Updated stb_textedit.h from 1.20 to 1.26 (many fixes). (#5075)

docs/CHANGELOG.txt

@@ -63,6 +63,7 @@ Other Changes:
 - Misc: Fixed IsAnyItemHovered() returning false when using navigation.
 - Misc: Added IMGUI_STB_SPRINTF_FILENAME to support custom path to stb_sprintf. (#5068, #2954) [@jakubtomsu]
 - Misc: Added constexpr to ImVec2/ImVec4 inline constructors. (#4995) [@Myriachan]
+- Misc: Updated stb_truetype.h from 1.20 to 1.26 (many fixes). (#5075)
 - Misc: Updated stb_textedit.h from 1.13 to 1.14 (our changes so this effectively is a no-op). (#5075)
 - Misc: Updated stb_rect_pack.h from 1.00 to 1.01 (minor). (#5075)
 - Misc: binary_to_compressed_c tool: Added -nostatic option. (#5021) [@podsvirov]

imstb_truetype.h

@@ -1,10 +1,19 @@
 // [DEAR IMGUI]
-// This is a slightly modified version of stb_truetype.h 1.20.
+// This is a slightly modified version of stb_truetype.h 1.26.
 // Mostly fixing for compiler and static analyzer warnings.
 // Grep for [DEAR IMGUI] to find the changes.
 
-// stb_truetype.h - v1.20 - public domain
+// stb_truetype.h - v1.26 - public domain
-// authored from 2009-2016 by Sean Barrett / RAD Game Tools
+// authored from 2009-2021 by Sean Barrett / RAD Game Tools
+//
+// =======================================================================
+//
+//    NO SECURITY GUARANTEE -- DO NOT USE THIS ON UNTRUSTED FONT FILES
+//
+// This library does no range checking of the offsets found in the file,
+// meaning an attacker can use it to read arbitrary memory.
+//
+// =======================================================================
 //
 //   This library processes TrueType files:
 //        parse files
@@ -37,11 +46,11 @@
 //       Daniel Ribeiro Maciel
 //
 //   Bug/warning reports/fixes:
-//       "Zer" on mollyrocket       Fabian "ryg" Giesen
+//       "Zer" on mollyrocket       Fabian "ryg" Giesen   github:NiLuJe
-//       Cass Everitt               Martins Mozeiko
+//       Cass Everitt               Martins Mozeiko       github:aloucks
-//       stoiko (Haemimont Games)   Cap Petschulat
+//       stoiko (Haemimont Games)   Cap Petschulat        github:oyvindjam
-//       Brian Hook                 Omar Cornut
+//       Brian Hook                 Omar Cornut           github:vassvik
-//       Walter van Niftrik         github:aloucks
+//       Walter van Niftrik         Ryan Griege
 //       David Gow                  Peter LaValle
 //       David Given                Sergey Popov
 //       Ivan-Assen Ivanov          Giumo X. Clanjor
@@ -49,11 +58,17 @@
 //       Johan Duparc               Thomas Fields
 //       Hou Qiming                 Derek Vinyard
 //       Rob Loach                  Cort Stratton
-//       Kenney Phillis Jr.         github:oyvindjam
+//       Kenney Phillis Jr.         Brian Costabile
-//       Brian Costabile            github:vassvik
+//       Ken Voskuil (kaesve)
 //
 // VERSION HISTORY
 //
+//   1.26 (2021-08-28) fix broken rasterizer
+//   1.25 (2021-07-11) many fixes
+//   1.24 (2020-02-05) fix warning
+//   1.23 (2020-02-02) query SVG data for glyphs; query whole kerning table (but only kern not GPOS)
+//   1.22 (2019-08-11) minimize missing-glyph duplication; fix kerning if both 'GPOS' and 'kern' are defined
+//   1.21 (2019-02-25) fix warning
 //   1.20 (2019-02-07) PackFontRange skips missing codepoints; GetScaleFontVMetrics()
 //   1.19 (2018-02-11) GPOS kerning, STBTT_fmod
 //   1.18 (2018-01-29) add missing function
@@ -248,19 +263,6 @@
 //   recommend it.
 //
 //
-// SOURCE STATISTICS (based on v0.6c, 2050 LOC)
-//
-//   Documentation & header file        520 LOC  \___ 660 LOC documentation
-//   Sample code                        140 LOC  /
-//   Truetype parsing                   620 LOC  ---- 620 LOC TrueType
-//   Software rasterization             240 LOC  \.
-//   Curve tessellation                 120 LOC   \__ 550 LOC Bitmap creation
-//   Bitmap management                  100 LOC   /
-//   Baked bitmap interface              70 LOC  /
-//   Font name matching & access        150 LOC  ---- 150
-//   C runtime library abstraction       60 LOC  ----  60
-//
-//
 // PERFORMANCE MEASUREMENTS FOR 1.06:
 //
 //                      32-bit     64-bit
@@ -275,8 +277,8 @@
 ////  SAMPLE PROGRAMS
 ////
 //
-//  Incomplete text-in-3d-api example, which draws quads properly aligned to be lossless
+//  Incomplete text-in-3d-api example, which draws quads properly aligned to be lossless.
-//
+//  See "tests/truetype_demo_win32.c" for a complete version.
 #if 0
 #define STB_TRUETYPE_IMPLEMENTATION  // force following include to generate implementation
 #include "stb_truetype.h"
@@ -302,6 +304,8 @@ void my_stbtt_initfont(void)
 void my_stbtt_print(float x, float y, char *text)
 {
    // assume orthographic projection with units = screen pixels, origin at top left
+   glEnable(GL_BLEND);
+   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, ftex);
    glBegin(GL_QUADS);
@@ -309,10 +313,10 @@ void my_stbtt_print(float x, float y, char *text)
       if (*text >= 32 && *text < 128) {
          stbtt_aligned_quad q;
          stbtt_GetBakedQuad(cdata, 512,512, *text-32, &x,&y,&q,1);//1=opengl & d3d10+,0=d3d9
-         glTexCoord2f(q.s0,q.t1); glVertex2f(q.x0,q.y0);
+         glTexCoord2f(q.s0,q.t0); glVertex2f(q.x0,q.y0);
-         glTexCoord2f(q.s1,q.t1); glVertex2f(q.x1,q.y0);
+         glTexCoord2f(q.s1,q.t0); glVertex2f(q.x1,q.y0);
-         glTexCoord2f(q.s1,q.t0); glVertex2f(q.x1,q.y1);
+         glTexCoord2f(q.s1,q.t1); glVertex2f(q.x1,q.y1);
-         glTexCoord2f(q.s0,q.t0); glVertex2f(q.x0,q.y1);
+         glTexCoord2f(q.s0,q.t1); glVertex2f(q.x0,q.y1);
       }
       ++text;
    }
@@ -719,7 +723,7 @@ struct stbtt_fontinfo
 
    int numGlyphs;                     // number of glyphs, needed for range checking
 
-   int loca,head,glyf,hhea,hmtx,kern,gpos; // table locations as offset from start of .ttf
+   int loca,head,glyf,hhea,hmtx,kern,gpos,svg; // table locations as offset from start of .ttf
    int index_map;                     // a cmap mapping for our chosen character encoding
    int indexToLocFormat;              // format needed to map from glyph index to glyph
 
@@ -802,6 +806,18 @@ STBTT_DEF int  stbtt_GetGlyphKernAdvance(const stbtt_fontinfo *info, int glyph1,
 STBTT_DEF int  stbtt_GetGlyphBox(const stbtt_fontinfo *info, int glyph_index, int *x0, int *y0, int *x1, int *y1);
 // as above, but takes one or more glyph indices for greater efficiency
 
+typedef struct stbtt_kerningentry
+{
+   int glyph1; // use stbtt_FindGlyphIndex
+   int glyph2;
+   int advance;
+} stbtt_kerningentry;
+
+STBTT_DEF int  stbtt_GetKerningTableLength(const stbtt_fontinfo *info);
+STBTT_DEF int  stbtt_GetKerningTable(const stbtt_fontinfo *info, stbtt_kerningentry* table, int table_length);
+// Retrieves a complete list of all of the kerning pairs provided by the font
+// stbtt_GetKerningTable never writes more than table_length entries and returns how many entries it did write.
+// The table will be sorted by (a.glyph1 == b.glyph1)?(a.glyph2 < b.glyph2):(a.glyph1 < b.glyph1)
 
 //////////////////////////////////////////////////////////////////////////////
 //
@@ -846,6 +862,12 @@ STBTT_DEF int stbtt_GetGlyphShape(const stbtt_fontinfo *info, int glyph_index, s
 STBTT_DEF void stbtt_FreeShape(const stbtt_fontinfo *info, stbtt_vertex *vertices);
 // frees the data allocated above
 
+STBTT_DEF unsigned char *stbtt_FindSVGDoc(const stbtt_fontinfo *info, int gl);
+STBTT_DEF int stbtt_GetCodepointSVG(const stbtt_fontinfo *info, int unicode_codepoint, const char **svg);
+STBTT_DEF int stbtt_GetGlyphSVG(const stbtt_fontinfo *info, int gl, const char **svg);
+// fills svg with the character's SVG data.
+// returns data size or 0 if SVG not found.
+
 //////////////////////////////////////////////////////////////////////////////
 //
 // BITMAP RENDERING
@@ -1347,6 +1369,22 @@ static stbtt__buf stbtt__get_subrs(stbtt__buf cff, stbtt__buf fontdict)
    return stbtt__cff_get_index(&cff);
 }
 
+// since most people won't use this, find this table the first time it's needed
+static int stbtt__get_svg(stbtt_fontinfo *info)
+{
+   stbtt_uint32 t;
+   if (info->svg < 0) {
+      t = stbtt__find_table(info->data, info->fontstart, "SVG ");
+      if (t) {
+         stbtt_uint32 offset = ttULONG(info->data + t + 2);
+         info->svg = t + offset;
+      } else {
+         info->svg = 0;
+      }
+   }
+   return info->svg;
+}
+
 static int stbtt_InitFont_internal(stbtt_fontinfo *info, unsigned char *data, int fontstart)
 {
    stbtt_uint32 cmap, t;
@@ -1426,6 +1464,8 @@ static int stbtt_InitFont_internal(stbtt_fontinfo *info, unsigned char *data, in
    else
       info->numGlyphs = 0xffff;
 
+   info->svg = -1;
+
    // find a cmap encoding table we understand *now* to avoid searching
    // later. (todo: could make this installable)
    // the same regardless of glyph.
@@ -1509,12 +1549,12 @@ STBTT_DEF int stbtt_FindGlyphIndex(const stbtt_fontinfo *info, int unicode_codep
       search += 2;
 
       {
-         stbtt_uint16 offset, start;
+         stbtt_uint16 offset, start, last;
          stbtt_uint16 item = (stbtt_uint16) ((search - endCount) >> 1);
 
-         STBTT_assert(unicode_codepoint <= ttUSHORT(data + endCount + 2*item));
          start = ttUSHORT(data + index_map + 14 + segcount*2 + 2 + 2*item);
-         if (unicode_codepoint < start)
+         last = ttUSHORT(data + endCount + 2*item);
+         if (unicode_codepoint < start || unicode_codepoint > last)
             return 0;
 
          offset = ttUSHORT(data + index_map + 14 + segcount*6 + 2 + 2*item);
@@ -1774,7 +1814,7 @@ static int stbtt__GetGlyphShapeTT(const stbtt_fontinfo *info, int glyph_index, s
          }
       }
       num_vertices = stbtt__close_shape(vertices, num_vertices, was_off, start_off, sx,sy,scx,scy,cx,cy);
-   } else if (numberOfContours == -1) {
+   } else if (numberOfContours < 0) {
       // Compound shapes.
       int more = 1;
       stbtt_uint8 *comp = data + g + 10;
@@ -1841,7 +1881,7 @@ static int stbtt__GetGlyphShapeTT(const stbtt_fontinfo *info, int glyph_index, s
                if (comp_verts) STBTT_free(comp_verts, info->userdata);
                return 0;
             }
-            if (num_vertices > 0) STBTT_memcpy(tmp, vertices, num_vertices*sizeof(stbtt_vertex)); //-V595
+            if (num_vertices > 0 && vertices) STBTT_memcpy(tmp, vertices, num_vertices*sizeof(stbtt_vertex));
             STBTT_memcpy(tmp+num_vertices, comp_verts, comp_num_verts*sizeof(stbtt_vertex));
             if (vertices) STBTT_free(vertices, info->userdata);
             vertices = tmp;
@@ -1851,9 +1891,6 @@ static int stbtt__GetGlyphShapeTT(const stbtt_fontinfo *info, int glyph_index, s
          // More components ?
          more = flags & (1<<5);
       }
-   } else if (numberOfContours < 0) {
-      // @TODO other compound variations?
-      STBTT_assert(0);
    } else {
       // numberOfCounters == 0, do nothing
    }
@@ -2107,7 +2144,7 @@ static int stbtt__run_charstring(const stbtt_fontinfo *info, int glyph_index, st
                subrs = stbtt__cid_get_glyph_subrs(info, glyph_index);
             has_subrs = 1;
          }
-         // fallthrough
+         // FALLTHROUGH
       case 0x1D: // callgsubr
          if (sp < 1) return STBTT__CSERR("call(g|)subr stack");
          v = (int) s[--sp];
@@ -2212,7 +2249,7 @@ static int stbtt__run_charstring(const stbtt_fontinfo *info, int glyph_index, st
       } break;
 
       default:
-         if (b0 != 255 && b0 != 28 && (b0 < 32 || b0 > 254)) //-V560
+         if (b0 != 255 && b0 != 28 && b0 < 32)
             return STBTT__CSERR("reserved operator");
 
          // push immediate
@@ -2282,6 +2319,48 @@ STBTT_DEF void stbtt_GetGlyphHMetrics(const stbtt_fontinfo *info, int glyph_inde
    }
 }
 
+STBTT_DEF int  stbtt_GetKerningTableLength(const stbtt_fontinfo *info)
+{
+   stbtt_uint8 *data = info->data + info->kern;
+
+   // we only look at the first table. it must be 'horizontal' and format 0.
+   if (!info->kern)
+      return 0;
+   if (ttUSHORT(data+2) < 1) // number of tables, need at least 1
+      return 0;
+   if (ttUSHORT(data+8) != 1) // horizontal flag must be set in format
+      return 0;
+
+   return ttUSHORT(data+10);
+}
+
+STBTT_DEF int stbtt_GetKerningTable(const stbtt_fontinfo *info, stbtt_kerningentry* table, int table_length)
+{
+   stbtt_uint8 *data = info->data + info->kern;
+   int k, length;
+
+   // we only look at the first table. it must be 'horizontal' and format 0.
+   if (!info->kern)
+      return 0;
+   if (ttUSHORT(data+2) < 1) // number of tables, need at least 1
+      return 0;
+   if (ttUSHORT(data+8) != 1) // horizontal flag must be set in format
+      return 0;
+
+   length = ttUSHORT(data+10);
+   if (table_length < length)
+      length = table_length;
+
+   for (k = 0; k < length; k++)
+   {
+      table[k].glyph1 = ttUSHORT(data+18+(k*6));
+      table[k].glyph2 = ttUSHORT(data+20+(k*6));
+      table[k].advance = ttSHORT(data+22+(k*6));
+   }
+
+   return length;
+}
+
 static int stbtt__GetGlyphKernInfoAdvance(const stbtt_fontinfo *info, int glyph1, int glyph2)
 {
    stbtt_uint8 *data = info->data + info->kern;
@@ -2336,7 +2415,8 @@ static stbtt_int32  stbtt__GetCoverageIndex(stbtt_uint8 *coverageTable, int glyp
                return m;
             }
          }
-        } break;
+         break;
+      }
 
       case 2: {
          stbtt_uint16 rangeCount = ttUSHORT(coverageTable + 2);
@@ -2360,12 +2440,10 @@ static stbtt_int32  stbtt__GetCoverageIndex(stbtt_uint8 *coverageTable, int glyp
                return startCoverageIndex + glyph - strawStart;
             }
          }
-        } break;
+         break;
+      }
 
-        default: {
+      default: return -1; // unsupported
-            // There are no other cases.
-            STBTT_assert(0);
-        } break;
    }
 
    return -1;
@@ -2383,10 +2461,8 @@ static stbtt_int32  stbtt__GetGlyphClass(stbtt_uint8 *classDefTable, int glyph)
 
          if (glyph >= startGlyphID && glyph < startGlyphID + glyphCount)
             return (stbtt_int32)ttUSHORT(classDef1ValueArray + 2 * (glyph - startGlyphID));
-
+         break;
-            // [DEAR IMGUI] Commented to fix static analyzer warning
+      }
-            //classDefTable = classDef1ValueArray + 2 * glyphCount;
-        } break;
 
       case 2: {
          stbtt_uint16 classRangeCount = ttUSHORT(classDefTable + 2);
@@ -2408,18 +2484,15 @@ static stbtt_int32  stbtt__GetGlyphClass(stbtt_uint8 *classDefTable, int glyph)
             else
                return (stbtt_int32)ttUSHORT(classRangeRecord + 4);
          }
-
+         break;
-            // [DEAR IMGUI] Commented to fix static analyzer warning
-            //classDefTable = classRangeRecords + 6 * classRangeCount;
-        } break;
-
-        default: {
-            // There are no other cases.
-            STBTT_assert(0);
-        } break;
       }
 
-    return -1;
+      default:
+         return -1; // Unsupported definition type, return an error.
+   }
+
+   // "All glyphs not assigned to a class fall into class 0". (OpenType spec)
+   return 0;
 }
 
 // Define to STBTT_assert(x) if you want to break on unimplemented formats.
@@ -2431,7 +2504,7 @@ static stbtt_int32  stbtt__GetGlyphGPOSInfoAdvance(const stbtt_fontinfo *info, i
    stbtt_uint8 *lookupList;
    stbtt_uint16 lookupCount;
    stbtt_uint8 *data;
-    stbtt_int32 i;
+   stbtt_int32 i, sti;
 
    if (!info->gpos) return 0;
 
@@ -2451,9 +2524,9 @@ static stbtt_int32  stbtt__GetGlyphGPOSInfoAdvance(const stbtt_fontinfo *info, i
       stbtt_uint16 lookupType = ttUSHORT(lookupTable);
       stbtt_uint16 subTableCount = ttUSHORT(lookupTable + 4);
       stbtt_uint8 *subTableOffsets = lookupTable + 6;
-        switch(lookupType) {
+      if (lookupType != 2) // Pair Adjustment Positioning Subtable
-            case 2: { // Pair Adjustment Positioning Subtable
+         continue;
-                stbtt_int32 sti;
+
       for (sti=0; sti<subTableCount; sti++) {
          stbtt_uint16 subtableOffset = ttUSHORT(subTableOffsets + 2 * sti);
          stbtt_uint8 *table = lookupTable + subtableOffset;
@@ -2468,20 +2541,15 @@ static stbtt_int32  stbtt__GetGlyphGPOSInfoAdvance(const stbtt_fontinfo *info, i
                int straw, needle;
                stbtt_uint16 valueFormat1 = ttUSHORT(table + 4);
                stbtt_uint16 valueFormat2 = ttUSHORT(table + 6);
+               if (valueFormat1 == 4 && valueFormat2 == 0) { // Support more formats?
                   stbtt_int32 valueRecordPairSizeInBytes = 2;
                   stbtt_uint16 pairSetCount = ttUSHORT(table + 8);
                   stbtt_uint16 pairPosOffset = ttUSHORT(table + 10 + 2 * coverageIndex);
                   stbtt_uint8 *pairValueTable = table + pairPosOffset;
                   stbtt_uint16 pairValueCount = ttUSHORT(pairValueTable);
                   stbtt_uint8 *pairValueArray = pairValueTable + 2;
-                            // TODO: Support more formats.
-                            STBTT_GPOS_TODO_assert(valueFormat1 == 4);
-                            if (valueFormat1 != 4) return 0;
-                            STBTT_GPOS_TODO_assert(valueFormat2 == 0);
-                            if (valueFormat2 != 0) return 0;
 
-                            STBTT_assert(coverageIndex < pairSetCount);
+                  if (coverageIndex >= pairSetCount) return 0;
-                            STBTT__NOTUSED(pairSetCount);
 
                   needle=glyph2;
                   r=pairValueCount-1;
@@ -2504,12 +2572,15 @@ static stbtt_int32  stbtt__GetGlyphGPOSInfoAdvance(const stbtt_fontinfo *info, i
                         return xAdvance;
                      }
                   }
-                        } break;
+               } else
+                  return 0;
+               break;
+            }
 
             case 2: {
                stbtt_uint16 valueFormat1 = ttUSHORT(table + 4);
                stbtt_uint16 valueFormat2 = ttUSHORT(table + 6);
-
+               if (valueFormat1 == 4 && valueFormat2 == 0) { // Support more formats?
                   stbtt_uint16 classDef1Offset = ttUSHORT(table + 8);
                   stbtt_uint16 classDef2Offset = ttUSHORT(table + 10);
                   int glyph1class = stbtt__GetGlyphClass(table + classDef1Offset, glyph1);
@@ -2517,36 +2588,24 @@ static stbtt_int32  stbtt__GetGlyphGPOSInfoAdvance(const stbtt_fontinfo *info, i
 
                   stbtt_uint16 class1Count = ttUSHORT(table + 12);
                   stbtt_uint16 class2Count = ttUSHORT(table + 14);
-                            STBTT_assert(glyph1class < class1Count);
+                  stbtt_uint8 *class1Records, *class2Records;
-                            STBTT_assert(glyph2class < class2Count);
+                  stbtt_int16 xAdvance;
 
-                            // TODO: Support more formats.
+                  if (glyph1class < 0 || glyph1class >= class1Count) return 0; // malformed
-                            STBTT_GPOS_TODO_assert(valueFormat1 == 4);
+                  if (glyph2class < 0 || glyph2class >= class2Count) return 0; // malformed
-                            if (valueFormat1 != 4) return 0;
-                            STBTT_GPOS_TODO_assert(valueFormat2 == 0);
-                            if (valueFormat2 != 0) return 0;
 
-                            if (glyph1class >= 0 && glyph1class < class1Count && glyph2class >= 0 && glyph2class < class2Count) {
+                  class1Records = table + 16;
-                                stbtt_uint8 *class1Records = table + 16;
+                  class2Records = class1Records + 2 * (glyph1class * class2Count);
-                                stbtt_uint8 *class2Records = class1Records + 2 * (glyph1class * class2Count);
+                  xAdvance = ttSHORT(class2Records + 2 * glyph2class);
-                                stbtt_int16 xAdvance = ttSHORT(class2Records + 2 * glyph2class);
                   return xAdvance;
-                            }
+               } else
-                        } break;
+                  return 0;
-
-                        default: {
-                            // There are no other cases.
-                            STBTT_assert(0);
                break;
-                        } // [DEAR IMGUI] removed ;
             }
-                }
-                break;
-            } // [DEAR IMGUI] removed ;
 
             default:
-                // TODO: Implement other stuff.
+               return 0; // Unsupported position format
-                break;
+         }
       }
    }
 
@@ -2559,8 +2618,7 @@ STBTT_DEF int  stbtt_GetGlyphKernAdvance(const stbtt_fontinfo *info, int g1, int
 
    if (info->gpos)
       xAdvance += stbtt__GetGlyphGPOSInfoAdvance(info, g1, g2);
-
+   else if (info->kern)
-   if (info->kern)
       xAdvance += stbtt__GetGlyphKernInfoAdvance(info, g1, g2);
 
    return xAdvance;
@@ -2621,6 +2679,45 @@ STBTT_DEF void stbtt_FreeShape(const stbtt_fontinfo *info, stbtt_vertex *v)
    STBTT_free(v, info->userdata);
 }
 
+STBTT_DEF stbtt_uint8 *stbtt_FindSVGDoc(const stbtt_fontinfo *info, int gl)
+{
+   int i;
+   stbtt_uint8 *data = info->data;
+   stbtt_uint8 *svg_doc_list = data + stbtt__get_svg((stbtt_fontinfo *) info);
+
+   int numEntries = ttUSHORT(svg_doc_list);
+   stbtt_uint8 *svg_docs = svg_doc_list + 2;
+
+   for(i=0; i<numEntries; i++) {
+      stbtt_uint8 *svg_doc = svg_docs + (12 * i);
+      if ((gl >= ttUSHORT(svg_doc)) && (gl <= ttUSHORT(svg_doc + 2)))
+         return svg_doc;
+   }
+   return 0;
+}
+
+STBTT_DEF int stbtt_GetGlyphSVG(const stbtt_fontinfo *info, int gl, const char **svg)
+{
+   stbtt_uint8 *data = info->data;
+   stbtt_uint8 *svg_doc;
+
+   if (info->svg == 0)
+      return 0;
+
+   svg_doc = stbtt_FindSVGDoc(info, gl);
+   if (svg_doc != NULL) {
+      *svg = (char *) data + info->svg + ttULONG(svg_doc + 4);
+      return ttULONG(svg_doc + 8);
+   } else {
+      return 0;
+   }
+}
+
+STBTT_DEF int stbtt_GetCodepointSVG(const stbtt_fontinfo *info, int unicode_codepoint, const char **svg)
+{
+   return stbtt_GetGlyphSVG(info, stbtt_FindGlyphIndex(info, unicode_codepoint), svg);
+}
+
 //////////////////////////////////////////////////////////////////////////////
 //
 // antialiasing software rasterizer
@@ -2970,6 +3067,23 @@ static void stbtt__handle_clipped_edge(float *scanline, int x, stbtt__active_edg
    }
 }
 
+static float stbtt__sized_trapezoid_area(float height, float top_width, float bottom_width)
+{
+   STBTT_assert(top_width >= 0);
+   STBTT_assert(bottom_width >= 0);
+   return (top_width + bottom_width) / 2.0f * height;
+}
+
+static float stbtt__position_trapezoid_area(float height, float tx0, float tx1, float bx0, float bx1)
+{
+   return stbtt__sized_trapezoid_area(height, tx1 - tx0, bx1 - bx0);
+}
+
+static float stbtt__sized_triangle_area(float height, float width)
+{
+   return height * width / 2;
+}
+
 static void stbtt__fill_active_edges_new(float *scanline, float *scanline_fill, int len, stbtt__active_edge *e, float y_top)
 {
    float y_bottom = y_top+1;
@@ -3024,13 +3138,13 @@ static void stbtt__fill_active_edges_new(float *scanline, float *scanline_fill,
                float height;
                // simple case, only spans one pixel
                int x = (int) x_top;
-               height = sy1 - sy0;
+               height = (sy1 - sy0) * e->direction;
                STBTT_assert(x >= 0 && x < len);
-               scanline[x] += e->direction * (1-((x_top - x) + (x_bottom-x))/2)  * height;
+               scanline[x]      += stbtt__position_trapezoid_area(height, x_top, x+1.0f, x_bottom, x+1.0f);
-               scanline_fill[x] += e->direction * height; // everything right of this pixel is filled
+               scanline_fill[x] += height; // everything right of this pixel is filled
             } else {
                int x,x1,x2;
-               float y_crossing, step, sign, area;
+               float y_crossing, y_final, step, sign, area;
                // covers 2+ pixels
                if (x_top > x_bottom) {
                   // flip scanline vertically; signed area is the same
@@ -3042,32 +3156,80 @@ static void stbtt__fill_active_edges_new(float *scanline, float *scanline_fill,
                   dx = -dx;
                   dy = -dy;
                   t = x0, x0 = xb, xb = t;
-                  // [DEAR IMGUI] Fix static analyzer warning
-                  (void)dx; // [ImGui: fix static analyzer warning]
                }
+               STBTT_assert(dy >= 0);
+               STBTT_assert(dx >= 0);
 
                x1 = (int) x_top;
                x2 = (int) x_bottom;
                // compute intersection with y axis at x1+1
-               y_crossing = (x1+1 - x0) * dy + y_top;
+               y_crossing = y_top + dy * (x1+1 - x0);
+
+               // compute intersection with y axis at x2
+               y_final = y_top + dy * (x2 - x0);
+
+               //           x1    x_top                            x2    x_bottom
+               //     y_top  +------|-----+------------+------------+--------|---+------------+
+               //            |            |            |            |            |            |
+               //            |            |            |            |            |            |
+               //       sy0  |      Txxxxx|............|............|............|............|
+               // y_crossing |            *xxxxx.......|............|............|............|
+               //            |            |     xxxxx..|............|............|............|
+               //            |            |     /-   xx*xxxx........|............|............|
+               //            |            | dy <       |    xxxxxx..|............|............|
+               //   y_final  |            |     \-     |          xx*xxx.........|............|
+               //       sy1  |            |            |            |   xxxxxB...|............|
+               //            |            |            |            |            |            |
+               //            |            |            |            |            |            |
+               //  y_bottom  +------------+------------+------------+------------+------------+
+               //
+               // goal is to measure the area covered by '.' in each pixel
+
+               // if x2 is right at the right edge of x1, y_crossing can blow up, github #1057
+               // @TODO: maybe test against sy1 rather than y_bottom?
+               if (y_crossing > y_bottom)
+                  y_crossing = y_bottom;
 
                sign = e->direction;
-               // area of the rectangle covered from y0..y_crossing
-               area = sign * (y_crossing-sy0);
-               // area of the triangle (x_top,y0), (x+1,y0), (x+1,y_crossing)
-               scanline[x1] += area * (1-((x_top - x1)+(x1+1-x1))/2);
 
-               step = sign * dy;
+               // area of the rectangle covered from sy0..y_crossing
+               area = sign * (y_crossing-sy0);
+
+               // area of the triangle (x_top,sy0), (x1+1,sy0), (x1+1,y_crossing)
+               scanline[x1] += stbtt__sized_triangle_area(area, x1+1 - x_top);
+
+               // check if final y_crossing is blown up; no test case for this
+               if (y_final > y_bottom) {
+                  y_final = y_bottom;
+                  dy = (y_final - y_crossing ) / (x2 - (x1+1)); // if denom=0, y_final = y_crossing, so y_final <= y_bottom
+               }
+
+               // in second pixel, area covered by line segment found in first pixel
+               // is always a rectangle 1 wide * the height of that line segment; this
+               // is exactly what the variable 'area' stores. it also gets a contribution
+               // from the line segment within it. the THIRD pixel will get the first
+               // pixel's rectangle contribution, the second pixel's rectangle contribution,
+               // and its own contribution. the 'own contribution' is the same in every pixel except
+               // the leftmost and rightmost, a trapezoid that slides down in each pixel.
+               // the second pixel's contribution to the third pixel will be the
+               // rectangle 1 wide times the height change in the second pixel, which is dy.
+
+               step = sign * dy * 1; // dy is dy/dx, change in y for every 1 change in x,
+               // which multiplied by 1-pixel-width is how much pixel area changes for each step in x
+               // so the area advances by 'step' every time
+
                for (x = x1+1; x < x2; ++x) {
-                  scanline[x] += area + step/2;
+                  scanline[x] += area + step/2; // area of trapezoid is 1*step/2
                   area += step;
                }
-               y_crossing += dy * (x2 - (x1+1));
+               STBTT_assert(STBTT_fabs(area) <= 1.01f); // accumulated error from area += step unless we round step down
+               STBTT_assert(sy1 > y_final-0.01f);
 
-               STBTT_assert(STBTT_fabs(area) <= 1.01f);
+               // area covered in the last pixel is the rectangle from all the pixels to the left,
-
+               // plus the trapezoid filled by the line segment in this pixel all the way to the right edge
-               scanline[x2] += area + sign * (1-((x2-x2)+(x_bottom-x2))/2) * (sy1-y_crossing);
+               scanline[x2] += area + sign * stbtt__position_trapezoid_area(sy1-y_final, (float) x2, x2+1.0f, x_bottom, x2+1.0f);
 
+               // the rest of the line is filled based on the total height of the line segment in this pixel
                scanline_fill[x2] += sign * (sy1-sy0);
             }
          } else {
@@ -3075,6 +3237,9 @@ static void stbtt__fill_active_edges_new(float *scanline, float *scanline_fill,
             // clipping logic. since this does not match the intended use
             // of this library, we use a different, very slow brute
             // force implementation
+            // note though that this does happen some of the time because
+            // x_top and x_bottom can be extrapolated at the top & bottom of
+            // the shape and actually lie outside the bounding box
             int x;
             for (x=0; x < len; ++x) {
                // cases:
@@ -3989,6 +4154,7 @@ static float stbtt__oversample_shift(int oversample)
 STBTT_DEF int stbtt_PackFontRangesGatherRects(stbtt_pack_context *spc, const stbtt_fontinfo *info, stbtt_pack_range *ranges, int num_ranges, stbrp_rect *rects)
 {
    int i,j,k;
+   int missing_glyph_added = 0;
 
    k=0;
    for (i=0; i < num_ranges; ++i) {
@@ -4000,7 +4166,7 @@ STBTT_DEF int stbtt_PackFontRangesGatherRects(stbtt_pack_context *spc, const stb
          int x0,y0,x1,y1;
          int codepoint = ranges[i].array_of_unicode_codepoints == NULL ? ranges[i].first_unicode_codepoint_in_range + j : ranges[i].array_of_unicode_codepoints[j];
          int glyph = stbtt_FindGlyphIndex(info, codepoint);
-         if (glyph == 0 && spc->skip_missing) {
+         if (glyph == 0 && (spc->skip_missing || missing_glyph_added)) {
             rects[k].w = rects[k].h = 0;
          } else {
             stbtt_GetGlyphBitmapBoxSubpixel(info,glyph,
@@ -4010,6 +4176,8 @@ STBTT_DEF int stbtt_PackFontRangesGatherRects(stbtt_pack_context *spc, const stb
                                             &x0,&y0,&x1,&y1);
             rects[k].w = (stbrp_coord) (x1-x0 + spc->padding + spc->h_oversample-1);
             rects[k].h = (stbrp_coord) (y1-y0 + spc->padding + spc->v_oversample-1);
+            if (glyph == 0)
+               missing_glyph_added = 1;
          }
          ++k;
       }
@@ -4044,7 +4212,7 @@ STBTT_DEF void stbtt_MakeGlyphBitmapSubpixelPrefilter(const stbtt_fontinfo *info
 // rects array must be big enough to accommodate all characters in the given ranges
 STBTT_DEF int stbtt_PackFontRangesRenderIntoRects(stbtt_pack_context *spc, const stbtt_fontinfo *info, stbtt_pack_range *ranges, int num_ranges, stbrp_rect *rects)
 {
-   int i,j,k, return_value = 1;
+   int i,j,k, missing_glyph = -1, return_value = 1;
 
    // save current values
    int old_h_over = spc->h_oversample;
@@ -4109,6 +4277,13 @@ STBTT_DEF int stbtt_PackFontRangesRenderIntoRects(stbtt_pack_context *spc, const
             bc->yoff     =       (float)  y0 * recip_v + sub_y;
             bc->xoff2    =                (x0 + r->w) * recip_h + sub_x;
             bc->yoff2    =                (y0 + r->h) * recip_v + sub_y;
+
+            if (glyph == 0)
+               missing_glyph = j;
+         } else if (spc->skip_missing) {
+            return_value = 0;
+         } else if (r->was_packed && r->w == 0 && r->h == 0 && missing_glyph >= 0) {
+            ranges[i].chardata_for_range[j] = ranges[i].chardata_for_range[missing_glyph];
          } else {
             return_value = 0; // if any fail, report failure
          }
@@ -4132,7 +4307,7 @@ STBTT_DEF void stbtt_PackFontRangesPackRects(stbtt_pack_context *spc, stbrp_rect
 STBTT_DEF int stbtt_PackFontRanges(stbtt_pack_context *spc, const unsigned char *fontdata, int font_index, stbtt_pack_range *ranges, int num_ranges)
 {
    stbtt_fontinfo info;
-   int i,j,n, return_value; // [DEAR IMGUI] removed = 1
+   int i, j, n, return_value; // [DEAR IMGUI] removed = 1;
    //stbrp_context *context = (stbrp_context *) spc->pack_info;
    stbrp_rect    *rects;
 
@@ -4301,15 +4476,14 @@ static int stbtt__compute_crossings_x(float x, float y, int nverts, stbtt_vertex
    float y_frac;
    int winding = 0;
 
-   orig[0] = x;
-   //orig[1] = y; // [DEAR IMGUI] commented double assignment
-
    // make sure y never passes through a vertex of the shape
    y_frac = (float) STBTT_fmod(y, 1.0f);
    if (y_frac < 0.01f)
       y += 0.01f;
    else if (y_frac > 0.99f)
       y -= 0.01f;
+
+   orig[0] = x;
    orig[1] = y;
 
    // test a ray from (-infinity,y) to (x,y)
@@ -4371,7 +4545,7 @@ static float stbtt__cuberoot( float x )
       return  (float) STBTT_pow( x,1.0f/3.0f);
 }
 
-// x^3 + c*x^2 + b*x + a = 0
+// x^3 + a*x^2 + b*x + c = 0
 static int stbtt__solve_cubic(float a, float b, float c, float* r)
 {
    float s = -a / 3;
@@ -4410,12 +4584,7 @@ STBTT_DEF unsigned char * stbtt_GetGlyphSDF(const stbtt_fontinfo *info, float sc
    int w,h;
    unsigned char *data;
 
-   // if one scale is 0, use same scale for both
+   if (scale == 0) return NULL;
-   if (scale_x == 0) scale_x = scale_y;
-   if (scale_y == 0) {
-      if (scale_x == 0) return NULL;  // if both scales are 0, return NULL
-      scale_y = scale_x;
-   }
 
    stbtt_GetGlyphBitmapBoxSubpixel(info, glyph, scale, scale, 0.0f,0.0f, &ix0,&iy0,&ix1,&iy1);
 
@@ -4481,18 +4650,17 @@ STBTT_DEF unsigned char * stbtt_GetGlyphSDF(const stbtt_fontinfo *info, float sc
             for (i=0; i < num_verts; ++i) {
                float x0 = verts[i].x*scale_x, y0 = verts[i].y*scale_y;
 
-               // check against every point here rather than inside line/curve primitives -- @TODO: wrong if multiple 'moves' in a row produce a garbage point, and given culling, probably more efficient to do within line/curve
+               if (verts[i].type == STBTT_vline && precompute[i] != 0.0f) {
-               float dist2 = (x0-sx)*(x0-sx) + (y0-sy)*(y0-sy);
+                  float x1 = verts[i-1].x*scale_x, y1 = verts[i-1].y*scale_y;
+
+                  float dist,dist2 = (x0-sx)*(x0-sx) + (y0-sy)*(y0-sy);
                   if (dist2 < min_dist*min_dist)
                      min_dist = (float) STBTT_sqrt(dist2);
 
-               if (verts[i].type == STBTT_vline) {
-                  float x1 = verts[i-1].x*scale_x, y1 = verts[i-1].y*scale_y;
-
                   // coarse culling against bbox
                   //if (sx > STBTT_min(x0,x1)-min_dist && sx < STBTT_max(x0,x1)+min_dist &&
                   //    sy > STBTT_min(y0,y1)-min_dist && sy < STBTT_max(y0,y1)+min_dist)
-                  float dist = (float) STBTT_fabs((x1-x0)*(y0-sy) - (y1-y0)*(x0-sx)) * precompute[i];
+                  dist = (float) STBTT_fabs((x1-x0)*(y0-sy) - (y1-y0)*(x0-sx)) * precompute[i];
                   STBTT_assert(i != 0);
                   if (dist < min_dist) {
                      // check position along line
@@ -4519,7 +4687,8 @@ STBTT_DEF unsigned char * stbtt_GetGlyphSDF(const stbtt_fontinfo *info, float sc
                      float ax = x1-x0, ay = y1-y0;
                      float bx = x0 - 2*x1 + x2, by = y0 - 2*y1 + y2;
                      float mx = x0 - sx, my = y0 - sy;
-                     float res[3],px,py,t,it;
+                     float res[3] = {0.f,0.f,0.f};
+                     float px,py,t,it,dist2;
                      float a_inv = precompute[i];
                      if (a_inv == 0.0) { // if a_inv is 0, it's 2nd degree so use quadratic formula
                         float a = 3*(ax*bx + ay*by);
@@ -4546,6 +4715,10 @@ STBTT_DEF unsigned char * stbtt_GetGlyphSDF(const stbtt_fontinfo *info, float sc
                         float d = (mx*ax+my*ay) * a_inv;
                         num = stbtt__solve_cubic(b, c, d, res);
                      }
+                     dist2 = (x0-sx)*(x0-sx) + (y0-sy)*(y0-sy);
+                     if (dist2 < min_dist*min_dist)
+                        min_dist = (float) STBTT_sqrt(dist2);
+
                      if (num >= 1 && res[0] >= 0.0f && res[0] <= 1.0f) {
                         t = res[0], it = 1.0f - t;
                         px = it*it*x0 + 2*t*it*x1 + t*t*x2;
@@ -4805,6 +4978,12 @@ STBTT_DEF int stbtt_CompareUTF8toUTF16_bigendian(const char *s1, int len1, const
 
 // FULL VERSION HISTORY
 //
+//   1.25 (2021-07-11) many fixes
+//   1.24 (2020-02-05) fix warning
+//   1.23 (2020-02-02) query SVG data for glyphs; query whole kerning table (but only kern not GPOS)
+//   1.22 (2019-08-11) minimize missing-glyph duplication; fix kerning if both 'GPOS' and 'kern' are defined
+//   1.21 (2019-02-25) fix warning
+//   1.20 (2019-02-07) PackFontRange skips missing codepoints; GetScaleFontVMetrics()
 //   1.19 (2018-02-11) OpenType GPOS kerning (horizontal only), STBTT_fmod
 //   1.18 (2018-01-29) add missing function
 //   1.17 (2017-07-23) make more arguments const; doc fix