From 645ab0cfa4ab46e057ab4df74066ab434ad5b90a Mon Sep 17 00:00:00 2001
From: Josh Blum <josh@joshknows.com>
Date: Tue, 6 Oct 2009 22:28:09 -0700
Subject: [PATCH] work on a special connect function that registers a callback

---
 gr-wxgui/src/python/common.py     | 20 ++++++++++++++++++++
 gr-wxgui/src/python/fftsink_gl.py |  5 +++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/gr-wxgui/src/python/common.py b/gr-wxgui/src/python/common.py
index f355fd3c..09ce4471 100644
--- a/gr-wxgui/src/python/common.py
+++ b/gr-wxgui/src/python/common.py
@@ -54,6 +54,26 @@ def bind_to_visible_event(win, callback):
 			win.Bind(wx.EVT_ACTIVATE, handler)
 		win = win.GetParent()
 
+from gnuradio import gr
+
+def special_connect(source, sink, hb, win, size):
+	nulls = [gr.null_sink(size), gr.null_source(size)]
+	def callback(visible, init=False):
+		if not init: hb.lock()
+		if visible:
+			if not init: hb.disconnect(source, nulls[0])
+			if not init: hb.disconnect(nulls[1], sink)
+			hb.connect(source, sink)
+			#hb.connect(nulls[1], nulls[0])
+		else:
+			if not init: hb.disconnect(source, sink)
+			#if not init: hb.disconnect(nulls[1], nulls[0])
+			hb.connect(source, nulls[0])
+			hb.connect(nulls[1], sink)
+		if not init: hb.unlock()
+	callback(False, init=True) #initially connect
+	bind_to_visible_event(win, callback)
+
 #A macro to apply an index to a key
 index_key = lambda key, i: "%s_%d"%(key, i+1)
 
diff --git a/gr-wxgui/src/python/fftsink_gl.py b/gr-wxgui/src/python/fftsink_gl.py
index 3f0a93fc..4edb11b4 100644
--- a/gr-wxgui/src/python/fftsink_gl.py
+++ b/gr-wxgui/src/python/fftsink_gl.py
@@ -73,8 +73,6 @@ class _fft_sink_base(gr.hier_block2):
 		)
 		msgq = gr.msg_queue(2)
 		sink = gr.message_sink(gr.sizeof_float*fft_size, msgq, True)
-		#connect
-		self.connect(self, fft, sink)
 		#controller
 		self.controller = pubsub()
 		self.controller.subscribe(AVERAGE_KEY, fft.set_average)
@@ -106,6 +104,9 @@ class _fft_sink_base(gr.hier_block2):
 		common.register_access_methods(self, self.win)
 		setattr(self.win, 'set_baseband_freq', getattr(self, 'set_baseband_freq')) #BACKWARDS
 		setattr(self.win, 'set_peak_hold', getattr(self, 'set_peak_hold')) #BACKWARDS
+		#connect
+		common.special_connect(self, fft, hb=self, win=self.win, size=self._item_size)
+		self.connect(fft, sink)
 
 class fft_sink_f(_fft_sink_base):
 	_fft_chain = blks2.logpwrfft_f
-- 
2.30.2