For qt backends, dont create a QApplication when the backend is

ddale · ddale · commit 55044b14c5d2 · 2006-08-27T17:25:57.000Z
imported. Do it in show().

svn path=/trunk/matplotlib/; revision=2711
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,3 +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
+
 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_qt.py b/examples/embedding_in_qt.py
@@ -12,14 +12,6 @@
 from qt import *
 
 from matplotlib.numerix import arange, sin, pi
-
-# The QApplication has to be created before backend_qt is imported, otherwise
-# it will create one itself.
-# Note: color-intensive applications may require a different color allocation
-# strategy.
-QApplication.setColorSpec(QApplication.NormalColor)
-app = QApplication(sys.argv)
-
 from matplotlib.backends.backend_qtagg import FigureCanvasQTAgg as FigureCanvas
 from matplotlib.figure import Figure
 
@@ -31,6 +23,10 @@
 progname = os.path.basename(sys.argv[0])
 progversion = "0.1"
 
+# Note: color-intensive applications may require a different color allocation
+# strategy.
+QApplication.setColorSpec(QApplication.NormalColor)
+app = QApplication(sys.argv)
 
 class MyMplCanvas(FigureCanvas):
     """Ultimately, this is a QWidget (as well as a FigureCanvasAgg, etc.)."""
diff --git a/examples/embedding_in_qt4.py b/examples/embedding_in_qt4.py
@@ -13,22 +13,9 @@
 from PyQt4 import QtGui, QtCore
 
 from matplotlib.numerix import arange, sin, pi
-
-# The QApplication has to be created before backend_qt is imported, otherwise
-# it will create one itself.
-# Note: color-intensive applications may require a different color allocation
-# strategy.
-QtGui.QApplication.setColorSpec(QtGui.QApplication.NormalColor)
-qApp = QtGui.QApplication(sys.argv)
-
 from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
 from matplotlib.figure import Figure
 
-# This seems to be what PyQt expects, according to the examples shipped in
-# its distribution.
-TRUE  = 1
-FALSE = 0
-
 progname = os.path.basename(sys.argv[0])
 progversion = "0.1"
 
@@ -44,7 +31,7 @@ def __init__(self, parent=None, width=5, height=4, dpi=100):
         self.compute_initial_figure()
         
         FigureCanvas.__init__(self, self.fig)
-        self.setParent(parent)#, QtCore.QPoint(0, 0))
+        self.setParent(parent)
 
         FigureCanvas.setSizePolicy(self,
                                    QtGui.QSizePolicy.Expanding,
@@ -117,7 +104,7 @@ def __init__(self):
         self.statusBar().showMessage("All hail matplotlib!", 2000)
 
     def fileQuit(self):
-        qApp.exit(0)
+        self.close()
 
     def closeEvent(self, ce):
         self.fileQuit()
@@ -132,13 +119,17 @@ def about(self):
 
 It may be used and modified with no restriction; raw copies as well as
 modified versions may be distributed without limitation."""
-                          % {"prog": progname, "version": progversion})
+% {"prog": progname, "version": progversion})
 
 
 def main():
+    # Note: color-intensive applications may require a different color
+    # allocation strategy.
+    QtGui.QApplication.setColorSpec(QtGui.QApplication.NormalColor)
+    qApp = QtGui.QApplication(sys.argv)
+    
     aw = ApplicationWindow()
     aw.setWindowTitle("%s" % progname)
-##    qApp.setMainWidget(aw)
     aw.show()
     sys.exit(qApp.exec_())
 
diff --git a/lib/matplotlib/backends/backend_qt.py b/lib/matplotlib/backends/backend_qt.py
@@ -49,6 +49,14 @@ def show( mainloop=True ):
         manager.window.show()
         
     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()
@@ -397,10 +405,3 @@ def exception_handler( type, value, tb ):
 
 
 FigureManager = FigureManagerQT
-
-# 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( [" "] )
diff --git a/lib/matplotlib/backends/backend_qt4.py b/lib/matplotlib/backends/backend_qt4.py
@@ -49,6 +49,14 @@ def show( mainloop=True ):
         manager.window.show()
         
     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()
@@ -367,10 +375,3 @@ def exception_handler( type, value, tb ):
 
 
 FigureManager = FigureManagerQT
-
-# 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( [" "] )
