added shading to TIA surface when emulation paused or dialog on top

src/emucore/FrameBuffer.cxx

@@ -346,10 +346,10 @@ void FrameBuffer::update(UpdateMode mode)
       {
         myPausedCount = uInt32(7 * myOSystem.frameRate());
         showTextMessage("Paused", MessagePosition::MiddleCenter);
-        myTIASurface->render();
+        myTIASurface->render(true);
       }
       if(rerender)
-        myTIASurface->render();
+        myTIASurface->render(true);
       break;  // EventHandlerState::PAUSE
     }
 
@@ -361,13 +361,13 @@ void FrameBuffer::update(UpdateMode mode)
       if(redraw)
       {
         clear();
-        myTIASurface->render();
+        myTIASurface->render(true);
         myOSystem.menu().draw(forceRedraw);
       }
       else if(rerender)
       {
         clear();
-        myTIASurface->render();
+        myTIASurface->render(true);
         myOSystem.menu().render();
       }
       break;  // EventHandlerState::OPTIONSMENU
@@ -380,7 +380,7 @@ void FrameBuffer::update(UpdateMode mode)
       if(redraw)
       {
         clear();
-        myTIASurface->render();
+        myTIASurface->render(true);
         myOSystem.commandMenu().draw(forceRedraw);
       }
       break;  // EventHandlerState::CMDMENU
@@ -393,13 +393,13 @@ void FrameBuffer::update(UpdateMode mode)
       if(redraw)
       {
         clear();
-        myTIASurface->render();
+        myTIASurface->render(true);
         myOSystem.highscoresMenu().draw(forceRedraw);
       }
       else if(rerender)
       {
         clear();
-        myTIASurface->render();
+        myTIASurface->render(true);
         myOSystem.highscoresMenu().render();
       }
       break;  // EventHandlerState::HIGHSCORESMENU
@@ -412,7 +412,7 @@ void FrameBuffer::update(UpdateMode mode)
       if(redraw)
       {
         clear();
-        myTIASurface->render();
+        myTIASurface->render(true);
         myOSystem.messageMenu().draw(forceRedraw);
       }
       break;  // EventHandlerState::MESSAGEMENU

src/emucore/TIASurface.cxx

@@ -75,6 +75,17 @@ TIASurface::TIASurface(OSystem& system)
   myBaseTiaSurface = myFB.allocateSurface(TIAConstants::frameBufferWidth*2,
                                           TIAConstants::frameBufferHeight);
 
+  // Create shading surface
+  uInt32 data = 0xff000000;
+
+  myShadeSurface = myFB.allocateSurface(1, 1, ScalingInterpolation::sharp, &data);
+
+  FBSurface::Attributes& attr = myShadeSurface->attributes();
+
+  attr.blending = true;
+  attr.blendalpha = 35; // darken stopped emulation by 35%
+  myShadeSurface->applyAttributes();
+
   myRGBFramebuffer.fill(0);
 
   // Enable/disable threading in the NTSC TV effects renderer
@@ -361,7 +372,7 @@ inline uInt32 TIASurface::averageBuffers(uInt32 bufOfs)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void TIASurface::render()
+void TIASurface::render(bool shade)
 {
   uInt32 width = myTIA->width(), height = myTIA->height();
 
@@ -438,6 +449,12 @@ void TIASurface::render()
   if(myScanlinesEnabled)
     mySLineSurface->render();
 
+  if(shade)
+  {
+    myShadeSurface->setDstRect(myTiaSurface->dstRect());
+    myShadeSurface->render();
+  }
+
   if(mySaveSnapFlag)
   {
     mySaveSnapFlag = false;

src/emucore/TIASurface.hxx

@@ -164,7 +164,7 @@ class TIASurface
     /**
       This method should be called to draw the TIA image(s) to the screen.
     */
-    void render();
+    void render(bool shade = false);
 
     /**
       This method prepares the current frame for taking a snapshot.
@@ -208,7 +208,7 @@ class TIASurface
     FrameBuffer& myFB;
     TIA* myTIA{nullptr};
 
-    shared_ptr<FBSurface> myTiaSurface, mySLineSurface, myBaseTiaSurface;
+    shared_ptr<FBSurface> myTiaSurface, mySLineSurface, myBaseTiaSurface, myShadeSurface;
 
     // NTSC object to use in TIA rendering mode
     NTSCFilter myNTSCFilter;