教你如何编程调用 NSIS 的插件

看见 NSIS 有不少很好的插件，例如 BT 下载的专用插件，如果你不想用 NSIS 来编写 BT 种子下载的专用程序，但是又不会写 BT 下载的客户端，怎么办，当然是最好能够调用这些现成的插件啦，所以以下我示范一下如何调用这些插件，不过我举的例子是使用 NSIS 的闪屏插件（splash.dll），不过因为 NSIS 插件都是统一规格的，所以只是调用参数稍稍不同而已，大同小异。以下为调用程序的源代码。

unit Unit1; interface uses   Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,   StdCtrls; type   TForm1 = class(TForm)     Button1: TButton;     procedure Button1Click(Sender: TObject);   private     { Private declarations }   public     { Public declarations }   end;   VarConstants = (     INST_0,     INST_1,      // $1     INST_2,      // $2     INST_3,      // $3     INST_4,      // $4     INST_5,      // $5     INST_6,      // $6     INST_7,      // $7     INST_8,      // $8     INST_9,      // $9     INST_R0,      // $R0     INST_R1,      // $R1     INST_R2,      // $R2     INST_R3,      // $R3     INST_R4,      // $R4     INST_R5,      // $R5     INST_R6,      // $R6     INST_R7,      // $R7     INST_R8,      // $R8     INST_R9,      // $R9     INST_CMDLINE, // $CMDLINE     INST_INSTDIR, // $INSTDIR     INST_OUTDIR,  // $OUTDIR     INST_EXEDIR,  // $EXEDIR     INST_LANG,    // $LANGUAGE     __INST_LAST     );   TVariableList = INST_0..__INST_LAST;   pstack_t = ^stack_t;   stack_t = record     next: pstack_t;     text: PChar;   end; var   g_stringsize: integer;   g_stacktop: ^pstack_t;   g_variables: PChar;   g_hwndParent: HWND;   ShowSplash: procedure (const hwndParent: HWND; const string_size: integer; const variables: PChar; const stacktop: pointer); cdecl;   Form1: TForm1; implementation {$R *.DFM} function PopString(): string; var   th: pstack_t; begin   if integer(g_stacktop^) <> 0 then begin     th := g_stacktop^;     Result := PChar(@th.text);     g_stacktop^ := th.next;     GlobalFree(HGLOBAL(th));   end; end; procedure PushString(const str: string=''); var   th: pstack_t; begin   if integer(g_stacktop) <> 0 then begin     th := pstack_t(GlobalAlloc(GPTR, SizeOf(stack_t) + g_stringsize));     lstrcpyn(@th.text, PChar(str), g_stringsize);     th.next := g_stacktop^;     g_stacktop^ := th;   end else begin     g_stacktop:=Pointer(GlobalAlloc(GPTR, SizeOf(g_stacktop)));     th := pstack_t(GlobalAlloc(GPTR, SizeOf(stack_t) + g_stringsize));     lstrcpyn(@th.text, PChar(str), g_stringsize);     th.next := nil;     g_stacktop^ := th;   end; end; function GetUserVariable(const varnum: TVariableList): string; begin   if (integer(varnum) >= 0) and (integer(varnum) < integer(__INST_LAST)) then     Result := g_variables + integer(varnum) * g_stringsize   else     Result := ''; end; procedure SetUserVariable(const varnum: TVariableList; const value: string); begin   if (value <> '') and (integer(varnum) >= 0) and (integer(varnum) < integer(__INST_LAST)) then     lstrcpy(g_variables + integer(varnum) * g_stringsize, PChar(value)) end; procedure TForm1.Button1Click(Sender: TObject); var   th: pstack_t;   DllHandle: THandle; begin   g_hwndParent:=handle;   g_stringsize:=MAX_PATH;   g_variables:=PChar(GlobalAlloc(GPTR, (integer(__INST_LAST)-integer(INST_0))*g_stringsize));   PushString('e:\logo'); //图片 logo.bmp 放到 e 盘根目录，调用时不要带扩展名，这是 splash.dll 的调用规则，所以调用之前，先看看这个插件的参数说明，免得调用失败没效果   PushString('1000');       DllHandle := LoadLibrary('splash.dll');       if DllHandle > 0 then       begin         ShowSplash := GetProcAddress(DllHandle, 'show');         if Assigned(ShowSplash) then           ShowSplash(g_hwndParent,g_stringsize,g_variables,g_stacktop);         FreeLibrary(DllHandle);       end;   GlobalFree(HGLOBAL(g_variables));   while g_stacktop^ <> nil do   begin     th := g_stacktop^;     g_stacktop^ := th.next;     GlobalFree(HGLOBAL(th));   end;   g_stacktop:=nil; end; end.