急求：win7下怎么更改显示器双屏模式为扩展模式（extend）?

Question

在双屏显示器时，我需要用代码更改双屏模式为“扩展屏模式”（默认为拷屏，duplicate mode） 。怎么改成扩展屏模式？通过api或者修改注册表对应值均可，各位帮帮忙哈这个问题比较急

Answer 1

ok我知道肿么搞了，

直接
DisplaySwitch /extend
就行，DisplaySwitch是个系统自带的程序可直接调用。/extend是切换成扩展屏模式，/clone是切换成拷屏模式

http://answers.microsoft.com/en-us/windows/forum/windows_7-hardware/how-does-displayswitchexe-work-in-windows-7/1d30ef62-881a-4a69-ac02-e496b1f794ef

Answer 2

SetDisplayConfig(0,NULL,0,NULL,SDC_TOPOLOGY_EXTEND|SDC_APPLY);

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Answer 3

我发现当为duplicate mode时，Screen.AllScreens里只有一个但实际上有两个物理显示器，怎么判断到底有几个显示器呢？