init

Telegram/lib_ui/ui/focus_persister.h

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+// This file is part of Desktop App Toolkit,
+// a set of libraries for developing nice desktop applications.
+//
+// For license and copyright information please follow this link:
+// https://github.com/desktop-app/legal/blob/master/LEGAL
+//
+#pragma once
+
+namespace Ui {
+
+class FocusPersister {
+public:
+	FocusPersister(QWidget *parent, QWidget *steal = nullptr)
+	: _weak(GrabFocused(parent)) {
+		if (steal) {
+			steal->setFocus();
+		}
+	}
+
+	~FocusPersister() {
+		if (auto strong = _weak.data()) {
+			if (auto window = strong->window()) {
+				if (window->focusWidget() != strong) {
+					strong->setFocus();
+				}
+			}
+		}
+	}
+
+private:
+	static QWidget *GrabFocused(QWidget *parent) {
+		if (auto window = parent ? parent->window() : nullptr) {
+			return window->focusWidget();
+		}
+		return nullptr;
+	}
+	QPointer<QWidget> _weak;
+
+};
+
+} // namespace Ui