如何以编程方式更改特定监视器的分辨率？

Question

您如何以编程方式更改特定显示器的分辨率？例如，可以通过编程方式更改辅助监视器的分辨率吗？

Answer 1

以下功能可能是您的起点。其试图改变被指定的索引的显示装置的分辨率Index的参数（如果存在这样的），以通过给定的宽度和高度（以像素为单位）Width，Height参数。如果找到具有给定索引的显示设备并且其分辨率已成功更改，则该函数返回True，否则返回False。

您尚未指定是要永久更改分辨率（如果要存储设置更改）还是仅临时更改分辨率。下面的示例临时执行此操作，但是如果在第二个ChangeDisplaySettingsEx函数中使用CDS_UPDATEREGISTRY该dwflags参数的值，则可以非常简单地更改此行为：

function ChangeMonitorResolution(Index, Width, Height: DWORD): Boolean;
var
  DeviceMode: TDeviceMode;
  DisplayDevice: TDisplayDevice;
begin
  Result := False;
  ZeroMemory(@DisplayDevice, SizeOf(DisplayDevice));
  DisplayDevice.cb := SizeOf(TDisplayDevice);
  // get the name of a device by the given index
  if EnumDisplayDevices(nil, Index, DisplayDevice, 0) then
  begin
    ZeroMemory(@DeviceMode, SizeOf(DeviceMode));
    DeviceMode.dmSize := SizeOf(TDeviceMode);
    DeviceMode.dmPelsWidth := Width;
    DeviceMode.dmPelsHeight := Height;
    DeviceMode.dmFields := DM_PELSWIDTH or DM_PELSHEIGHT;
    // check if it's possible to set a given resolution; if so, then...
    if (ChangeDisplaySettingsEx(PChar(@DisplayDevice.DeviceName[0]), 
      DeviceMode, 0, CDS_TEST, nil) = DISP_CHANGE_SUCCESSFUL)
    then
      // change the resolution temporarily (if you use CDS_UPDATEREGISTRY
      // value for the penultimate parameter, the graphics mode will also
      // be saved to the registry under the user's profile; for more info
      // see the ChangeDisplaySettingsEx reference, dwflags parameter)
      Result := ChangeDisplaySettingsEx(PChar(@DisplayDevice.DeviceName[0]),
        DeviceMode, 0, 0, nil) = DISP_CHANGE_SUCCESSFUL;
  end;
end;

如何将辅助显示设备（索引为1的设备）的分辨率更改为800x600的示例：

procedure TForm1.Button1Click(Sender: TObject);
begin
  if ChangeMonitorResolution(1, 800, 600) then
    ShowMessage('Resolution of display device with index 1 has been changed!')
  else
    ShowMessage('Display device with index 1 doesn''t exist, doesn''t support ' +
      'resolution 800x600 or changing failed due to a reason, which you might ' +
      'know if the author of this function wouldn''t be so lazy!');
end;