Rudimentary arithmetic property assignment

git-svn-id: https://mlt.svn.sourceforge.net/svnroot/mlt/trunk/mlt@322 d19143bc-622f-0410-bfdd-b5b2a6649095

diff --git a/src/framework/mlt_properties.c b/src/framework/mlt_properties.c
index cf6c792..895be28 100644 (file)
--- a/src/framework/mlt_properties.c
+++ b/src/framework/mlt_properties.c
@@ -25,6 +25,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <ctype.h>
 
 /* ---------------- // Private Implementation // ---------------- */
 
@@ -286,11 +287,59 @@ int mlt_properties_set( mlt_properties this, char *name, char *value )
        mlt_property property = mlt_properties_fetch( this, name );
 
        // Set it if not NULL
-       if ( property != NULL )
+       if ( property != NULL && ( value == NULL || value[ 0 ] != '@' ) )
        {
                error = mlt_property_set_string( property, value );
                mlt_properties_do_mirror( this, name );
        }
+       else if ( property != NULL && value[ 0 ] == '@' )
+       {
+               int total = 0;
+               int current = 0;
+               char id[ 255 ];
+               char op = '+';
+
+               value ++;
+
+               while ( *value != '\0' )
+               {
+                       int length = strcspn( value, "+-*/" );
+
+                       // Get the identifier
+                       strncpy( id, value, length );
+                       id[ length ] = '\0';
+                       value += length;
+
+                       // Determine the value
+                       if ( isdigit( id[ 0 ] ) )
+                               current = atof( id );
+                       else
+                               current = mlt_properties_get_int( this, id );
+
+                       // Apply the operation
+                       switch( op )
+                       {
+                               case '+':
+                                       total += current;
+                                       break;
+                               case '-':
+                                       total -= current;
+                                       break;
+                               case '*':
+                                       total *= current;
+                                       break;
+                               case '/':
+                                       total /= current;
+                                       break;
+                       }
+
+                       // Get the next op
+                       op = *value != '\0' ? *value ++ : ' ';
+               }
+
+               error = mlt_property_set_int( property, total );
+               mlt_properties_do_mirror( this, name );
+       }
 
        return error;
 }