子类化NSView具有透明背景 [英] Subclassing NSView to have a transparent background

问题描述

我正在创建一个应用，其中我需要一个带有透明PNG图像的透明NSView.问题是，我正在绘制的NSView带有灰色背景.我有它的子类化(如TransparentRectangleView)，但不知道在drawRect中放入什么使其透明.

I am creating an app where I need to have a transparent NSView with a transparent PNG image inside. The problem is, the NSView I'm drawing has a gray background on it. I have it subclassed (as TransparentRectangleView) but don't know what to put in drawRect to make it transparent.

我已经重写了isOpaque方法以返回NO，但这似乎无济于事...

I have already overridden the isOpaque method to return NO but it doesn't seem to help...

或者，已经有一个类似于iPhone的UIImageView的子类NSView(只要我可以在其中添加子视图，我就需要在其中添加一些文本).

Alternatively, is there already a subclassed NSView that is similar to the iPhone's UIImageView (as long as I can add subviews inside, I need to add some text inside).

推荐答案

要使视图透明，只需用[NSColor clearColor]填充它即可.

To make a view transparent, simply fill it with [NSColor clearColor].

- (void)drawRect:(NSRect)rect {
    [[NSColor clearColor] set];
    NSRectFill(rect);
}

isOpaque的默认实现返回NO，因此，如果您要继承NSView而不是其他某个视图，则无需担心会覆盖它.

The default implementation of isOpaque returns NO, so if you are subclassing NSView and not some other view you don't need to worry about overriding it.

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