正确使用GetClipRgn？ [英] correct usage of GetClipRgn?

问题描述

我想写一个函数，需要在DC上设置剪切区域，但是在DC上还原任何现有的剪切区域。

I want to write a function that needs to set the clipping region on a DC but restore any existing clipping region on the DC when it is done.

找到 GetClipRgn 听起来像我想要的，但似乎混乱。我找不到任何使用它的例子，Petzold没有提供任何东西。

So I found GetClipRgn which sounds like exactly what I want but seems confusing. I couldn't find any examples of using it and Petzold had nothing to offer.

我想出的是：

void DrawStuff( HDC hDC )
{
    HRGN restoreRegion = CreateRectRgn( 0, 0, 0, 0 );
    if (GetClipRgn( hDC, restoreRegion ) != 1)
    {
        DeleteObject( restoreRegion );
        restoreRegion = NULL;
    }

    // 
    // Set new region, do drawing
    //

    SelectClipRgn( hDC, restoreRegion );
    if (restoreRegion != NULL)
    {
        DeleteObject( restoreRegion );
    }
}

看起来很奇怪，我需要创建一个区域以获得当前区域。

It just seems weird that I need to create a region in order to get the current region.

这是否是正确的用法？

相同的效果？

推荐答案

对于正确答案最接近的事情是Hans Passant的评论：

Well the closest thing to a correct answer is Hans Passant's comment:

是的，这是一个奇怪的函数。您的代码看起来不错。

Yeah, it's a weird function. Your code looks okay.

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