From 24fa5b78c0f9e963a899c2e0c94f8f61be6428f8 2016-01-18 14:47:22
From: Thomas Kluyver <thomas@kluyver.me.uk>
Date: 2016-01-18 14:47:22
Subject: [PATCH] Add GLUT input hook

---

diff --git a/IPython/terminal/pt_inputhooks/glut.py b/IPython/terminal/pt_inputhooks/glut.py
new file mode 100644
index 0000000..f336e68
--- /dev/null
+++ b/IPython/terminal/pt_inputhooks/glut.py
@@ -0,0 +1,141 @@
+"""GLUT Input hook for interactive use with prompt_toolkit
+"""
+from __future__ import print_function
+
+
+# GLUT is quite an old library and it is difficult to ensure proper
+# integration within IPython since original GLUT does not allow to handle
+# events one by one. Instead, it requires for the mainloop to be entered
+# and never returned (there is not even a function to exit he
+# mainloop). Fortunately, there are alternatives such as freeglut
+# (available for linux and windows) and the OSX implementation gives
+# access to a glutCheckLoop() function that blocks itself until a new
+# event is received. This means we have to setup the idle callback to
+# ensure we got at least one event that will unblock the function.
+#
+# Furthermore, it is not possible to install these handlers without a window
+# being first created. We choose to make this window invisible. This means that
+# display mode options are set at this level and user won't be able to change
+# them later without modifying the code. This should probably be made available
+# via IPython options system.
+
+import sys
+import time
+import signal
+import OpenGL.GLUT as glut
+import OpenGL.platform as platform
+from timeit import default_timer as clock
+
+# Frame per second : 60
+# Should probably be an IPython option
+glut_fps = 60
+
+# Display mode : double buffeed + rgba + depth
+# Should probably be an IPython option
+glut_display_mode = (glut.GLUT_DOUBLE |
+                     glut.GLUT_RGBA   |
+                     glut.GLUT_DEPTH)
+
+glutMainLoopEvent = None
+if sys.platform == 'darwin':
+    try:
+        glutCheckLoop = platform.createBaseFunction(
+            'glutCheckLoop', dll=platform.GLUT, resultType=None,
+            argTypes=[],
+            doc='glutCheckLoop(  ) -> None',
+            argNames=(),
+            )
+    except AttributeError:
+        raise RuntimeError(
+            '''Your glut implementation does not allow interactive sessions'''
+            '''Consider installing freeglut.''')
+    glutMainLoopEvent = glutCheckLoop
+elif glut.HAVE_FREEGLUT:
+    glutMainLoopEvent = glut.glutMainLoopEvent
+else:
+    raise RuntimeError(
+        '''Your glut implementation does not allow interactive sessions. '''
+        '''Consider installing freeglut.''')
+
+
+def glut_display():
+    # Dummy display function
+    pass
+
+def glut_idle():
+    # Dummy idle function
+    pass
+
+def glut_close():
+    # Close function only hides the current window
+    glut.glutHideWindow()
+    glutMainLoopEvent()
+
+def glut_int_handler(signum, frame):
+    # Catch sigint and print the defaultipyt   message
+    signal.signal(signal.SIGINT, signal.default_int_handler)
+    print('\nKeyboardInterrupt')
+    # Need to reprint the prompt at this stage
+
+# Initialisation code
+glut.glutInit( sys.argv )
+glut.glutInitDisplayMode( glut_display_mode )
+# This is specific to freeglut
+if bool(glut.glutSetOption):
+    glut.glutSetOption( glut.GLUT_ACTION_ON_WINDOW_CLOSE,
+                        glut.GLUT_ACTION_GLUTMAINLOOP_RETURNS )
+glut.glutCreateWindow( b'ipython' )
+glut.glutReshapeWindow( 1, 1 )
+glut.glutHideWindow( )
+glut.glutWMCloseFunc( glut_close )
+glut.glutDisplayFunc( glut_display )
+glut.glutIdleFunc( glut_idle )
+
+
+def inputhook(context):
+    """Run the pyglet event loop by processing pending events only.
+
+    This keeps processing pending events until stdin is ready.  After
+    processing all pending events, a call to time.sleep is inserted.  This is
+    needed, otherwise, CPU usage is at 100%.  This sleep time should be tuned
+    though for best performance.
+    """
+    # We need to protect against a user pressing Control-C when IPython is
+    # idle and this is running. We trap KeyboardInterrupt and pass.
+
+    signal.signal(signal.SIGINT, glut_int_handler)
+
+    try:
+        t = clock()
+
+        # Make sure the default window is set after a window has been closed
+        if glut.glutGetWindow() == 0:
+            glut.glutSetWindow( 1 )
+            glutMainLoopEvent()
+            return 0
+
+        while not context.input_is_ready():
+            glutMainLoopEvent()
+            # We need to sleep at this point to keep the idle CPU load
+            # low.  However, if sleep to long, GUI response is poor.  As
+            # a compromise, we watch how often GUI events are being processed
+            # and switch between a short and long sleep time.  Here are some
+            # stats useful in helping to tune this.
+            # time    CPU load
+            # 0.001   13%
+            # 0.005   3%
+            # 0.01    1.5%
+            # 0.05    0.5%
+            used_time = clock() - t
+            if used_time > 10.0:
+                # print 'Sleep for 1 s'  # dbg
+                time.sleep(1.0)
+            elif used_time > 0.1:
+                # Few GUI events coming in, so we can sleep longer
+                # print 'Sleep for 0.05 s'  # dbg
+                time.sleep(0.05)
+            else:
+                # Many GUI events coming in, so sleep only very little
+                time.sleep(0.001)
+    except KeyboardInterrupt:
+        pass
diff --git a/examples/IPython Kernel/gui/gui-glut.py b/examples/IPython Kernel/gui/gui-glut.py
index 2643b3e..573690b 100755
--- a/examples/IPython Kernel/gui/gui-glut.py
+++ b/examples/IPython Kernel/gui/gui-glut.py
@@ -38,7 +38,7 @@ if glut.glutGetWindow() > 0:
 else:
     interactive = False
 
-glut.glutCreateWindow('gui-glut')
+glut.glutCreateWindow(b'gui-glut')
 glut.glutDisplayFunc(display)
 glut.glutReshapeFunc(resize)
 # This is necessary on osx to be able to close the window