AXIS: Add [DISPLAY] PREVIEW_TIMEOUT setting.

Previously AXIS would freeze when loading a G-code file that takes very
long to execute and/or never terminates. This commit adds an optional
timeout that stops the loading of preview and shows a notice.

Retains old behavior if the .ini file setting is not specified.

Author: PetteriAimonen

docs/src/config/ini-config.adoc

@@ -305,6 +305,7 @@ User Manual.
   If the update time is not set right the screen can become unresponsive or very jerky.
   A value of 100ms (0.1 seconds) is a common setting though a range of 50 - 200ms (.05 - .2 seconds) may be useable.
   An under powered CPU may see improvement with a longer setting. Usually the default is fine.
+* 'PREVIEW_TIMEOUT = 5' - Timeout (in seconds) for loading graphical preview of G-code. Currently AXIS only.
 
 [NOTE]
 The following [DISPLAY] items are used by GladeVCP, see the

src/emc/usr_intf/axis/scripts/axis.py

@@ -1069,6 +1069,15 @@ def __init__(self, widget, text, linecount, progress, arcdivision):
         self.progress = progress
         self.aborted = False
         self.arcdivision = arcdivision
+        self.timeout_time = None
+
+    def set_timeout(self, timeout):
+        '''Abort loading of G-code if it takes more than timeout seconds from
+        the time this method was called. Set timeout to None to disable.'''
+        if timeout is None or timeout <= 0:
+            self.timeout_time = None
+        else:
+            self.timeout_time = time.time() + timeout
 
     def change_tool(self, pocket):
         GLCanon.change_tool(self, pocket)
@@ -1081,6 +1090,11 @@ def do_cancel(self, event):
 
     def check_abort(self):
         root_window.update()
+
+        if self.timeout_time is not None and self.timeout_time < time.time():
+            notifications.add("info", _("G-code preview loading timed out"))
+            self.aborted = True
+
         if self.aborted: raise KeyboardInterrupt
 
     def next_line(self, st):
@@ -1217,6 +1231,10 @@ def open_file_guts(f, filtered=False, addrecent=True):
             shutil.copy(parameter, temp_parameter)
         canon.parameter_file = temp_parameter
 
+        timeout = inifile.find("DISPLAY", "PREVIEW_TIMEOUT") or ""
+        if timeout:
+            canon.set_timeout(float(timeout))
+
         initcode = inifile.find("EMC", "RS274NGC_STARTUP_CODE") or ""
         if initcode == "":
             initcode = inifile.find("RS274NGC", "RS274NGC_STARTUP_CODE") or ""