Add wx.App.DisplayAvailable() which can be used to determine if a GUI

can be created in the current environment.  (Still need an
implementation for wxMSW...)


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@40828 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

wxPython/docs/CHANGES.txt

@@ -162,8 +162,9 @@ Added wx.HyperlinkCtrl.
 Added battery and power related functions and events (wxMSW only so
 far.)  See wx.PowerEvent, wx.GetPowerType and wx.GetBatteryState.
 
-Added wx.ListCtrl.HitTestSubItem which returns the sub-item that was
+Added wx.ListCtrl.HitTestSubItem which returns the sub-item (i.e. the
-hit (if any) in addition to the item and flags.
+column in report mode) that was hit (if any) in addition to the item
+and flags.
 
 Added wrappers for wx.ColourPickerCtrl, wx.DirPickerCtrl,
 wx.FilePickerCtrl, and wx.FontPickerCtrl.
@@ -195,6 +196,9 @@ wx.BitmapFromBufferRGBA factory functions.  They enable loading of am
 image or bitmap directly from a Python object that implements the
 buffer interface, such as strings, arrays, etc.
 
+Added wx.App.DisplayAvailable() which can be used to determine if a
+GUI can be created in the current environment.  (Still need an
+implementation for wxMSW...)
 
 
 

wxPython/include/wx/wxPython/wxPython_int.h

@@ -251,10 +251,11 @@ bool wxPoint2D_helper(PyObject* source, wxPoint2D** obj);
 bool wxPySimple_typecheck(PyObject* source, const wxChar* classname, int seqLen);
 bool wxColour_typecheck(PyObject* source);
 
-bool wxPyCheckForApp();
-
 
 // Other helpful stuff
+bool wxPyCheckForApp();
+bool wxPyTestDisplayAvailable();
+
 bool wxPy2int_seq_helper(PyObject* source, int* i1, int* i2);
 bool wxPy4int_seq_helper(PyObject* source, int* i1, int* i2, int* i3, int* i4);
 

wxPython/src/_app.i

@@ -290,6 +290,27 @@ it wasn't found at all.  Raises an exception on non-Windows platforms.", "");
             { wxPyRaiseNotImplemented(); return 0; }
     }
 #endif
+
+    %extend {
+        DocStr(DisplayAvailable,
+               "Tests if it is possible to create a GUI in the current environment.
+This will mean different things on the different platforms.
+
+   * On X Windows systems this function will return ``False`` if it is
+     not able to open a connection to the X display, which can happen
+     if $DISPLAY is not set, or is not set correctly.
+
+   * On Mac OS X a ``False`` return value will mean that wx is not
+     able to access the window manager, which can happen if logged in
+     remotely or if running from the normal version of python instead
+     of the framework version, (i.e., pythonw.)
+
+   * On MS Windows...
+", "");
+        static bool DisplayAvailable() {
+            return wxPyTestDisplayAvailable();
+        }
+    }
 };
 
 

wxPython/src/_app_ex.py

@@ -69,7 +69,7 @@ class PyOnDemandOutputWindow:
 #----------------------------------------------------------------------
 
 _defRedirect = (wx.Platform == '__WXMSW__' or wx.Platform == '__WXMAC__')
-
+        
 class App(wx.PyApp):
     """
     The ``wx.App`` class represents the application and is used to:
@@ -127,22 +127,26 @@ class App(wx.PyApp):
             initialization to ensure that the system, toolkit and
             wxWidgets are fully initialized.
         """
+        
         wx.PyApp.__init__(self)
 
-        if wx.Platform == "__WXMAC__":
+        # make sure we can create a GUI
-            try:
+        if not self.DisplayAvailable():
-                import MacOS
+            
-                if not MacOS.WMAvailable():
+            if wx.Platform == "__WXMAC__":
-                    print """\
+                msg = """This program needs access to the screen.
-This program needs access to the screen. Please run with 'pythonw',
+Please run with 'pythonw', not 'python', and only when you are logged
-not 'python', and only when you are logged in on the main display of
+in on the main display of your Mac."""
-your Mac."""
+                
-                    _sys.exit(1)
+            elif wx.Platform == "__WXGTK__":
-            except SystemExit:
+                msg ="Unable to access the X Display, is $DISPLAY set properly?"
-                raise
-            except:
-                pass
 
+            else:
+                msg = "Unable to create GUI"
+                # TODO: more description is needed for wxMSW...
+
+            raise SystemExit(msg)
+        
         # This has to be done before OnInit
         self.SetUseBestVisual(useBestVisual)
 

wxPython/src/helpers.cpp

@@ -2753,6 +2753,62 @@ int wxPyImageHandler::GetImageCount( wxInputStream& stream ) {
 }
 
 
+//----------------------------------------------------------------------
+// Function to test if the Display (or whatever is the platform equivallent)
+// can be connected to.  This is accessable from wxPython as a staticmethod of
+// wx.App called DisplayAvailable().
+
+
+bool wxPyTestDisplayAvailable()
+{
+#ifdef __WXGTK__
+    Display* display;
+    display = XOpenDisplay(NULL);
+    if (display == NULL)
+        return false;
+    XCloseDisplay(display);
+    return true;
+#endif
+
+#ifdef __WXMAC__
+    // This is adapted from Python's Mac/Modules/MacOS.c in the
+    // MacOS_WMAvailable function.
+    bool rv;
+    ProcessSerialNumber psn;
+		
+    /*
+    ** This is a fairly innocuous call to make if we don't have a window
+    ** manager, or if we have no permission to talk to it. It will print
+    ** a message on stderr, but at least it won't abort the process.
+    ** It appears the function caches the result itself, and it's cheap, so
+    ** no need for us to cache.
+    */
+#ifdef kCGNullDirectDisplay
+    /* On 10.1 CGMainDisplayID() isn't available, and
+    ** kCGNullDirectDisplay isn't defined.
+    */
+    if (CGMainDisplayID() == 0) {
+        rv = false;
+    } else 
+#endif
+    {
+        // Also foreground the application on the first call as a side-effect.
+        if (GetCurrentProcess(&psn) < 0 || SetFrontProcess(&psn) < 0) {
+            rv = false;
+        } else {
+            rv = true;
+        }
+    }
+    return rv;
+#endif
+
+#ifdef __WXMSW__
+    // TODO...
+    return true;
+#endif
+}
+
+
 //----------------------------------------------------------------------
 //----------------------------------------------------------------------