Gerbview: accept any structured comment as X2 attribute.

A structured comment is a comment line starting by "G04 #@! " and in fact containing
a X2 attribute. It is used to create Gerber files contianing X2 metadata, but compatible
with X1 file format

gerbview/gerber_file_image.h

@@ -298,11 +298,20 @@ public:
 
     /**
      * Function ExecuteRS274XCommand
-     * executes 1 command
+     * executes a RS274X command
      */
     bool ExecuteRS274XCommand( int aCommand, char* aBuff,
                                unsigned int aBuffSize, char*& aText );
 
+    /**
+     * reads two bytes of data and assembles them into an int with the first
+     * byte in the sequence put into the most significant part of a 16 bit value
+     * to build a RS274X command identifier.
+     * @param text A reference to a pointer to read bytes from and to advance as
+     *             they are read.
+     * @return a RS274X command identifier.
+     */
+    int ReadXCommandID( char*& text );
 
     /**
      * Function ReadApertureMacro

gerbview/readgerb.cpp

@@ -83,6 +83,7 @@ bool GERBVIEW_FRAME::Read_GERBER_File( const wxString& GERBER_FullFileName )
     }
 
     auto canvas = GetGalCanvas();
+
     if( canvas )
     {
         auto view = canvas->GetView();

gerbview/rs274d.cpp

@@ -42,7 +42,7 @@
  * G01 linear interpolation (right trace)
  * G02, G20, G21 Circular interpolation, meaning trig <0 (clockwise)
  * G03, G30, G31 Circular interpolation, meaning trigo> 0 (counterclockwise)
- * G04 = comment. Since Sept 2014, file attributes can be found here
+ * G04 = comment. Since Sept 2014, file attributes and other X2 attributes can be found here
  *       if the line starts by G04 #@!
  * G06 parabolic interpolation
  * G07 Cubic Interpolation
@@ -478,22 +478,32 @@ bool GERBER_FILE_IMAGE::Execute_G_Command( char*& text, int G_command )
         break;
 
     case GC_COMMENT:
-        // Skip comment, but only if the line does not start by "G04 #@! TF"
-        // which is a metadata
-        if( strncmp( text, " #@! TF", 7 ) == 0 )
+        // Skip comment, but only if the line does not start by "G04 #@! "
+        // which is a metadata, i.e. a X2 command inside the comment.
+        // this comment is called a "structured comment"
+        if( strncmp( text, " #@! ", 5 ) == 0 )
         {
-            text += 7;
-            X2_ATTRIBUTE dummy;
-            dummy.ParseAttribCmd( m_Current_File, NULL, 0, text, m_LineNum );
-            if( dummy.IsFileFunction() )
+            text += 5;
+            // The string starting at text is the same as the X2 attribute,
+            // but a X2 attribute ends by '%'. So we build the X2 attribute string
+            std::string x2buf;
+
+            while( *text && (*text != '*') )
             {
-                delete m_FileFunction;
-                m_FileFunction = new X2_ATTRIBUTE_FILEFUNCTION( dummy );
+                x2buf += *text;
+                text++;
             }
+            // add the end of X2 attribute string
+            x2buf += "*%";
+            x2buf += '\0';
+
+            char* cptr = (char*)x2buf.data();
+            int code_command = ReadXCommandID( cptr );
+            ExecuteRS274XCommand( code_command, NULL, 0, cptr );
         }
 
-        while ( *text && (*text != '*') )
-                    text++;
+        while( *text && (*text != '*') )
+            text++;
         break;
 
     case GC_LINEAR_INTERPOL_10X:

gerbview/rs274x.cpp

@@ -111,17 +111,11 @@ enum RS274X_PARAMETERS {
 };
 
 
-/**
- * Function ReadXCommand
- * reads in two bytes of data and assembles them into an int with the first
- * byte in the sequence put into the most significant part of a 16 bit value
- * and the second byte put into the least significant part of the 16 bit value.
- * @param text A reference to a pointer to read bytes from and to advance as
- *             they are read.
- * @return int - with 16 bits of data in the ls bits, upper bits zeroed.
- */
-static int ReadXCommand( char*& text )
+int GERBER_FILE_IMAGE::ReadXCommandID( char*& text )
 {
+    /* reads  two bytes of data and assembles them into an int with the first
+     * byte in the sequence put into the most significant part of a 16 bit value
+     */
     int result;
     int currbyte;
 
@@ -218,7 +212,7 @@ bool GERBER_FILE_IMAGE::ReadRS274XCommand( char *aBuff, unsigned int aBuffSize,
                 break;
 
             default:
-                code_command = ReadXCommand( aText );
+                code_command = ReadXCommandID( aText );
                 ok = ExecuteRS274XCommand( code_command, aBuff, aBuffSize, aText );
                 if( !ok )
                     goto exit;
@@ -403,7 +397,7 @@ bool GERBER_FILE_IMAGE::ExecuteRS274XCommand( int aCommand, char* aBuff,
         break;
 
     case MODE_OF_UNITS:
-        code = ReadXCommand( aText );
+        code = ReadXCommandID( aText );
         if( code == INCH )
             m_GerbMetric = false;
         else if( code == MILLIMETER )
@@ -433,7 +427,7 @@ bool GERBER_FILE_IMAGE::ExecuteRS274XCommand( int aCommand, char* aBuff,
      }
         break;
 
-    case APERTURE_ATTRIBUTE:    // Command %TA ... Not yet supported
+    case APERTURE_ATTRIBUTE:    // Command %TA
         {
         X2_ATTRIBUTE dummy;
         dummy.ParseAttribCmd( m_Current_File, aBuff, aBuffSize, aText, m_LineNum );