在 Delphi 下使用 DirectSound (1): 枚举播放设备

//枚举函数
function DirectSoundEnumerate(
lpDSEnumCallback: TDSEnumCallback; //回调函数
lpContext: Pointer                 //用户指针
): HResult; stdcall; //返回错误代码, 成功则返回 DS_OK(0)

//DirectSoundEnumerate 需要的回调函数的原形:
TDSEnumCallback = function(
lpGuid: PGUID;            //设备的 GUID
lpcstrDescription: PChar; //设备描述
lpcstrModule: PChar;      //模块标识
lpContext: Pointer        //由 DirectSoundEnumerate 提供的用户指针
): BOOL; stdcall; //返回 True 表示要继续枚举, 不在继续找了就返回 False

unit Unit1;

interface

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

type
TForm1 = class(TForm)
ListBox1: TListBox; //只在窗体上放了一个列表框
procedure FormCreate(Sender: TObject);
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

uses DirectSound; //!

function EnumCallback(lpGuid: PGUID; lpcstrDescription, lpcstrModule: PChar;
lpContext: Pointer): BOOL; stdcall;
begin
Form1.ListBox1.Items.Add(lpcstrDescription);
Result := True;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
DirectSoundEnumerate(EnumCallback, nil);
end;

end.

uses DirectSound;

function EnumCallback(lpGuid: PGUID; lpcstrDescription, lpcstrModule: PChar;
lpContext: Pointer): BOOL; stdcall;
begin
TStrings(lpContext).Add(lpcstrDescription);
Result := True;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
DirectSoundEnumerate(EnumCallback, ListBox1.Items);
end;

uses DirectSound;

function EnumCallback(lpGuid: PGUID; lpcstrDescription, lpcstrModule: PChar;
lpContext: Pointer): BOOL; stdcall;
begin
if lpGuid <> nil then TStrings(lpContext).Add(GUIDToString(lpGuid^));
TStrings(lpContext).Add(lpcstrDescription);
if lpcstrModule <> nil then TStrings(lpContext).Add(lpcstrModule);
TStrings(lpContext).Add(EmptyStr);
Result := True;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
DirectSoundEnumerate(EnumCallback, ListBox1.Items);
end;