MDI From使用PackageLoad建立Child Form

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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;
   
8. 
   
9. procedure ExecuteChild;
   
10. begin
    
11.   TPackageMDIChildForm.Create(Application);
    
12. end;
    
13. 
    
14. exports
    
15.   //NOTE!! The export name
    
16.   //is CASE SENSITIVE
    
17.   ExecuteChild;
    
18. end.

複製代碼

重新回到MDI主程序，以下是MDI主表單的所有代碼：

1. type
   
2. 
   
3. //signature of the "ExecuteChild"
   
4. //procedure from the Package
   
5. TExecuteChild = procedure;
   
6. 
   
7. TMainForm = class(TForm)
   
8. ...
   
9. private
   
10.   PackageModule : HModule;
    
11.   ExecuteChild : TExecuteChild;
    
12.   procedure PackageLoad;
    
13. end;
    
14. 
    
15. var
    
16.   MainForm: TMainForm;
    
17. 
    
18. implementation
    
19. 
    
20. {$R *.dfm}
    
21. 
    
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');
    
28. 
    
29. 
    
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;
    
40. 
    
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;
    
51. 
    
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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