Delphi7通过SendMessage来实现默认打印机的切换

具体代码

1. procedure SetDefaultPrinter(NewDefPrinter: string); 
2. var
3.   ResStr: array[0..255] of Char;
4. begin
5.   StrPCopy(ResStr, NewdefPrinter);
6.   WriteProfileString('windows', 'device', ResStr);
7.   StrCopy(ResStr, 'windows');
8.   SendMessage(HWND_BROADCAST, WM_WININICHANGE, 0, Longint(@ResStr));
9. end;

复制代码

参数：NewDefPrinter是具体的打印机名称，可以到控制面板-设备和打印机下查看，例如:Microsoft XPS Document Writer
使用代码

1. SetDefaultPrinter('Microsoft XPS Document Writer');

简单案例

 

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs,Printers, StdCtrls;

type
TForm1 = class(TForm)
Button3: TButton;
ComboBox1: TComboBox;
procedure Button3Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure SetDefaultPrinter(NewDefPrinter: string);
var
ResStr: array[0..255] of Char;
begin
StrPCopy(ResStr, NewdefPrinter);
WriteProfileString('windows', 'device', ResStr);
StrCopy(ResStr, 'windows');
SendMessage(HWND_BROADCAST, WM_WININICHANGE, 0, Longint(@ResStr));
end;

procedure TForm1.Button3Click(Sender: TObject);

begin
ComboBox1.Items:=printer.Printers;
ComboBox1.Text:=IntToStr(SizeOf(ComboBox1.Items));
SetDefaultPrinter('Microsoft XPS Document Writer');

end;

end.