From d4a6844727c9b673dc1980ab01d4dabcdfe739ec Mon Sep 17 00:00:00 2001
From: Cameron Cawley <ccawley2011@gmail.com>
Date: Mon, 29 Jan 2018 17:29:19 +0000
Subject: [PATCH] SDL: Fix changing screen size when using OpenGL ES 2

---
 src/platform/sdl/gl-common.c |  7 +++++++
 src/platform/sdl/gl-common.h |  1 +
 src/platform/sdl/gl-sdl.c    | 11 ++---------
 src/platform/sdl/gles2-sdl.c | 10 ++++++++++
 4 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/src/platform/sdl/gl-common.c b/src/platform/sdl/gl-common.c
index 13c20811b..0b73cc519 100644
--- a/src/platform/sdl/gl-common.c
+++ b/src/platform/sdl/gl-common.c
@@ -7,6 +7,13 @@
 
 #include <mgba/core/version.h>
 
+void mSDLGLDoViewport(int w, int h, struct VideoBackend* v) {
+	v->resized(v, w, h);
+	v->clear(v);
+	v->swap(v);
+	v->clear(v);
+}
+
 void mSDLGLCommonSwap(struct VideoBackend* context) {
 	struct mSDLRenderer* renderer = (struct mSDLRenderer*) context->user;
 #if SDL_VERSION_ATLEAST(2, 0, 0)
diff --git a/src/platform/sdl/gl-common.h b/src/platform/sdl/gl-common.h
index b517dd436..307da756f 100644
--- a/src/platform/sdl/gl-common.h
+++ b/src/platform/sdl/gl-common.h
@@ -12,6 +12,7 @@ CXX_GUARD_START
 
 #include "main.h"
 
+void mSDLGLDoViewport(int w, int h, struct VideoBackend* v);
 void mSDLGLCommonSwap(struct VideoBackend* context);
 void mSDLGLCommonInit(struct mSDLRenderer* renderer);
 
diff --git a/src/platform/sdl/gl-sdl.c b/src/platform/sdl/gl-sdl.c
index b723a495c..bc992c720 100644
--- a/src/platform/sdl/gl-sdl.c
+++ b/src/platform/sdl/gl-sdl.c
@@ -11,13 +11,6 @@
 #include <mgba/core/thread.h>
 #include "platform/opengl/gl.h"
 
-static void _doViewport(int w, int h, struct VideoBackend* v) {
-	v->resized(v, w, h);
-	v->clear(v);
-	v->swap(v);
-	v->clear(v);
-}
-
 static bool mSDLGLInit(struct mSDLRenderer* renderer);
 static void mSDLGLRunloop(struct mSDLRenderer* renderer, void* user);
 static void mSDLGLDeinit(struct mSDLRenderer* renderer);
@@ -44,7 +37,7 @@ bool mSDLGLInit(struct mSDLRenderer* renderer) {
 	renderer->gl.d.init(&renderer->gl.d, 0);
 	renderer->gl.d.setDimensions(&renderer->gl.d, renderer->width, renderer->height);
 
-	_doViewport(renderer->viewportWidth, renderer->viewportHeight, &renderer->gl.d);
+	mSDLGLDoViewport(renderer->viewportWidth, renderer->viewportHeight, &renderer->gl.d);
 	return true;
 }
 
@@ -60,7 +53,7 @@ void mSDLGLRunloop(struct mSDLRenderer* renderer, void* user) {
 			// Event handling can change the size of the screen
 			if (renderer->player.windowUpdated) {
 				SDL_GetWindowSize(renderer->window, &renderer->viewportWidth, &renderer->viewportHeight);
-				_doViewport(renderer->viewportWidth, renderer->viewportHeight, v);
+				mSDLGLDoViewport(renderer->viewportWidth, renderer->viewportHeight, v);
 				renderer->player.windowUpdated = 0;
 			}
 #endif
diff --git a/src/platform/sdl/gles2-sdl.c b/src/platform/sdl/gles2-sdl.c
index 9f9778c3f..3a832546f 100644
--- a/src/platform/sdl/gles2-sdl.c
+++ b/src/platform/sdl/gles2-sdl.c
@@ -114,6 +114,8 @@ bool mSDLGLES2Init(struct mSDLRenderer* renderer) {
 	renderer->gl2.d.swap = mSDLGLCommonSwap;
 	renderer->gl2.d.init(&renderer->gl2.d, 0);
 	renderer->gl2.d.setDimensions(&renderer->gl2.d, renderer->width, renderer->height);
+
+	mSDLGLDoViewport(renderer->viewportWidth, renderer->viewportHeight, &renderer->gl2.d);
 	return true;
 }
 
@@ -125,6 +127,14 @@ void mSDLGLES2Runloop(struct mSDLRenderer* renderer, void* user) {
 	while (context->state < THREAD_EXITING) {
 		while (SDL_PollEvent(&event)) {
 			mSDLHandleEvent(context, &renderer->player, &event);
+#if SDL_VERSION_ATLEAST(2, 0, 0)
+			// Event handling can change the size of the screen
+			if (renderer->player.windowUpdated) {
+				SDL_GetWindowSize(renderer->window, &renderer->viewportWidth, &renderer->viewportHeight);
+				mSDLGLDoViewport(renderer->viewportWidth, renderer->viewportHeight, v);
+				renderer->player.windowUpdated = 0;
+			}
+#endif
 		}
 
 		if (mCoreSyncWaitFrameStart(&context->sync)) {