NSView mouseMoved 事件有时不会触发

Question

我有一个视频播放应用程序，其中显示了一个 NSView，跟踪到鼠标坐标，以显示用户悬停在某个区域上时的时间位置。

这在 70% 的时间里都能完美运行，但它经常根本不触发。最有可能发生这种情况的时间似乎是第一次将鼠标带入视图内以及将鼠标悬停在该区域之外然后再次回到内部。

NSView子类里面的代码如下：

- (void)viewDidMoveToWindow
{
    if ([self window]) {
        [self resetTrackingRect];
    }
}

- (void)clearTrackingRect
{
    if (rolloverTrackingRectTag > 0)
    {
        [self removeTrackingRect:rolloverTrackingRectTag];
        rolloverTrackingRectTag = 0;
    }
}

- (void)resetTrackingRect
{
    [self clearTrackingRect];
    rolloverTrackingRectTag = [self addTrackingRect:[self visibleRect]
                                          owner:self userData:NULL assumeInside:NO];
}

- (void)resetCursorRects
{
    [super resetCursorRects];
    [self resetTrackingRect];
}

- (void)mouseEntered:(NSEvent *)theEvent
{
    // Only ask for mouse move events when inside rect because they are expensive
    [[self window] setAcceptsMouseMovedEvents:YES];
    [[self window] makeFirstResponder:self];

    // Tells the observer to show the time view
    [[NSNotificationCenter defaultCenter] postNotificationName:@"MWTimelineHover" object:self userInfo:[NSDictionary dictionaryWithObjectsAndKeys:theEvent,@"event",nil]];
}

- (void)mouseExited:(NSEvent *)theEvent
{
    [[self window] setAcceptsMouseMovedEvents:NO];
    [[self window] resignFirstResponder];

    // Tells the observer to hide the time view
    [[NSNotificationCenter defaultCenter] postNotificationName:@"MWTimelineHoverLeave" object:self];
}

- (void)mouseMoved:(NSEvent *)theEvent
{
    [super mouseMoved:theEvent];

    // Tells the observer to show the time view
    [[NSNotificationCenter defaultCenter] postNotificationName:@"MWTimelineHover" object:self userInfo:[NSDictionary dictionaryWithObjectsAndKeys:theEvent,@"event",nil]];
}

注意：在停止的情况下，不会调用 mouseExited 并且视图没有丢失 firstResponder 状态。我也没有拖动鼠标，只是正常移动它。

Answer 1

您需要使用 NSTrackingArea。这是参考NSTrackingArea Class Reference。

- (void)commonInit {
    CGRect rect = CGRectMake(0.0f, 0.0f, self.frame.size.width, self.frame.size.height);
    NSTrackingAreaOptions options = NSTrackingActiveInKeyWindow | NSTrackingMouseMoved | NSTrackingInVisibleRect;
    _trackingArea = [[NSTrackingArea alloc] initWithRect:rect options:options owner:self userInfo:nil];
    [self addTrackingArea:_trackingArea];
}

希望对你有帮助。