Delphi 枚举设备使用代码

delphi 枚举设备使用代码

现在的 delphi(2010、xe) 已经自带了 directx 的相关单元(...sourcertlwin).
--------------------------------------------------------------------------------

//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 s_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

--------------------------------------------------------------------------------

这是常见的代码:
--------------------------------------------------------------------------------
 
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.

--------------------------------------------------------------------------------

在回调函数中直接使用窗体控件不好, 修改如下:
--------------------------------------------------------------------------------
 
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;

--------------------------------------------------------------------------------

获取更多信息:
--------------------------------------------------------------------------------
 
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;