Fix button colors in some themes

iOS/GBBackgroundView.m

@@ -497,7 +497,7 @@ static GB_key_mask_t angleToKeyMask(double angle)
     
     if (@available(iOS 13.0, *)) {
         self.overrideUserInterfaceStyle = layout.theme.isDark? UIUserInterfaceStyleDark : UIUserInterfaceStyleLight;
-        self.tintColor = layout.theme.brandColor;
+        self.tintColor = layout.theme.buttonColor;
     }
 
     _screenLabel.frame = screenFrame;

iOS/GBTheme.h

@@ -2,6 +2,7 @@
 
 @interface GBTheme : NSObject
 @property (readonly, direct) UIColor *brandColor;
+@property (readonly, direct) UIColor *buttonColor;
 @property (readonly, direct) UIColor *backgroundGradientTop;
 @property (readonly, direct) UIColor *backgroundGradientBottom;
 @property (readonly, direct) UIColor *bezelsGradientTop;

iOS/GBTheme.m

@@ -155,6 +155,16 @@ __attribute__((objc_direct_members))
 }
 
 
+- (UIColor *)buttonColor
+{
+    double r, g, b;
+    [_brandColor getRed:&r green:&g blue:&b alpha:NULL];
+    if (r == 1.0 && g == 1.0 && b == 1.0) {
+        return _backgroundGradientTop;
+    }
+    return [UIColor colorWithRed:r green:g blue:b alpha:1.0];
+}
+
 - (bool)isDark
 {
     double r, g, b;

iOS/GBViewController.m

@@ -229,7 +229,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
             [[GBHorizontalLayout alloc] initWithTheme:theme cutoutOnRight:true] :
             _horizontalLayoutLeft;
         _verticalLayout = [[GBVerticalLayout alloc] initWithTheme:theme];
-        _printerSpinner.color = theme.brandColor;
+        _printerSpinner.color = theme.buttonColor;
 
         [self willRotateToInterfaceOrientation:[UIApplication sharedApplication].statusBarOrientation
                                           duration:0];
@@ -376,7 +376,7 @@ static void rumbleCallback(GB_gameboy_t *gb, double amp)
     _printerButton = [[UIButton alloc] init];
     _printerSpinner = [[UIActivityIndicatorView alloc] init];
     _printerSpinner.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhite;
-    _printerSpinner.color = _verticalLayout.theme.brandColor;
+    _printerSpinner.color = _verticalLayout.theme.buttonColor;
     [self didRotateFromInterfaceOrientation:[UIApplication sharedApplication].statusBarOrientation];
     
     if (@available(iOS 13.0, *)) {