EnumDisplayDevices.md

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Function name : EnumDisplayDevices

Group: Device Context - Library: user32

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The EnumDisplayDevices function lets you obtain information about the display devices in a system.

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Code examples:

How to change display settings: screen resolution, screen refresh rate
How to detect if additional monitor is connected and active

Declaration:

BOOL EnumDisplayDevices(
  LPCTSTR lpDevice,                // device name
  DWORD iDevNum,                   // display device
  PDISPLAY_DEVICE lpDisplayDevice, // device information
  DWORD dwFlags                    // reserved
);  

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FoxPro declaration:

DECLARE INTEGER EnumDisplayDevices IN user32;
	STRING    lpDevice,;
	INTEGER   iDevNum,;
	STRING  @ lpDisplayDevice,;
	INTEGER   dwFlags  

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Parameters:

lpDevice [in] Pointer to the device name. If NULL, function returns information for the display adapter(s) on the machine, based on iDevNum.

iDevNum [in] Index value that specifies the display device of interest.

lpDisplayDevice [out] Pointer to a DISPLAY_DEVICE structure that receives information about the display device specified by iDevNum.

dwFlags This parameter is currently not used and should be set to zero.

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Return value:

If the function succeeds, the return value is nonzero.

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Comments:

To query all display devices in the system, call this function in a loop, starting with iDevNum set to 0, and incrementing iDevNum until the function fails.

To get information on the display adapter, call EnumDisplayDevices with lpDevice set to NULL. Then DISPLAY_DEVICE.DeviceString contains the adapter name.

To obtain information on a display monitor, first call EnumDisplayDevices with lpDevice set to NULL. Then call EnumDisplayDevices with lpDevice set to DISPLAY_DEVICE.DeviceName from the first call to EnumDisplayDevices and with iDevNum set to zero. Then DISPLAY_DEVICE.DeviceString is the monitor name.

See also MonitorFromWindow, GetMonitorInfo, EnumDisplaySettings functions.

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