Qt: Add Windows Auto HDR option to Graphics display settings.

 Registers PCSX2 in the Windows registry to force Auto HDR to activate. Requires restarting PCSX2 to take effect.

Author: jasaaved

pcsx2-qt/QtHost.cpp

@@ -2037,6 +2037,74 @@ static void SignalHandler(int signal)
 
 #ifdef _WIN32
 
+static void RegisterAutoHDR(bool enable)
+{
+	// Get the actual exe path (varies by build: pcsx2-qt.exe, pcsx2-qtx64.exe, etc.)
+	wchar_t exe_path[MAX_PATH];
+	if (GetModuleFileNameW(nullptr, exe_path, MAX_PATH) == 0)
+		return;
+
+	HKEY base_key;
+	if (RegCreateKeyExW(HKEY_CURRENT_USER, L"SOFTWARE\\Microsoft\\Direct3D",
+			0, nullptr, 0, KEY_READ | KEY_WRITE, nullptr, &base_key, nullptr) != ERROR_SUCCESS)
+		return;
+
+	// Find an existing entry for this exe or the first free slot.
+	wchar_t subkey_name[32];
+	HKEY app_key = nullptr;
+	bool is_existing = false;
+	for (int i = 0; i < 128; i++)
+	{
+		swprintf_s(subkey_name, L"Application%d", i);
+
+		HKEY candidate;
+		if (RegCreateKeyExW(base_key, subkey_name, 0, nullptr, 0, KEY_READ | KEY_WRITE,
+				nullptr, &candidate, nullptr) != ERROR_SUCCESS)
+			break;
+
+		wchar_t name_val[MAX_PATH] = {};
+		DWORD name_val_size = sizeof(name_val);
+		DWORD type = 0;
+		const bool has_name = RegQueryValueExW(candidate, L"Name", nullptr, &type,
+								  reinterpret_cast<BYTE*>(name_val), &name_val_size) == ERROR_SUCCESS;
+
+		if (!has_name || _wcsicmp(name_val, exe_path) == 0)
+		{
+			app_key = candidate;
+			is_existing = has_name;
+			break;
+		}
+		RegCloseKey(candidate);
+	}
+
+	if (app_key)
+	{
+		if (enable)
+		{
+			RegSetValueExW(app_key, L"Name", 0, REG_SZ,
+				reinterpret_cast<const BYTE*>(exe_path), static_cast<DWORD>((wcslen(exe_path) + 1) * sizeof(wchar_t)));
+
+			constexpr const wchar_t behaviors[] = L"BufferUpgradeOverride=1";
+			RegSetValueExW(app_key, L"D3DBehaviors", 0, REG_SZ,
+				reinterpret_cast<const BYTE*>(behaviors), sizeof(behaviors));
+		}
+		else if (is_existing)
+		{
+			// Remove D3DBehaviors so Auto HDR no longer activates.
+			RegDeleteValueW(app_key, L"D3DBehaviors");
+		}
+
+		RegCloseKey(app_key);
+	}
+
+	RegCloseKey(base_key);
+}
+
+void QtHost::UpdateAutoHDRRegistration(bool enable)
+{
+	RegisterAutoHDR(enable);
+}
+
 static BOOL WINAPI ConsoleCtrlHandler(DWORD dwCtrlType)
 {
 	if (dwCtrlType != CTRL_C_EVENT)
@@ -2297,8 +2365,8 @@ bool QtHost::ParseCommandLineOptions(const QStringList& args, std::shared_ptr<VM
 		Console.Warning("Skipping autoboot due to no boot parameters.");
 		autoboot.reset();
 	}
-	
-	if(autoboot && autoboot->start_turbo.value_or(false) && autoboot->start_unlimited.value_or(false))
+
+	if (autoboot && autoboot->start_turbo.value_or(false) && autoboot->start_unlimited.value_or(false))
 	{
 		Console.Warning("Both turbo and unlimited frame limit modes requested. Using unlimited.");
 		autoboot->start_turbo.reset();
@@ -2415,6 +2483,10 @@ int main(int argc, char* argv[])
 	if (!QtHost::InitializeConfig())
 		return EXIT_FAILURE;
 
+#ifdef _WIN32
+	RegisterAutoHDR(Host::GetBoolSettingValue("EmuCore/GS", "EnableAutoHDR", false));
+#endif
+
 	// Are we just setting up the configuration?
 	if (s_test_config_and_exit)
 		return EXIT_SUCCESS;

pcsx2-qt/QtHost.h

@@ -298,4 +298,9 @@ namespace QtHost
 	/// inside its exec function, which would cause a crash.
 	void LockVMWithDialog();
 	void UnlockVMWithDialog();
+
+#ifdef _WIN32
+	/// Registers or unregisters PCSX2 with Windows for Auto HDR.
+	void UpdateAutoHDRRegistration(bool enable);
+#endif
 } // namespace QtHost

pcsx2-qt/Settings/GraphicsDisplaySettingsTab.ui

@@ -87,6 +87,16 @@
        </property>
       </widget>
      </item>
+     <item row="3" column="1">
+      <widget class="QCheckBox" name="enableAutoHDR">
+       <property name="toolTip">
+        <string>Registers PCSX2 with Windows so that Auto HDR is applied to the game image. Requires Direct3D 11 or Direct3D 12. Requires restarting PCSX2 to take effect.</string>
+       </property>
+       <property name="text">
+        <string>Enable Windows Auto HDR</string>
+       </property>
+      </widget>
+     </item>
     </layout>
    </item>
    <item row="2" column="0">

pcsx2-qt/Settings/GraphicsSettingsWidget.cpp

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-3.0+
 
 #include "GraphicsSettingsWidget.h"
+#include "QtHost.h"
 #include "QtUtils.h"
 #include "SettingWidgetBinder.h"
 #include "SettingsWindow.h"
@@ -222,6 +223,7 @@ GraphicsSettingsWidget::GraphicsSettingsWidget(SettingsWindow* settings_dialog,
 	// Advanced Settings
 	//////////////////////////////////////////////////////////////////////////
 	SettingWidgetBinder::BindWidgetToBoolSetting(sif, m_advanced.useBlitSwapChain, "EmuCore/GS", "UseBlitSwapChain", false);
+	SettingWidgetBinder::BindWidgetToBoolSetting(sif, m_display.enableAutoHDR, "EmuCore/GS", "EnableAutoHDR", false);
 	SettingWidgetBinder::BindWidgetToBoolSetting(sif, m_advanced.useDebugDevice, "EmuCore/GS", "UseDebugDevice", false);
 	SettingWidgetBinder::BindWidgetToBoolSetting(sif, m_advanced.disableMailboxPresentation, "EmuCore/GS", "DisableMailboxPresentation", false);
 	SettingWidgetBinder::BindWidgetToBoolSetting(sif, m_advanced.extendedUpscales, "EmuCore/GS", "ExtendedUpscalingMultipliers", false);
@@ -271,6 +273,11 @@ GraphicsSettingsWidget::GraphicsSettingsWidget(SettingsWindow* settings_dialog,
 
 	connect(m_header.rendererDropdown, &QComboBox::currentIndexChanged, this, &GraphicsSettingsWidget::onRendererChanged);
 	connect(m_header.adapterDropdown, &QComboBox::currentIndexChanged, this, &GraphicsSettingsWidget::onAdapterChanged);
+#ifdef _WIN32
+	connect(m_display.enableAutoHDR, &QCheckBox::checkStateChanged, this, [](Qt::CheckState state) {
+		QtHost::UpdateAutoHDRRegistration(state == Qt::Checked);
+	});
+#endif
 	connect(m_hw.enableHWFixes, &QCheckBox::checkStateChanged, this, &GraphicsSettingsWidget::updateRendererDependentOptions);
 	connect(m_advanced.extendedUpscales, &QCheckBox::checkStateChanged, this, &GraphicsSettingsWidget::updateRendererDependentOptions);
 	connect(m_hw.textureFiltering, &QComboBox::currentIndexChanged, this, &GraphicsSettingsWidget::onTextureFilteringChange);
@@ -281,6 +288,8 @@ GraphicsSettingsWidget::GraphicsSettingsWidget(SettingsWindow* settings_dialog,
 	// Exclusive fullscreen control is Windows-only.
 	m_advanced.advancedOptionsFormLayout->removeRow(2);
 	m_advanced.exclusiveFullscreenControl = nullptr;
+	// Auto HDR is Windows-only.
+	m_display.enableAutoHDR->setVisible(false);
 #endif
 
 #ifndef PCSX2_DEVBUILD
@@ -738,6 +747,12 @@ GraphicsSettingsWidget::GraphicsSettingsWidget(SettingsWindow* settings_dialog,
 			tr("Change the compression algorithm used when creating a GS dump."));
 
 		//: Blit = a data operation. You might want to write it as-is, but fully uppercased. More information: https://en.wikipedia.org/wiki/Bit_blit \nSwap chain: see Microsoft's Terminology Portal.
+		dialog()->registerWidgetHelp(m_display.enableAutoHDR, tr("Enable Windows Auto HDR"), tr("Unchecked"),
+			tr("Registers PCSX2 with Windows to enable Auto HDR on the game image. "
+			   "Windows Auto HDR automatically enhances SDR content with high dynamic range on supported displays. "
+			   "Only applies when using the Direct3D 11 or Direct3D 12 renderers. "
+			   "Requires restarting PCSX2 to take effect."));
+
 		dialog()->registerWidgetHelp(m_advanced.useBlitSwapChain, tr("Use Blit Swap Chain"), tr("Unchecked"),
 			//: Blit = a data operation. You might want to write it as-is, but fully uppercased. More information: https://en.wikipedia.org/wiki/Bit_blit
 			tr("Uses a blit presentation model instead of flipping when using the Direct3D 11 "