Undo feature for a graphical programming system

• US 5,990,906 A
• Filed: 08/19/1997
• Issued: 11/23/1999
• Est. Priority Date: 06/25/1997
• Status: Expired due to Term

• Current Assignee: National Instruments Corporation (Emerson Electric Company)
• Original Assignee: National Instruments Corporation (Emerson Electric Company)
• Inventors: Hudson, Duncan, Jensen, Melanie, Kodosky, Jeffrey L.
• Primary Examiner(s): Nguyen, Phu K.
• Application Number:
  US08/914,554
• Time in Patent Office: 826 Days
• Field of Search: 345/439, 345/355, 345/356, 345/357, 345/127, 345/131, 345/433
• US Class Current: 345/666
• CPC Class Codes: G06F 8/34 Graphical or visual programming

Abstract

An Undo/Redo feature for a graphical programming system which minimizes the required data storage. The graphical programming system includes a plurality of interconnected objects, including fixed size objects and variable size objects. A variable size object is an object which typically changes in size, i.e., grows or shrinks, in response to user modification, whereas fixed size objects do not change in size. When an object is modified by the user, the method of the present invention stores a backup copy for undo purposes. For modification of an object, the backup is performed differently depending on whether the object is a variable size object or a fixed size object. For a variable size object, the method stores the original object as the previous object in the backup list, and the method stores a copy of the original object as the current object in the backup list. For a fixed size object, the method stores a copy of the original object as the previous object in the backup list, and the method stores the original object as the current object in the backup list. For a fixed size object, the original object thus remains as the current or foreground object in the graphical program. Since the original object stays in the foreground, other objects which reference this object maintain their references, and thus are not also required to be backed up. Therefore, the present invention provides a unique system and method for performing undo/redo in a graphical system which minimizes the amount of memory required for undo purposes.

Claims

1. A method for performing undo in a graphical system, wherein the graphical system includes a plurality of interconnected objects, wherein said interconnected objects include fixed size objects and variable size objects, the method comprising:

receiving user input which modifies an object;

determining if the object is a fixed size object or a variable size object;

backing up the object in a data structure in response to said user input which modifies the object, wherein the data structure includes one or more pairs each comprising a current element and a previous element, wherein, if the object is a fixed size object, said backing up the object comprises;

creating a copy of the object;

storing the copy of the object as the previous element in the data structure; and

storing the object as the current element in the data structure, wherein the object remains a foreground object in the graphical system.

2. The method of claim 1, wherein the object is a fixed size object, the method further comprising:

receiving user input to undo said modification to said object;

undoing said modification to said object, wherein said undoing comprises swapping contents of the current and previous elements in the data structure.

3. The method of claim 1, wherein, if the object is a variable size object, said backing up the object comprises:

storing the object as the previous element in the data structure;

creating a copy of the object; and

storing the copy of the object as the current element in the data structure wherein the copy of the object becomes the foreground object in the graphical system.

4. The method of claim 3, wherein the object is a variable size object, the method further comprising:

receiving user input to undo said modification to said object;

undoing said modification to said object, wherein said undoing comprises swapping the current and previous elements in the data structure.

5. The method of claim 1, wherein said determining if the object is a fixed size object or a variable size object comprises determining if the object is a type which changes in size in response to user modification.

6. The method of claim 1, wherein said determining if the object is a fixed size object or a variable size object comprises determining if the object changes in size in response to said receiving user input.

7. The method of claim 1, wherein a variable size object is an object which generally changes in size in response to user modification;

wherein a fixed size object is an object which does not change in size in response to user modification.

8. The method of claim 1, wherein the object is stored in a first memory location prior to said receiving user input;

wherein the object remains stored in said first memory location after said backing up the object in the data structure.

9. The method of claim 8, wherein the object is referenced by one or more other objects, wherein said one or more other objects each include a reference to the object;

wherein said references to the object are unbroken since the object remains stored in said first memory location after said backing up the object in the data structure;

wherein said one or more other objects are not required to be backed up since said references to the object are unbroken.

10. The method of claim 1, wherein the object is referenced by one or more other objects, wherein said one or more other objects each include a reference to the object;

wherein said storing the copy of the object as the previous element in the data structure and storing the object as the current object in the data structure causes said references to the object to be unbroken;

wherein said one or more other objects are not required to be backed up since said references to the object are unbroken.

11. The method of claim 1, further comprising:

determining if the object is required to be modified after said receiving user input and prior to said backing up the object;

wherein said backing up the object in the data structure is performed in response to determining that the object is required to be modified.

12. The method of claim 11, wherein the object is comprised in an object hierarchy, wherein the object hierarchy comprises a plurality of objects, the method further comprising:

constructing a message in response to said receiving user input, wherein said message includes an object path of the object and the action signified by the user input, wherein said constructing the message is performed after said receiving user input which modifies an object and prior to said determining if the object is required to be modified

wherein said steps of determining if the object is required to be modified, determining if the object is a fixed size object or a variable size object, and backing up the object in a data structure are performed for each of said plurality of objects in the object hierarchy.

13. The method of claim 1, wherein the graphical system comprises a graphical programming system;

wherein said receiving user input which modifies an object is performed during creation of a graphical program in the graphical programming system.

14. A computer system which performs undo in a graphical system, the computer system comprising:

a CPU which executes code and data;

a memory coupled to the CPU which stores a plurality of interconnected objects, wherein said interconnected objects include fixed size objects and variable size objects;

a user input device for receiving user input which modifies an object;

a software program stored in the memory which performs undo operations, wherein the software program is executable by the CPU to determine if the object is a fixed size object or a variable size object;

a data structure stored in the memory of the computer system for storing backups of objects, wherein the data structure includes one or more pairs each comprising a current element and a previous element;

wherein the software program is further executable to back up the object in the data structure in response to said user input which modifies the object, wherein, if the object is a fixed size object, the software program is executable to create a copy of the object, store the copy of the object as the previous element in the data structure, and store the object as the current element in the data structure, wherein the object remains a foreground object in the graphical system.

15. The computer system of claim 14, wherein the object is a fixed size object;

wherein the user input device is operable to receive user input to undo said modification to said object;

wherein the software program is further executable to undo said modification to said object by swapping contents of the current and previous elements in the data structure.

16. The computer system of claim 14, wherein, if the object is a variable size object, the software program is executable to store the object as the previous element in the data structure, create a copy of the object, and store the copy of the object as the current element in the data structure, wherein the copy of the object becomes the foreground object in the graphical system.

17. The computer system of claim 16, wherein the object is a variable size object;

wherein the user input device is operable to receive user input to undo said modification to said object;

wherein the software program is further executable to undo said modification to said object by swapping the current and previous elements in the data structure.

18. The computer system of claim 14, wherein the software program determines if the object is a fixed size object or a variable size object by determining if the object is a type which changes in size in response to user modification.

19. The computer system of claim 14, wherein the software program determines if the object is a fixed size object or a variable size object by determining if the object changes in size in response to said receiving user input.

20. The computer system of claim 14, wherein a variable size object is an object which generally changes in size in response to user modification;

wherein a fixed size object is an object which does not change in size in response to user modification.

21. The computer system of claim 14, wherein the object is stored in a first memory location in said memory prior to said receiving user input;

wherein the object remains stored in said first memory location in said memory after the object is backed up in the data structure.

22. The computer system of claim 21, wherein the memory stores one or more other objects which reference said object, wherein said one or more other objects each include a reference to the object;

wherein said references to the object are unbroken since the object remains stored in said first memory location after said backing up the object in the data structure;

wherein said one or more other objects are not required to be backed up since said references to the object are unbroken.

23. The computer system of claim 14, wherein the memory stores one or more other objects which reference said object, wherein said one or more other objects each include a reference to said object;

wherein said software program operates to store the copy of the object as the previous element in the data structure and store the object as the current object in the data structure to cause said references to the object to be unbroken;

wherein said one or more other objects are not required to be backed up since said references to the object are unbroken.

24. A memory media which store program instructions for performing undo in a graphical system, wherein the graphical system includes a plurality of interconnected objects, wherein said interconnected objects include fixed size objects and variable size objects, wherein the program instructions are executable to implement the steps of:

receiving user input which modifies an object;

determining if the object is a fixed size object or a variable size object;

backing up the object in a data structure in response to said user input which modifies the object, wherein the data structure includes one or more pairs each comprising a current element and a previous element, wherein, if the object is a fixed size object, said backing up the object comprises;

creating a copy of the object;

storing the copy of the object as the previous element in the data structure; and

storing the object as the current element in the data structure, wherein the object remains a foreground object in the graphical system.

25. The memory media of claim 24, wherein the object is a fixed size object, wherein the program instructions are further executable to implement the steps of:

receiving user input to undo said modification to said object;

undoing said modification to said object, wherein said undoing comprises swapping contents of the current and previous elements in the data structure.

26. The memory media of claim 24, wherein, if the object is a variable size object, said backing up the object comprises:

storing the object as the previous element in the data structure;

creating a copy of the object; and

storing the copy of the object as the current element in the data structure, wherein the copy of the object becomes the foreground object in the graphical system.

27. The memory media of claim 26, wherein the object is a variable size object, wherein the program instructions are further executable to implement the steps of:

receiving user input to undo said modification to said object;

undoing said modification to said object, wherein said undoing comprises swapping the current and previous elements in the data structure.

28. The memory media of claim 24, wherein said determining if the object is a fixed size object or a variable size object comprises determining if the object is a type which changes in size in response to user modification.

29. The memory media of claim 24, wherein said determining if the object is a fixed size object or a variable size object comprises determining if the object changes in size in response to said receiving user input.

30. The memory media of claim 24, wherein a variable size object is an object which generally changes in size in response to user modification;

wherein a fixed size object is an object which does not change in size in response to user modification.

31. The memory media of claim 24, wherein the object is stored in a first memory location prior to said receiving user input;

wherein the object remains stored in said first memory location after said backing up the object in the data structure.

32. The memory media of claim 31, wherein the object is referenced by one or more other objects, wherein said one or more other objects each include a reference to the object;

wherein said references to the object are unbroken since the object remains stored in said first memory location after said backing up the object in the data structure;

wherein said one or more other objects are not required to be backed up since said references to the object arc unbroken.

33. The memory media of claim 24, wherein the object is referenced by one or more other objects, wherein said one or more other objects each include a reference to the object;

wherein said storing the copy of the object as the previous element in the data structure and storing the object as the current object in the data structure causes said references to the object to be unbroken;

wherein said one or more other objects are not required to be backed up since said references to the object are unbroken.