1 files changed, 64 insertions, 0 deletions
diff --git a/lib/gui/simulator/simulator_renderer.py b/lib/gui/simulator/simulator_renderer.py
new file mode 100644
index 00000000..efe55ccb
--- /dev/null
+++ b/lib/gui/simulator/simulator_renderer.py
@@ -0,0 +1,64 @@
+# Authors: see git history
+#
+# Copyright (c) 2024 Authors
+# Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
+from threading import Event, Thread
+
+import wx
+
+from ...debug.debug import debug
+from ...utils.threading import ExitThread
+
+
+class PreviewRenderer(Thread):
+    """Render stitch plan in a background thread."""
+
+    def __init__(self, render_stitch_plan_hook, rendering_completed_hook):
+        super(PreviewRenderer, self).__init__()
+        self.daemon = True
+        self.refresh_needed = Event()
+
+        self.render_stitch_plan_hook = render_stitch_plan_hook
+        self.rendering_completed_hook = rendering_completed_hook
+
+        # This is read by utils.threading.check_stop_flag() to abort stitch plan
+        # generation.
+        self.stop = Event()
+
+    def update(self):
+        """Request to render a new stitch plan.
+
+        self.render_stitch_plan_hook() will be called in a background thread, and then
+        self.rendering_completed_hook() will be called with the resulting stitch plan.
+        """
+
+        if not self.is_alive():
+            self.start()
+
+        self.stop.set()
+        self.refresh_needed.set()
+
+    def run(self):
+        while True:
+            self.refresh_needed.wait()
+            self.refresh_needed.clear()
+            self.stop.clear()
+
+            try:
+                debug.log("update_patches")
+                self.render_stitch_plan()
+            except ExitThread:
+                debug.log("ExitThread caught")
+                self.stop.clear()
+
+    def render_stitch_plan(self):
+        try:
+            stitch_plan = self.render_stitch_plan_hook()
+            if stitch_plan:
+                # rendering_completed() will be called in the main thread.
+                wx.CallAfter(self.rendering_completed_hook, stitch_plan)
+        except ExitThread:
+            raise
+        except:  # noqa: E722
+            import traceback
+            debug.log("unhandled exception in PreviewRenderer.render_stitch_plan(): " + traceback.format_exc())