UI: Line Break on Conditional Punctuation

This PR adds new typographical line breaking opportunities, characters
that break depending on what follows. For example comma if not followed
by a space or a number. Period if not followed by a space or another
period. Along with related non-Latin equivalents, like Greek question
mark, full width punctuation, Hebrew, Arabic, etc.

Pull Request: https://projects.blender.org/blender/blender/pulls/137934

source/blender/blenfont/intern/blf_font.cc

@@ -1351,13 +1351,21 @@ static void blf_font_wrap_apply(FontBLF *font,
       clip_bytes = BLI_str_utf8_from_unicode_len(codepoint_prev);
     }
     else if (UNLIKELY((int(mode) & int(BLFWrapMode::Typographical)) &&
-                      BLI_str_utf32_char_is_optional_break(codepoint, codepoint_prev)))
+                      BLI_str_utf32_char_is_optional_break_after(codepoint, codepoint_prev)))
     {
       /* Optional break after various characters, keeping it. */
       wrap.last[0] = i;
       wrap.last[1] = i;
       clip_bytes = 0;
     }
+    else if (UNLIKELY((int(mode) & int(BLFWrapMode::Typographical)) &&
+                      BLI_str_utf32_char_is_optional_break_before(codepoint, codepoint_prev)))
+    {
+      /* Optional break before various characters. */
+      wrap.last[0] = i_curr;
+      wrap.last[1] = i_curr;
+      clip_bytes = 0;
+    }
 
     if (UNLIKELY(do_draw)) {
 #if 0

source/blender/blenlib/BLI_string_utf8.h

@@ -198,7 +198,8 @@ char32_t BLI_str_utf32_char_to_upper(char32_t wc);
 char32_t BLI_str_utf32_char_to_lower(char32_t wc);
 
 bool BLI_str_utf32_char_is_breaking_space(char32_t codepoint);
-bool BLI_str_utf32_char_is_optional_break(char32_t codepoint, char32_t codepoint_prev);
+bool BLI_str_utf32_char_is_optional_break_after(char32_t codepoint, char32_t codepoint_prev);
+bool BLI_str_utf32_char_is_optional_break_before(char32_t codepoint, char32_t codepoint_prev);
 
 /**
  * \warning can return -1 on bad chars.

source/blender/blenlib/intern/string_utf8.cc

@@ -792,7 +792,7 @@ bool BLI_str_utf32_char_is_breaking_space(char32_t codepoint)
               0x3000); /* Ideographic space. */
 }
 
-bool BLI_str_utf32_char_is_optional_break(char32_t codepoint, char32_t codepoint_prev)
+bool BLI_str_utf32_char_is_optional_break_after(char32_t codepoint, char32_t codepoint_prev)
 {
   /* Subset of the characters that are line breaking opportunities
    * according to the Unicode Line Breaking Algorithm (Standard Annex #14).
@@ -833,6 +833,71 @@ bool BLI_str_utf32_char_is_optional_break(char32_t codepoint, char32_t codepoint
   return false;
 }
 
+bool BLI_str_utf32_char_is_optional_break_before(char32_t codepoint, char32_t codepoint_prev)
+{
+  /* Do not break on any of these if a space follows. */
+  if (BLI_str_utf32_char_is_breaking_space(codepoint)) {
+    return false;
+  }
+
+  /* Infix Numeric Separators. Allow break on these if not numbers afterward. */
+  if (ELEM(codepoint_prev,
+           ',',    /* Comma. */
+           ':',    /* Colon. */
+           ';',    /* Semicolon. */
+           0x037E, /* Greek question mark. */
+           0x0589, /* Armenian full stop. */
+           0x060C, /* Arabic comma. */
+           0x060D, /* Arabic date separator. */
+           0x07F8, /* N'Ko comma. */
+           0x2044) /* Fraction slash. */
+      && !(codepoint >= '0' && codepoint <= '9'))
+  {
+    return true;
+  }
+
+  /* Break on full stop only if not followed by another, or by a number. */
+  if (codepoint_prev == '.' && codepoint != '.' && !(codepoint >= '0' && codepoint <= '9')) {
+    return true;
+  }
+
+  /* Close punctuation. */
+  if (ELEM(codepoint_prev,
+           0x3001,  /* Ideographic Comma. */
+           0x3002,  /* Ideographic Full Stop. */
+           0xFE10,  /* Presentation Form for Vertical Ideographic Comma. */
+           0xFE11,  /* Presentation Form for Vertical Ideographic Full Stop. */
+           0xFE12,  /* Presentation Form for Vertical Ideographic Colon. */
+           0xFE50,  /* Small Comma. */
+           0xFE52,  /* Small Full Stop. */
+           0xFF0C,  /* Fullwidth Comma. */
+           0xFF0E,  /* Fullwidth Full Stop. */
+           0XFF61,  /* Halfwidth Ideographic Full Stop. */
+           0Xff64)) /* Halfwidth Ideographic Comma. */
+  {
+    return true;
+  }
+
+  /* Exclamation/Interrogation. */
+  if (ELEM(codepoint_prev,
+           '!',     /* Exlamation Mark. */
+           '?',     /* Question Mark. */
+           0x05C6,  /* Hebrew punctuation maqaf. */
+           0x061B,  /* Arabic semicolon. */
+           0x061E,  /* Arabic triple dot. */
+           0x061F,  /* Arabic question mark. */
+           0x06D4,  /* Arabic full stop. */
+           0x07F9,  /* N'Ko question mark. */
+           0x0F0D,  /* Tibetan shad mark. */
+           0xFF01,  /* Fullwidth Exclamation Mark. */
+           0xFF1F)) /* Fullwidth Question Mark. */
+  {
+    return true;
+  }
+
+  return false;
+}
+
 /** \} */ /* -------------------------------------------------------------------- */
 
 int BLI_str_utf8_size_or_error(const char *p)