Video: polish aspect ratio related code comments to make it clearer

Source/Core/VideoCommon/Present.h

@@ -46,7 +46,7 @@ public:
 
   void ConfigChanged(u32 changed_bits);
 
-  // Display resolution
+  // Window resolution (display resolution if fullscreen)
   int GetBackbufferWidth() const { return m_backbuffer_width; }
   int GetBackbufferHeight() const { return m_backbuffer_height; }
   float GetBackbufferScale() const { return m_backbuffer_scale; }
@@ -58,6 +58,7 @@ public:
 
   void UpdateDrawRectangle();
 
+  // Returns the target aspect ratio the XFB output should be drawn with.
   float CalculateDrawAspectRatio(bool allow_stretch = true) const;
 
   // Crops the target rectangle to the framebuffer dimensions, reducing the size of the source
@@ -126,6 +127,9 @@ private:
   Common::Flag m_surface_changed;
   Common::Flag m_surface_resized;
 
+  // The presentation rectangle.
+  // Width and height correspond to the final output resolution.
+  // Offsets imply black borders (if the window aspect ratio doesn't match the game's one).
   MathUtil::Rectangle<int> m_target_rectangle = {};
 
   RcTcacheEntry m_xfb_entry;

Source/Core/VideoCommon/VertexManagerBase.cpp

@@ -91,8 +91,9 @@ static bool IsAnamorphicProjection(const Projection::Raw& projection, const View
                                    const VideoConfig& config)
 {
   // If ratio between our projection and viewport aspect ratios is similar to 16:9 / 4:3
-  // we have an anamorphic projection. This value can be overridden
-  // by a GameINI.
+  // we have an anamorphic projection. This value can be overridden by a GameINI.
+  // Game cheats that change the aspect ratio to natively unsupported ones
+  // won't be automatically recognized here.
 
   return std::abs(CalculateProjectionViewportRatio(projection, viewport) -
                   config.widescreen_heuristic_widescreen_ratio) <

Source/Core/VideoCommon/Widescreen.cpp

@@ -53,6 +53,7 @@ void WidescreenManager::Update()
 }
 
 // Heuristic to detect if a GameCube game is in 16:9 anamorphic widescreen mode.
+// Cheats that change the game aspect ratio to natively unsupported ones won't be recognized here.
 void WidescreenManager::UpdateWidescreenHeuristic()
 {
   const auto flush_statistics = g_vertex_manager->ResetFlushAspectRatioCount();

Source/Core/VideoCommon/Widescreen.h

@@ -11,11 +11,14 @@
 class PointerWrap;
 
 // This class is responsible for tracking the game's aspect ratio.
+// This exclusively supports 4:3 or 16:9 detection by default.
 class WidescreenManager
 {
 public:
   WidescreenManager();
 
+  // Just a helper to tell whether the game seems to be running in widescreen,
+  // or if it's being forced to.
   bool IsGameWidescreen() const { return m_is_game_widescreen; }
 
   void DoState(PointerWrap& p);