Fixed ui_print, #6. Calls now processed in main thread.

src/user_interface.py

@@ -1760,6 +1760,9 @@ class OutputConsole(Frame):
     def __init__(self, parent):
         Frame.__init__(self, parent, relief=SUNKEN, bd=1)
 
+        # Queue for messages to print when this class currently has main thread control
+        self.print_queue = Queue()
+
         # configure Tkinter grid:
         self.grid_rowconfigure(ALL, weight=1)
         self.grid_columnconfigure(0, weight=1, minsize=60)  # console needs to have a minimum width
@@ -1773,3 +1776,23 @@ class OutputConsole(Frame):
         # link scrollbar to the console
         scrollbar.config(command=self.console.yview)
         self.console.config(yscrollcommand=scrollbar.set)
+
+        # Start the main thread for printing queued messages
+        self.print_thread()
+
+    def print_thread(self):
+        """ Continuous thread that checks if messages are present, and prints them if they are. """
+        try:
+            while True:
+                msg = self.print_queue.get(block=False)
+                # print to console
+                self.console.insert(END, "\n" + msg)
+        except Empty:
+            pass
+        self.console.see(END)  # scroll console to bottom
+
+        # Print messages every 100 ms in the main Tkinter loop
+        self.after(100, self.print_thread)
+
+    def put(self, message):
+        self.print_queue.put(message)

src/utility.py

@@ -7,9 +7,9 @@ def ui_print(*content):
     """prints text to built-in console, use exactly like normal print(). Requires the ui to be initialized"""
     output = " ".join([str(c) for c in content])
 
-    if not g.exit_flag and g.app is not None:  # application is still running --> output window is visible
-        output = "".join(("\n", output))  # begin new line each time
-        g.app.OutputConsole.console.insert(END, output)  # print to console
-        g.app.OutputConsole.console.see(END)  # scroll console to bottom
-    else:  # if window is not open, do normal print
-        print(output)
+    if not g.exit_flag and g.app is not None:
+        # application is still running --> output window is visible
+        g.app.OutputConsole.put(output)
+    else:
+        # if window is not open, do normal print
+        print(output)