Delphi 枚舉設備使用代碼

delphi 枚舉設備使用代碼

現在的 delphi(2010、xe) 已經自帶了 directx 的相關單元(...sourcertlwin).
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//枚舉函數
function directsoundenumerate(
  lpdsenumcallback: tdsenumcallback; //回調函數
  lpcontext: pointer                 //用戶指針
): hresult; stdcall; //返回錯誤代碼, 成功則返回 s_ok(0)

//directsoundenumerate 需要的回調函數的原形:
tdsenumcallback = function(
  lpguid: pguid;            //設備的 guid
  lpcstrdescription: pchar; //設備描述
  lpcstrmodule: pchar;      //模塊標識
  lpcontext: pointer        //由 directsoundenumerate 提供的用戶指針
): bool; stdcall; //返回 true 表示要繼續枚舉, 不在繼續找了就返回 false

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這是常見的代碼:
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unit unit1;

interface

uses
  windows, messages, sysutils, variants, classes, graphics, controls, forms,
  dialogs, stdctrls;

type
  tform1 = class(tform)
    listbox1: tlistbox; //只在窗體上放了一個列表框
    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.

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在回調函數中直接使用窗體控件不好, 修改如下:
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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;

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獲取更多信息:
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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;