asked on

Delphi: How to change secondary display resolution

Hi i want to change the secondary display resolution, im using the following code
but it only changes the main display.

function NewRes(XRes, YRes: DWORD; devnum : cardinal): Integer;
var
DevMode: TDeviceMode;
lpDisplayDevice: TDisplayDevice;
begin

  lpdisplaydevice.cb := sizeof(lpdisplaydevice);
  EnumDisplayDevices(nil,devnum,lpDisplayDevice,0 );   

EnumDisplaySettings(lpdisplaydevice.DeviceName, 0, DevMode);
DevMode.dmFields := DM_PELSWIDTH or DM_PELSHEIGHT or
DM_DISPLAYFREQUENCY;
DevMode.dmPelsWidth := XRes;
DevMode.dmPelsHeight := YRes;
//DevMode.dmDisplayFrequency := Frequency;
Result := ChangeDisplaySettings(DevMode, 0);
end;

Open in new window

ASKER CERTIFIED SOLUTION

developmentguru

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

Slinkkkk

ASKER

Thx developmentguru,
Here goes the working code if someone else need it

function NewRes(XRes, YRes: DWORD; devnum : cardinal): Integer;
var
DevMode: TDeviceMode;
lpDisplayDevice: TDisplayDevice;
begin

  lpdisplaydevice.cb := sizeof(lpdisplaydevice);
  EnumDisplayDevices(nil,devnum,lpDisplayDevice,0 );   

EnumDisplaySettings(lpdisplaydevice.DeviceName, 0, DevMode);
DevMode.dmFields := DM_PELSWIDTH or DM_PELSHEIGHT or
DM_DISPLAYFREQUENCY;
DevMode.dmPelsWidth := XRes;
DevMode.dmPelsHeight := YRes;
//DevMode.dmDisplayFrequency := Frequency;
Result := ChangeDisplaySettingsEx (lpdisplaydevice.DeviceName,DevMode,0, (CDS_UPDATEREGISTRY), nil);
end;

Open in new window

Slinkkkk

ASKER

function NewRes(XRes, YRes: DWORD; devnum : cardinal): Integer;
var
DevMode: TDeviceMode;
lpDisplayDevice: TDisplayDevice;
begin

lpdisplaydevice.cb := sizeof(lpdisplaydevice);
EnumDisplayDevices(nil,devnum,lpDisplayDevice,0 );

EnumDisplaySettings(lpdisplaydevice.DeviceName, 0, DevMode);
DevMode.dmFields := DM_PELSWIDTH or DM_PELSHEIGHT or
DM_DISPLAYFREQUENCY;
DevMode.dmPelsWidth := XRes;
DevMode.dmPelsHeight := YRes;
//DevMode.dmDisplayFrequency := Frequency;
Result := ChangeDisplaySettingsEx (lpdisplaydevice.DeviceName,DevMode,0, (CDS_UPDATEREGISTRY), nil);
end;