分段故障使用SDL与C ++，试图Blit图像 [英] Segmentation fault using SDL with C++, trying to Blit images

问题描述

确定 - 我在这里有一个有趣的。我正在做一个tetris克隆（基本上是提高我的技能）。我试图重构我的代码，让它以我想要的方式抽象。虽然它以前工作很好，现在我得到一个分割错误，任何图像可以blitted。我尝试调试它没有效果。

OK - I have an interesting one here. I'm working on a tetris clone (basically to "level-up" my skills). I was trying to refactor my code to get it abstracted the way I wanted it. While it was working just fine before, now I get a segmentation fault before any images can be blitted. I've tried debugging it to no avail.

我已经发布了我的SVN工作副本的项目这里。

I have posted my SVN working copy of the project here.

这只是一个小项目，比我和一个好的调试器可能会搞清楚。唯一的依赖关系是 SDL 。 Kudos给可以告诉我我做错了的人。

It's just a small project and someone with more knowledge than me and a good debugger will probably figure it out in a snap. The only dependency is SDL. Kudos to the person that can tell me what I'm doing wrong.

编辑：据我所知，我现在和我以前的是逻辑相同，所以我不会认为我现在会导致分段错误。只需在工作副本上运行svn revert，重新编译，你可以看到它正在工作...

As far as I can tell, what I have now and what I had before are logically the same, so I wouldn't think that what I have now would cause a segmentation fault. Just run an svn revert on the working copy, recompile and you can see that it was working...

推荐答案

Surface.cpp的15到18：

Look at line 15 to 18 of Surface.cpp:

	surface = SDL_DisplayFormatAlpha( tempSurface );
	surface = tempSurface;
}
SDL_FreeSurface( tempSurface );

我假设它是segfaults，因为当你以后使用这个表面时，你实际上是操作tempSurface行：

I assume it segfaults because when you use this surface later, you are actually operating on tempSurface because of this line:

surface = tempSurface;

，而不是由SDL_DisplayFormatAlpha因为你自由tempSurface，surface现在指向无效的内存。要修复，只需删除else块中的第二行。

and not the surface returned by SDL_DisplayFormatAlpha(). Since you free tempSurface, surface is now pointing to invalid memory. To fix, simply remove the second line in the else block.

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