There's a way to detect if my Screen of the Desktop PC, is ON or OFF in Delphi? When I say OFF is that you press the power button of the monitor. I was thinking today about it, the power button is pure hardware or is possible to detect by software?
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Theoretically, yes. But you need to be careful what question you're actually asking. As it stands, your question is primarily asking if it's possible or not, which will result in very simple yes or no answers. You should avoid those, and go straight to "How to..." – Jerry Dodge May 10 '16 at 23:26
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1NO, it cannot be done. `GetDevicePowerState function Retrieves the current power state of the specified device. This function cannot be used to query the power state of a display device.` https://msdn.microsoft.com/en-us/library/windows/desktop/aa372690%28v=vs.85%29.aspx – Johan May 10 '16 at 23:43
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@Johan Actually it is possible but it depends on monitor and your graphics card capabilities. Some older monitors for instance broke connection between pins that graphics cards used to detect whether the monitor is connected or not which in turn allowed PC to detect when monitor was powered off. Such feature is still commonly used in projectors that still use old VGA port for connection. Newer monitors that use Display Port have even greater capabilities of being able to use full two way communication so you are able to change your monitor settings directly from PC. ... – SilverWarior May 11 '16 at 20:13
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... So with proper software you can get a whole bunch of information from these monitors. What I just can't find now is any whitepaper on the used protocol for this. – SilverWarior May 11 '16 at 20:15
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@SilverWarior, did you mean: https://msdn.microsoft.com/en-us/library/dd376775 It's in the linked answers. I'm not sure which exact device it queries. – Johan May 11 '16 at 21:24
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@Johan No I was actually referring to VESA Display Data Channel Command Interface http://caxapa.ru/thumbs/349020/ddcciv1.pdf – SilverWarior May 12 '16 at 02:10