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標題: MDI From使用PackageLoad建立Child Form [打印本頁]
作者: bestlong    時間: 2007-3-6 15:13     標題: MDI From使用PackageLoad建立Child Form

MDI From使用PackageLoad建立Child Form

1、 建立一個新的MDI應用程式。你可以使用（File - New - Other - Projects - MDI Application）
2、 確保Main Form的FormStyle屬性已經設置為fsMDIForm
3、 增加一個MainMenu控制項
4、 確保在產生應用程式的時候，是和package一起產生的。在Project – Options功能表中，選擇Packages選項，然後選中“Build with run-time packages”選項。你至少要選中rtl package和vcl package

在真正編碼前，首先生成該package，並且向其增加一個MDI子表單

1、 創建一個新的運行時package
2、 package增加一個TForm物件，確保該物件的FormStyle屬性已經設置為fsMDIChild
3、 添加一個導出過程，用於創建子表單的實例：

  1. procedure TPackageMDIChildForm.FormClose (Sender: TObject; var Action: TCloseAction);
  2. begin
  3.   //since this is an MDI child, make sure
  4.   //it gets closed when the user
  5.   //clicks the x button.
  6.   Action := caFree;
  7. end;

  9. procedure ExecuteChild;
  10. begin
  11.   TPackageMDIChildForm.Create(Application);
  12. end;

  14. exports
  15.   //NOTE!! The export name
  16.   //is CASE SENSITIVE
  17.   ExecuteChild;
  18. end.
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重新回到MDI主程序，以下是MDI主表單的所有代碼：

  1. type

  3. //signature of the "ExecuteChild"
  4. //procedure from the Package
  5. TExecuteChild = procedure;

  7. TMainForm = class(TForm)
  8. ...
  9. private
  10.   PackageModule : HModule;
  11.   ExecuteChild : TExecuteChild;
  12.   procedure PackageLoad;
  13. end;

  15. var
  16.   MainForm: TMainForm;

  18. implementation

  20. {$R *.dfm}

  22. procedure TMainForm.PackageLoad;
  23. begin
  24.   //try loading the package
  25.   //(let's presume it's in the same
  26.   //folder, where the main app. exe is)
  27.   PackageModule := LoadPackage('MDIPackage.bpl');


  30.   //if loaded, try locating
  31.   //the ExecuteChild procedure
  32.   if PackageModule <> 0 then
  33.     try
  34.       @ExecuteChild := GetProcAddress(PackageModule,'ExecuteChild');
  35.     except
  36.       //display an error message if we fail
  37.       ShowMessage ('Package not found');
  38.     end;
  39. end;

  41. //menu click
  42. procedure TMainForm.mnuCallFromDLLClick(Sender: TObject);
  43. begin
  44.   //lazzy load package
  45.   if PackageModule = 0 then PackageLoad;
  46.   
  47.   //if the ExecuteChild procedure
  48.   //was found in the package, call it
  49.   if Assigned(ExecuteChild) then ExecuteChild;
  50. end;

  52. procedure TMainForm.FormDestroy(Sender: TObject);
  53. begin
  54.   //if the package was loaded,
  55.   //make sure to free the resources
  56.   if PackageModule <> 0 then
  57.     UnloadPackage(PackageModule);
  58. end;
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