libsaria: Fix up the audio seek() function

It now seeks forward or backward through a song by dt seconds.

include/libsaria/audio.h

@@ -33,8 +33,9 @@ class Audio
 		bool pause();
 
 		/* Functions related to position in the song */
-		void seek();
+		bool seek(int);
 		bool seek_to(double);
+		bool get_position(gint64 &);
 		bool get_duration(gint64 &);
 };
 

libsaria/audio/progress.cpp

@@ -3,33 +3,51 @@
 
 bool Audio::get_duration(gint64 &duration)
 {
-	GstFormat format;
 	return gst_element_query_duration(GST_ELEMENT(player),
-				   &format,
-				   &duration);
+					  NULL,
+					  &duration);
+}
+
+bool Audio::get_position(gint64 &position)
+{
+	GstFormat fmt = GST_FORMAT_TIME;
+	return gst_element_query_position(GST_ELEMENT(player),
+					  &fmt,
+					  &position);
 }
 
 bool Audio::seek_to(double prcnt)
 {
 	bool ret;
 	gint64 duration;
+
 	ret = get_duration(duration);
-	gst_element_seek_simple(GST_ELEMENT(player),
-				GST_FORMAT_TIME,
-				GST_SEEK_FLAG_FLUSH,
-				duration * prcnt);
+	if (ret == true) {
+		gst_element_seek_simple(GST_ELEMENT(player),
+					GST_FORMAT_TIME,
+					GST_SEEK_FLAG_FLUSH,
+					duration * prcnt);
+	}
 	return ret;
 }
 
-/*
- * Right now I just seek to the beginning of the song.
- * Eventually I should allow the user to seek anywhere.
- */
-void Audio::seek()
+/* Use to seek forward or backward in a song */
+bool Audio::seek(int dt)
 {
-	gst_element_seek_simple(GST_ELEMENT(player),
-				GST_FORMAT_TIME,
-				GST_SEEK_FLAG_FLUSH,
-				// Convert seconds to nano-seconds
-				0 * GST_SECOND);
+	bool ret;
+	gint64 cur_pos;
+	gint64 new_pos;
+
+	ret = get_position(cur_pos);
+	if (ret == true) {
+		/* Convert seconds to nano-seconds */
+		new_pos = cur_pos + (dt * GST_SECOND);
+		if (new_pos < 0)
+			new_pos = 0;
+		gst_element_seek_simple(GST_ELEMENT(player),
+					GST_FORMAT_TIME,
+					GST_SEEK_FLAG_FLUSH,
+					new_pos);
+	}
+	return ret;
 }

libsaria/progress.cpp

@@ -12,7 +12,7 @@ void Libsaria::seek_to(double prcnt)
 
 void Libsaria::seek(int dt)
 {
-	audio.seek();
+	audio.seek(dt);
 }
 
 /*