将 macOS 屏保 BG 设置为黑色？

Question

我是 Obj-C 的新手，如果我的代码有问题，请见谅。

我制作了一个 DVD 徽标的屏幕保护程序，每次弹跳都会改变颜色。我唯一的问题是背景——它是深灰色而不是黑色。我希望有人能帮助我。

这是我的一些代码：

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;}

这里是 download of the saver，如果你想看看我在说什么。

Answer 1

如果我遵循您的代码片段并正确解决问题，您的 drawRect 开头为：

const float g = 15.0f/255.0f;
[[NSColor colorWithRed:g green:g blue:g alpha:1] setFill];
NSRectFill(rectParam);

这会用深灰色填充 rectParam 定义的区域。为什么选择 15.0f/255.0f 作为 RGB 分量？黑色只是 0 但使用 blackColor 更容易获得：

[[NSColor blackColor] setFill];

HTH

将 macOS 屏保 BG 设置为黑色？

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