From 904345ff828016cc3e351edbb3a5a24ae490657e Mon Sep 17 00:00:00 2001
From: refractionpcsx2 <refraction@gmail.com>
Date: Fri, 15 Apr 2022 19:33:20 +0100
Subject: [PATCH] GS: Get display width for frame when offsets off

---
 pcsx2/GS/GSState.cpp | 22 +++++++++++++++++++++-
 pcsx2/GS/GSState.h   |  1 +
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/pcsx2/GS/GSState.cpp b/pcsx2/GS/GSState.cpp
index 3be72d2735..ab32f3597b 100644
--- a/pcsx2/GS/GSState.cpp
+++ b/pcsx2/GS/GSState.cpp
@@ -416,6 +416,20 @@ GSVector4i GSState::GetFrameMagnifiedRect(int i)
 	return rectangle;
 }
 
+int GSState::GetDisplayHMagnification()
+{
+	// Pick one of the DISPLAY's and hope that they are both the same. Favour DISPLAY[1]
+	for (int i = 1; i >= 0; i--)
+	{
+		if (IsEnabled(i))
+			return m_regs->DISP[i].DISPLAY.MAGH + 1;
+	}
+
+	// If neither DISPLAY is enabled, fallback to resolution offset (should never happen)
+	const GSVideoMode videomode = GetVideoMode();
+	return VideoModeDividers[(int)videomode - 1].x + 1;
+}
+
 GSVector4i GSState::GetDisplayRect(int i)
 {
 	GSVector4i rectangle = { 0, 0, 0, 0 };
@@ -479,10 +493,16 @@ GSVector2i GSState::GetResolution()
 
 	if (ignore_offset)
 	{
+		// Ideally we'd just cut the width at the resolution, but of course we have to hack the hack...
+		// Some games (Mortal Kombat Armageddon) render the image at 834 pixels then shrink it to 624 pixels
+		// which does fit, but when we ignore offsets we go on framebuffer size and some other games
+		// such as Johnny Mosleys Mad Trix and Transformers render too much but design it to go off the screen.
+		int magnified_width = VideoModeDividers[(int)videomode - 1].z / GetDisplayHMagnification();
+
 		GSVector4i total_rect = GetDisplayRect(0).runion(GetDisplayRect(1));
 		total_rect.z = total_rect.z - total_rect.x;
 		total_rect.w = total_rect.w - total_rect.y;
-		total_rect.z = std::min(total_rect.z, resolution.x);
+		total_rect.z = std::min(total_rect.z, magnified_width);
 		total_rect.w = std::min(total_rect.w, resolution.y);
 		resolution.x = total_rect.z;
 		resolution.y = total_rect.w;
diff --git a/pcsx2/GS/GSState.h b/pcsx2/GS/GSState.h
index 807a27e691..000e751dc5 100644
--- a/pcsx2/GS/GSState.h
+++ b/pcsx2/GS/GSState.h
@@ -288,6 +288,7 @@ public:
 	void ResetHandlers();
 
 	int GetFramebufferHeight();
+	int GetDisplayHMagnification();
 	GSVector4i GetDisplayRect(int i = -1);
 	GSVector4i GetFrameMagnifiedRect(int i = -1);
 	GSVector2i GetResolutionOffset(int i = -1);