From e1358b966a1a2f48d5ef6af2cd1b5ffc302ef6f2 Mon Sep 17 00:00:00 2001
From: Bastien Bouclet <bastien.bouclet@gmail.com>
Date: Fri, 14 Feb 2020 06:21:46 +0100
Subject: [PATCH] 3DS: Defer texture updates when the palette changes

Fixes a performance issue with the Gob engine where the palette is
updated a large number of times during a single frame.
---
 backends/platform/3ds/osystem-graphics.cpp | 14 ++++++++------
 backends/platform/3ds/osystem.cpp          |  1 +
 backends/platform/3ds/osystem.h            |  1 +
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/backends/platform/3ds/osystem-graphics.cpp b/backends/platform/3ds/osystem-graphics.cpp
index a94557b3c16..b4ff84cbcaa 100644
--- a/backends/platform/3ds/osystem-graphics.cpp
+++ b/backends/platform/3ds/osystem-graphics.cpp
@@ -329,12 +329,9 @@ float OSystem_3DS::getScaleRatio() const {
 void OSystem_3DS::setPalette(const byte *colors, uint start, uint num) {
 	assert(start + num <= 256);
 	memcpy(_palette + 3 * start, colors, 3 * num);
-
-	// Manually update all color that were changed
-	if (_gameScreen.format.bytesPerPixel == 1) {
-		flushGameScreen();
-	}
+	_gameTextureDirty = true;
 }
+
 void OSystem_3DS::grabPalette(byte *colors, uint start, uint num) const {
 	assert(start + num <= 256);
 	memcpy(colors, _palette + 3 * start, 3 * num);
@@ -391,7 +388,7 @@ Graphics::Surface *OSystem_3DS::lockScreen() {
 	return &_gameScreen;
 }
 void OSystem_3DS::unlockScreen() {
-	flushGameScreen();
+	_gameTextureDirty = true;
 }
 
 void OSystem_3DS::updateScreen() {
@@ -399,6 +396,11 @@ void OSystem_3DS::updateScreen() {
 		return;
 	}
 
+	if (_gameTextureDirty) {
+		flushGameScreen();
+		_gameTextureDirty = false;
+	}
+
 // 	updateFocus();
 	updateMagnify();
 
diff --git a/backends/platform/3ds/osystem.cpp b/backends/platform/3ds/osystem.cpp
index 11022b6ec93..ce68f97815a 100644
--- a/backends/platform/3ds/osystem.cpp
+++ b/backends/platform/3ds/osystem.cpp
@@ -78,6 +78,7 @@ OSystem_3DS::OSystem_3DS():
 	_magY(0),
 	_magWidth(400),
 	_magHeight(240),
+	_gameTextureDirty(false),
 	_overlayVisible(false),
 	_screenChangeId(0),
 	_magnifyMode(MODE_MAGOFF),
diff --git a/backends/platform/3ds/osystem.h b/backends/platform/3ds/osystem.h
index 93439d50611..d4fa6e4ed3e 100644
--- a/backends/platform/3ds/osystem.h
+++ b/backends/platform/3ds/osystem.h
@@ -222,6 +222,7 @@ private:
 	byte _cursorPalette[3 * 256];
 
 	Graphics::Surface _gameScreen;
+	bool _gameTextureDirty;
 	Sprite _gameTopTexture;
 	Sprite _gameBottomTexture;
 	Sprite _overlay;