Handle VideoSoftware's present fallback better

Not a good idea to abuse bSupportsPostProcessing

Source/Core/VideoBackends/Null/NullGfx.cpp

@@ -29,6 +29,11 @@ bool NullGfx::IsHeadless() const
   return true;
 }
 
+bool NullGfx::SupportsUtilityDrawing() const
+{
+  return false;
+}
+
 std::unique_ptr<AbstractTexture> NullGfx::CreateTexture(const TextureConfig& config,
                                                         [[maybe_unused]] std::string_view name)
 {

Source/Core/VideoBackends/Null/NullGfx.h

@@ -15,6 +15,7 @@ public:
   ~NullGfx() override;
 
   bool IsHeadless() const override;
+  virtual bool SupportsUtilityDrawing() const override;
 
   std::unique_ptr<AbstractTexture> CreateTexture(const TextureConfig& config,
                                                  std::string_view name) override;

Source/Core/VideoBackends/Software/SWGfx.cpp

@@ -27,6 +27,11 @@ bool SWGfx::IsHeadless() const
   return m_window->IsHeadless();
 }
 
+bool SWGfx::SupportsUtilityDrawing() const
+{
+  return false;
+}
+
 std::unique_ptr<AbstractTexture> SWGfx::CreateTexture(const TextureConfig& config,
                                                       [[maybe_unused]] std::string_view name)
 {

Source/Core/VideoBackends/Software/SWGfx.h

@@ -15,6 +15,7 @@ public:
   SWGfx(std::unique_ptr<SWOGLWindow> window);
 
   bool IsHeadless() const override;
+  virtual bool SupportsUtilityDrawing() const override;
 
   std::unique_ptr<AbstractTexture> CreateTexture(const TextureConfig& config,
                                                  std::string_view name) override;

Source/Core/VideoCommon/AbstractGfx.h

@@ -59,6 +59,9 @@ public:
 
   virtual bool IsHeadless() const = 0;
 
+  // Does the backend support drawing a UI or doing post-processing
+  virtual bool SupportsUtilityDrawing() const { return true; }
+
   virtual void SetPipeline(const AbstractPipeline* pipeline) {}
   virtual void SetScissorRect(const MathUtil::Rectangle<int>& rc) {}
   virtual void SetTexture(u32 index, const AbstractTexture* texture) {}

Source/Core/VideoCommon/Present.cpp

@@ -393,12 +393,6 @@ void Presenter::RenderXFBToScreen(const MathUtil::Rectangle<int>& target_rc,
                                   const AbstractTexture* source_texture,
                                   const MathUtil::Rectangle<int>& source_rc)
 {
-  if (!g_ActiveConfig.backend_info.bSupportsPostProcessing)
-  {
-    g_gfx->ShowImage(source_texture, source_rc);
-    return;
-  }
-
   if (g_ActiveConfig.stereo_mode == StereoMode::QuadBuffer &&
       g_ActiveConfig.backend_info.bUsesExplictQuadBuffering)
   {
@@ -463,6 +457,14 @@ void Presenter::Present()
 {
   m_last_xfb_id = m_xfb_entry->id;
 
+  if (!g_gfx->SupportsUtilityDrawing())
+  {
+    // Video Software doesn't support Drawing a UI or doing post-processing
+    // So just Show the XFB
+    g_gfx->ShowImage(m_xfb_entry->texture.get(), m_xfb_rect);
+    return;
+  }
+
   // Since we use the common pipelines here and draw vertices if a batch is currently being
   // built by the vertex loader, we end up trampling over its pointer, as we share the buffer
   // with the loader, and it has not been unmapped yet. Force a pipeline flush to avoid this.