From 53952ba1319a1c88a97e23b8fcd69abc0b7a6590 Mon Sep 17 00:00:00 2001
From: Damien Elmes <gpg@ankiweb.net>
Date: Fri, 6 Mar 2020 14:19:25 +1000
Subject: [PATCH] export in a background thread

---
 qt/aqt/exporting.py | 79 ++++++++++++++++++++++++++-------------------
 1 file changed, 46 insertions(+), 33 deletions(-)

diff --git a/qt/aqt/exporting.py b/qt/aqt/exporting.py
index 2e63e65e7..0b2bfdf21 100644
--- a/qt/aqt/exporting.py
+++ b/qt/aqt/exporting.py
@@ -6,6 +6,7 @@ from __future__ import annotations
 import os
 import re
 import time
+from concurrent.futures import Future
 from typing import List, Optional
 
 import aqt
@@ -131,7 +132,7 @@ class ExportDialog(QDialog):
             break
         self.hide()
         if file:
-            self.mw.progress.start(immediate=True)
+            # check we can write to file
             try:
                 f = open(file, "wb")
                 f.close()
@@ -139,39 +140,51 @@ class ExportDialog(QDialog):
                 showWarning(_("Couldn't save file: %s") % str(e))
             else:
                 os.unlink(file)
-                exportedMedia = lambda cnt: self.mw.progress.update(
-                    label=ngettext(
-                        "Exported %d media file", "Exported %d media files", cnt
+
+            # progress handler
+            def exported_media(cnt):
+                self.mw.taskman.run_on_main(
+                    lambda: self.mw.progress.update(
+                        label=ngettext(
+                            "Exported %d media file", "Exported %d media files", cnt
+                        )
+                        % cnt
                     )
-                    % cnt
                 )
-                hooks.media_files_did_export.append(exportedMedia)
+
+            def do_export():
                 self.exporter.exportInto(file)
-                hooks.media_files_did_export.remove(exportedMedia)
-                period = 3000
-                if self.isVerbatim:
-                    msg = _("Collection exported.")
-                    self.mw.reopen()
-                else:
-                    if self.isTextNote:
-                        msg = (
-                            ngettext(
-                                "%d note exported.",
-                                "%d notes exported.",
-                                self.exporter.count,
-                            )
-                            % self.exporter.count
-                        )
-                    else:
-                        msg = (
-                            ngettext(
-                                "%d card exported.",
-                                "%d cards exported.",
-                                self.exporter.count,
-                            )
-                            % self.exporter.count
-                        )
-                tooltip(msg, period=period)
-            finally:
+
+            def on_done(future: Future):
                 self.mw.progress.finish()
-        QDialog.accept(self)
+                hooks.media_files_did_export.remove(exported_media)
+                # raises if exporter failed
+                future.result()
+                self.on_export_finished()
+
+            self.mw.progress.start(immediate=True)
+            hooks.media_files_did_export.append(exported_media)
+
+            self.mw.taskman.run_in_background(do_export, on_done)
+
+    def on_export_finished(self):
+        if self.isVerbatim:
+            msg = _("Collection exported.")
+            self.mw.reopen()
+        else:
+            if self.isTextNote:
+                msg = (
+                    ngettext(
+                        "%d note exported.", "%d notes exported.", self.exporter.count,
+                    )
+                    % self.exporter.count
+                )
+            else:
+                msg = (
+                    ngettext(
+                        "%d card exported.", "%d cards exported.", self.exporter.count,
+                    )
+                    % self.exporter.count
+                )
+        tooltip(msg, period=3000)
+        QDialog.reject(self)