Keep desktop crop workers owned until their dialog closes

tools/chatgui/src/avatars/avatarcrop.cpp

@@ -67,25 +67,24 @@ bool selectAvatarCrop(const QString& source, QRectF& crop, QWidget* parent) {
     buttons->button(QDialogButtonBox::Ok)->setEnabled(false); layout->addWidget(buttons);
     QObject::connect(buttons, &QDialogButtonBox::accepted, &dialog, &QDialog::accept);
     QObject::connect(buttons, &QDialogButtonBox::rejected, &dialog, &QDialog::reject);
-    QPointer<CropView> guard(view); QPointer<QDialog> owner(&dialog);
-    QThreadPool::globalInstance()->start(QRunnable::create([source, guard, owner, status, buttons] {
+    QThreadPool pool; pool.setMaxThreadCount(1);
+    pool.start(QRunnable::create([source, &dialog, view, status, buttons] {
         QImageReader reader(source); reader.setAutoTransform(true); const QSize size = reader.size(); QImage image;
         if (QFileInfo(source).size() <= AvatarCache::OriginalMaxBytes && size.isValid() &&
             qint64(size.width())*size.height() <= 16*1024*1024 &&
             (reader.format()=="jpeg" || reader.format()=="png" || reader.format()=="webp")) {
             reader.setScaledSize(size.scaled(1600,1600,Qt::KeepAspectRatio)); image = reader.read();
         }
-        if (!owner) return;
-        QMetaObject::invokeMethod(owner, [guard, image, status, buttons] {
-            if (!guard) return;
+        QMetaObject::invokeMethod(&dialog, [view, image, status, buttons] {
             if (image.isNull()) {
                 DEBUG_WARN(DEBUG_CATEGORY_MEDIA, "avatar: editor cannot decode selected source");
                 status->setText(QCoreApplication::translate("ChatGui", "Cannot load avatar image")); return;
             }
-            guard->image=image; guard->update(); buttons->button(QDialogButtonBox::Ok)->setEnabled(true);
+            view->image=image; view->update(); buttons->button(QDialogButtonBox::Ok)->setEnabled(true);
         }, Qt::QueuedConnection);
     }));
-    if (dialog.exec()!=QDialog::Accepted) { DEBUG_DEBUG(DEBUG_CATEGORY_MEDIA, "avatar: crop cancelled"); return false; }
+    const int result=dialog.exec(); pool.waitForDone();
+    if (result!=QDialog::Accepted) { DEBUG_DEBUG(DEBUG_CATEGORY_MEDIA, "avatar: crop cancelled"); return false; }
     crop=view->selection(); DEBUG_INFO(DEBUG_CATEGORY_MEDIA, "avatar: crop selected x=%.5f y=%.5f w=%.5f h=%.5f",
         crop.x(), crop.y(), crop.width(), crop.height()); return true;
 }