Resizing window on Qt (#556)

* Qt: Add screen resize

* Qt: Allocate screen on heap for setCentralWidget

* Fix header inclusion order

* Switch to std::function for resize callback

* rdeepfried

include/panda_qt/screen.hpp

@@ -1,5 +1,6 @@
 #pragma once
 #include <QWidget>
+#include <functional>
 #include <memory>
 
 #include "gl/context.h"
@@ -10,15 +11,28 @@ class ScreenWidget : public QWidget {
 	Q_OBJECT
 
   public:
-	ScreenWidget(QWidget* parent = nullptr);
+	using ResizeCallback = std::function<void(u32, u32)>;
+
+	ScreenWidget(ResizeCallback resizeCallback, QWidget* parent = nullptr);
+	void resizeEvent(QResizeEvent* event) override;
+	// Called by the emulator thread for resizing the actual GL surface, since the emulator thread owns the GL context
+	void resizeSurface(u32 width, u32 height);
+
 	GL::Context* getGLContext() { return glContext.get(); }
 
 	// Dimensions of our output surface
 	u32 surfaceWidth = 0;
 	u32 surfaceHeight = 0;
+	WindowInfo windowInfo;
+
+	// Cached "previous" dimensions, used when resizing our window
+	u32 previousWidth = 0;
+	u32 previousHeight = 0;
 
   private:
 	std::unique_ptr<GL::Context> glContext = nullptr;
+	ResizeCallback resizeCallback;
+
 	bool createGLContext();
 
 	qreal devicePixelRatioFromScreen() const;