library: libCore
#include "TQCommand.h"

TQCommand


class description - source file - inheritance tree (.pdf)

class TQCommand : public TList, public TQObject

Inheritance Chart:
TObject
<-
TCollection
<-
TSeqCollection
<-
TList
TQObject
<-
TQCommand
<-
TQUndoManager

    protected:
virtual void Init(const char* cl, void* object, const char* redo, const char* undo) public:
TQCommand(const char* cl = "0", void* object = 0, const char* redo = "0", const char* undo = "0") TQCommand(TObject* obj, const char* redo = "0", const char* undo = "0") TQCommand(const TQCommand& com) virtual ~TQCommand() virtual void Add(TObject* obj, Option_t* opt) virtual void Add(TObject* obj) virtual Bool_t CanCompress(TQCommand* c) const virtual Bool_t CanMerge(TQCommand* c) const virtual Bool_t CanRedo() const virtual Bool_t CanUndo() const static TClass* Class() virtual void Compress(TQCommand* c) virtual void Delete(Option_t* option = "") static TQCommand* gCommand() virtual const char* GetName() const Int_t GetNRargs() const Int_t GetNUargs() const void* GetObject() const TQConnection* GetRedo() const Long_t* GetRedoArgs() const const char* GetRedoName() const Int_t GetStatus() const virtual const char* GetTitle() const TQConnection* GetUndo() const Long_t* GetUndoArgs() const const char* GetUndoName() const virtual TClass* IsA() const virtual Bool_t IsEqual(const TObject* obj) const Bool_t IsExecuting() const Bool_t IsMacro() const Bool_t IsRedoing() const virtual Bool_t IsSetter() const Bool_t IsUndoing() const virtual void ls(Option_t* option = "") const virtual void Merge(TQCommand* c) virtual void Print(Option_t* option = "") const virtual void Print(Option_t*, Option_t* option) const virtual void Redo(Option_t* option = "") virtual void SetArgs(Int_t nargs) virtual void SetName(const char* name) virtual void SetRedoArgs(Int_t nargs) virtual void SetTitle(const char* title) virtual void SetUndoArgs(Int_t nargs) virtual void ShowMembers(TMemberInspector& insp, char* parent) virtual void Streamer(TBuffer& b) void StreamerNVirtual(TBuffer& b) virtual void Undo(Option_t* option = "")

Data Members


    protected:
TQConnection* fRedo do/redo action TQConnection* fUndo undo action Long_t* fRedoArgs redo values Long_t* fUndoArgs undo values Int_t fNRargs number of redo arguments Int_t fNUargs number of undo arguments Int_t fState -1 undoing on, 1 redoing on, 0 nothing in progress Int_t fStatus fStatus++ after Redo(), fStatus-- after Undo() Bool_t fNewDelete kTRUE if Redo/Undo methods are new/delete TString fName command name. Default is "ClassName::RedoName(args)" TString fTitle command description void* fObject object to which undo/redo actions applied

Class Description

                                                                      
 The Command design pattern is based on the idea, that all editing    
 in an application is done by creating instances of command objects.  
 Command objects apply changes to the edited object and then are      
 stored  on a command stack. Furthermore, each command knows how to   
 undo its changes to bring the edited object back to its previous     
 state. As long as the application only uses command objects to       
 change the state of the edited object, it is possible to undo        
 a sequence of commands by traversing the command stack downwards and 
 calling the "undo" method of each command in turn. It is also        
 possible to redo a sequence of commands by traversing the command    
 stack upwards and calling the "redo" method of each command.         
                                                                      
                                                                      
 Examples:                                                            
                                                                      
 1. Create a new command                                              
                                                                      
 TQCommand *com = new TQCommand("TH1", hpx, "SetFillColor(Color_t)"   
                                "SetFillColor(Color_t)");             
                                                                      
 1st parameter - the name of class                                    
 2nd parameter - object                                               
 3rd parameter - the name of do/redo method                           
 4th parameter - the name of undo method                              
                                                                      
 Since redo,undo methods are the same, undo name can be omitted, e.g. 
                                                                      
 TQCommand *com = new TQCommand("TH1", hpx, "SetFillColor(Color_t)"); 
                                                                      
 For objects derived from TObject class name can be omitted, e.g.     
                                                                      
    TQCommand *com = new TQCommand(hpx, "SetFillColor(Color_t)");     
                                                                      
 2. Setting undo, redo parameters.                                    
                                                                      
    Color_t old_color = hpx->GetFillColor();                          
    Color_t new_color = 4;  // blue color                             
                                                                      
    com->SetRedoArgs(1, new_color);                                   
    com->SetUndoArgs(1, old_color);                                   
                                                                      
 1st argument - the number of undo, redo parameters                   
 the other arguments - undo, redo values                              
                                                                      
 Since the number of undo,redo parameters is the same one can use     
                                                                      
    com->SetArgs(1, new_color, old_color);                            
                                                                      
 3. Undo, redo method execution                                       
                                                                      
    com->Redo(); // execute redo method                               
    com->Undo(); // execute undo method                               
                                                                      
 4. Merged commands                                                   
                                                                      
 It possible to group several commands together so an end user        
 can undo and redo them with one command.                             
                                                                      
    TQCommand *update = new TQCommand(gPad, "Modified()");            
    com->Add(update);                                                 
                                                                      
 5. Macro commands                                                    
                                                                      
 "Merging" allows to create macro commands, e.g.                      
                                                                      
    TQCommand *macro = new TQCommand("my macro");                     
    macro->Add(com1);                                                 
    macro->Add(com2);                                                 
    ...                                                               
                                                                      
 During Redo operation commands composing macro command are executed  
 sequentially in direct  order (first in first out). During Undo,     
 they are executed in reverse order (last in first out).              
                                                                      
 6. Undo manager.                                                     
                                                                      
 TQUndoManager is recorder of undo and redo operations. This is       
 command history list which can be traversed backwards and upwards    
 performing undo and redo operations.                                 
 To register command TQUndoManager::Add(TObject*) method is used.     
                                                                      
    TQUndoManager *history = new TQUndoManager();                     
    history->Add(com);                                                
                                                                      
 TQUndoManager::Add automatically invokes execution of command's      
 Redo method.                                                         
                                                                      
 Use TQUndoManager::Undo to undo commands in  history list.           
 Redo is Undo for undo action. Use TQUndoManager::Redo method for that
                                                                      


void Init(const char *clname, void *obj, const char *redo, const char *undo)
 common protected method used in several constructors

TQCommand(const char *clname, void *obj, const char *redo, const char *undo) : TList(), TQObject()
 Constructor.

   Input parameters:
     1. clname - class name.
     2. obj - an object
     3. redo - method or function to do/redo operation
     4. undo - method or function to undo operation

 Comments:
    - if either clname or obj is NULL that means that redo/undo is function
    - to specify default arguments for redo/undo method/function
       '=' must precede to argument value.

  Example:
    TQCommand("TPad", gPad, "SetEditable(=kTRUE)", "SetEditable(=kFALSE)");

    - undo method can be same as redo one. In that case undo parameter
       can be omitted.

  Example:
    TQCommand("TPad", gPad, "SetFillStyle(Style_t)");

TQCommand(TObject *obj, const char *redo, const char *undo) : TList(), TQObject()
 Constructor.

   Input parameters:
     1. obj - an object
     2. redo - method or function to do/redo operation
     3. undo - method or function to undo operation

 Comments:
    - to specify default arguments for redo/undo method/function
       '=' must precede to argument value.

  Example:
    TQCommand(gPad, "SetEditable(=kTRUE)", "SetEditable(=kFALSE)");

    - undo method can be same as redo one. In that case "undo"
       can parameter be omitted.

  Example:
    TQCommand(gPad, "SetFillStyle(Style_t)");

TQCommand(const TQCommand &com) : TList(), TQObject()
 Copy constructor.

~TQCommand()
 dtor.

TQCommand* gCommand()
 Return a command which is doing redo/undo action

 This static method allows to set undo parameters dynamically, i.e.
 during execution of Redo function.

 Example:
    For redo actions like TGTextEdit::DelChar() it is not possible to
    know ahead what character will be deleted.
    To set arguments for undo action ( e.g. TGTextEdit::InsChar(char)),
    one needs to call TQCommand::SetUndoArgs(1, character) from
    inside of TGTextEdit::DelChar() method, i.e.

    TQCommand::gCommand()->SetUndoArgs(1, somechar);

void Delete(Option_t *opt)
 If "opt" is not zero delete every merged command which option string is
 equal to "opt". If "opt" is zero - delete all merged commands.

Bool_t CanMerge(TQCommand *) const
 Two commands can be merged if they can be composed into
 a single command (Macro command).

 To allow merging commands user might override this function.

void Merge(TQCommand *c)
 Add command to the list of merged commands.
 This make it possible to group complex actions together so an end user
 can undo and redo them with one command. Execution of TQUndoManager::Undo(),
 TQUndoManager::Redo() methods only invokes the top level command as a whole.

 Merge method is analogous to logical join operation.

 Note:  Merge method invokes redo action.

void Add(TObject *obj, Option_t *opt)
 Add command to the list of merged commands.

 Option string can contain substrings:
  "compress" - try to compress input command
  "radd" - execute redo action of input command
  "uadd" - execute undo action of input command

Bool_t CanCompress(TQCommand *c) const
 By default, commands can be compressed if they are:

  - equal
  - setter commands

 More complicated commands might want to override this function.

void Compress(TQCommand *c)
 Compress command. Compression is analogous to arithmetic "addition operation".

 Note:
    - The compressed command will be deleted.
    - Execution Compress method invokes Redo action with new redo arguments
      inheritied from compressed command.

 More complicated commands might want to override this function.

Bool_t IsEqual(const TObject* obj) const
 Equal comparison. The commands are equal if they are
 applied to the same object and have the same Redo/Undo actions

 More complicated commands might want to override this function.

Bool_t IsSetter() const
 Returns kTRUE is command if Redo is the same as Undo function
 and is the setter action.

 By default, all functions with names like "SetXXX" or "setXXX"
 considered as setters. Another type of setters are Move, Resize operations

 More complicated commands might want to override this function.

void SetArgs(Int_t narg, ...)
 Set do/redo and undo parameters. The format is
    SetArgs(number_of_params, redo_params, undo_params)

 Example:
     move_command->SetArgs(2, 100, 100, 200, 200);
      2 params, (100,100) - do/redo position, (200,200) - undo position

void SetRedoArgs(Int_t narg, ...)
 Set redo parameters. The format is
    SetRedoArgs(number_of_params, params)

 Example:
     move_command->SetRedoArgs(2, 100, 100);

void SetUndoArgs(Int_t narg, ...)
 Set undo parameters. The format is
    SetUndoArgs(number_of_params, params)

 Example:
     move_command->SetUndoArgs(2, 200, 200);

Bool_t CanRedo() const
 Returns kTRUE if Redo action is possible, kFALSE if it's not.
 By default, only single sequential redo action is possible.

Bool_t CanUndo() const
 Returns kTRUE if Undo action is possible, kFALSE if it's not.
 By default, only single tial undo action is possible.

void Redo(Option_t *)
 Execute command and then smerged commands

void Undo(Option_t *)
 Unexecute all merged commands and the command.
 Merged commands are executed in reverse order.

const char* GetName() const
 Returns the command name. Default name is "ClassName::RedoName(args)"
 If list of merged commands is not empty the name is
 "ClassName::RedoName(args):cname1:cname2 ..."

const char* GetTitle() const
 Returns command description.
 By default, "ClassName::RedoName(args)_ClassName::UndoName(args)"

const char* GetRedoName() const
 Returns the name of redo command

const char* GetUndoName() const
 Returns the name of undo command

Long_t* GetRedoArgs() const
 Returns a pointer to array of redo arguments

Long_t* GetUndoArgs() const
 Returns a pointer to array of undo arguments

Int_t GetNRargs() const
 Returns a number of redo arguments

Int_t GetNUargs() const
 Returns a number of undo arguments

void* GetObject() const
 Returns an object for which undo redo acions are applied

Int_t GetStatus() const
 Returns a number of sequential undo or redo operations

Bool_t IsMacro() const
 Returns kTRUE if neither redo nor undo action specified

Bool_t IsUndoing() const
 Undo action is in progress

Bool_t IsRedoing() const
 Redo action is in progress

Bool_t IsExecuting() const
 Returns kTRUE if command execution is in progress

void SetName(const char *name)
 Sets name of the command

void SetTitle(const char *title)
 Sets description of the command

void ls(Option_t *) const
 ls this command and merged commands

void Print(Option_t *option) const
 print this command and all merged commands



Inline Functions


        TQConnection* GetRedo() const
        TQConnection* GetUndo() const
                 void Print(Option_t*, Option_t* option) const
                 void Add(TObject* obj)
              TClass* Class()
              TClass* IsA() const
                 void ShowMembers(TMemberInspector& insp, char* parent)
                 void Streamer(TBuffer& b)
                 void StreamerNVirtual(TBuffer& b)


Author: Valeriy Onuchin 04/27/2004
Last update: root/base:$Name: $:$Id: TQCommand.cxx,v 1.4 2005/02/11 18:40:08 rdm Exp $
Copyright (C) 1995-2001, Rene Brun and Fons Rademakers. *


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