library SampleTask;

// Simple Task Plugin for UltraExplorer.
//   - Does not use the TUltraExplorerTaskForm class defined in FormUltaExplorerTask.pas
//   - Does not use TBX or SpTBX
//   - Uses FastShareMem.pas to support sharing memory allocations across process boundries
//   - Sets the Application, Screen, and HintWindowClass to that of the EXE application
//   - The DLL MUST export the following two function to have UE load it..
//         CreatePluginServer,
//         SetVCLVariables;
//   - Supports only one Plugin from the DLL.  See the UltraExplorerCommon folder
//     for the common standard UltraExplorer plugins to see how to support
//     multiple plugins in a single DLL.
//   - PERFORMANCE:  For performance reasons loading DLLs is slow so if possible put as many
//       plugins into a single DLL as possible.
//
//
// Notes on Creating Forms in a DLL
//   - Creating the Form in the DLL then using a parent from a control in the
//     main app fails because if the Form from the DLL is recreated from an event
//     in the app the DFM resources are linked into the DLL and not the app.  This
//     causes the form to not have any designtime objects when it is recreated (can't
//     find the resources..)
//   - The DLL the can take the TApplication and TScreen from the app, save the ones
//     created in the DLL and cause the DLL to use the applications objects instead.
//     On releasing the DLL the objects are set back to the original saved versions.
//     This still does not fix any Tab or Arrow Dialog Key message issues but it does
//     at least track the Form with the screen and such.  It may help some issues.
//
//  - Hints: These will just plain fail.  In the VCL this is used to find the control
//    to show the hint on:

//       function FindControl(Handle: HWnd): TWinControl;
//       var
//         OwningProcess: DWORD;
//       begin
//         Result := nil;
//         if (Handle <> 0) and (GetWindowThreadProcessID(Handle, OwningProcess) <> 0) and
//            (OwningProcess = GetCurrentProcessId) then
//          ....
//       end;
//
//   The control is never found becase the window handle is created in the DLL's
//   process.
//

uses
  FastShareMem in '..\FastShareMem.pas', // MUST BE FIRST IN THE LIST
  SysUtils,
  Classes,
  Forms,
  Windows,
  Controls,  
  UltraTaskInf in '..\UltraTaskInf.pas',
  SamplePlugin in 'SamplePlugin.pas' {SamplePluginForm};

{$R *.res}
{$Include Compilers.inc}

{$IFNDEF COMPILER_5_UP}
var
  // D5 Fixes this problem;
   ControlWord: Word;
 { SavedApplication: TApplication = nil;
  SavedScreen: TScreen = nil;
  SavedHintWindowClass: THintWindowClass = nil;  }    
{$ENDIF}

function CreatePluginServer: IUltraPlugin;
begin
  Result := TSamplePlugin.Create;
end;

function RestoreVCLVariables: Boolean;
begin
 { if Assigned(SavedApplication) then
    Application := SavedApplication;

  if Assigned(SavedScreen) then
    Screen := SavedScreen;

  if Assigned(SavedHintWindowClass) then
    HintWindowClass := SavedHintWindowClass;      }

  Result := True;
end;

function SetVCLVariables(ParentApplication, ParentScreen, ParentHintWindowClass: Longword): Boolean;
begin
  // The memory layout of TApplication between D7 and D2006 has changed <grrr>
  // so this type of typecasting fails miserably.

 { if not Assigned(SavedApplication) then
  begin
    SavedApplication := Application;
    Application := TApplication( ParentApplication);
  end;

  if not Assigned(SavedScreen) then
  begin
    SavedScreen := Screen;
    Screen := TScreen( ParentScreen);
  end;

  if not Assigned(SavedHintWindowClass) then
  begin
    SavedHintWindowClass := HintWindowClass;
    HintWindowClass := THintWindowClass( ParentHintWindowClass)
  end;          }

  Result := True;
end;

exports
  CreatePluginServer,
  SetVCLVariables;

procedure DLLEntryProc(EntryCode: integer);
begin
  case EntryCode of
    DLL_PROCESS_DETACH:
      begin
        RestoreVCLVariables;
        {$IFNDEF COMPILER_5_UP}
        Set8087CW(ControlWord);
        {$ENDIF}
      end;
    DLL_PROCESS_ATTACH:
      begin
        {$IFNDEF COMPILER_5_UP}
        Set8087CW($133f);
        {$ENDIF}
      end;
    DLL_THREAD_ATTACH:
      begin
      end;
    DLL_THREAD_DETACH:
      begin
      end;
  end;
end;

begin
  IsMultiThread := True;
  DLLProc := @DLLEntryProc;
  DLLEntryProc(DLL_PROCESS_ATTACH);
end.