问题描述
我需要制作一个只显示大纲的控件，我需要将它放在一个显示视频的控件上.如果我让我的控件透明，那么视频就会被遮挡，因为透明控件是由它们的父控件绘制的，而视频不是由控件绘制的；它使用 DirectShow 或其他库显示，因此父控件会绘制其 BackColor.
I need to make a Control which shows only an outline, and I need to place it over a control that's showing a video. If I make my Control transparent, then the video is obscured, because transparent controls are painted by their parent control and the video isn't painted by the control; it's shown using DirectShow or another library, so instead the parent control paints its BackColor.
那么 - 我可以制作一个完全不绘制的控件，除了不透明的地方吗?这样，父控件就不会覆盖视频.
So - can I make a control that doesn't get painted at all, except where it's opaque? That way, the parent control wouldn't paint over the video.
我知道我可以用四个控件来制作边框(或者更多，如果我想让它变成虚线)，但是否可以只使用一个控件来做我想做的事?
I know I could make the border out of four controls (or more if I want it dashed) but is it possible to do what I want using just one control?
rslite 是对的——尽管你甚至不需要像他的例子那样使用 PInvoke——Control.Region 属性就完全足够了.
rslite is right - although you don't even need to go so far as to use PInvoke like his example does - the Control.Region property is entirely sufficient.
推荐答案
你可以尝试制作一个里面有洞的 Region，并用 SetWindowRgn 设置控制区域.
You could try to make a Region with a hole inside and set the control region with SetWindowRgn.
这是一个示例(我无法找不到更好的了).这个想法是创建两个区域并从外部区域中减去内部区域.我认为这应该给你你需要的东西.
Here is an example (I couldn't find a better one). The idea is to create two regions and subtract the inner one from the outer one. I think that should give you what you need.
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