objective-c - 我应该在 NSCell 上调用什么方法

Question

我正在使用自定义 NSCell 编写自定义 NSControl。它是一个控件，因此它必须响应鼠标。我在我的控件上创建了一个 NSTrackingArea，实现了 -mouseEntered:、-mouseExited: 和 -mouseMoved:。 (我必须实现 -mouseUp/Down:，但我不知道在那里要做什么，所以现在我还没有覆盖这些方法。)在这些方法中，我成功确定鼠标当前位于哪个单元格上。现在我有两个问题:

• 这是跟踪鼠标的好方法吗？如果没有，我该怎么办？
• 当鼠标单击、鼠标进入单元格、当鼠标离开单元格等时，我应该在 NSCell 上调用什么方法？ Apple 的文档对此不是很清楚。

所以，基本上:我应该什么时候调用 NSCell 上的什么方法来让它响应鼠标事件？

编辑:
重读文档，我想我应该调用 NSCell 的 -trackMouse:inRect:ofView:untilMouseUp: 并覆盖 -startTrackingAt:inView:, -continueTracking:at:inView : 和 -stopTracking:at:inView:mouseIsUp:。同样有两个问题:1)文档给人的印象是这些仅在鼠标按下时才被调用。那是对的吗？那我该怎么办呢？ 2) 我应该在哪里/什么时候调用 NSCell 的 -trackMouse:inRect:ofView:untilMouseUp:？

Answer 1

我最终实现了自己的鼠标跟踪机制:

// MyControl.m:

- (void)mouseDown:(NSEvent *)theEvent {
    int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
    if (currentCellIndex < [cells count]) {
        MKListCell *cell = [cells objectAtIndex:currentCellIndex];
        currentCell = cell;
        [currentCell mouseDown:theEvent];
    }
}

- (void)mouseUp:(NSEvent *)theEvent {
    int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
    if (currentCellIndex < [cells count]) {
        MKListCell *cell = [cells objectAtIndex:currentCellIndex];
        [cell mouseUp:theEvent];
    }
}

- (void)mouseEntered:(NSEvent *)theEvent {
    int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
    if (currentCellIndex < [cells count]) {
        MKListCell *cell = [cells objectAtIndex:currentCellIndex];
        currentCell = cell;
        [currentCell mouseEntered:theEvent];
    }
}

- (void)mouseExited:(NSEvent *)theEvent {
    int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
    if (currentCellIndex < [cells count]) {
        MKListCell *cell = [cells objectAtIndex:currentCellIndex];
        [cell mouseExited:theEvent];
        currentCell = nil;
    }
}

- (void)mouseMoved:(NSEvent *)theEvent {
    int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
    MKListCell *cell;
    if (currentCellIndex < [cells count]) {
        cell = [cells objectAtIndex:currentCellIndex];
    }
    if (currentCell != cell) {
        [currentCell mouseExited:theEvent];
        [cell mouseEntered:theEvent];
        currentCell = cell;
    }
    else {
        [currentCell mouseMoved:theEvent];
    }
}

- (void)mouseDragged:(NSEvent *)theEvent {
    int currentCellIndex = [self indexOfCellAtPoint:[self convertPoint:[theEvent locationInWindow] fromView:nil]];
    MKListCell *cell = nil;
    if (currentCellIndex < [cells count]) {
        cell = [cells objectAtIndex:currentCellIndex];
    }
    if (currentCell != cell) {
        [currentCell mouseExited:theEvent];
        [cell mouseEntered:theEvent];
        currentCell = cell;
    }
    else {
        [currentCell mouseMoved:theEvent];
    }   
}

- (int)indexOfCellAtPoint:(NSPoint)p {
    int cellIndex = (self.bounds.size.height - p.y) / cellHeight;
    return cellIndex;
}

当然，在MyCell.h中:

- (void)mouseDown:(NSEvent *)event;
- (void)mouseUp:(NSEvent *)event;
- (void)mouseMoved:(NSEvent *)event;
- (void)mouseEntered:(NSEvent *)event;
- (void)mouseExited:(NSEvent *)event;

这些方法的实现为空(因此编译器不会提示，我可以将鼠标处理方法的实现留给子类)。