delphi - 创建替代 TApplication 进行实验？

Question

有一天，我有了一个疯狂的想法，要制作一个全新的 TApplication 替代品来进行实验。我已经编译和运行了所有内容，它确实正确显示了主窗体，一切都响应良好，但是关闭窗体后，应用程序不会停止。我确定我从原始 Forms.pas TApplication (注册关闭事件)中复制了所有必要的内容，但我没有看到它工作。我必须以令人讨厌的方式终止调试 session 。

我在这个小实验中的目标是为非常简单的事情构建一个轻量级应用程序，而不是 TApplication 可以处理的所有可能的事情，而且主要是因为我在这个领域有一些很好的经验。

这是我现在拥有的单元，下面是它的实现。

unit JDForms;

interface

uses
  Forms, Classes, SysUtils, StrUtils, Windows, Win7, XPMan, Variants,
  Messages, Dialogs;

type
  TJDForm = class;
  TJDApplication = class; 
  TJDApplicationThread = class;

  TJDForm = class(TCustomForm)
  private

  public

  published

  end;

  TJDApplication = class(TComponent)
  private
    fRunning: Bool;
    fTerminated: Bool;
    fThread: TJDApplicationThread;
    fMainForm: TJDForm;
    fOnMessage: TMessageEvent;
    fShowMainForm: Bool;
    fHandle: HWND;
    procedure ThreadTerminated(Sender: TObject);
    procedure HandleMessage;
    procedure ProcessMessages;
    function ProcessMessage(var Msg: TMsg): Boolean;
    procedure ThreadSync(Sender: TObject);
  public
    constructor Create(AOwner: TComponent); override;
    property Thread: TJDApplicationThread read fThread;
    procedure Initialize;
    procedure Run;
    procedure CreateForm(InstanceClass: TComponentClass; var Reference);
    procedure Terminate;
    property Terminated: Bool read fTerminated;
    procedure HandleException(Sender: TObject);
    property Handle: HWND read fHandle;
  published
    property ShowMainForm: Bool read fShowMainForm write fShowMainForm;
    property OnMessage: TMessageEvent read fOnMessage write fOnMessage;
  end;

  TJDApplicationThread = class(TThread)
  private
    fOwner: TJDApplication;
    fStop: Bool;
    fOnSync: TNotifyEvent;
    procedure DoSync;
  protected
    procedure Execute; override;
  public
    constructor Create(AOwner: TJDApplication);
    destructor Destroy; override;
    procedure Start;
    procedure Stop;
  published
    property OnSync: TNotifyEvent read fOnSync write fOnSync;
  end;

var
  JDApplication: TJDApplication;

implementation

procedure DoneApplication;
begin
  with JDApplication do begin
    if Handle <> 0 then ShowOwnedPopups(Handle, False);
    //ShowHint := False;
    Destroying;
    DestroyComponents;
  end;
end;

{ TJDApplication }

constructor TJDApplication.Create(AOwner: TComponent);
begin                                    
  fRunning:= False;
  fTerminated:= False;
  fMainForm:= nil;
  fThread:= TJDApplicationThread.Create(Self);
  fThread.FreeOnTerminate:= True;
  fThread.OnTerminate:= ThreadTerminated;
  fShowMainForm:= True;
end;

procedure TJDApplication.CreateForm(InstanceClass: TComponentClass; var Reference);
var
  Instance: TComponent;
begin
  Instance:= TComponent(InstanceClass.NewInstance);
  TComponent(Reference) := Instance;
  try
    Instance.Create(Self);
  except
    TComponent(Reference):= nil;
    raise;
  end;
  if (fMainForm = nil) and (Instance is TForm) then begin
    TForm(Instance).HandleNeeded;
    fMainForm:= TJDForm(Instance);

  end;
end;

procedure TJDApplication.HandleException(Sender: TObject);
begin
  {
  if GetCapture <> 0 then SendMessage(GetCapture, WM_CANCELMODE, 0, 0);
  if ExceptObject is Exception then
  begin
    if not (ExceptObject is EAbort) then
      if Assigned(FOnException) then
        FOnException(Sender, Exception(ExceptObject))
      else
        ShowException(Exception(ExceptObject));
  end else
    SysUtils.ShowException(ExceptObject, ExceptAddr);
  }
end;

procedure TJDApplication.HandleMessage;
var
  Msg: TMsg;
begin
  if not ProcessMessage(Msg) then begin
    //Idle(Msg);
  end;
end;

function TJDApplication.ProcessMessage(var Msg: TMsg): Boolean;
var
  Handled: Boolean;
begin
  Result := False;
  if PeekMessage(Msg, 0, 0, 0, PM_REMOVE) then
  begin
    Result := True;
    if Msg.Message <> WM_QUIT then begin
      Handled := False;
      if Assigned(FOnMessage) then FOnMessage(Msg, Handled);
      //if not IsHintMsg(Msg) and not Handled and not IsMDIMsg(Msg) and
        //not IsKeyMsg(Msg) and not IsDlgMsg(Msg) then
      begin
        TranslateMessage(Msg);
        DispatchMessage(Msg);
      end;
    end else begin
      fTerminated:= True;
    end;
  end;
end;

procedure TJDApplication.ProcessMessages;
var
  Msg: TMsg;
begin
  while ProcessMessage(Msg) do {loop};
end;

procedure TJDApplication.Initialize;
begin
  if InitProc <> nil then TProcedure(InitProc);
end;

procedure TJDApplication.Run;
begin  {
  fRunning := True;
  try
    AddExitProc(DoneApplication);
    if FMainForm <> nil then
    begin
      case CmdShow of
        SW_SHOWMINNOACTIVE: FMainForm.FWindowState := wsMinimized;
        SW_SHOWMAXIMIZED: MainForm.WindowState := wsMaximized;
      end;
      if FShowMainForm then
        if FMainForm.FWindowState = wsMinimized then
          Minimize else
          FMainForm.Visible := True;
      repeat
        try
          HandleMessage;
        except
          HandleException(Self);
        end;
      until Terminated;
    end;
  finally
    FRunning := False;
  end;
        }



  fRunning:= True;
  try
    AddExitProc(DoneApplication);
    if fMainForm <> nil then begin
      fHandle:= fMainForm.Handle;
      if fShowMainForm then begin
        fMainForm.Show;
      end;    
      fThread.Start;
      repeat
        try
          HandleMessage;
          //--- THREAD HANDLING MESSAGES ---

        except
          HandleException(Self);
        end;
      until fTerminated;
    end else begin
      //Main form is nil - can not run
    end;
  finally
    fRunning:= False;
    fTerminated:= True;
  end;
end;

procedure TJDApplication.Terminate;
begin
  fTerminated:= True;
  try
    fThread.Stop;
  except

  end;     
  if CallTerminateProcs then PostQuitMessage(0);
end;

procedure TJDApplication.ThreadTerminated(Sender: TObject);
begin
  //Free objects

end;

procedure TJDApplication.ThreadSync(Sender: TObject);
var
  Msg: TMsg;
begin
  if not ProcessMessage(Msg) then begin
    //Idle(Msg);
  end;
end;

{ TJDApplicationThread }

constructor TJDApplicationThread.Create(AOwner: TJDApplication);
begin
  inherited Create(True);
  fOwner:= AOwner;
end;

destructor TJDApplicationThread.Destroy;
begin

  inherited;
end;

procedure TJDApplicationThread.DoSync;
begin
  Self.fOwner.ThreadSync(Self);
//  if assigned(fOnSync) then fOnSync(Self);
end;

procedure TJDApplicationThread.Execute;
var
  ST: Integer;
begin
  ST:= 5;
  fStop:= False;
  while (not Terminated) and (not fStop) do begin
    //----- BEGIN -----

    Synchronize(DoSync);

    //-----  END  -----
    //Sleep(1000 * ST);
  end;
end;

procedure TJDApplicationThread.Start;
begin
  fStop:= False;
  Resume;
end;

procedure TJDApplicationThread.Stop;
begin
  fStop:= True;
  Suspend;
end;

initialization
  JDApplication:= TJDApplication.Create(nil);

finalization
  if assigned(JDApplication) then begin

    JDApplication.Free;
    JDApplication:= nil;
  end;

end.

这是一个使用它的应用程序:

program Win7FormTestD7;

uses
  Forms,
  W7Form1 in 'W7Form1.pas' {Win7Form1},
  JDForms in 'JDForms.pas';

begin
  JDApplication.Initialize;
  JDApplication.CreateForm(TWin7Form1, Win7Form1);
  JDApplication.Run;
end.

表单“W7Form1”只是一个普通表单，上面有几个随机控件可供测试。

这里的用户不应该问我为什么要这样做，我有我的理由。我通过实践来学习，而不是通过某人向我展示或通过阅读某本书或找到一堆我不知道其工作原理的代码来学习。这是我更好地学习应用程序工作原理并能够扩展我在该领域的知识的一种方式，以便能够在未来构建更复杂的应用程序。

Answer 1

请记住，TCustomForm 没有 TJDApplication 类的概念，它仅适用于 Forms.TApplication 类。确保当 Forms.TApplication.Termulated 属性设置为 True 时，您的 TJDApplication.Run() 方法正在退出。