Merge pull request #1648 from jangarrevoet/1106-no_x_session

add support for running without an X-session

src/sardana/spock/ipython_01_00/genutils.py

@@ -76,6 +76,7 @@
     from IPython.utils.path import get_ipython_dir
 
 
+from sardana.util.graphics import display_available
 import taurus
 #from taurus.core import Release as TCRelease
 
@@ -116,10 +117,15 @@
 def get_gui_mode():
     try:
         import taurus.external.qt.Qt
-        return 'qt'
+        ret_val = 'qt'
     except ImportError:
         return None
 
+    # Check for running without an X-session on linux
+    if not display_available():
+        ret_val = None
+
+    return ret_val
 
 def get_pylab_mode():
     return get_app().pylab
@@ -1303,6 +1309,11 @@ def prepare_input_handler():
         except ImportError:
             raise Exception("Cannot use Spock Qt input handler!")
 
+        if not display_available():
+            raise Exception(
+                "Running without graphical user interface support."
+                " Cannot use Spock Qt input handler!"
+            )
 
 def prepare_cmdline(argv=None):
     if argv is None:

src/sardana/spock/magic.py

@@ -31,12 +31,14 @@
            'post_mortem', 'macrodata', 'edmac', 'spock_late_startup_hook',
            'spock_pre_prompt_hook']
 
+from sardana.util.graphics import display_available
 from sardana.util.whichpython import which_python_executable
 from .genutils import MSG_DONE, MSG_FAILED
 from .genutils import get_ipapi
 from .genutils import page, get_door, get_macro_server, ask_yes_no, arg_split
 
 
+
 def expconf(self, parameter_s=''):
     """Launches a GUI for configuring the environment variables
     for the experiments (scans)"""
@@ -49,6 +51,15 @@ def expconf(self, parameter_s=''):
               "https://sardana-controls.org/users/standard_macro_catalog.html#experiment-configuration-macros)")
         return
 
+    if not display_available():
+        print(
+            "Running without graphical user interface support. "
+            "ExpConf cannot work without it. "
+            "(hint: maybe you want to use experiment configuration macros? "
+            "https://sardana-controls.org/users/standard_macro_catalog.html#experiment-configuration-macros)"
+        )
+        return
+
     try:
         from sardana.taurus.qt.qtgui.extra_sardana import ExpDescriptionEditor
     except:
@@ -97,6 +108,13 @@ def showscan(self, parameter_s=''):
         print("Qt binding is not available. Showscan cannot work without it.")
         return
 
+    if not display_available():
+        print(
+            "Running without graphical user interface support."
+            " Showscan cannot work without it."
+        )
+        return
+
     params = parameter_s.split()
     door = get_door()
     scan_nb = None
@@ -118,6 +136,13 @@ def spsplot(self, parameter_s=''):
         print("Qt binding is not available. SPSplot cannot work without it.")
         return
 
+    if not display_available():
+        print(
+            "Running without graphical user interface support."
+            " SPSplot cannot work without it."
+        )
+        return
+
     get_door().plot()
 
 

src/sardana/spock/spockms.py

@@ -38,6 +38,7 @@
 from sardana.sardanautils import is_pure_str, is_non_str_seq
 from sardana.spock import genutils
 from sardana.util.parser import ParamParser
+from sardana.util.graphics import display_available
 from sardana import sardanacustomsettings
 
 CHANGE_EVTS = TaurusEventType.Change, TaurusEventType.Periodic
@@ -519,6 +520,11 @@ def processRecordData(self, data):
                 except ImportError:
                     print("Qt binding is not available. Macro plotting cannot work without it.")
                     return
+                if not display_available():
+                    print("Running without graphical user interface support."
+                          " Macro plotting cannot work without it."
+                    )
+                    return
                 func_name = self.MathFrontend + "." + func_name
             args = data['args']
             kwargs = data['kwargs']

src/sardana/util/graphics.py

@@ -0,0 +1,72 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+##############################################################################
+##
+# This file is part of Sardana
+##
+# http://www.sardana-controls.org/
+##
+# Copyright 2011 CELLS / ALBA Synchrotron, Bellaterra, Spain
+##
+# Sardana is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+##
+# Sardana is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+##
+# You should have received a copy of the GNU Lesser General Public License
+# along with Sardana.  If not, see <http://www.gnu.org/licenses/>.
+##
+##############################################################################
+
+"""This package provides graphics related helper functions"""
+
+import os
+import sys
+
+
+def display_available():
+    """
+    Checks if a graphical display is available.
+
+    :returns: True when a display is available. False when not.
+    :rtype: bool
+
+    .. note ::
+        This is only used for linux since it can run without graphical
+         sessions.
+        For Windows this always returns True since it can not run without.
+    """
+
+    ret_val = True
+
+    if sys.platform.startswith("linux"):
+        ret_val = xsession_available()
+
+    return ret_val
+
+
+def xsession_available():
+    """
+    Checks if an X-session is available.
+
+    :returns: True when an X-session is available. False when not.
+    :rtype: bool
+    """
+
+    ret_val = True
+
+    # No display environment
+    if os.environ.get("DISPLAY") is None:
+        ret_val = False
+
+    # In docker without X-session auth
+    elif not os.path.exists("/tmp/.X11-unix"):
+        ret_val = False
+
+    return ret_val