Delphi enumeration device code _ PHP Tutorial

Delphi enumeration device code. Delphi enumeration device use code current delphi (2010, xe) already comes with directx related units (... sourcertlwin). ---------------------------------------------------------------- delphi enumeration device use code

Currently, delphi (2010, xe) has built-in directx-related units (... sourcertlwin ).
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// Enumeration function
Function directsoundenumerate (
Lpdsenumcallback: tdsenumcallback; // callback function
Lpcontext: pointer // User pointer
): Hresult; stdcall; // return the error code. if the code is successful, s_ OK (0) is returned)

// Original form of the callback function required by directsoundenumerate:
Tdsenumcallback = function (
Lpguid: pguid; // guid of the device
Lpcstrdescription: pchar; // device description
Lpcstrmodule: pchar; // module id
Lpcontext: pointer // User pointer provided by directsoundenumerate
): Bool; stdcall; // returns true, indicating that the enumeration is to be continued. if you do not continue searching, false is returned.

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This is a common code:
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Unit unit1;

Interface

Uses
Windows, messages, sysutils, variants, classes, graphics, controls, forms,
Dialogs, stdctrls;

Type
Tform1 = class (tform)
Listbox1: tlistbox; // only a list box is placed on the form.
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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It is difficult to directly use the form control in the callback function. the modification is as follows:
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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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For more information:
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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;

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