moved qApp creation from show() to FigureCanvasQt.__init__()

ddale · ddale · commit 6e63f03ff510 · 2006-08-27T19:43:46.000Z
svn path=/trunk/matplotlib/; revision=2712
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,6 +1,7 @@
 2006-08-27 qt backends: don't create a QApplication when backend is 
-           imported, do it in show(). Simplifies embedding mpl in qt 
-           applications. Updated embedding_in_qt* examples - DSD
+           imported, do it when the FigureCanvasQt is created. Simplifies 
+           applications where mpl is embedded in qt. Updated 
+           embedding_in_qt* examples - DSD
 
 2006-08-27 mahtext2.py: Now the fonts are searched in the OS font dir and
            in the mpl-data dir. Also env is not a dict anymore. - ES
diff --git a/examples/embedding_in_qt4.py b/examples/embedding_in_qt4.py
@@ -131,7 +131,8 @@ def main():
     aw = ApplicationWindow()
     aw.setWindowTitle("%s" % progname)
     aw.show()
-    sys.exit(qApp.exec_())
+#    sys.exit(qApp.exec_())
+    qApp.exec_()
 
 
 if __name__ == "__main__": main()
diff --git a/lib/matplotlib/backends/backend_qt.py b/lib/matplotlib/backends/backend_qt.py
@@ -40,6 +40,17 @@ def draw_if_interactive():
         if figManager != None:
             figManager.canvas.draw()
 
+def _create_qApp():
+    """
+    Only one qApp can exist at a time, so check before creating one
+    """
+    if qt.QApplication.startingUp():
+        if DEBUG: print "Starting up QApplication"
+        global qApp
+        qApp = qt.QApplication( [" "] )
+        qt.QObject.connect( qApp, qt.SIGNAL( "lastWindowClosed()" ),
+                            qApp, qt.SLOT( "quit()" ) )
+
 def show( mainloop=True ):
     """
     Show all the figures and enter the qt main loop
@@ -50,30 +61,21 @@ def show( mainloop=True ):
         
     if DEBUG: print 'Inside show'
 
-    # We need one and only one QApplication before we can build any Qt widgets
-    # Detect if a QApplication exists.
-    createQApp = qt.QApplication.startingUp()
-    if createQApp:
-        if DEBUG: print "Starting up QApplication"
-        qtapplication = qt.QApplication( [" "] )
-
     figManager =  Gcf.get_active()
     if figManager != None:
         figManager.canvas.draw()
         #if ( createQApp ):
-        #   qtapplication.setMainWidget( figManager.canvas )
+        #   qApp.setMainWidget( figManager.canvas )
 
-    if mainloop and createQApp:
-        qt.QObject.connect( qtapplication, qt.SIGNAL( "lastWindowClosed()" ),
-                            qtapplication, qt.SLOT( "quit()" ) )
-        qtapplication.exec_loop()    
+    if mainloop:
+        qt.qApp.exec_loop()
 
 
 def new_figure_manager( num, *args, **kwargs ):
     """
     Create a new figure manager instance
     """
-    FigureClass = kwargs.pop('FigureClass', Figure)    
+    FigureClass = kwargs.pop('FigureClass', Figure)
     thisFig = FigureClass( *args, **kwargs )
     canvas = FigureCanvasQT( thisFig )
     manager = FigureManagerQT( canvas, num )
@@ -89,6 +91,8 @@ class FigureCanvasQT( qt.QWidget, FigureCanvasBase ):
     buttond = {1:1, 2:3, 4:2}
     def __init__( self, figure ):
         if DEBUG: print 'FigureCanvasQt: ', figure
+        _create_qApp()
+        
         qt.QWidget.__init__( self, None, "QWidget figure" )
         FigureCanvasBase.__init__( self, figure )
         self.figure = figure
diff --git a/lib/matplotlib/backends/backend_qt4.py b/lib/matplotlib/backends/backend_qt4.py
@@ -40,6 +40,17 @@ def draw_if_interactive():
         if figManager != None:
             figManager.canvas.draw()
 
+def _create_qApp():
+    """
+    Only one qApp can exist at a time, so check before creating one.
+    """
+    if QtGui.QApplication.startingUp():
+        if DEBUG: print "Starting up QApplication"
+        global qApp
+        qApp = QtGui.QApplication( [" "] )
+        QtCore.QObject.connect( qApp, QtCore.SIGNAL( "lastWindowClosed()" ),
+                            qApp, QtCore.SLOT( "quit()" ) )
+
 def show( mainloop=True ):
     """
     Show all the figures and enter the qt main loop
@@ -50,23 +61,14 @@ def show( mainloop=True ):
         
     if DEBUG: print 'Inside show'
 
-    # We need one and only one QApplication before we can build any Qt widgets
-    # Detect if a QApplication exists.
-    createQApp = QtGui.QApplication.startingUp()
-    if createQApp:
-        if DEBUG: print "Starting up QApplication"
-        qtapplication = QtGui.QApplication( [" "] )
-
     figManager =  Gcf.get_active()
     if figManager != None:
         figManager.canvas.draw()
         #if ( createQApp ):
         #   qtapplication.setMainWidget( figManager.canvas )
 
-    if mainloop and createQApp:
-        QtCore.QObject.connect( qtapplication, QtCore.SIGNAL( "lastWindowClosed()" ),
-                            qtapplication, QtCore.SLOT( "quit()" ) )
-        qtapplication.exec_()
+    if mainloop:
+        qApp.exec_()
 
 
 def new_figure_manager( num, *args, **kwargs ):
@@ -88,6 +90,8 @@ class FigureCanvasQT( QtGui.QWidget, FigureCanvasBase ):
     buttond = {1:1, 2:3, 4:2}
     def __init__( self, figure ):
         if DEBUG: print 'FigureCanvasQt: ', figure
+        _create_qApp()
+
         QtGui.QWidget.__init__( self )
         FigureCanvasBase.__init__( self, figure )
         self.figure = figure
