From a92adee7f88c0ff946c33c4754d037bd1a6cae51 Mon Sep 17 00:00:00 2001
From: Amaryllis Kulla <ancurio@mapleshrine.eu>
Date: Fri, 5 Nov 2021 17:49:16 +0100
Subject: [PATCH] EventThread: Add 'recenter' parameter to window resize
 request

If true, centers the window on the current screen with the
new size.
---
 binding-mri/graphics-binding.cpp |  5 +++--
 src/eventthread.cpp              | 37 ++++++++++++++++++++++++++++----
 src/eventthread.h                |  2 +-
 3 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/binding-mri/graphics-binding.cpp b/binding-mri/graphics-binding.cpp
index 2c5351c..0ac9274 100644
--- a/binding-mri/graphics-binding.cpp
+++ b/binding-mri/graphics-binding.cpp
@@ -201,9 +201,10 @@ RB_METHOD(graphicsResizeWindow)
 	RB_UNUSED_PARAM;
 
 	int width, height;
-	rb_get_args(argc, argv, "ii", &width, &height RB_ARG_END);
+	bool recenter = false;
+	rb_get_args(argc, argv, "ii|b", &width, &height, &recenter RB_ARG_END);
 
-	shState->eThread().requestWindowResize(width, height);
+	shState->eThread().requestWindowResize(width, height, recenter);
 
 	return Qnil;
 }
diff --git a/src/eventthread.cpp b/src/eventthread.cpp
index 448fdc4..ed95cf9 100644
--- a/src/eventthread.cpp
+++ b/src/eventthread.cpp
@@ -101,6 +101,36 @@ bool EventThread::allocUserEvents()
 	return true;
 }
 
+static void writeResizeRequest(SDL_WindowEvent &event, int w, int h, bool recenter)
+{
+	event.data1 = w;
+	event.data2 = h;
+	event.padding3 = recenter ? 1 : 0;
+}
+
+static void handleResizeRequest(SDL_Window *win, SDL_WindowEvent &event)
+{
+	int newWidth = event.data1;
+	int newHeight = event.data2;
+	bool recenter = event.padding3 == 1;
+
+	if (recenter)
+	{
+		int display = SDL_GetWindowDisplayIndex(win);
+		if (display >= 0)
+		{
+			SDL_DisplayMode dm;
+			SDL_GetDesktopDisplayMode(display, &dm);
+			int newX = (dm.w - newWidth) / 2;
+			int newY = (dm.h - newHeight) / 2;
+
+			SDL_SetWindowPosition(win, newX, newY);
+		}
+	}
+
+	SDL_SetWindowSize(win, newWidth, newHeight);
+}
+
 EventThread::EventThread()
     : fullscreen(false),
       showCursor(false)
@@ -410,7 +440,7 @@ void EventThread::process(RGSSThreadData &rtData)
 				break;
 
 			case REQUEST_WINRESIZE :
-				SDL_SetWindowSize(win, event.window.data1, event.window.data2);
+				handleResizeRequest(win, event.window);
 				break;
 
 			case REQUEST_MESSAGEBOX :
@@ -581,12 +611,11 @@ void EventThread::requestFullscreenMode(bool mode)
 	SDL_PushEvent(&event);
 }
 
-void EventThread::requestWindowResize(int width, int height)
+void EventThread::requestWindowResize(int width, int height, bool recenter)
 {
 	SDL_Event event;
 	event.type = usrIdStart + REQUEST_WINRESIZE;
-	event.window.data1 = width;
-	event.window.data2 = height;
+	writeResizeRequest(event.window, width, height, recenter);
 	SDL_PushEvent(&event);
 }
 
diff --git a/src/eventthread.h b/src/eventthread.h
index 432ad7d..f36a56c 100644
--- a/src/eventthread.h
+++ b/src/eventthread.h
@@ -88,7 +88,7 @@ public:
 
 	/* Called from RGSS thread */
 	void requestFullscreenMode(bool mode);
-	void requestWindowResize(int width, int height);
+	void requestWindowResize(int width, int height, bool recenter = false);
 	void requestShowCursor(bool mode);
 
 	void requestTerminate();