怎么样获得当前打印机支持的纸张类型(50分)

当我们放一个QUICKREPORT控件时可以选择他的page属性的纸张类型如（A3，A4）。
我现在想把这部分放在FORM上设置，就是要打印之前让用户自己选A3或A4,也就是枚举当前
的打印纸张类型。 分不多了只能给50了

function GetDeviceName():String;
var MyReg: TRegistry;
szDeviceName: String;
begin

try
MyReg := TRegistry.Create;
MyReg.RootKey := HKEY_CURRENT_CONFIG;
if MyReg.OpenKey('/System/CurrentControlSet/Control/Print/Printers',False) then

szDeviceName:=MyReg.ReadString('Default')
else

szDeviceName:='';
Except
MyReg.Free;
end;

result:=szDeviceName;
end;


function GetPortName(): String;
var MyReg: TRegistry;
szPortName: String;
begin

try
MyReg := TRegistry.Create;
MyReg.RootKey := HKEY_LOCAL_MACHINE;
if MyReg.OpenKey('/System/CurrentControlSet/Control/Print/Printers/'+GetDeviceName(),False) then

szPortName:=MyReg.ReadString('Port')
else

szPortName:='';
Except
MyReg.Free;
end;

result:=szPortName;
end;


function SetPaperSize(var nWidth,nHeight,nOrient:Word;var nHandle: THandle):integer;
export;
var
szPrinterKey: array[0..99] of Char;
szDeviceName: String;
szPort: String;
cbBuffer: DWORD;
dwRV: DWORD;
dwPapers: DWord;
lpwPapers: array[0..255] of Word;
fSupportUserDefind: Boolean;
fSupportA3: Boolean;
fSupportA4: Boolean;
fSupportB5: Boolean;
hDriver: THandle;
hMem: HGLOBAL;
lpDevMode: Pdevicemode;
a1: Pdevicemode;
i: integer;
begin

fSupportUserDefind:=FALSE;
fSupportA3:=FALSE;
fSupportA4:=FALSE;
fSupportB5:=FALSE;

//取当前默认打印机设备名
szDeviceName:=GetDeviceName();
if szDeviceName='' then

result:=-1;

//取打印机端口
szPort:=GetPortName();
if szPort='' then

result:=-2;

//取打印机支持的全部纸型
dwPapers:=DeviceCapabilities(PChar(szDeviceName),PChar(szPort),DC_PAPERS,@lpwPapers,nil);
if (dwPapers<1)or(dwPapers>256) then

result:=-3;

//判断打印机是否支持自定义、A3、A4、B5纸型
while (dwPapers > 0)do

begin

case DWORD(lpwPapers[dwPapers]) of
DMPAPER_USER: fSupportUserDefind:=TRUE;
DMPAPER_A3: fSupportA3:=TRUE;
DMPAPER_A4: fSupportA4:=TRUE;
DMPAPER_B5: fSupportB5:=TRUE;
end;

dwPapers:=dwPapers-1;
end;


//取打印机的DeviceMode
a1:=nil;
if not(OpenPrinter(PChar(szDeviceName),hDriver,nil)) then
result:=-4;
hMem:=GlobalAlloc(GPTR,DocumentPropertiesA(nHandle,hDriver,PChar(szDeviceName),a1^,a1^,0));
lpDevMode:=GlobalLock(hMem);
a1:=nil;
do
cumentProperties(nHandle,hDriver,PChar(szDeviceName),lpDevMode^,a1^,DM_OUT_BUFFER);

//设置纸型或大小
i:=0;
if ((nWidth=2970)and(nHeight=4200))and(fSupportA3) then
i:=1;
if ((nWidth=2100)and(nHeight=2970))and(fSupportA4) then
i:=i+2;
if ((nWidth=1820)and(nHeight=2570))and(fSupportB5) then
i:=i+3;

case i of
1: begin
//A3
lpDevMode.dmFields:=DM_PAPERSIZE;
lpDevMode.dmPaperSize:=DMPAPER_A3;
end;

2: begin
//A4
lpDevMode.dmFields:=DM_PAPERSIZE;
lpDevMode.dmPaperSize:=DMPAPER_A4;
end;

3: begin
//B5
lpDevMode.dmFields:=DM_PAPERSIZE;
lpDevMode.dmPaperSize:=DMPAPER_B5;
end;

else

if fSupportUserDefind then

begin

lpDevMode.dmFields:=DM_PAPERSIZE or DM_PAPERWIDTH or DM_PAPERLENGTH;
lpDevMode.dmPaperSize:=DMPAPER_USER;
lpDevMode.dmPaperWidth:=nWidth;
lpDevMode.dmPaperLength:=nHeight;
end
else

lpDevMode.dmFields:=0;
end;


//设置方向
case nOrient of
0: begin

lpDevMode.dmFields:=lpDevMode.dmFields or DM_ORIENTATION;
lpDevMode.dmOrientation:=DMORIENT_PORTRAIT;
end;

1: begin

lpDevMode.dmFields:=lpDevMode.dmFields or DM_ORIENTATION;
lpDevMode.dmOrientation:=DMORIENT_LANDSCAPE;
end;

end;


a1:=nil;
do
cumentProperties(nHandle,hDriver,PChar(szDeviceName),a1^,lpDevMode^,DM_IN_BUFFER or DM_UPDATE);
GlobalUnlock(hMem);
GlobalFree(hMem);
ClosePrinter(hDriver);

result:=1;
end;


以前的帖子改改可以用

接受答案了.