Gerber files: update unicode coding to the 2019 06 Gerber specifications.

In gbr files, not allowed chars are coded using a 16 bit (4 hexa digits)
unicode sequence.
Previously, it was \XXXX and now is \uXXXX escape sequence.

Changes from master branch.

common/gbr_metadata.cpp

@@ -268,33 +268,78 @@ std::string GBR_APERTURE_METADATA::FormatAttribute( GBR_APERTURE_ATTRIB aAttribu
     return full_attribute_string;
 }
 
+
+// Helper function to convert a ascii hex char to its integer value
+// If the char is not a hexa char, return -1
+int char2Hex( unsigned aCode )
+{
+    if( aCode >= '0' && aCode <= '9' )
+        return aCode - '0';
+
+    if( aCode >= 'A' && aCode <= 'F' )
+        return aCode - 'A' + 10;
+
+    if( aCode >= 'a' && aCode <= 'f' )
+        return aCode - 'a' + 10;
+
+    return -1;
+}
+
+
 wxString FormatStringFromGerber( const wxString& aString )
 {
     // make the inverse conversion of formatStringToGerber()
     // It converts a "normalized" gerber string and convert it to a 16 bits sequence unicode
     // and return a wxString (unicode 16) from the gerber string
+    // Note the initial gerber string can already contain unicode chars.
     wxString txt;
 
-    for( unsigned ii = 0; ii < aString.Length(); ++ii )
+    unsigned count = aString.Length();
+
+    for( unsigned ii = 0; ii < count; ++ii )
     {
         unsigned code = aString[ii];
 
-        if( code == '\\' )
+        if( code == '\\' && ii < count-5 && aString[ii+1] == 'u' )
         {
-            // Convert 4 hexadecimal digits to a 16 bit unicode
+            // Note the latest Gerber X2 spec (2019 06) uses \uXXXX to encode
+            // the unicode XXXX hexadecimal value
+            // If 4 chars next to 'u' are hexadecimal chars,
+            // convert these 4 hexadecimal digits to a 16 bit unicode
             // (Gerber allows only 4 hexadecimal digits)
+            // If an error occurs, the escape sequence is not translated,
+            // and used "as this"
             long value = 0;
+            bool error = false;
 
             for( int jj = 0; jj < 4; jj++ )
             {
                 value <<= 4;
-                code = aString[++ii];
+                code = aString[ii+jj+2];
-                // Very basic conversion, but it expects a valid gerber file
+
-                int hexa = (code <= '9' ? code - '0' : code - 'A' + 10) & 0xF;
+                int hexa = char2Hex( code );
+
+                if( hexa >= 0 )
                     value += hexa;
+                else
+                {
+                    error = true;
+                    break;
+                }
             }
 
+            if( !error )
+            {
+                if( value >= ' ' )  // Is a valid wxChar ?
                     txt.Append( wxChar( value ) );
+
+                ii += 5;
+            }
+            else
+            {
+                txt.Append( aString[ii] );
+                continue;
+            }
         }
         else
             txt.Append( aString[ii] );
@@ -334,12 +379,10 @@ std::string formatStringToGerber( const wxString& aString )
 
         if( convert || code > 0x7F )
         {
-            txt += '\\';
-
             // Convert code to 4 hexadecimal digit
             // (Gerber allows only 4 hexadecimal digit)
             char hexa[32];
-            sprintf( hexa,"%4.4X", code & 0xFFFF);
+            sprintf( hexa,"\\u%4.4X", code & 0xFFFF);
             txt += hexa;
         }
         else

gerbview/rs274x.cpp

@@ -34,6 +34,7 @@
 #include <gerbview.h>
 #include <gerber_file_image.h>
 #include <X2_gerber_attributes.h>
+#include <gbr_metadata.h>
 
 extern int ReadInt( char*& text, bool aSkipSeparator = true );
 extern double ReadDouble( char*& text, bool aSkipSeparator = true );
@@ -138,50 +139,6 @@ int GERBER_FILE_IMAGE::ReadXCommandID( char*& text )
     return result;
 }
 
-/**
- * Convert a string read from a gerber file to an unicode string
- * Usual chars (ASCII7 values) are the only values allowed in Gerber files,
- * and are just copied.
- * However Gerber format allows using non ASCII7 values by coding them in a
- * sequence of 4 hexadecimal chars (16 bits hexadecimal value)
- * Hexadecimal coded values ("\hhhh") are converted to
- * the unicode char value
- */
-static const wxString fromGerberString( const wxString& aGbrString )
-{
-    wxString text;
-
-    for( unsigned ii = 0; ii < aGbrString.size(); ++ii )
-    {
-        if( aGbrString[ii] == '\\' )
-        {
-            unsigned value = 0;
-
-            for( int jj = 0; jj < 4; jj++ )
-            {   // Convert 4 hexa digits to binary value:
-                ii++;
-                value <<= 4;
-                int digit = aGbrString[ii];
-
-                if( digit >= '0' && digit <= '9' )
-                    digit -= '0';
-                else if( digit >= 'A' && digit <= 'F' )
-                    digit -= 'A' - 10;
-                else if( digit >= 'a' && digit <= 'f' )
-                    digit -= 'a' - 10;
-                else digit = 0;
-
-                value += digit & 0xF;
-            }
-
-            text.Append( wxUniChar( value ) );
-        }
-        else
-            text.Append( aGbrString[ii] );
-    }
-
-    return text;
-}
 
 bool GERBER_FILE_IMAGE::ReadRS274XCommand( char *aBuff, unsigned int aBuffSize, char*& aText )
 {
@@ -451,18 +408,18 @@ bool GERBER_FILE_IMAGE::ExecuteRS274XCommand( int aCommand, char* aBuff,
         if( dummy.GetAttribute() == ".N" )
         {
             m_NetAttributeDict.m_NetAttribType |= GBR_NETLIST_METADATA::GBR_NETINFO_NET;
-            m_NetAttributeDict.m_Netname = fromGerberString( dummy.GetPrm( 1 ) );
+            m_NetAttributeDict.m_Netname = FormatStringFromGerber( dummy.GetPrm( 1 ) );
         }
         else if( dummy.GetAttribute() == ".C" )
         {
             m_NetAttributeDict.m_NetAttribType |= GBR_NETLIST_METADATA::GBR_NETINFO_CMP;
-            m_NetAttributeDict.m_Cmpref = fromGerberString( dummy.GetPrm( 1 ) );
+            m_NetAttributeDict.m_Cmpref = FormatStringFromGerber( dummy.GetPrm( 1 ) );
         }
         else if( dummy.GetAttribute() == ".P" )
         {
             m_NetAttributeDict.m_NetAttribType |= GBR_NETLIST_METADATA::GBR_NETINFO_PAD;
-            m_NetAttributeDict.m_Cmpref = fromGerberString( dummy.GetPrm( 1 ) );
+            m_NetAttributeDict.m_Cmpref = FormatStringFromGerber( dummy.GetPrm( 1 ) );
-            m_NetAttributeDict.m_Padname = fromGerberString( dummy.GetPrm( 2 ) );
+            m_NetAttributeDict.m_Padname = FormatStringFromGerber( dummy.GetPrm( 2 ) );
         }
         }
         break;