UWP: Fix DPI calculations for touch. Implement back button support.

GPU/Common/ShaderTranslation.cpp

@@ -15,6 +15,8 @@
 // Official git repository and contact information can be found at
 // https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.
 
+#include "ppsspp_config.h"
+
 #if !defined(ANDROID)
 
 #include <memory>
@@ -55,13 +57,13 @@ static EShLanguage GetLanguage(const Draw::ShaderStage stage) {
 }
 
 void ShaderTranslationInit() {
-	// TODO: We have TLS issues on mobile
+	// TODO: We have TLS issues on UWP
-#ifndef _M_ARM
+#if !PPSSPP_PLATFORM(UWP)
 	glslang::InitializeProcess();
 #endif
 }
 void ShaderTranslationShutdown() {
-#ifndef _M_ARM
+#if !PPSSPP_PLATFORM(UWP)
 	glslang::FinalizeProcess();
 #endif
 }
@@ -172,7 +174,7 @@ bool TranslateShader(std::string *dest, ShaderLanguage destLang, TranslatedShade
 	if (srcLang != GLSL_300 && srcLang != GLSL_140)
 		return false;
 
-#ifdef _M_ARM
+#if PPSSPP_PLATFORM(UWP)
 	return false;
 #endif
 

UI/GamepadEmu.cpp

@@ -620,11 +620,6 @@ UI::ViewGroup *CreatePadLayout(float xres, float yres, bool *pause) {
 
 	const int roundImage = g_Config.iTouchButtonStyle ? I_ROUND_LINE : I_ROUND;
 
-	// These platforms always need the pause menu button to be shown.
-#if defined(IOS)
-	root->Add(new BoolButton(pause, roundImage, I_ARROW, 1.0f, new AnchorLayoutParams(halfW, 20, NONE, NONE, true)))->SetAngle(90);
-#endif
-
 	if (g_Config.bShowTouchControls) {
 		const int rectImage = g_Config.iTouchButtonStyle ? I_RECT_LINE : I_RECT;
 		const int shoulderImage = g_Config.iTouchButtonStyle ? I_SHOULDER_LINE : I_SHOULDER;
@@ -633,10 +628,10 @@ UI::ViewGroup *CreatePadLayout(float xres, float yres, bool *pause) {
 		const int stickBg = g_Config.iTouchButtonStyle ? I_STICK_BG_LINE : I_STICK_BG;
 		static const int comboKeyImages[5] = { I_1, I_2, I_3, I_4, I_5 };
 
-#if !defined(IOS)
+		if (!System_GetPropertyInt(SYSPROP_HAS_BACK_BUTTON)) {
-		if (g_Config.bShowTouchPause)
 			root->Add(new BoolButton(pause, roundImage, I_ARROW, 1.0f, new AnchorLayoutParams(halfW, 20, NONE, NONE, true)))->SetAngle(90);
-#endif
+		}
+
 		if (g_Config.bShowTouchCircle)
 			root->Add(new PSPButton(CTRL_CIRCLE, roundImage, I_CIRCLE, Action_button_scale, new AnchorLayoutParams(Action_circle_button_X, Action_circle_button_Y, NONE, NONE, true)));
 
@@ -685,6 +680,12 @@ UI::ViewGroup *CreatePadLayout(float xres, float yres, bool *pause) {
 		if (g_Config.bShowComboKey4)
 			root->Add(new ComboKey(g_Config.iCombokey4, roundImage, comboKeyImages[4], combo4_key_scale, new AnchorLayoutParams(combo4_key_X, combo4_key_Y, NONE, NONE, true)));
 	}
+	else {
+		// If there's no hardware back button (or ESC key), add a soft button.
+		if (!System_GetPropertyInt(SYSPROP_HAS_BACK_BUTTON)) {
+			root->Add(new BoolButton(pause, roundImage, I_ARROW, 1.0f, new AnchorLayoutParams(halfW, 20, NONE, NONE, true)))->SetAngle(90);
+		}
+	}
 
 	return root;
 }

UWP/App.cpp

@@ -90,9 +90,26 @@ void App::SetWindow(CoreWindow^ window) {
 	window->PointerCaptureLost += ref new TypedEventHandler<CoreWindow^, PointerEventArgs^>(this, &App::OnPointerCaptureLost);
 	window->PointerWheelChanged += ref new TypedEventHandler<CoreWindow^, PointerEventArgs^>(this, &App::OnPointerWheelChanged);
 
+	if (Windows::Foundation::Metadata::ApiInformation::IsTypePresent("Windows.Phone.UI.Input.HardwareButtons")) {
+		m_hardwareButtons.insert(HardwareButton::BACK);
+	}
+
+	Windows::UI::Core::SystemNavigationManager::GetForCurrentView()->
+		BackRequested += ref new Windows::Foundation::EventHandler<
+		Windows::UI::Core::BackRequestedEventArgs^>(
+			this, &App::App_BackRequested);
+
 	m_deviceResources->SetWindow(window);
 }
 
+bool App::HasBackButton() {
+	return m_hardwareButtons.find(HardwareButton::BACK) != m_hardwareButtons.end();
+}
+
+void App::App_BackRequested(Platform::Object^ sender, Windows::UI::Core::BackRequestedEventArgs^ e) {
+	e->Handled = m_main->OnHardwareButton(HardwareButton::BACK);
+}
+
 void App::OnKeyDown(Windows::UI::Core::CoreWindow^ sender, Windows::UI::Core::KeyEventArgs^ args) {
 	m_main->OnKeyDown(args->KeyStatus.ScanCode, args->VirtualKey, args->KeyStatus.RepeatCount);
 }
@@ -185,6 +202,10 @@ void App::Uninitialize() {
 void App::OnActivated(CoreApplicationView^ applicationView, IActivatedEventArgs^ args) {
 	// Run() won't start until the CoreWindow is activated.
 	CoreWindow::GetForCurrentThread()->Activate();
+	// On mobile, we force-enter fullscreen mode.
+#ifdef _ARM
+	Windows::UI::ViewManagement::ApplicationView::GetForCurrentView()->TryEnterFullScreenMode();
+#endif
 }
 
 void App::OnSuspending(Platform::Object^ sender, SuspendingEventArgs^ args) {

UWP/App.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <set>
+
 #include "pch.h"
 #include "Common/DeviceResources.h"
 #include "PPSSPP_UWPMain.h"
@@ -45,6 +47,10 @@ namespace UWP {
 		Touch touches[maxTouches]{};
 	};
 
+	enum class HardwareButton {
+		BACK,
+	};
+
 	// Main entry point for our app. Connects the app with the Windows shell and handles application lifecycle events.
 	ref class App sealed : public Windows::ApplicationModel::Core::IFrameworkView {
 	public:
@@ -57,6 +63,8 @@ namespace UWP {
 		virtual void Run();
 		virtual void Uninitialize();
 
+		bool HasBackButton();
+
 	protected:
 		// Application lifecycle event handlers.
 		void OnActivated(Windows::ApplicationModel::Core::CoreApplicationView^ applicationView, Windows::ApplicationModel::Activation::IActivatedEventArgs^ args);
@@ -85,8 +93,11 @@ namespace UWP {
 		void OnPointerCaptureLost(Windows::UI::Core::CoreWindow^ sender, Windows::UI::Core::PointerEventArgs^ args);
 		void OnPointerWheelChanged(Windows::UI::Core::CoreWindow^ sender, Windows::UI::Core::PointerEventArgs^ args);
 
+		void App_BackRequested(Platform::Object^ sender, Windows::UI::Core::BackRequestedEventArgs^ e);
+
 	private:
 		std::shared_ptr<DX::DeviceResources> m_deviceResources;
+		std::set<HardwareButton> m_hardwareButtons;
 		std::unique_ptr<PPSSPP_UWPMain> m_main;
 		bool m_windowClosed;
 		bool m_windowVisible;

UWP/Common/DeviceResources.cpp

@@ -19,7 +19,7 @@ namespace DisplayMetrics
 	// games attempt to render at 60 frames per second at full fidelity.
 	// The decision to render at full fidelity across all platforms and form factors
 	// should be deliberate.
-	static const bool SupportHighResolutions = false;
+	static const bool SupportHighResolutions = true;
 
 	// The default thresholds that define a "high resolution" display. If the thresholds
 	// are exceeded and SupportHighResolutions is false, the dimensions will be scaled
@@ -441,7 +441,6 @@ void DX::DeviceResources::UpdateRenderTargetSize()
 			m_effectiveDpi /= 2.0f;
 		}
 	}
-
 	// Calculate the necessary render target size in pixels.
 	m_outputSize.Width = DX::ConvertDipsToPixels(m_logicalSize.Width, m_effectiveDpi);
 	m_outputSize.Height = DX::ConvertDipsToPixels(m_logicalSize.Height, m_effectiveDpi);

UWP/Common/DeviceResources.h

@@ -30,6 +30,7 @@ namespace DX
 		// The size of the render target, in dips.
 		Windows::Foundation::Size	GetLogicalSize() const					{ return m_logicalSize; }
 		float	GetDpi() const { return m_effectiveDpi; }
+		float GetActualDpi() const { return m_dpi; }
 
 		// D3D Accessors.
 		ID3D11Device3*				GetD3DDevice() const					{ return m_d3dDevice.Get(); }

UWP/NativeUWP/NativeUWP.vcxproj

@@ -1163,7 +1163,6 @@
     </ClCompile>
     <ClCompile Include="..\..\ext\native\ext\vjson\block_allocator.cpp" />
     <ClCompile Include="..\..\ext\native\ext\vjson\json.cpp" />
-    <ClCompile Include="..\..\ext\native\ext\vjson\main.cpp" />
     <ClCompile Include="..\..\ext\native\file\chunk_file.cpp" />
     <ClCompile Include="..\..\ext\native\file\fd_util.cpp" />
     <ClCompile Include="..\..\ext\native\file\file_util.cpp" />

UWP/NativeUWP/NativeUWP.vcxproj.filters

@@ -220,9 +220,6 @@
     <ClCompile Include="..\..\ext\native\ext\vjson\json.cpp">
       <Filter>ext\vjson</Filter>
     </ClCompile>
-    <ClCompile Include="..\..\ext\native\ext\vjson\main.cpp">
-      <Filter>ext\vjson</Filter>
-    </ClCompile>
     <ClCompile Include="..\..\ext\native\ext\libzip\mkstemp.c">
       <Filter>ext\libzip</Filter>
     </ClCompile>

UWP/PPSSPP_UWPMain.cpp

@@ -26,6 +26,7 @@
 #include "UWPHost.h"
 #include "UWPUtil.h"
 #include "StorageFileLoader.h"
+#include "App.h"
 
 using namespace UWP;
 using namespace Windows::Foundation;
@@ -145,10 +146,10 @@ PPSSPP_UWPMain::~PPSSPP_UWPMain() {
 
 // Updates application state when the window size changes (e.g. device orientation change)
 void PPSSPP_UWPMain::CreateWindowSizeDependentResources() {
-	// TODO: Replace this with the size-dependent initialization of your app's content.
 	ctx_->GetDrawContext()->HandleEvent(Draw::Event::LOST_BACKBUFFER, 0, 0, nullptr);
 
 	NativeResized();
+
 	int width = m_deviceResources->GetScreenViewport().Width;
 	int height = m_deviceResources->GetScreenViewport().Height;
 	ctx_->GetDrawContext()->HandleEvent(Draw::Event::GOT_BACKBUFFER, width, height, m_deviceResources->GetBackBufferRenderTargetView());
@@ -169,8 +170,12 @@ bool PPSSPP_UWPMain::Render() {
 	time_update();
 	auto context = m_deviceResources->GetD3DDeviceContext();
 
-	// Reset the viewport to target the whole screen.
+	auto bounds = Windows::UI::ViewManagement::ApplicationView::GetForCurrentView()->VisibleBounds;
-	auto viewport = m_deviceResources->GetScreenViewport();
+
+	int boundTop = bounds.Top;
+	int boundLeft = bounds.Left;
+	int boundedWidth = bounds.Width;
+	int boundedHeight = bounds.Height;
 
 	switch (m_deviceResources->ComputeDisplayRotation()) {
 	case DXGI_MODE_ROTATION_IDENTITY: g_display_rotation = DisplayRotation::ROTATE_0; break;
@@ -181,6 +186,9 @@ bool PPSSPP_UWPMain::Render() {
 	// Not super elegant but hey.
 	memcpy(&g_display_rot_matrix, &m_deviceResources->GetOrientationTransform3D(), sizeof(float) * 16);
 
+	// Reset the viewport to target the whole screen.
+	auto viewport = m_deviceResources->GetScreenViewport();
+
 	pixel_xres = viewport.Width;
 	pixel_yres = viewport.Height;
 
@@ -189,14 +197,15 @@ bool PPSSPP_UWPMain::Render() {
 		std::swap(pixel_xres, pixel_yres);
 	}
 
-	g_dpi = m_deviceResources->GetDpi();
+	g_dpi = m_deviceResources->GetActualDpi();
+	pixel_xres = (g_dpi / 96.0f) * boundedWidth;
+	pixel_yres = (g_dpi / 96.0f) * boundedHeight;
 
 	if (System_GetPropertyInt(SYSPROP_DEVICE_TYPE) == DEVICE_TYPE_MOBILE) {
 		// Boost DPI a bit to look better.
-		g_dpi_scale = 120.0f / g_dpi;
+		g_dpi *= 96.0f / 136.0f;
-	} else {
-		g_dpi_scale = 96.0f / g_dpi;
 	}
+	g_dpi_scale = 96.0f / g_dpi;
 
 	pixel_in_dps = 1.0f / g_dpi_scale;
 
@@ -260,30 +269,29 @@ void PPSSPP_UWPMain::OnMouseWheel(float delta) {
 	NativeKey(keyInput);
 }
 
-void PPSSPP_UWPMain::RotateXYToDisplay(float &x, float &y) {
+bool PPSSPP_UWPMain::OnHardwareButton(HardwareButton button) {
-	switch (m_deviceResources->ComputeDisplayRotation()) {
+	KeyInput keyInput{};
-	case DXGI_MODE_ROTATION_IDENTITY:
+	keyInput.deviceId = DEVICE_ID_KEYBOARD;
-		// Nothing to do here.
+	keyInput.flags = KEY_DOWN | KEY_UP;
-		break;
+	switch (button) {
-	case DXGI_MODE_ROTATION_ROTATE90:
+	case HardwareButton::BACK:
-		// TODO
+		keyInput.keyCode = NKCODE_BACK;
-		break;
+		return NativeKey(keyInput);
-	case DXGI_MODE_ROTATION_ROTATE180:
+	default:
-		x = m_deviceResources->GetScreenViewport().Width - x;
+		return false;
-		y = m_deviceResources->GetScreenViewport().Height - y;
-		break;
-	case DXGI_MODE_ROTATION_ROTATE270:
-		// TODO
-		break;
 	}
 }
 
 void PPSSPP_UWPMain::OnTouchEvent(int touchEvent, int touchId, float x, float y, double timestamp) {
+	// We get the coordinate in Windows' device independent pixels already. So let's undo that,
+	// and then apply our own "dpi".
+	float dpiFactor = m_deviceResources->GetActualDpi() / 96.0f;
+	dpiFactor /= pixel_in_dps;
+
 	TouchInput input{};
 	input.id = touchId;
-	RotateXYToDisplay(x, y);
+	input.x = x * dpiFactor;
-	input.x = x * pixel_in_dps;
+	input.y = y * dpiFactor;
-	input.y = y * pixel_in_dps;
 	input.flags = touchEvent;
 	input.timestamp = timestamp;
 	NativeTouch(input);
@@ -360,8 +368,10 @@ int System_GetPropertyInt(SystemProperty prop) {
 #else
 		return DEVICE_TYPE_DESKTOP;
 #endif
+	case SYSPROP_HAS_BACK_BUTTON:
+		return 1;
 	case SYSPROP_HAS_FILE_BROWSER:
-		return true;
+		return 1;
 	default:
 		return -1;
 	}
@@ -389,16 +399,6 @@ void System_SendMessage(const char *command, const char *parameter) {
 			if (file) {
 				g_main->LoadStorageFile(file);
 			}
-			/*
-			std::thread([file] {
-				create_task(file->OpenReadAsync()).then([](IRandomAccessStreamWithContentType^ imgStream) {
-					imgStream->Seek(0);
-					IBuffer ^buffer = ref new Streams::Buffer(2048);
-					auto readTask = create_task(imgStream->ReadAsync(buffer, 2048, InputStreamOptions::None));
-					readTask.wait();
-				});
-			}).detach();
-			*/
 		});
 	}
 }
@@ -441,7 +441,7 @@ bool System_InputBoxGetWString(const wchar_t *title, const std::wstring &default
 	return false;
 }
 
-// Emulation of TlsAlloc for Windows 10. Used by glslang.
+// Emulation of TlsAlloc for Windows 10. Used by glslang. Doesn't actually seem to work, other than fixing the linking errors?
 
 extern "C" {
 DWORD WINAPI __imp_TlsAlloc() {

UWP/PPSSPP_UWPMain.h

@@ -12,6 +12,7 @@
 namespace UWP {
 
 ref class App;
+enum class HardwareButton;
 
 class UWPGraphicsContext : public GraphicsContext {
 public:
@@ -50,6 +51,7 @@ public:
 
 	void OnMouseWheel(float delta);
 
+	bool OnHardwareButton(HardwareButton button);
 
 	void RotateXYToDisplay(float &x, float &y);
 

UWP/UWP.vcxproj

@@ -117,9 +117,11 @@
   </ImportGroup>
   <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+    <Import Project="$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props" Condition="exists('$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props')" />
   </ImportGroup>
   <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+    <Import Project="$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props" Condition="exists('$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props')" />
   </ImportGroup>
   <ImportGroup Condition="'$(Configuration)|$(Platform)'=='UWP Gold|Win32'" Label="PropertySheets">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
@@ -127,9 +129,11 @@
   </ImportGroup>
   <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|ARM'">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+    <Import Project="$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props" Condition="exists('$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props')" />
   </ImportGroup>
   <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|ARM'">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+    <Import Project="$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props" Condition="exists('$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props')" />
   </ImportGroup>
   <ImportGroup Condition="'$(Configuration)|$(Platform)'=='UWP Gold|ARM'" Label="PropertySheets">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
@@ -137,9 +141,11 @@
   </ImportGroup>
   <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+    <Import Project="$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props" Condition="exists('$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props')" />
   </ImportGroup>
   <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+    <Import Project="$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props" Condition="exists('$([Microsoft.Build.Utilities.ToolLocationHelper]::GetPlatformExtensionSDKLocation(`WindowsMobile, Version=10.0.10586.0`, $(TargetPlatformIdentifier), $(TargetPlatformVersion),  $(SDKReferenceDirectoryRoot), $(SDKExtensionDirectoryRoot), $(SDKReferenceRegistryRoot)))\DesignTime\CommonConfiguration\Neutral\WindowsMobile.props')" />
   </ImportGroup>
   <ImportGroup Condition="'$(Configuration)|$(Platform)'=='UWP Gold|x64'" Label="PropertySheets">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
@@ -470,6 +476,9 @@ copy AssetsGold\*.* Assets /Y</Command>
       <DeploymentContent>true</DeploymentContent>
     </Text>
   </ItemGroup>
+  <ItemGroup>
+    <SDKReference Include="WindowsMobile, Version=10.0.10586.0" />
+  </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
     <Import Project="$(VSINSTALLDIR)\Common7\IDE\Extensions\Microsoft\VsGraphics\ImageContentTask.targets" />

Windows/main.cpp

@@ -214,6 +214,8 @@ int System_GetPropertyInt(SystemProperty prop) {
 		return ScreenDPI();
 	case SYSPROP_HAS_FILE_BROWSER:
 		return true;
+	case SYSPROP_HAS_BACK_BUTTON:
+		return 1;
 	default:
 		return -1;
 	}

android/jni/app-android.cpp

@@ -443,6 +443,8 @@ int System_GetPropertyInt(SystemProperty prop) {
 		return (int)(display_hz * 1000.0);
 	case SYSPROP_SUPPORTS_PERMISSIONS:
 		return androidVersion >= 23;	// 6.0 Marshmallow introduced run time permissions.
+	case SYSPROP_HAS_BACK_BUTTON:
+		return 1;
 	default:
 		return -1;
 	}

ext/native/base/NativeApp.h

@@ -153,6 +153,7 @@ enum SystemProperty {
 	SYSPROP_GPUDRIVER_VERSION,
 
 	SYSPROP_HAS_FILE_BROWSER,
+	SYSPROP_HAS_BACK_BUTTON,
 
 	// Available as Int:
 	SYSPROP_SYSTEMVERSION,

ext/native/base/PCMain.cpp

@@ -339,6 +339,8 @@ int System_GetPropertyInt(SystemProperty prop) {
 #else
 		return DEVICE_TYPE_DESKTOP;
 #endif
+	case SYSPROP_HAS_BACK_BUTTON:
+		return 1;
 	default:
 		return -1;
 	}

ext/native/base/QtMain.cpp

@@ -77,6 +77,8 @@ int System_GetPropertyInt(SystemProperty prop) {
 #else
 		return DEVICE_TYPE_DESKTOP;
 #endif
+	case SYSPROP_HAS_BACK_BUTTON:
+		return 1;
   default:
     return -1;
   }

ios/main.mm

@@ -66,6 +66,8 @@ int System_GetPropertyInt(SystemProperty prop) {
 		return 60000;
 	case SYSPROP_DEVICE_TYPE:
 		return DEVICE_TYPE_MOBILE;
+	case SYSPROP_HAS_BACK_BUTTON:
+		return 0;
 	default:
 		return -1;
 	}