0029225: Visualization - Font_FTFont::AdvanceX() retrieves kerning value for incorrect characters pair

Fixed FT_Get_Kerning misuse within Font_FTFont::AdvanceX()/Font_FTFont::AdvanceY().
Font_FTFont::loadGlyph() has been corrected to not return TRUE
in case if method called with 0 argument second+ time.

src/Font/Font_FTFont.cxx

@@ -35,7 +35,6 @@ Font_FTFont::Font_FTFont (const Handle(Font_FTLibrary)& theFTLib)
   myWidthScaling(1.0),
   myLoadFlags   (FT_LOAD_NO_HINTING | FT_LOAD_TARGET_NORMAL),
   myIsSingleLine(false),
-  myKernAdvance (new FT_Vector()),
   myUChar       (0U)
 {
   if (myFTLib.IsNull())
@@ -51,7 +50,6 @@ Font_FTFont::Font_FTFont (const Handle(Font_FTLibrary)& theFTLib)
 Font_FTFont::~Font_FTFont()
 {
   Release();
-  delete myKernAdvance;
 }
 
 // =======================================================================
@@ -136,7 +134,7 @@ bool Font_FTFont::loadGlyph (const Standard_Utf32Char theUChar)
 {
   if (myUChar == theUChar)
   {
-    return true;
+    return myUChar != 0;
   }
 
   myGlyphImg.Clear();
@@ -239,8 +237,8 @@ float Font_FTFont::LineSpacing() const
 // function : AdvanceX
 // purpose  :
 // =======================================================================
-float Font_FTFont::AdvanceX (const Standard_Utf32Char theUChar,
+float Font_FTFont::AdvanceX (Standard_Utf32Char theUChar,
-                             const Standard_Utf32Char theUCharNext)
+                             Standard_Utf32Char theUCharNext)
 {
   loadGlyph (theUChar);
   return AdvanceX (theUCharNext);
@@ -250,49 +248,65 @@ float Font_FTFont::AdvanceX (const Standard_Utf32Char theUChar,
 // function : AdvanceY
 // purpose  :
 // =======================================================================
-float Font_FTFont::AdvanceY (const Standard_Utf32Char theUChar,
+float Font_FTFont::AdvanceY (Standard_Utf32Char theUChar,
-                             const Standard_Utf32Char theUCharNext)
+                             Standard_Utf32Char theUCharNext)
 {
   loadGlyph (theUChar);
   return AdvanceY (theUCharNext);
 }
 
+bool Font_FTFont::getKerning (FT_Vector& theKern,
+                              Standard_Utf32Char theUCharCurr,
+                              Standard_Utf32Char theUCharNext) const
+{
+  theKern.x = 0;
+  theKern.y = 0;
+  if (theUCharNext != 0 && FT_HAS_KERNING(myFTFace) != 0)
+  {
+    const FT_UInt aCharCurr = FT_Get_Char_Index (myFTFace, theUCharCurr);
+    const FT_UInt aCharNext = FT_Get_Char_Index (myFTFace, theUCharNext);
+    if (aCharCurr == 0 || aCharNext == 0
+     || FT_Get_Kerning (myFTFace, aCharCurr, aCharNext, FT_KERNING_UNFITTED, &theKern) != 0)
+    {
+      theKern.x = 0;
+      theKern.y = 0;
+      return false;
+    }
+    return true;
+  }
+  return false;
+}
+
 // =======================================================================
 // function : AdvanceX
 // purpose  :
 // =======================================================================
-float Font_FTFont::AdvanceX (const Standard_Utf32Char theUCharNext)
+float Font_FTFont::AdvanceX (Standard_Utf32Char theUCharNext) const
 {
   if (myUChar == 0)
   {
     return 0.0f;
   }
 
-  if (FT_HAS_KERNING (myFTFace) == 0 || theUCharNext == 0
+  FT_Vector aKern;
-   || FT_Get_Kerning (myFTFace, myUChar, theUCharNext, FT_KERNING_UNFITTED, myKernAdvance) != 0)
+  getKerning (aKern, myUChar, theUCharNext);
-  {
+  return myWidthScaling * fromFTPoints<float> (myFTFace->glyph->advance.x + aKern.x);
-    return myWidthScaling * fromFTPoints<float> (myFTFace->glyph->advance.x);
-  }
-  return myWidthScaling * fromFTPoints<float> (myKernAdvance->x + myFTFace->glyph->advance.x);
 }
 
 // =======================================================================
 // function : AdvanceY
 // purpose  :
 // =======================================================================
-float Font_FTFont::AdvanceY (const Standard_Utf32Char theUCharNext)
+float Font_FTFont::AdvanceY (Standard_Utf32Char theUCharNext) const
 {
   if (myUChar == 0)
   {
     return 0.0f;
   }
 
-  if (FT_HAS_KERNING (myFTFace) == 0 || theUCharNext == 0
+  FT_Vector aKern;
-   || FT_Get_Kerning (myFTFace, myUChar, theUCharNext, FT_KERNING_UNFITTED, myKernAdvance) != 0)
+  getKerning (aKern, myUChar, theUCharNext);
-  {
+  return fromFTPoints<float> (myFTFace->glyph->advance.y + aKern.y);
-    return fromFTPoints<float> (myFTFace->glyph->advance.y);
-  }
-  return fromFTPoints<float> (myKernAdvance->y + myFTFace->glyph->advance.y);
 }
 
 // =======================================================================

src/Font/Font_FTFont.hxx

@@ -114,23 +114,29 @@ public:
     myWidthScaling = theScaleFactor;
   }
 
-  //! Compute advance to the next character with kerning applied when applicable.
+  //! Compute horizontal advance to the next character with kerning applied when applicable.
   //! Assuming text rendered horizontally.
-  Standard_EXPORT float AdvanceX (const Standard_Utf32Char theUCharNext);
+  //! @param theUCharNext the next character to compute advance from current one
+  Standard_EXPORT float AdvanceX (Standard_Utf32Char theUCharNext) const;
 
-  //! Compute advance to the next character with kerning applied when applicable.
+  //! Compute horizontal advance to the next character with kerning applied when applicable.
   //! Assuming text rendered horizontally.
-  Standard_EXPORT float AdvanceX (const Standard_Utf32Char theUChar,
+  //! @param theUChar     the character to be loaded as current one
-                                  const Standard_Utf32Char theUCharNext);
+  //! @param theUCharNext the next character to compute advance from current one
+  Standard_EXPORT float AdvanceX (Standard_Utf32Char theUChar,
+                                  Standard_Utf32Char theUCharNext);
 
-  //! Compute advance to the next character with kerning applied when applicable.
+  //! Compute vertical advance to the next character with kerning applied when applicable.
   //! Assuming text rendered vertically.
-  Standard_EXPORT float AdvanceY (const Standard_Utf32Char theUCharNext);
+  //! @param theUCharNext the next character to compute advance from current one
+  Standard_EXPORT float AdvanceY (Standard_Utf32Char theUCharNext) const;
 
-  //! Compute advance to the next character with kerning applied when applicable.
+  //! Compute vertical advance to the next character with kerning applied when applicable.
   //! Assuming text rendered vertically.
-  Standard_EXPORT float AdvanceY (const Standard_Utf32Char theUChar,
+  //! @param theUChar     the character to be loaded as current one
-                                  const Standard_Utf32Char theUCharNext);
+  //! @param theUCharNext the next character to compute advance from current one
+  Standard_EXPORT float AdvanceY (Standard_Utf32Char theUChar,
+                                  Standard_Utf32Char theUCharNext);
 
   //! @return glyphs number in this font.
   Standard_EXPORT Standard_Integer GlyphsNumber() const;
@@ -166,6 +172,11 @@ protected:
   //! Load glyph without rendering it.
   Standard_EXPORT bool loadGlyph (const Standard_Utf32Char theUChar);
 
+  //! Wrapper for FT_Get_Kerning - retrieve kerning values.
+  Standard_EXPORT bool getKerning (FT_Vector& theKern,
+                                   Standard_Utf32Char theUCharCurr,
+                                   Standard_Utf32Char theUCharNext) const;
+
 protected:
 
   Handle(Font_FTLibrary) myFTLib;        //!< handle to the FT library object
@@ -177,7 +188,6 @@ protected:
   bool                   myIsSingleLine; //!< single stroke font flag, FALSE by default
 
   Image_PixMap           myGlyphImg;     //!< cached glyph plane
-  FT_Vector*             myKernAdvance;  //!< buffer variable
   Standard_Utf32Char     myUChar;        //!< currently loaded unicode character
 
 public:

tests/3rdparty/fonts/B3

@@ -2,8 +2,7 @@ puts "============"
 puts "OCC24181 Render text as BRep (check alphabet)"
 puts "============"
 puts ""
-pload MODELING
+pload MODELING VISUALIZATION
-pload VISUALIZATION
 
 vfont add [locate_data_file DejaVuSans.ttf] SansFont
 
@@ -18,6 +17,7 @@ asdfghjkl;'
 ASDFGHJKL:"
 zxcvbnm,./
 ZXCVBNM<>?§
+AVATAR Y.
 }
 
 text2brep aBTextN $THE_TEXT -font $THE_FONT_NAME -height $THE_FONT_SIZE -aspect regular -composite off
@@ -26,12 +26,12 @@ checkshape aBTextN
 checkshape aBTextC
 
 ttranslate aBTextC 220 0 0
-vsetdispmode 1
-vtop
-vdisplay aBTextN
-vdisplay aBTextC
 
+vclear
+vinit View1
+vtop
+vdisplay -dispMode 1 aBTextN aBTextC
 vfit
 
 vglinfo
-checkview -screenshot -3d -path ${imagedir}/${test_image}.png
+vdump ${imagedir}/${casename}.png