added signalproxy class

SignalProxy.py

+# -*- coding: utf-8 -*-
+from PyQt4 import QtCore
+from ptime import time
+
+def proxyConnect(source, signal, slot, delay=0.3):
+    """Connect a signal to a slot with delay. Returns the SignalProxy
+    object that was created. Be sure to store this object so it is not
+    garbage-collected immediately."""
+    sp = SignalProxy(source, signal, delay)
+    sp.connect(sp, signal, slot)
+    return sp
+
+class SignalProxy(QtCore.QObject):
+    """Object which collects rapid-fire signals and condenses them
+    into a single signal. Used, for example, to prevent a SpinBox
+    from generating multiple signals when the mouse wheel is rolled
+    over it."""
+    
+    def __init__(self, source, signal, delay=0.3):
+        QtCore.QObject.__init__(self)
+        source.connect(source, signal, self.signal)
+        self.delay = delay
+        self.waitUntil = 0
+        self.args = None
+        self.timers = 0
+        self.signal = signal
+        
+    def setDelay(self, delay):
+        self.delay = delay
+        
+    def flush(self):
+        """If there is a signal queued up, send it now."""
+        if self.args is None:
+            return False
+        self.emit(self.signal, *self.args)
+        self.args = None
+        return True
+        
+        
+    def signal(self, *args):
+        """Received signal, queue to be forwarded later."""
+        self.waitUntil = time() + self.delay
+        self.args = args
+        self.timers += 1
+        QtCore.QTimer.singleShot((self.delay*1000)+1, self.tryEmit)
+        
+    def tryEmit(self):
+        """Emit signal if it has been long enougn since receiving the last signal."""
+        if self.args is None:
+            return False
+        self.timers -= 1
+        t = time()
+        if t >= self.waitUntil:
+            return self.flush()
+        else:
+            if self.timers == 0:
+                self.timers += 1
+                QtCore.QTimer.singleShot((self.waitUntil - t) * 1000, self.tryEmit)
+        return True
+                
+        
+    
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