From f7e251e69b3323cb448c2d22c21603c241fcee4d Mon Sep 17 00:00:00 2001
From: Ian MacArthur <imacarthur@gmail.com>
Date: Wed, 6 Apr 2011 21:02:35 +0000
Subject: [PATCH] Initial work to fix handling of surrogate pairs on win32 -
 draw() was not handling any Unicode char above U+FFFF as we did not handle
 the case where more than one UTF16 cell was required to hold the full glyph.
 This change works, but is incomplete, other sections of the win32 code (and
 possibly OSX code) are making the same invalid assumptions about UTF16 chars.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@8567 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
---
 src/fl_font_win32.cxx | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/fl_font_win32.cxx b/src/fl_font_win32.cxx
index 90c6a08b4..9aac9dd2b 100644
--- a/src/fl_font_win32.cxx
+++ b/src/fl_font_win32.cxx
@@ -339,24 +339,33 @@ void Fl_GDI_Graphics_Driver::draw(const char* str, int n, int x, int y) {
   int lx = 0;
   char *end = (char *)&str[n];
   COLORREF oldColor = SetTextColor(fl_gc, fl_RGB());
-   SelectObject(fl_gc, font_descriptor()->fid);
+  SelectObject(fl_gc, font_descriptor()->fid);
   while (i < n) {
-    unsigned int u;
-    unsigned int u1;
-    unsigned short ucs;
-//  int l = fl_utf2ucs((const unsigned char*)str + i, n - i, &u);
-    int l;
+    unsigned int u;  // UCS value of next glyph
+    unsigned int u1; // UCS non-spacing glyph
+    unsigned cc;     // UTF16 cell count for glyph - usually 1
+    unsigned short ucs[4]; // Array for UTF16 cells
+    int l; // byte-count of current UTF8 glyph
     u = fl_utf8decode((const char*)(str + i), end, &l);
     if ( (u1 = fl_nonspacing(u)) ) {
       x -= lx;
-	  u = u1;
+      u = u1;
     } else {
       lx = (int) width(u);
     }
-    ucs = u;
+    // Do we need a surrogate pair for this UCS value?
+    if(u > 0xFFFF) {
+      cc = fl_utf8toUtf16((str + i), l, ucs, 4);
+// This is the - essentially identical - MS API equivalent
+//cc = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, (str + i), l, (WCHAR*)ucs, 4);
+    }
+    else { // not a surrogate pair, use a single value
+      ucs[0] = u;
+      cc = 1;
+    }
+    TextOutW(fl_gc, x, y, (WCHAR*)ucs, cc);
     if (l < 1) l = 1;
     i += l;
-    TextOutW(fl_gc, x, y, (WCHAR*)&ucs, 1);
     x += lx;
   }
   SetTextColor(fl_gc, oldColor);