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/main_window.hpp

@@ -50,6 +50,7 @@ class MainWindow : public QMainWindow {
 		PressTouchscreen,
 		ReleaseTouchscreen,
 		ReloadUbershader,
+		SetScreenSize,
 	};
 
 	// Tagged union representing our message queue messages
@@ -81,6 +82,11 @@ class MainWindow : public QMainWindow {
 				u16 x;
 				u16 y;
 			} touchscreen;
+
+			struct {
+				u32 width;
+				u32 height;
+			} screenSize;
 		};
 	};
 
@@ -95,7 +101,7 @@ class MainWindow : public QMainWindow {
 
 	QMenuBar* menuBar = nullptr;
 	InputMappings keyboardMappings;
-	ScreenWidget screen;
+	ScreenWidget* screen;
 	AboutWindow* aboutWindow;
 	ConfigWindow* configWindow;
 	CheatsWindow* cheatsEditor;
@@ -141,4 +147,6 @@ class MainWindow : public QMainWindow {
 	void loadLuaScript(const std::string& code);
 	void reloadShader(const std::string& shader);
 	void editCheat(u32 handle, const std::vector<uint8_t>& cheat, const std::function<void(u32)>& callback);
+
+	void handleScreenResize(u32 width, u32 height);
 };

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;

src/panda_qt/main_window.cpp

@@ -11,13 +11,17 @@
 #include "input_mappings.hpp"
 #include "services/dsp.hpp"
 
-MainWindow::MainWindow(QApplication* app, QWidget* parent) : QMainWindow(parent), keyboardMappings(InputMappings::defaultKeyboardMappings()), screen(this) {
+MainWindow::MainWindow(QApplication* app, QWidget* parent) : QMainWindow(parent), keyboardMappings(InputMappings::defaultKeyboardMappings()) {
 	setWindowTitle("Alber");
 	// Enable drop events for loading ROMs
 	setAcceptDrops(true);
 	resize(800, 240 * 4);
-	screen.show();
 
+	// We pass a callback to the screen widget that will be triggered every time we resize the screen
+	screen = new ScreenWidget([this](u32 width, u32 height) { handleScreenResize(width, height); }, this);
+	setCentralWidget(screen);
+
+	screen->show();
 	appRunning = true;
 
 	// Set our menu bar up
@@ -69,7 +73,7 @@ MainWindow::MainWindow(QApplication* app, QWidget* parent) : QMainWindow(parent)
 	connect(aboutAction, &QAction::triggered, this, &MainWindow::showAboutMenu);
 
 	emu = new Emulator();
-	emu->setOutputSize(screen.surfaceWidth, screen.surfaceHeight);
+	emu->setOutputSize(screen->surfaceWidth, screen->surfaceHeight);
 
 	// Set up misc objects
 	aboutWindow = new AboutWindow(nullptr);
@@ -101,7 +105,7 @@ MainWindow::MainWindow(QApplication* app, QWidget* parent) : QMainWindow(parent)
 
 		if (usingGL) {
 			// Make GL context current for this thread, enable VSync
-			GL::Context* glContext = screen.getGLContext();
+			GL::Context* glContext = screen->getGLContext();
 			glContext->MakeCurrent();
 			glContext->SetSwapInterval(emu->getConfig().vsyncEnabled ? 1 : 0);
 
@@ -145,13 +149,13 @@ void MainWindow::emuThreadMainLoop() {
 
 	// Unbind GL context if we're using GL, otherwise some setups seem to be unable to join this thread
 	if (usingGL) {
-		screen.getGLContext()->DoneCurrent();
+		screen->getGLContext()->DoneCurrent();
 	}
 }
 
 void MainWindow::swapEmuBuffer() {
 	if (usingGL) {
-		screen.getGLContext()->SwapBuffers();
+		screen->getGLContext()->SwapBuffers();
 	} else {
 		Helpers::panic("[Qt] Don't know how to swap buffers for the current rendering backend :(");
 	}
@@ -360,6 +364,15 @@ void MainWindow::dispatchMessage(const EmulatorMessage& message) {
 			emu->getRenderer()->setUbershader(*message.string.str);
 			delete message.string.str;
 			break;
+
+		case MessageType::SetScreenSize: {
+			const u32 width = message.screenSize.width;
+			const u32 height = message.screenSize.height;
+
+			emu->setOutputSize(width, height);
+			screen->resizeSurface(width, height);
+			break;
+		}
 	}
 }
 
@@ -423,13 +436,13 @@ void MainWindow::keyReleaseEvent(QKeyEvent* event) {
 void MainWindow::mousePressEvent(QMouseEvent* event) {
 	if (event->button() == Qt::MouseButton::LeftButton) {
 		const QPointF clickPos = event->globalPosition();
-		const QPointF widgetPos = screen.mapFromGlobal(clickPos);
+		const QPointF widgetPos = screen->mapFromGlobal(clickPos);
 
 		// Press is inside the screen area
-		if (widgetPos.x() >= 0 && widgetPos.x() < screen.width() && widgetPos.y() >= 0 && widgetPos.y() < screen.height()) {
+		if (widgetPos.x() >= 0 && widgetPos.x() < screen->width() && widgetPos.y() >= 0 && widgetPos.y() < screen->height()) {
 			// Go from widget positions to [0, 400) for x and [0, 480) for y
-			uint x = (uint)std::round(widgetPos.x() / screen.width() * 400.f);
-			uint y = (uint)std::round(widgetPos.y() / screen.height() * 480.f);
+			uint x = (uint)std::round(widgetPos.x() / screen->width() * 400.f);
+			uint y = (uint)std::round(widgetPos.y() / screen->height() * 480.f);
 
 			// Check if touch falls in the touch screen area
 			if (y >= 240 && y <= 480 && x >= 40 && x < 40 + 320) {
@@ -482,6 +495,14 @@ void MainWindow::editCheat(u32 handle, const std::vector<uint8_t>& cheat, const
 	sendMessage(message);
 }
 
+void MainWindow::handleScreenResize(u32 width, u32 height) {
+	EmulatorMessage message{.type = MessageType::SetScreenSize};
+	message.screenSize.width = width;
+	message.screenSize.height = height;
+
+	sendMessage(message);
+}
+
 void MainWindow::initControllers() {
 	// Make SDL use consistent positional button mapping
 	SDL_SetHint(SDL_HINT_GAMECONTROLLER_USE_BUTTON_LABELS, "0");

src/panda_qt/screen.cpp

@@ -18,7 +18,7 @@
 // and https://github.com/melonDS-emu/melonDS/blob/master/src/frontend/qt_sdl/main.cpp
 
 #ifdef PANDA3DS_ENABLE_OPENGL
-ScreenWidget::ScreenWidget(QWidget* parent) : QWidget(parent) {
+ScreenWidget::ScreenWidget(ResizeCallback resizeCallback, QWidget* parent) : QWidget(parent), resizeCallback(resizeCallback) {
 	// Create a native window for use with our graphics API of choice
 	resize(800, 240 * 4);
 	
@@ -35,6 +35,30 @@ ScreenWidget::ScreenWidget(QWidget* parent) : QWidget(parent) {
 	}
 }
 
+void ScreenWidget::resizeEvent(QResizeEvent* event) {
+	previousWidth = surfaceWidth;
+	previousHeight = surfaceHeight;
+	QWidget::resizeEvent(event);
+
+	// Update surfaceWidth/surfaceHeight following the resize
+	std::optional<WindowInfo> windowInfo = getWindowInfo();
+	if (windowInfo) {
+		this->windowInfo = *windowInfo;
+	}
+
+	// This will call take care of calling resizeSurface from the emulator thread
+	resizeCallback(surfaceWidth, surfaceHeight);
+}
+
+// Note: This will run on the emulator thread, we don't want any Qt calls happening there.
+void ScreenWidget::resizeSurface(u32 width, u32 height) {
+	if (previousWidth != width || previousHeight != height) {
+		if (glContext) {
+			glContext->ResizeSurface(width, height);
+		}
+	}
+}
+
 bool ScreenWidget::createGLContext() {
 	// List of GL context versions we will try. Anything 4.1+ is good
 	static constexpr std::array<GL::Context::Version, 6> versionsToTry = {
@@ -45,6 +69,8 @@ bool ScreenWidget::createGLContext() {
 
 	std::optional<WindowInfo> windowInfo = getWindowInfo();
 	if (windowInfo.has_value()) {
+		this->windowInfo = *windowInfo;
+
 		glContext = GL::Context::Create(*getWindowInfo(), versionsToTry);
 		glContext->DoneCurrent();
 	}
@@ -110,4 +136,4 @@ std::optional<WindowInfo> ScreenWidget::getWindowInfo() {
 
 	return wi;
 }
-#endif
+#endif