Question

How to make the UNDO action in image processing? If I am change the image position(Resize, Rotation, 3D Transform) then click UNDO button, I want the previous state of the image. How to do? Please give sample source code or give some idea about this. Thanks in advance.

Answer 1

Make a NSDictionary with all effects providing / or can be applid with your editor

1. Store NSDictionary into an NSMutableArray with [lastEffectArray addObject:effectDictionary];
2. If user presses UNDO, load and applied effectDictionary effects from lastEffectArray with key/value pair. Here, you can do two things :

Can Remove last effectDictionary object from lastEffectArray or, Add it for REDO action into other array.

Your effectDictionary should store each & every effects which can be available or applied with your editor. You can make some easy-to-use function to apply / remove effects!!!

Lastly, don’t forget to [release] all effects Array & dictionaries.

Note, This isn’t a solution, but can be implemented with own innovative logic.