wm: add WindowManager module with ext-workspace support

src/windowmanager/windowmanager.cpp

@@ -0,0 +1,41 @@
+#include "windowmanager.hpp"
+#include <functional>
+#include <utility>
+
+#include <qobject.h>
+
+#include "../core/qmlscreen.hpp"
+#include "screenprojection.hpp"
+
+namespace qs::wm {
+
+std::function<WindowManager*()> WindowManager::provider;
+
+void WindowManager::setProvider(std::function<WindowManager*()> provider) {
+	WindowManager::provider = std::move(provider);
+}
+
+WindowManager* WindowManager::instance() {
+	static auto* instance = WindowManager::provider();
+	return instance;
+}
+
+ScreenProjection* WindowManager::screenProjection(QuickshellScreenInfo* screen) {
+	auto* qscreen = screen->screen;
+	auto it = this->mScreenProjections.find(qscreen);
+	if (it != this->mScreenProjections.end()) {
+		return *it;
+	}
+
+	auto* projection = new ScreenProjection(qscreen, this);
+	this->mScreenProjections.insert(qscreen, projection);
+
+	QObject::connect(qscreen, &QObject::destroyed, this, [this, projection, qscreen]() {
+		this->mScreenProjections.remove(qscreen);
+		delete projection;
+	});
+
+	return projection;
+}
+
+} // namespace qs::wm