1st part of implementing blended screenshots (see #395)

src/emucore/EventHandler.cxx

@@ -46,6 +46,7 @@
 #include "M6532.hxx"
 #include "MouseControl.hxx"
 #include "PNGLibrary.hxx"
+#include "TIASurface.hxx"
 
 #include "EventHandler.hxx"
 
@@ -386,7 +387,8 @@ void EventHandler::handleEvent(Event::Type event, Int32 state)
       return;
 
     case Event::TakeSnapshot:
-      if(state) myOSystem.png().takeSnapshot();
+      //if(state) myOSystem.png().takeSnapshot();
+      if(state) myOSystem.frameBuffer().tiaSurface().saveSnapShot();
       return;
 
     case Event::LauncherMode:

src/emucore/TIASurface.cxx

@@ -23,6 +23,7 @@
 #include "OSystem.hxx"
 #include "Console.hxx"
 #include "TIA.hxx"
+    #include "PNGLibrary.hxx"
 #include "TIASurface.hxx"
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -34,7 +35,8 @@ TIASurface::TIASurface(OSystem& system)
     myUsePhosphor(false),
     myPhosphorPercent(0.60f),
     myScanlinesEnabled(false),
-    myPalette(nullptr)
+    myPalette(nullptr),
+    saveFlag(false)
 {
   // Load NTSC filter settings
   myNTSCFilter.loadConfig(myOSystem.settings());
@@ -389,6 +391,12 @@ void TIASurface::render()
   // Draw overlaying scanlines
   if(myScanlinesEnabled)
     mySLineSurface->render();
+
+  if(saveFlag)
+  {
+    saveFlag = false;
+    myOSystem.png().takeSnapshot();
+  }
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

src/emucore/TIASurface.hxx

@@ -155,6 +155,11 @@ class TIASurface
     */
     void reRender();
 
+    /**
+      Save a snapshot after rendering.
+    */
+    void saveSnapShot() { saveFlag = true; }
+
   private:
     OSystem& myOSystem;
     FrameBuffer& myFB;
@@ -202,6 +207,9 @@ class TIASurface
     // Palette for normal TIA rendering mode
     const uInt32* myPalette;
 
+    // Flag for saving a snapshot
+    bool saveFlag;
+
   private:
     // Following constructors and assignment operators not supported
     TIASurface() = delete;