printer settings don't change (winapi: documentproperties) - delphi

Question

Language: delphi 6
I succeeded in opening the dialog using documentproperties.
However, I changed the settings and clicked OK, but it does not change.
I want to change the paper to A3.
Please tell me how to do it.
code:
var
FPrinterHandle:THandle;
aDevice: array[0..255] of char;
DevMode: PDeviceMode;
StubDevMode: TDeviceMode;
DeviceMode: THandle;
begin
strpcopy(aDevice, Combobox1.Text);
if OpenPrinter(aDevice,FPrinterHandle,nil) then begin
DeviceMode := GlobalAlloc(GHND, DocumentProperties(self.handle, FPrinterHandle, ADevice, StubDevMode, StubDevMode, 0));
if DeviceMode <> 0 then begin
DevMode := GlobalLock(DeviceMode);
DocumentProperties(0, FPrinterHandle, ADevice, DevMode^, DevMode^, DM_OUT_BUFFER);
DevMode^.dmFields := DM_PAPERSIZE;
DevMode^.dmPaperSize := DMPAPER_A3;
DocumentProperties(0, FPrinterHandle, ADevice, DevMode^, DevMode^, DM_OUT_BUFFER or DM_IN_BUFFER);
GlobalUnlock(DeviceMode);
GlobalFree(DeviceMode);
end;
end;
end;

Answer 1

It's not the code I wrote, it's from somewhere. Hope it helps.
Pass the printer name and desired paper size as parameters. (I used GetPrinter procedure)
If parameter(integer) is 0, it is set to A3, and if it is 1, it is set to A4.
And when I printed pdf file with shellexecute, I checked that it prints in the desired size.
※ Before print, the tray of the printer should be set to 'automatic selection'.
procedure SetPrinterInfo(APrinterName: PChar; Psize: Integer);
var
HPrinter : THandle;
InfoSize, BytesNeeded: Cardinal;
DevMode: PDeviceMode;
PI2: PPrinterInfo2;
PrinterDefaults: TPrinterDefaults;
begin
with PrinterDefaults do
begin
DesiredAccess := PRINTER_ACCESS_USE;
pDatatype := nil;
pDevMode := nil;
end;
if OpenPrinter(APrinterName, HPrinter, #PrinterDefaults) then
try
SetLastError(0);
//Determine the number of bytes to allocate for the PRINTER_INFO_2 construct...
if not GetPrinter(HPrinter, 2, nil, 0, #BytesNeeded) then
begin
//Allocate memory space for the PRINTER_INFO_2 pointer (PrinterInfo2)...
PI2 := AllocMem(BytesNeeded);
try
InfoSize := SizeOf(TPrinterInfo2);
if GetPrinter(HPrinter, 2, PI2, BytesNeeded, #BytesNeeded) then
begin
DevMode := PI2.pDevMode;
DevMode.dmFields := DevMode.dmFields or DM_PAPERSIZE;
if Psize = 0 then DevMode.dmPaperSize := DMPAPER_A3
else if Psize = 1 then DevMode.dmPaperSize := DMPAPER_A4;
PI2.pSecurityDescriptor := nil;
// Apply settings to the printer
if DocumentProperties(0, hPrinter, APrinterName, PI2.pDevMode^,
PI2.pDevMode^, DM_IN_BUFFER or DM_OUT_BUFFER) = IDOK then
begin
SetPrinter(HPrinter, 2, PI2, 0); // Ignore the result of this call...
end;
end;
finally
FreeMem(PI2, BytesNeeded);
end;
end;
finally
ClosePrinter(HPrinter);
end;
end;