NSCell自定义亮点

问题描述

我试图子类化 NSCell 来绘制自定义背景高亮。文档似乎暗示，重写的 highlight：withFrame：inView：应该允许我这样做，但是该方法从未被调用。

I'm trying to subclass NSCell to draw a custom background highlight. The documentation seems to suggest that the overriding highlight:withFrame:inView: should allow me to do this but the method is never called.

相反，我覆盖了 drawInteriorWithFrame：inView：这很好 - 我可以在单元格中绘制我想要的。但是，问题是，我必须自己绘制一切，失去NSCell类型的功能，我扩展 - 例如NSTextFieldCell的显示文本的能力：

Instead, I've overridden drawInteriorWithFrame:inView: which works fine - I can draw what I want in the cell. However, the issue is that I have to draw everything myself, losing the functionality of the type of NSCell I am extending - for example an NSTextFieldCell's ability to display text:

自定义

但是，我只想重绘背景（突出显示），并保留使用扩展单元格的主要功能的能力：

However, I just want to redraw the background (the highlight), and retain the ability to use the main functionality of the extended cell:

>

我可以，当然，只是自己绘制文本，但我希望有一个更简单的方法这样做。

I could, of course, just draw the text myself too but I'm hoping there is an easier way of doing this.

任何帮助是非常感谢。 / p>

Any help is much appreciated.

推荐答案

感谢@Bavarious的帮助，我已经努力工作了。我的扩展NSTextFieldCell类实现现在包含：

Thanks to the help of @Bavarious I've managed to work it out. My extended NSTextFieldCell class implementation now contains:

-(NSColor *)highlightColorWithFrame:(NSRect)cellFrame inView:(NSView *)controlView {
    return nil;
}

- (void)drawWithFrame:(NSRect)cellFrame inView:(NSView *)controlView {
    if ([self isHighlighted]) {
        // Draw highlight background here
    }

    [super drawInteriorWithFrame:cellFrame inView:controlView];
}

关键是要确保你返回 nil for highlightColorWithFrame：inView：停止 drawInteriorWithFrame：inView：绘制背景，它绘制主要内容（在这种情况下是文本）。

The key is to make sure you return nil for highlightColorWithFrame:inView: to stop drawInteriorWithFrame:inView: drawing a background and yet still calling it to draw the main content (in this case text).

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