Qt: Fix crash when switching from high-resolution OpenGL renderer to software

CHANGES

@@ -11,6 +11,7 @@ Other fixes:
  - GBA e-Reader: Fix bitmap short strip scanning
  - GBA Video: Fix mode 5 frame 1 caching (fixes mgba.io/i/2075)
  - GBA Video: Don't attempt to copy invalid registers when switching renderer
+ - Qt: Fix crash when switching from high-resolution OpenGL renderer to software
 Misc:
  - Core: Truncate preloading ROMs that slightly exceed max size (fixes mgba.io/i/2093)
  - GBA: Default-enable VBA bug compat for Ruby and Emerald ROM hacks

src/platform/qt/DisplayGL.cpp

@@ -368,6 +368,10 @@ void PainterGL::resizeContext() {
 	m_interrupter.resume();
 
 	QSize size = m_context->screenDimensions();
+	if (m_dims == size) {
+		return;
+	}
+	dequeueAll();
 	m_backend->setDimensions(m_backend, size.width(), size.height());
 }
 
@@ -560,9 +564,6 @@ void PainterGL::dequeueAll() {
 			m_free.append(buffer);
 		}
 	}
-	if (buffer) {
-		m_backend->postFrame(m_backend, buffer);
-	}
 	if (m_buffer) {
 		m_free.append(m_buffer);
 		m_buffer = nullptr;

src/platform/qt/DisplayGL.h

@@ -142,7 +142,7 @@ private:
 	QList<uint32_t*> m_free;
 	QQueue<uint32_t*> m_queue;
 	QAtomicInt m_lagging = 0;
-	uint32_t* m_buffer;
+	uint32_t* m_buffer = nullptr;
 	QPainter m_painter;
 	QMutex m_mutex;
 	QWindow* m_surface;
@@ -158,6 +158,7 @@ private:
 	VideoShader m_shader{};
 	VideoBackend* m_backend = nullptr;
 	QSize m_size;
+	QSize m_dims;
 	MessagePainter* m_messagePainter = nullptr;
 	QElapsedTimer m_delayTimer;
 	std::shared_ptr<VideoProxy> m_videoProxy;