pixbuf: let begin property be passed as a query string parameter

src/modules/gtk2/producer_pixbuf.c

@@ -22,6 +22,7 @@
 #include <framework/mlt_frame.h>
 #include <framework/mlt_cache.h>
 #include <framework/mlt_log.h>
+#include <framework/mlt_tokeniser.h>
 #include <gdk-pixbuf/gdk-pixbuf.h>
 
 #include "config.h"
@@ -155,7 +156,7 @@ static int load_svg( producer_pixbuf self, mlt_properties properties, const char
 	return result;
 }
 
-static int load_sequence( producer_pixbuf self, mlt_properties properties, const char *filename )
+static int load_sequence_sprintf( producer_pixbuf self, mlt_properties properties, const char *filename )
 {
 	int result = 0;
 
@@ -193,11 +194,12 @@ static int load_sequence( producer_pixbuf self, mlt_properties properties, const
 	return result;
 }
 
-static int load_sequence2( producer_pixbuf self, mlt_properties properties, const char *filename )
+static int load_sequence_deprecated( producer_pixbuf self, mlt_properties properties, const char *filename )
 {
 	int result = 0;
 	const char *start;
 
+	// This approach is deprecated in favor of the begin querystring parameter.
 	// Obtain filenames with pattern containing a begin value, e.g. foo%1234d.png
 	if ( ( start = strchr( filename, '%' ) ) )
 	{
@@ -213,13 +215,33 @@ static int load_sequence2( producer_pixbuf self, mlt_properties properties, cons
 			s = calloc( 1, strlen( filename ) );
 			strncpy( s, filename, start - filename );
 			sprintf( s + ( start - filename ), ".%d%s", n, end );
-			result = load_sequence( self, properties, s );
+			result = load_sequence_sprintf( self, properties, s );
 			free( s );
 		}
 	}
 	return result;
 }
 
+static int load_sequence_querystring( producer_pixbuf self, mlt_properties properties, const char *filename )
+{
+	int result = 0;
+
+	// Obtain filenames with pattern and begin value in query string
+	if ( strchr( filename, '%' ) && strchr( filename, '?' ) && strstr( filename, "begin=" ) )
+	{
+		// Split filename into pattern and query string
+		char *s = strdup( filename );
+		char *querystring = strrchr( s, '?' );
+		*querystring++ = '\0';
+		mlt_properties_set( properties, "begin", strstr( querystring, "begin=" ) + 6 );
+		// Coerce to an int value so serialization does not have any extra query string cruft
+		mlt_properties_set_int( properties, "begin", mlt_properties_get_int( properties, "begin" ) );
+		result = load_sequence_sprintf( self, properties, s );
+		free( s );
+	}
+	return result;
+}
+
 static int load_folder( producer_pixbuf self, mlt_properties properties, const char *filename )
 {
 	int result = 0;
@@ -248,8 +270,9 @@ static void load_filenames( producer_pixbuf self, mlt_properties properties )
 	self->filenames = mlt_properties_new( );
 
 	if (!load_svg( self, properties, filename ) &&
-		!load_sequence( self, properties, filename ) &&
-		!load_sequence2( self, properties, filename ) &&
+		!load_sequence_querystring( self, properties, filename ) &&
+		!load_sequence_sprintf( self, properties, filename ) &&
+		!load_sequence_deprecated( self, properties, filename ) &&
 		!load_folder( self, properties, filename ) )
 	{
 		mlt_properties_set( self->filenames, "0", filename );

src/modules/gtk2/producer_pixbuf.yml

@@ -28,9 +28,11 @@ parameters:
         
         If "%" in filename, the filename is used with sprintf to generate a
         filename from a counter for multi-file/flipbook animation. The file 
-        sequence ends when numeric discontinuity >100. If the file sequence
-        does not begin with the count of 100, you can also embed the number
-        of the first image between the "%" and a "d", "i", or "u".
+        sequence ends when numeric discontinuity >100.
+        
+        If the file sequence does not begin within the count of 100,
+        you can pass the begin property like a query string paramter, for
+        example: anim-%04d.png?begin=1000.
         
         If filename contains "/.all.", suffix with an extension to load all 
         pictures with matching extension from a directory.