From 43bfb183c22de508afd2f1b156c9aed15260b01a Mon Sep 17 00:00:00 2001
From: Silent <zdanio95@gmail.com>
Date: Sun, 21 Jul 2019 17:29:08 +0200
Subject: [PATCH] D3D11: Show a warning message about unsupported features when
 switching to D3D11 backend on Windows 7

---
 Source/Core/VideoBackends/D3D/VideoBackend.h |  1 +
 Source/Core/VideoBackends/D3D/main.cpp       | 25 ++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/Source/Core/VideoBackends/D3D/VideoBackend.h b/Source/Core/VideoBackends/D3D/VideoBackend.h
index 0b4c61fc66..e5b996c7e1 100644
--- a/Source/Core/VideoBackends/D3D/VideoBackend.h
+++ b/Source/Core/VideoBackends/D3D/VideoBackend.h
@@ -17,6 +17,7 @@ public:
 
   std::string GetName() const override;
   std::string GetDisplayName() const override;
+  std::optional<std::string> GetWarningMessage() const override;
 
   void InitBackendInfo() override;
 
diff --git a/Source/Core/VideoBackends/D3D/main.cpp b/Source/Core/VideoBackends/D3D/main.cpp
index 6c4bf20dd1..33c9117f25 100644
--- a/Source/Core/VideoBackends/D3D/main.cpp
+++ b/Source/Core/VideoBackends/D3D/main.cpp
@@ -37,6 +37,31 @@ std::string VideoBackend::GetDisplayName() const
   return _trans("Direct3D 11");
 }
 
+std::optional<std::string> VideoBackend::GetWarningMessage() const
+{
+  std::optional<std::string> result;
+
+  // If user is on Win7, show a warning about partial DX11.1 support
+  // This is being called BEFORE FillBackendInfo is called for this backend,
+  // so query for logic op support manually
+  bool supportsLogicOp = false;
+  if (D3DCommon::LoadLibraries())
+  {
+    supportsLogicOp = D3D::SupportsLogicOp(g_Config.iAdapter);
+    D3DCommon::UnloadLibraries();
+  }
+
+  if (!supportsLogicOp)
+  {
+    result = _trans("Direct3D 11 renderer requires support for features not supported by your "
+                    "system configuration. This is most likely because you are using Windows 7. "
+                    "You may still use this backend, but you might encounter graphical artifacts."
+                    "\n\nDo you really want to switch to Direct3D 11? If unsure, select 'No'.");
+  }
+
+  return result;
+}
+
 void VideoBackend::InitBackendInfo()
 {
   if (!D3DCommon::LoadLibraries())