dx9: Avoid triggering reset when size unchanged.

Core/Core.cpp

@@ -111,27 +111,34 @@ void Core_WaitInactive(int milliseconds) {
 	}
 }
 
-void UpdateScreenScale(int width, int height) {
-	dp_xres = width;
-	dp_yres = height;
-	pixel_xres = width;
-	pixel_yres = height;
+bool UpdateScreenScale(int width, int height) {
 	g_dpi = 72;
 	g_dpi_scale = 1.0f;
-#ifdef __SYMBIAN32__
-	dp_xres *= 1.4f;
-	dp_yres *= 1.4f;
+#if defined(__SYMBIAN32__)
 	g_dpi_scale = 1.4f;
-#endif
-#ifdef _WIN32
+#elif defined(_WIN32)
 	if (pixel_xres < 480 + 80) {
-		dp_xres *= 2;
-		dp_yres *= 2;
 		g_dpi_scale = 2.0f;
 	}
 #endif
-	pixel_in_dps = (float)pixel_xres / dp_xres;
-	NativeResized();
+	pixel_in_dps = 1.0f / g_dpi_scale;
+
+	int new_dp_xres = width * g_dpi_scale;
+	int new_dp_yres = height * g_dpi_scale;
+
+	bool dp_changed = new_dp_xres != dp_xres || new_dp_yres != dp_yres;
+	bool px_changed = pixel_xres != width || pixel_yres != height;
+
+	if (dp_changed || px_changed) {
+		dp_xres = new_dp_xres;
+		dp_yres = new_dp_yres;
+		pixel_xres = width;
+		pixel_yres = height;
+
+		NativeResized();
+		return true;
+	}
+	return false;
 }
 
 void UpdateRunLoop() {

Core/Core.h

@@ -42,7 +42,7 @@ bool Core_IsInactive();
 void Core_WaitInactive();
 void Core_WaitInactive(int milliseconds);
 
-void UpdateScreenScale(int width, int height);
+bool UpdateScreenScale(int width, int height);
 
 // Don't run the core when minimized etc.
 void Core_NotifyWindowHidden(bool hidden);

Windows/D3D9Base.cpp

@@ -192,12 +192,16 @@ bool D3D9_Init(HWND wnd, bool windowed, std::string *error_message) {
 }
 
 void D3D9_Resize(HWND window) {
-	// Allow call from only EMU thread.
-	if (device) {
+	// This should only be called from the emu thread.
+
+	int xres, yres;
+	GetRes(xres, yres);
+	bool w_changed = pp.BackBufferWidth != xres;
+	bool h_changed = pp.BackBufferHeight != yres;
+
+	if (device && (w_changed || h_changed)) {
 		DX9::fbo_shutdown();
 
-		int xres, yres;
-		GetRes(xres, yres);
 		pp.BackBufferWidth = xres;
 		pp.BackBufferHeight = yres;
 		HRESULT hr = device->Reset(&pp);

Windows/WndMainWindow.cpp

@@ -262,8 +262,9 @@ namespace MainWindow
 		UpdateRenderResolution();
 		
 		if (!noWindowMovement) {
-			UpdateScreenScale(width, height);
-			NativeMessageReceived("gpu resized", "");
+			if (UpdateScreenScale(width, height)) {
+				NativeMessageReceived("gpu resized", "");
+			}
 		}
 	}