Fix minor compile warnings, including using float instead of double in a few places.

src/common/FrameBufferSDL2.cxx

@@ -221,7 +221,7 @@ bool FrameBufferSDL2::setVideoMode(const string& title, const VideoMode& mode)
     posX = posY = SDL_WINDOWPOS_CENTERED_DISPLAY(displayIndex);
   else
   {
-    posX = myWindowedPos.x,
+    posX = myWindowedPos.x;
     posY = myWindowedPos.y;
 
     // make sure the window is at least partially visibile

src/emucore/FrameBuffer.cxx

@@ -835,10 +835,10 @@ void FrameBuffer::toggleGrabMouse()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-double FrameBuffer::maxZoomForScreen(uInt32 baseWidth, uInt32 baseHeight,
+float FrameBuffer::maxZoomForScreen(uInt32 baseWidth, uInt32 baseHeight,
                                     uInt32 screenWidth, uInt32 screenHeight) const
 {
-  double multiplier = 1;
+  float multiplier = 1;
   for(;;)
   {
     // Figure out the zoomed size of the window
@@ -868,7 +868,7 @@ void FrameBuffer::setAvailableVidModes(uInt32 baseWidth, uInt32 baseHeight)
   EventHandlerState state = myOSystem.eventHandler().state();
   bool tiaMode = (state != EventHandlerState::DEBUGGER &&
                   state != EventHandlerState::LAUNCHER);
-  double overscan = 1 - myOSystem.settings().getInt("tia.fs_overscan") / 100.0;
+  float overscan = 1 - myOSystem.settings().getInt("tia.fs_overscan") / 100.0;
 
   // TIA mode allows zooming at integral factors in windowed modes,
   // and also non-integral factors in fullscreen mode
@@ -887,7 +887,7 @@ void FrameBuffer::setAvailableVidModes(uInt32 baseWidth, uInt32 baseHeight)
   #endif
 
     // Determine all zoom levels
-    for(double zoom = minZoom; zoom <= myTIAMaxZoom; zoom += ZOOM_STEPS)
+    for(float zoom = minZoom; zoom <= myTIAMaxZoom; zoom += ZOOM_STEPS)
     {
       ostringstream desc;
       desc << "Zoom " << zoom << "x";
@@ -901,7 +901,8 @@ void FrameBuffer::setAvailableVidModes(uInt32 baseWidth, uInt32 baseHeight)
     for(uInt32 i = 0; i < myFullscreenDisplays.size(); ++i)
     {
       myTIAMaxZoom = maxZoomForScreen(baseWidth, baseHeight,
-                    myFullscreenDisplays[i].w * overscan, myFullscreenDisplays[i].h * overscan);
+          myFullscreenDisplays[i].w * overscan,
+          myFullscreenDisplays[i].h * overscan);
 
       // Add both normal aspect and filled modes
       // It's easier to define them both now, and simply switch between
@@ -984,8 +985,8 @@ FrameBuffer::VideoMode::VideoMode()
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 FrameBuffer::VideoMode::VideoMode(uInt32 iw, uInt32 ih, uInt32 sw, uInt32 sh,
-                                  Stretch smode, double overscan, const string& desc,
-                                  double zoomLevel, Int32 fsindex)
+                                  Stretch smode, float overscan, const string& desc,
+                                  float zoomLevel, Int32 fsindex)
   : stretch(smode),
     description(desc),
     zoom(zoomLevel),
@@ -1118,7 +1119,7 @@ void FrameBuffer::VideoModeList::next()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void FrameBuffer::VideoModeList::setByZoom(double zoom)
+void FrameBuffer::VideoModeList::setByZoom(float zoom)
 {
   for(uInt32 i = 0; i < myModeList.size(); ++i)
   {

src/emucore/FrameBuffer.hxx

@@ -63,12 +63,12 @@ class FrameBuffer
       Common::Size screen;
       Stretch stretch;
       string description;
-      double zoom;
+      float zoom;
       Int32 fsIndex;
 
       VideoMode();
-      VideoMode(uInt32 iw, uInt32 ih, uInt32 sw, uInt32 sh, Stretch smode, double overscan = 1.0,
-                const string& desc = "", double zoomLevel = 1, Int32 fsindex = -1);
+      VideoMode(uInt32 iw, uInt32 ih, uInt32 sw, uInt32 sh, Stretch smode, float overscan = 1.0,
+                const string& desc = "", float zoomLevel = 1, Int32 fsindex = -1);
 
       friend ostream& operator<<(ostream& os, const VideoMode& vm)
       {
@@ -81,7 +81,7 @@ class FrameBuffer
     };
 
     // Zoom level step interval
-    static constexpr double ZOOM_STEPS = 0.25;
+    static constexpr float ZOOM_STEPS = 0.25;
 
   public:
     /**
@@ -198,9 +198,11 @@ class FrameBuffer
     const VariantList& supportedRenderers() const { return myRenderers; }
 
     /**
-      Get the maximum supported TIA zoom level (windowed mode) for the framebuffer.
+      Get the minimum/maximum supported TIA zoom level (windowed mode)
+      for the framebuffer.
     */
-    const double supportedTIAMaxZoom() const { return myTIAMaxZoom;  }
+    float supportedTIAMinZoom() const { return 2 * hidpiScaleFactor(); }
+    float supportedTIAMaxZoom() const { return myTIAMaxZoom; }
 
     /**
       Get the TIA surface associated with the framebuffer.
@@ -454,7 +456,7 @@ class FrameBuffer
       Calculate the maximum level by which the base window can be zoomed and
       still fit in the given screen dimensions.
     */
-    double maxZoomForScreen(uInt32 baseWidth, uInt32 baseHeight,
+    float maxZoomForScreen(uInt32 baseWidth, uInt32 baseHeight,
                uInt32 screenWidth, uInt32 screenHeight) const;
 
     /**
@@ -493,7 +495,7 @@ class FrameBuffer
         const FrameBuffer::VideoMode& current() const;
         void next();
 
-        void setByZoom(double zoom);
+        void setByZoom(float zoom);
         void setByStretch(FrameBuffer::VideoMode::Stretch stretch);
 
         friend ostream& operator<<(ostream& os, const VideoModeList& l)
@@ -595,7 +597,7 @@ class FrameBuffer
     vector<VideoModeList> myFullscreenModeLists;
 
     // Maximum TIA zoom level that can be used for this framebuffer
-    double myTIAMaxZoom;
+    float myTIAMaxZoom;
 
     // Holds a reference to all the surfaces that have been created
     vector<shared_ptr<FBSurface>> mySurfaceList;

src/gui/VideoDialog.cxx

@@ -337,6 +337,7 @@ void VideoDialog::loadConfig()
   // TIA zoom levels
   // These are dynamically loaded, since they depend on the size of
   // the desktop and which renderer we're using
+  myTIAZoom->setMinValue(instance().frameBuffer().supportedTIAMinZoom() * 100);
   myTIAZoom->setMaxValue(instance().frameBuffer().supportedTIAMaxZoom() * 100);
   myTIAZoom->setTickmarkIntervals((instance().frameBuffer().supportedTIAMaxZoom() - 2) * 2);
   myTIAZoom->setValue(instance().settings().getFloat("tia.zoom") * 100);