在NSCollectionView中将鼠标悬停在效果上

Question

我有一个里面有几个NSView的NSCollectionView。NSView中有一个NSBox，当它被选中时，它会改变颜色。我还想让NSBox在悬停时改变颜色。

我继承了NSBox并添加了mouseEntered和mouseExited方法。我在viewWillMoveToWindow中使用了addTrackingRect，但问题是，只有当我首先选择框所在的子视图时，才会出现悬停效果。

此外，只有选中的方框才会发生悬停效果。我如何实现悬停效果，以便我的NSCollectionView中的所有NSView都立即显示该效果？

Answer 1

您可以在NSView的子类中覆盖updateTrackingAreas来实现此行为：

接口

@interface HoverView : NSView

@property (strong, nonatomic) NSColor *hoverColor;

@end

Implementation

@interface HoverView ()

@property (strong, nonatomic) NSTrackingArea *trackingArea;
@property (assign, nonatomic) BOOL mouseInside;

@end

@implementation HoverView

- (void) drawRect:(NSRect)dirtyRect {
    [super drawRect:dirtyRect];

    // Draw a white/alpha gradient
    if (self.mouseInside) {
        [_hoverColor set];
        NSRectFill(self.bounds);
    }
}


- (void) updateTrackingAreas {
    [super updateTrackingAreas];

    [self ensureTrackingArea];
    if (![[self trackingAreas] containsObject:_trackingArea]) {
        [self addTrackingArea:_trackingArea];
    }
}

- (void) ensureTrackingArea {
    if (_trackingArea == nil) {
        self.trackingArea = [[NSTrackingArea alloc] initWithRect:NSZeroRect
                                                         options:NSTrackingInVisibleRect | NSTrackingActiveAlways | NSTrackingMouseEnteredAndExited
                                                           owner:self
                                                        userInfo:nil];
    }
}

- (void) mouseEntered:(NSEvent *)theEvent {
    self.mouseInside = YES;
}

- (void) mouseExited:(NSEvent *)theEvent {
    self.mouseInside = NO;
}

- (void) setMouseInside:(BOOL)value {
    if (_mouseInside != value) {
        _mouseInside = value;
        [self setNeedsDisplay:YES];
    }
}


@end

Answer 2

Swift 5

    var mouseInside : Bool = false { didSet {
        needsDisplay = true
    }}
    @IBInspectable var hoverColor : NSColor = .controlAccentColor
    var trackingArea : NSTrackingArea?

    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)
        
        if mouseInside {
            hoverColor.setFill()
            bounds.fill()
        }
    }
    
    override func updateTrackingAreas() {
        super.updateTrackingAreas()
        
        ensureTrackingArea()
        
        if let trackingArea = trackingArea, !trackingAreas.contains(trackingArea) {
            addTrackingArea(trackingArea)
        }
    }
    
    func ensureTrackingArea() {
        if trackingArea == nil {
            trackingArea = NSTrackingArea(rect: .zero,
                                          options: [
                                            .inVisibleRect,
                                            .activeAlways,
                                            .mouseEnteredAndExited],
                                          owner: self,
                                          userInfo: nil)
        }
    }
    
    override func mouseEntered(with event: NSEvent) {
        mouseInside = true
    }
    
    override func mouseExited(with event: NSEvent) {
        mouseInside = false
    }
    
    
    
}