objective-c - 在 NSTableCellView 中滚动时跟踪鼠标事件的问题

Question

我在自定义表格单元格 View 上有弹出按钮，当鼠标光标移到一个单元格上时，将显示该单元格的这些按钮，并且只有这一个单元格应显示按钮。如果我缓慢移动鼠标光标，一切都会正常工作，但是当我用鼠标中键更快地滚动表格 View 时，会显示太多带有弹出按钮的单元格，这确实应该避免。不知何故，滚动时无法正确跟踪鼠标事件。我从苹果示例库中获得了这个跟踪代码。您能为这个问题提供一些建议吗？

#import "BasisCellView.h"

@implementation BasisCellView

- (void)drawRect:(NSRect)dirtyRect {
    [super drawRect:dirtyRect];
    // Drawing code here.
    [[NSImage imageNamed:@"background"] drawInRect:dirtyRect fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:0.1];
}

- (void)setBackgroundStyle:(NSBackgroundStyle)backgroundStyle {
    [super setBackgroundStyle: NSBackgroundStyleLight];
}

- (void)setMouseInside:(BOOL)value {
    if (mouseInside != value) {
        mouseInside = value;
        [self.deleteButton setHidden:!value];
        [self.bookmarkButton setHidden:!value];
        [self setNeedsDisplay:YES];
        NSLog(@"redrawn");
    }
}

- (BOOL)mouseInside {
    return mouseInside;
}

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

- (void)updateTrackingAreas {
    [super updateTrackingAreas];
    [self ensureTrackingArea];
    if (![[self trackingAreas] containsObject:trackingArea]) {
        [self addTrackingArea:trackingArea];
    }
}

- (void)mouseEntered:(NSEvent *)theEvent {
    NSLog(@"1");
    self.mouseInside = YES;
}

- (void)mouseExited:(NSEvent *)theEvent {
    NSLog(@"0");
    self.mouseInside = NO;
}

@end

这是打印出来的日志:

2015-02-05 08:59:33.267 Clever[1286:25969] 1
2015-02-05 08:59:33.267 Clever[1286:25969] redrawn
2015-02-05 08:59:33.299 Clever[1286:25969] 0
2015-02-05 08:59:33.299 Clever[1286:25969] redrawn
2015-02-05 08:59:33.333 Clever[1286:25969] 1
2015-02-05 08:59:33.333 Clever[1286:25969] redrawn
2015-02-05 08:59:33.350 Clever[1286:25969] 0
2015-02-05 08:59:33.350 Clever[1286:25969] redrawn
2015-02-05 08:59:33.382 Clever[1286:25969] 1
2015-02-05 08:59:33.383 Clever[1286:25969] redrawn
2015-02-05 08:59:33.669 Clever[1286:25969] 1
2015-02-05 08:59:33.669 Clever[1286:25969] redrawn
2015-02-05 08:59:33.736 Clever[1286:25969] 1
2015-02-05 08:59:33.736 Clever[1286:25969] redrawn
2015-02-05 08:59:33.769 Clever[1286:25969] 0
2015-02-05 08:59:33.769 Clever[1286:25969] redrawn
2015-02-05 08:59:33.769 Clever[1286:25969] 1
2015-02-05 08:59:33.770 Clever[1286:25969] redrawn
2015-02-05 08:59:34.101 Clever[1286:25969] 1
2015-02-05 08:59:34.101 Clever[1286:25969] redrawn
2015-02-05 08:59:34.102 Clever[1286:25969] 0
2015-02-05 08:59:34.102 Clever[1286:25969] redrawn
2015-02-05 08:59:34.136 Clever[1286:25969] 0
2015-02-05 08:59:34.136 Clever[1286:25969] redrawn
2015-02-05 08:59:34.150 Clever[1286:25969] 1
2015-02-05 08:59:34.150 Clever[1286:25969] redrawn
2015-02-05 08:59:34.187 Clever[1286:25969] 1
2015-02-05 08:59:34.187 Clever[1286:25969] redrawn
2015-02-05 08:59:34.235 Clever[1286:25969] 1
2015-02-05 08:59:34.272 Clever[1286:25969] 0

Answer 1

这是设置跟踪区域所需的代码的快速版本:

class MyCustomTableCellView: NSTableCellView {

    func setUpTrackingArea()
    {
        let trackingArea = NSTrackingArea(rect: self.frame, options: [NSTrackingAreaOptions.MouseEnteredAndExited, NSTrackingAreaOptions.ActiveAlways], owner: self, userInfo: nil)
        self.addTrackingArea(trackingArea)
    }

    override init(frame frameRect: NSRect) {
        super.init(frame: frameRect)

        setUpTrackingArea()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)

        setUpTrackingArea()
    }

    override func mouseEntered(theEvent: NSEvent) {
        Swift.print("mouse Entered")
    }

    override func mouseExited(theEvent: NSEvent) {
        Swift.print("mouse exited")
    }
}