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Merge pull request #2294 from bfroehle/inputhook_qt4_alt...
Bussonnier Matthias -
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1 1 # -*- coding: utf-8 -*-
2 2 """
3 3 Qt4's inputhook support function
4 4
5 5 Author: Christian Boos
6 6 """
7 7
8 8 #-----------------------------------------------------------------------------
9 9 # Copyright (C) 2011 The IPython Development Team
10 10 #
11 11 # Distributed under the terms of the BSD License. The full license is in
12 12 # the file COPYING, distributed as part of this software.
13 13 #-----------------------------------------------------------------------------
14 14
15 15 #-----------------------------------------------------------------------------
16 16 # Imports
17 17 #-----------------------------------------------------------------------------
18 18
19 19 from IPython.core.interactiveshell import InteractiveShell
20 20 from IPython.external.qt_for_kernel import QtCore, QtGui
21 21 from IPython.lib.inputhook import allow_CTRL_C, ignore_CTRL_C, stdin_ready
22 22
23 23 #-----------------------------------------------------------------------------
24 24 # Code
25 25 #-----------------------------------------------------------------------------
26 26
27 27 def create_inputhook_qt4(mgr, app=None):
28 28 """Create an input hook for running the Qt4 application event loop.
29 29
30 30 Parameters
31 31 ----------
32 32 mgr : an InputHookManager
33 33
34 34 app : Qt Application, optional.
35 35 Running application to use. If not given, we probe Qt for an
36 36 existing application object, and create a new one if none is found.
37 37
38 38 Returns
39 39 -------
40 40 A pair consisting of a Qt Application (either the one given or the
41 41 one found or created) and a inputhook.
42 42
43 43 Notes
44 44 -----
45 45 We use a custom input hook instead of PyQt4's default one, as it
46 46 interacts better with the readline packages (issue #481).
47 47
48 48 The inputhook function works in tandem with a 'pre_prompt_hook'
49 49 which automatically restores the hook as an inputhook in case the
50 50 latter has been temporarily disabled after having intercepted a
51 51 KeyboardInterrupt.
52 52 """
53 53
54 54 if app is None:
55 55 app = QtCore.QCoreApplication.instance()
56 56 if app is None:
57 57 app = QtGui.QApplication([" "])
58 58
59 59 # Re-use previously created inputhook if any
60 60 ip = InteractiveShell.instance()
61 61 if hasattr(ip, '_inputhook_qt4'):
62 62 return app, ip._inputhook_qt4
63 63
64 64 # Otherwise create the inputhook_qt4/preprompthook_qt4 pair of
65 65 # hooks (they both share the got_kbdint flag)
66 66
67 67 got_kbdint = [False]
68 68
69 69 def inputhook_qt4():
70 70 """PyOS_InputHook python hook for Qt4.
71 71
72 72 Process pending Qt events and if there's no pending keyboard
73 73 input, spend a short slice of time (50ms) running the Qt event
74 74 loop.
75 75
76 76 As a Python ctypes callback can't raise an exception, we catch
77 77 the KeyboardInterrupt and temporarily deactivate the hook,
78 78 which will let a *second* CTRL+C be processed normally and go
79 79 back to a clean prompt line.
80 80 """
81 81 try:
82 82 allow_CTRL_C()
83 83 app = QtCore.QCoreApplication.instance()
84 84 if not app: # shouldn't happen, but safer if it happens anyway...
85 85 return 0
86 86 app.processEvents(QtCore.QEventLoop.AllEvents, 300)
87 87 if not stdin_ready():
88 # Generally a program would run QCoreApplication::exec()
89 # from main() to enter and process the Qt event loop until
90 # quit() or exit() is called and the program terminates.
91 #
92 # For our input hook integration, we need to repeatedly
93 # enter and process the Qt event loop for only a short
94 # amount of time (say 50ms) to ensure that Python stays
95 # responsive to other user inputs.
96 #
97 # A naive approach would be to repeatedly call
98 # QCoreApplication::exec(), using a timer to quit after a
99 # short amount of time. Unfortunately, QCoreApplication
100 # emits an aboutToQuit signal before stopping, which has
101 # the undesirable effect of closing all modal windows.
102 #
103 # To work around this problem, we instead create a
104 # QEventLoop and call QEventLoop::exec(). Other than
105 # setting some state variables which do not seem to be
106 # used anywhere, the only thing QCoreApplication adds is
107 # the aboutToQuit signal which is precisely what we are
108 # trying to avoid.
88 109 timer = QtCore.QTimer()
89 timer.timeout.connect(app.quit)
110 event_loop = QtCore.QEventLoop()
111 timer.timeout.connect(event_loop.quit)
90 112 while not stdin_ready():
91 113 timer.start(50)
92 app.exec_()
114 event_loop.exec_()
93 115 timer.stop()
94 116 except KeyboardInterrupt:
95 117 ignore_CTRL_C()
96 118 got_kbdint[0] = True
97 119 print("\nKeyboardInterrupt - Ctrl-C again for new prompt")
98 120 mgr.clear_inputhook()
99 121 except: # NO exceptions are allowed to escape from a ctypes callback
100 122 ignore_CTRL_C()
101 123 from traceback import print_exc
102 124 print_exc()
103 125 print("Got exception from inputhook_qt4, unregistering.")
104 126 mgr.clear_inputhook()
105 127 finally:
106 128 allow_CTRL_C()
107 129 return 0
108 130
109 131 def preprompthook_qt4(ishell):
110 132 """'pre_prompt_hook' used to restore the Qt4 input hook
111 133
112 134 (in case the latter was temporarily deactivated after a
113 135 CTRL+C)
114 136 """
115 137 if got_kbdint[0]:
116 138 mgr.set_inputhook(inputhook_qt4)
117 139 got_kbdint[0] = False
118 140
119 141 ip._inputhook_qt4 = inputhook_qt4
120 142 ip.set_hook('pre_prompt_hook', preprompthook_qt4)
121 143
122 144 return app, inputhook_qt4
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