Question

有一天，我有了一个疯狂的想法，为实验做出全新的TApplication替换。我得到了编译和运行的所有东西，它确实显示了主要表单，一切响应都很好，但在关闭表单后，应用程序不会停止。我确定我从最初的Forms.pas TApplication（注册close事件）中复制了所有必要的东西，但我看不到它的工作原理。我必须以令人讨厌的方式终止调试会话。

我在这个小实验中的目标是为非常简单的东西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东西，而且大多数情况下我在这样的领域都有一些很好的经验。

这是我现在拥有的单位，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.

表格'W7Form1'只是一个简单的表格，上面有几个随机控件供测试。

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，而不是通过向我展示或阅读一些书籍或找到一堆我不知道它如何运作的代码。这是一种让我更好地学习应用程序的工作方式，并能够扩展我在该领域的知识，以便将来能够构建更复杂的应用程序。

Answer 1

如果构建轻量级应用程序是你的座右铭，我建议你去玩：

KOL Library
SDA Framework
VCL Light
LVCL基于SO成员Arnaud Bouchez的VCL Light代码。

Answer 2

请注意，TCustomForm没有TJDApplication类的概念，它只适用于Forms.TApplication类。当TJDApplication.Run()属性设置为True时，请确保您的Forms.TApplication.Terminated方法已退出。

创建替代TApplication进行实验？

2 个答案: