Yanghn Notes

unit Unit1;

interface

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

type
  //晚綁定，也就是動態調用外部函數主要用以下三個命令：
  //LoadLibrary：獲取 DLL
  //GetProcAddress：獲取函數
  //FreeLibrary：釋放

  //定義一個過程類型，參數要和需要的函數一致
  TMB = function(hWnd: HWND; lpText, lpCaption: PChar; uType: UINT): Integer; stdcall;

  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    MB: TMB;  {聲明函數 MB}
    inst: LongWord;  {聲明一個變量來記錄要使用的 DLL 句柄}
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  inst := LoadLibrary('user32.dll');
  if inst <> 0 then
    MB := GetProcAddress(inst, 'MessageBoxW');
end;

//調用測試：
procedure TForm1.Button1Click(Sender: TObject);
var
  t,b: PChar;
begin
  t := '標題';
  b := '內容';
  MB(0, b, t, 0);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  FreeLibrary(inst);  {記得釋放}
end;

end.