Make BG of macOS screensaver black? - objective-c

Question

I'm new to Obj-C so apologies if my code is messy.
I've made a screensaver of a DVD logo that changes colour on each bounce. My only problem is the background--it's dark grey instead of black. I'm hoping somebody could help me out.
Here is some of my code:
NSString * dvdPath = [[NSBundle bundleForClass:[self class]] pathForResource:#"dvdlogo" ofType:#"png"];
self.dvdLogo = [[NSImage alloc] initWithContentsOfFile:dvdPath];[self hitWall];}return self;}
- (void)startAnimation
{[super startAnimation];}
- (void)stopAnimation
{[super stopAnimation];}
- (void)drawRect:(NSRect)rectParam
{const float g = 15.0f/255.0f;
[[NSColor colorWithRed:g green:g blue:g alpha:1] setFill];
NSRectFill(rectParam);
NSRect rect;
rect.size = NSMakeSize(self.dvdWidth, self.dvdHeight);
self.x += self.xSpeed;
self.y += self.ySpeed;
rect.origin = CGPointMake(self.x, self.y);
self.dirtyRect = rect;
[self.dvdLogo drawInRect:rect];
CGPoint centre = CGPointMake(CGRectGetMidX(rect), CGRectGetMidY(rect));
if (centre.x + self.dvdWidth / 2 >= WIDTH || centre.x - self.dvdWidth / 2 <= 0) {
self.xSpeed *= -1;
[self hitWall];}
if (centre.y + self.dvdHeight / 2 >= HEIGHT || centre.y - self.dvdHeight / 2 <= 0) {
self.ySpeed *= -1;
[self hitWall];}}
- (void)hitWall
{NSArray * colours = #[[NSColor redColor],
[NSColor blueColor],
[NSColor yellowColor],
[NSColor cyanColor],
[NSColor orangeColor],
[NSColor magentaColor],
[NSColor greenColor]];
self.dvdColor = colours[arc4random() % [colours count]];
[self.dvdLogo lockFocus];
[self.dvdColor set];
NSRect imageRect = {NSZeroPoint, [self.dvdLogo size]};
NSRectFillUsingOperation(imageRect, NSCompositingOperationSourceAtop);
[self.dvdLogo unlockFocus];}
- (void)animateOneFrame
{//[self setNeedsDisplay:true];
[self setNeedsDisplayInRect:self.dirtyRect];
return;}
Here's a download of the saver, if you wanna see what I'm talking about.

Answer 1

If I follow your code fragment and problem correctly your drawRect starts with:
const float g = 15.0f/255.0f;
[[NSColor colorWithRed:g green:g blue:g alpha:1] setFill];
NSRectFill(rectParam);
This fills the area defined by rectParam with dark gray. Why did you choose 15.0f/255.0f for the RGB components? Black is just 0 but more easily obtained using blackColor:
[[NSColor blackColor] setFill];
HTH