我应该在NSCell上调用什么方法

Question

我正在用自定义nscell编写一个自定义NSControl。它是一个控件，所以它必须响应鼠标。我在我的控制下创建了一个NSTrackingArea，实现了-mouseEntered:, -mouseExited:和-mouseMoved:。(我将不得不实现-mouseUp/Down:，但我不知道在那里做什么，所以现在我还没有覆盖这些方法。)在这些方法中，我成功地确定了鼠标当前在哪个细胞上。现在我有两个问题:

• 这是跟踪鼠标的好方法吗?如果不是，我该怎么做呢?
• 当鼠标进入单元格时，当鼠标离开单元格时，我应该在我的ncell上调用什么方法?苹果的文档对此不是很清楚。

所以，基本上:我什么时候应该在我的NSCell上调用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:和覆盖-startTrackingAt:inView:, -continueTracking:at:inView:和-stopTracking:at:inView:mouseIsUp:。还有两个问题:1)文档给人的印象是，只有当鼠标按下时才会调用这些文档。对吗?那我该怎么办呢?2)我应该在哪里/何时调用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(因此编译器不会抱怨，我可以将鼠标处理方法的实现留给子类)。