState *state, double x, double y,
       }
     }
   }
+  if (uc) {
+      gfree (uc);
+  }
   if (curWord) {
     curWord->charLen += nBytes;
   }
diff --git a/poppler/UnicodeCompEquivTables.h b/poppler/UnicodeCompEquivTables.h
new file mode 100644
index 0000000..7b28ea1
--- /dev/null
+++ b/poppler/UnicodeCompEquivTables.h
@@ -0,0 +1,54 @@
+// Generated by combining.pl at Thu Mar 24 11:44:21 2011
+
+typedef struct {
+	Unicode character;
+	Unicode combining;
+} combine_equiv;
+
+#define COMBINE_EQUIV_TABLE_LENGTH 43
+
+static const combine_equiv combine_equiv_table[] = {
+    { 0x0022, 0x030e },
+    { 0x0027, 0x0301 },
+    { 0x005e, 0x0302 },
+    { 0x005f, 0x0332 },
+    { 0x0060, 0x0300 },
+    { 0x007e, 0x0303 },
+    { 0x00a8, 0x0308 },
+    { 0x00af, 0x0305 },
+    { 0x00b0, 0x030a },
+    { 0x00b4, 0x0301 },
+    { 0x00b8, 0x0327 },
+    { 0x02b1, 0x0324 },
+    { 0x02b2, 0x0321 },
+    { 0x02b7, 0x032b },
+    { 0x02b9, 0x0301 },
+    { 0x02ba, 0x030b },
+    { 0x02bb, 0x0312 },
+    { 0x02bc, 0x0315 },
+    { 0x02bd, 0x0314 },
+    { 0x02c0, 0x0309 },
+    { 0x02c6, 0x0302 },
+    { 0x02c7, 0x030c },
+    { 0x02c8, 0x030d },
+    { 0x02c9, 0x0304 },
+    { 0x02ca, 0x0301 },
+    { 0x02cb, 0x0300 },
+    { 0x02cc, 0x0329 },
+    { 0x02cd, 0x0331 },
+    { 0x02d4, 0x0323 },
+    { 0x02d5, 0x031e },
+    { 0x02d6, 0x031f },
+    { 0x02d7, 0x0320 },
+    { 0x02d8, 0x0306 },
+    { 0x02d9, 0x0307 },
+    { 0x02da, 0x030a },
+    { 0x02db, 0x0328 },
+    { 0x02dc, 0x0303 },
+    { 0x02dd, 0x030b },
+    { 0x0384, 0x0301 },
+    { 0x0559, 0x0314 },
+    { 0x055a, 0x0313 },
+    { 0x0901, 0x0310 },
+    { 0x2017, 0x0333 },
+};
diff --git a/poppler/UnicodeTypeTable.cc b/poppler/UnicodeTypeTable.cc
index c0483a5..cf4c762 100644
--- a/poppler/UnicodeTypeTable.cc
+++ b/poppler/UnicodeTypeTable.cc
@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include "CharTypes.h"
 #include "UnicodeTypeTable.h"
+#include "UnicodeCompEquivTables.h"
 #include "goo/gmem.h"
 
 struct UnicodeMapTableEntry {
@@ -1095,6 +1096,26 @@ static GBool combine(Unicode base, Unicode add, Unicode *out) {
       (((v) - HANGUL_V_BASE) + (HANGUL_V_COUNT * ((l) - HANGUL_L_BASE)))))
 #define HANGUL_COMPOSE_LV_T(lv, t) ((lv) + ((t) - HANGUL_T_BASE))
 
+GBool unicodeCombineEquiv(Unicode in, Unicode *out) {
+    int start = 0, end = COMBINE_EQUIV_TABLE_LENGTH;
+
+    while (gTrue) {
+        int midpoint = (start+end) / 2;
+        if (combine_equiv_table[midpoint].character == in) {
+            *out = combine_equiv_table[midpoint].combining;
+            return gTrue;
+        }
+        else if (start == midpoint)
+            break;
+        else if (in > combine_equiv_table[midpoint].character)
+            start = midpoint;
+        else
+            end = midpoint;
+    }
+
+    return gFalse;
+}
+
 // Converts Unicode string @in of length @len to its normalization in form 
 // NFKC (compatibility decomposition + canonical composition). The length of
 // the resulting Unicode string is returned in @out_len. If non-NULL, @indices
diff --git a/poppler/UnicodeTypeTable.h b/poppler/UnicodeTypeTable.h
index 939e916..cabe80e 100644
--- a/poppler/UnicodeTypeTable.h
+++ b/poppler/UnicodeTypeTable.h
@@ -28,6 +28,8 @@ extern GBool unicodeTypeR(Unicode c);
 
 extern Unicode unicodeToUpper(Unicode c);
 
+extern GBool unicodeCombineEquiv(Unicode in, Unicode *out);
+
 extern Unicode *unicodeNormalizeNFKC(Unicode *in, int len, 
 				     int *out_len, int **offsets);
 
-- 
1.7.2.3


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