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What do you need to implement the undo/redo feature in an application?
To implement Undo , you work backward from the tail of the linked-list, using a ‘current-node’ pointer or index: where the change was insert , you do a delete but without updating the linked-list; and where it was a delete you insert the data from the data in the linked-list buffer.
Why do we need undo redo?
The undo function is used to reverse a mistake, such as deleting the wrong word in a sentence. The redo function restores any actions that were previously undone using an undo. For example, if you typed a word, and then deleted it using an undo, the redo function restores the word you deleted (“undid”). …
Which design pattern makes provisions for an undo or redo function?
If you’re talking GoF, the Memento pattern specifically addresses undo. As others have stated, the command pattern is a very powerful method of implementing Undo/Redo.
What is redo undo feature?
To undo an action, press Ctrl + Z. To redo an undone action, press Ctrl + Y. The Undo and Redo features let you remove or repeat single or multiple typing actions, but all actions must be undone or redone in the order you did or undid them – you can’t skip actions.
Is undo in word processor application of stack?
The standard is to keep the Command objects in a stack to support multi level undo. In order to support redo, a second stack keeps all the commands you’ve Undone. So when you pop the undo stack to undo a command, you push the same command you popped into the redo stack.
Why do you use undo and redo in Adobe Photoshop?
While writing text or creating graphics, ‘Undo’ lets users make changes and go back step-by-step through changes that were made. ‘Redo’ lets users undo the undo, which means that once they go back a few steps, they are able to move forward through their changes again. ‘Undo’ can be extremely helpful when users choose system function by mistake.
Is there a way to undo multiple steps in Photoshop?
Use the Undo or Redo commands. Beginning with the October 2018 release of Photoshop CC (20.0), you can undo multiple steps in your Photoshop document using Control + Z (Win) / Command + Z (Mac). This new multiple undo mode is enabled by default.
Which is the most important rule of UI design?
Most of the principles are applicable to any interactive systems — traditional GUI environments (such as desktop and mobile apps, websites) and non-GUI interfaces (such as voice-based interaction systems). 1. Place users in control of the interface Good UIs instill a sense of control in their users.
How do I go back to legacy undo mode in Photoshop?
To switch back to the legacy undo mode in Photoshop, do the following: From the menu bar, choose Edit > Keyboards Shortcuts. In the Keyboard Shortcuts And Menus dialog, select Use Legacy Undo Shortcuts and click OK. Restart Photoshop.