Add options for which displays to show screen saver

EpochFlipClock.m

@@ -3,15 +3,53 @@
 
 @implementation EpochFlipClock
 
+static NSString * const epochFlipClockModule = @"com.epochflipclock";
+
 - (id)initWithFrame:(NSRect)frame isPreview:(BOOL)isPreview {
     if (!(self = [super initWithFrame:frame isPreview:isPreview])) return nil;
-
+    
+    // Preference Defaults
+    ScreenSaverDefaults *defaults;
+    defaults = [ScreenSaverDefaults defaultsForModuleWithName:epochFlipClockModule];
+    
+    [defaults registerDefaults:[NSDictionary dictionaryWithObjectsAndKeys:
+        @"0", @"screenDisplayOption", // Default to show only on primary display
+        nil]];
+    
+    // Webview
     NSURL* indexHTMLDocumentURL = [NSURL URLWithString:[[[NSURL fileURLWithPath:[[NSBundle bundleForClass:self.class].resourcePath stringByAppendingString:@"/Webview/index.html"] isDirectory:NO] description] stringByAppendingFormat:@"?screensaver=1%@", self.isPreview ? @"&is_preview=1" : @""]];
 
     WebView* webView = [[WebView alloc] initWithFrame:NSMakeRect(0, 0, frame.size.width, frame.size.height)];
     webView.drawsBackground = NO; // Avoids a "white flash" just before the index.html file has loaded
     [webView.mainFrame loadRequest:[NSURLRequest requestWithURL:indexHTMLDocumentURL cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30.0]];
-    [self addSubview:webView];
+    
+    // Show on screens based on preferences
+    NSArray* screens = [NSScreen screens];
+    NSScreen* primaryScreen = [screens objectAtIndex:0];
+    
+    switch ([defaults integerForKey:@"screenDisplayOption"]) {
+        // Primary screen (System Preferences > Displays).
+        // The screen the menubar is shown on under 'arrangement'
+        case 0:
+            if ((primaryScreen.frame.origin.x == frame.origin.x) || isPreview) {
+                [self addSubview:webView];
+            }
+            break;
+        // Last Focussed Screen
+        // This _sometimes_ results in nothing being shown when previewing in system prefs.
+        case 1:
+            if (([NSScreen mainScreen].frame.origin.x == frame.origin.x) || isPreview) {
+                [self addSubview:webView];
+            }
+            break;
+        // All Screens
+        case 2:
+            [self addSubview:webView];
+            break;
+        default:
+            [self addSubview:webView];
+            break;
+    }
 
     return self;
 }
@@ -19,7 +57,50 @@
 #pragma mark - ScreenSaverView
 
 - (void)animateOneFrame { [self stopAnimation]; }
-- (BOOL)hasConfigureSheet { return NO; }
+
+#pragma mark - Config
+// http://cocoadevcentral.com/articles/000088.php
+
+- (BOOL)hasConfigureSheet { return YES; }
+
+- (NSWindow *)configureSheet
+{
+    ScreenSaverDefaults *defaults;
+    defaults = [ScreenSaverDefaults defaultsForModuleWithName:epochFlipClockModule];
+    
+    if (!configSheet)
+    {
+        if (![NSBundle loadNibNamed:@"ConfigureSheet" owner:self])
+        {
+            NSLog( @"Failed to load configure sheet." );
+        }
+    }
+    
+    [screenDisplayOption selectItemAtIndex:[defaults integerForKey:@"screenDisplayOption"]];
+
+    return configSheet;
+}
+
+- (IBAction)cancelClick:(id)sender
+{
+    [[NSApplication sharedApplication] endSheet:configSheet];
+}
+
+- (IBAction) okClick: (id)sender
+{
+    ScreenSaverDefaults *defaults;
+    defaults = [ScreenSaverDefaults defaultsForModuleWithName:epochFlipClockModule];
+    
+    // Update our defaults
+    [defaults setInteger:[screenDisplayOption indexOfSelectedItem]
+               forKey:@"screenDisplayOption"];
+    
+    // Save the settings to disk
+    [defaults synchronize];
+    
+    // Close the sheet
+    [[NSApplication sharedApplication] endSheet:configSheet];
+}
 
 #pragma mark - WebFrameLoadDelegate