implemented software fallback for text effect

dialogs/preferencesdialog.cpp

@@ -120,6 +120,8 @@ void PreferencesDialog::save() {
 		return;
 	}
 
+    bool needs_restart = false;
+
 	config.css_path = custom_css_fn->text();
 	mainWindow->load_css_from_file(config.css_path);
 	config.recording_mode = recordingComboBox->currentIndex() + 1;
@@ -130,13 +132,26 @@ void PreferencesDialog::save() {
 	config.upcoming_queue_type = upcoming_queue_type->currentIndex();
 	config.previous_queue_size = previous_queue_spinbox->value();
 	config.previous_queue_type = previous_queue_type->currentIndex();
+
+    if (config.effect_textbox_lines != effect_textbox_lines_field->value()) {
+        needs_restart = true;
+    }
 	config.effect_textbox_lines = effect_textbox_lines_field->value();
 
+    if (config.use_software_fallback != use_software_fallbacks_checkbox->isChecked()) {
+        needs_restart = true;
+    }
+    config.use_software_fallback = use_software_fallbacks_checkbox->isChecked();
+
 	// save keyboard shortcuts
 	for (int i=0;i<key_shortcut_fields.size();i++) {
 		key_shortcut_fields.at(i)->set_action_shortcut();
 	}
 
+    if (needs_restart) {
+        QMessageBox::information(this, tr("Warning"), tr("Some changed settings will require restarting Olive to take effect"));
+    }
+
 	accept();
 }
 
@@ -304,6 +319,12 @@ void PreferencesDialog::setup_ui() {
 	effect_textbox_lines_field->setValue(config.effect_textbox_lines);
 	general_layout->addWidget(effect_textbox_lines_field, 3, 1, 1, 2);
 
+    // General -> Use Software Fallbacks When Possible
+    use_software_fallbacks_checkbox = new QCheckBox(general_tab);
+    use_software_fallbacks_checkbox->setText(tr("Use Software Fallbacks When Possible"));
+    use_software_fallbacks_checkbox->setChecked(config.use_software_fallback);
+    general_layout->addWidget(use_software_fallbacks_checkbox, 4, 0, 1, 1);
+
 	tabWidget->addTab(general_tab, tr("General"));
 
 	// Behavior