From a9041b122ff7d6d16482a3ca2a58c24b103d69ed Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Mon, 10 Feb 2025 02:23:53 -0800
Subject: [PATCH] GBA Video: Allow proxy flush timing configuration

---
 include/mgba/internal/gba/renderers/proxy.h |  1 +
 src/gba/core.c                              | 12 ++++++++++++
 src/gba/extra/proxy.c                       |  8 +++++++-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/include/mgba/internal/gba/renderers/proxy.h b/include/mgba/internal/gba/renderers/proxy.h
index 6cb58d092..3d70d5666 100644
--- a/include/mgba/internal/gba/renderers/proxy.h
+++ b/include/mgba/internal/gba/renderers/proxy.h
@@ -17,6 +17,7 @@ struct GBAVideoProxyRenderer {
 	struct GBAVideoRenderer d;
 	struct GBAVideoRenderer* backend;
 	struct mVideoLogger* logger;
+	int flushScanline;
 };
 
 void GBAVideoProxyRendererCreate(struct GBAVideoProxyRenderer* renderer, struct GBAVideoRenderer* backend, struct mVideoLogger* logger);
diff --git a/src/gba/core.c b/src/gba/core.c
index da782d06c..b369c92df 100644
--- a/src/gba/core.c
+++ b/src/gba/core.c
@@ -479,6 +479,14 @@ static void _GBACoreReloadConfigOption(struct mCore* core, const char* option, c
 			GBAVideoAssociateRenderer(&gba->video, renderer);
 		}
 	}
+
+#ifndef MINIMAL_CORE
+	if (strcmp("threadedVideo.flushScanline", option) == 0) {
+		int flushScanline = -1;
+		mCoreConfigGetIntValue(config, "threadedVideo.flushScanline", &flushScanline);
+		gbacore->proxyRenderer.flushScanline = flushScanline;
+	}
+#endif
 }
 
 static void _GBACoreSetOverride(struct mCore* core, const void* override) {
@@ -730,6 +738,10 @@ static void _GBACoreReset(struct mCore* core) {
 		if (renderer && core->videoLogger) {
 			GBAVideoProxyRendererCreate(&gbacore->proxyRenderer, renderer, core->videoLogger);
 			renderer = &gbacore->proxyRenderer.d;
+
+			int flushScanline = -1;
+			mCoreConfigGetIntValue(&core->config, "threadedVideo.flushScanline", &flushScanline);
+			gbacore->proxyRenderer.flushScanline = flushScanline;
 		}
 #endif
 		if (renderer) {
diff --git a/src/gba/extra/proxy.c b/src/gba/extra/proxy.c
index e33c7b568..bcf91f5f4 100644
--- a/src/gba/extra/proxy.c
+++ b/src/gba/extra/proxy.c
@@ -75,6 +75,7 @@ void GBAVideoProxyRendererCreate(struct GBAVideoProxyRenderer* renderer, struct
 	logger->vramSize = GBA_SIZE_VRAM;
 	logger->oamSize = GBA_SIZE_OAM;
 
+	renderer->flushScanline = -1;
 	renderer->backend = backend;
 }
 
@@ -359,6 +360,9 @@ void GBAVideoProxyRendererWriteOAM(struct GBAVideoRenderer* renderer, uint32_t o
 
 void GBAVideoProxyRendererDrawScanline(struct GBAVideoRenderer* renderer, int y) {
 	struct GBAVideoProxyRenderer* proxyRenderer = (struct GBAVideoProxyRenderer*) renderer;
+	if (proxyRenderer->flushScanline == y) {
+		mVideoLoggerRendererFlush(proxyRenderer->logger);
+	}
 	if (!proxyRenderer->logger->block) {
 		_copyExtraState(proxyRenderer);
 		proxyRenderer->backend->drawScanline(proxyRenderer->backend, y);
@@ -375,7 +379,9 @@ void GBAVideoProxyRendererFinishFrame(struct GBAVideoRenderer* renderer) {
 		proxyRenderer->backend->finishFrame(proxyRenderer->backend);
 	}
 	mVideoLoggerRendererFinishFrame(proxyRenderer->logger);
-	mVideoLoggerRendererFlush(proxyRenderer->logger);
+	if (proxyRenderer->flushScanline < 0) {
+		mVideoLoggerRendererFlush(proxyRenderer->logger);
+	}
 }
 
 static void GBAVideoProxyRendererGetPixels(struct GBAVideoRenderer* renderer, size_t* stride, const void** pixels) {