Question

在Cocoa应用程序上工作，应用程序需要做两件事 - ：

1）鼠标进入或退出

2）将鼠标拖到应用程序

我有看A，视图A已注册用于接收拖动事件和具有用于接收鼠标进入和退出事件的跟踪区域，

问题是：如果我将文件拖到视图A; view A接收mouseEntered：事件而不是draggingEntered：event。

- (NSDragOperation)draggingEntered:(id < NSDraggingInfo >)sender
{
   NSLog(@"draggingEntered called");
}


- (void)mouseEntered:(NSEvent *)theEvent
{
   NSLog(@"mouseEntered called");
}

2018-02-05 14：08：58.273 XXX_APP [3420：119122] mouseEntered叫

2018-02-05 14：08：58.273 XXX_APP [3420：119122] draggingEntered叫

问题是每当我将文件拖到视图中时;它进入mouseEntered（）不要进入mouseDragged（）。有没有解决方法呢？

提前致谢。

Answer 1

我可能错了，但我相信拖动操作取决于鼠标进入视图，所以如果你跟踪鼠标事件，将始终首先调用mouseEntered:方法。也就是说，您可以延迟使用mouseEntered:事件做一些事情，让查看时间看是否后跟拖动操作，如果是，则取消mouseEntered:调用。这可以使用performSelector:withObject:afterDelay:（使用可能不会引起用户注意的非常短暂的延迟）和cancelPreviousPerformRequestsWithTarget:这样完成：

- (void)updateTrackingAreas {
    [super updateTrackingAreas];
    for (NSTrackingArea *trackingArea in self.trackingAreas) {
        [self removeTrackingArea:trackingArea];
    }
    [self addTrackingArea:[[NSTrackingArea alloc] initWithRect:self.bounds options:(NSTrackingMouseEnteredAndExited | NSTrackingActiveAlways) owner:self userInfo:nil]];
}

- (void)_mouseEntered:(NSEvent *)event {
    NSLog(@"mouseEntered");
    //do something...
}

- (void)mouseEntered:(NSEvent *)event {
    //pause 0.05 seconds before acting on this event,
    //giving the view time to see if a draggingEntered: event is triggered
    [self performSelector:@selector(_mouseEntered:) withObject:event afterDelay:0.05];
}

- (void)mouseExited:(NSEvent *)event {
    NSLog(@"mouseExited");
    //do something...
}

//assumes you've registered for drag events (e.g., in init):
//  [self registerForDraggedTypes:[NSArray arrayWithObject:NSFilenamesPboardType]];
- (NSDragOperation)draggingEntered:(id <NSDraggingInfo>)sender {
    //cancel pending _mouseEntered: call:
    [NSObject cancelPreviousPerformRequestsWithTarget:self]; 
    NSLog(@"draggingEntered");
    NSPasteboard *pasteboard = [sender draggingPasteboard];
    return (([pasteboard.types containsObject:NSFilenamesPboardType]) ? NSDragOperationLink : NSDragOperationNone);
}

- (BOOL)performDragOperation:(id <NSDraggingInfo>)sender {
    NSPasteboard *pasteboard = [sender draggingPasteboard];
    if ([pasteboard.types containsObject:NSFilenamesPboardType]) {
        for (NSString *filePath in [pasteboard propertyListForType:NSFilenamesPboardType]) {
            NSLog(@"dropped file: %@", filePath);
        }
    }
    return YES;
}

拖动事件未接收如果mouseEntered（）事件由Cocoa App跟踪

1 个答案: