Assuming that paint lets its users undo changes, I wonder whether it's possible to redo those changes by any computer means after the initial file has been saved.
Steps to reproduce:
1. Open a .jpg file in paint
2. Draw a line
3. Save as New.jpg
4. Open New.jpg in paint
5. Delete that line
Is the 5th step actually doable using any software/by coding whatever?
This is a question for SuperUser more than StackOverflow.
However, the answer is that it's only possible if the software stores the history of change steps to the saved file. Most common interchangeable image formats, like the JPG example in your question, do not support storage of that information.
An image editor could save to a format, likely to be specific to the editor, which preserves the history of alterations to the image. However, this could lead to a lot of storage of data that is usually not useful in the future, so there isn't a huge amount of demand for the feature.
Note that what is sought in the question could be done by a new operation to erase the line or parts of it, but not as an undo operation from the prior editing session.
Related
How do you make a specific folder that has subfolders to be uneditable in Sublime text? ? I know it's possible but how ? Like i have some old projects that I want to use as a reference to study my old code, but i"m worried that I mistakenly edited some parts of that specific module / file, when I'm mindlessly touring around my code.. How do I do it ? like making a specific folder to be uneditable in sublime text that only modifying it can change it . I mean I tried installing this one package : https://packagecontrol.io/packages/Toggle%20Read-Only
But it still gives me a prompt whenever I want to changed something from a file
Your best bet is to make sure that your source code is covered by some sort of Source Control, such as git or Subversion; this is just always a good idea in general and unrelated to your particular question. Having your code under source control means that when you edit a file (accidentally or on purpose) you can see exactly what you edited or throw those edits away and go back to what you had if you want to. If you also push your code to an external server, such as GitHUb (if you use git) then you also have a cheap and easy off-site backup of your code as well.
That said, if you want to make files uneditable, that's more the job of your file system than the tools that you're using to edit the files (in this case Sublime Text).
All file systems and operating systems should have the concept of a read-only file, which sounds like what you want. A file being marked as read-only stops you from accidentally modifying it; depending on the software that you use, edits are either impossible or will need to be confirmed.
In your case, you can do this in a couple of different ways. If you only want to protect a couple of files, then you would do a Right click and choose Properties; in the bottom of the General tab there is a check box you can check to make that file read-only:
If you have many files, you can do the same thing by editing the properties of the folder that contains the code instead:
When you do this to a folder, the property set works a little differently; since you're modifying the folder as a whole, you need to click the box twice to change it from a square (shown above) to a check mark. When you apply the change, you will be asked if you only want to make files inside of that directory read-only, or all files in that folder as well as all folders under it; choose as appropriate.
Sublime will let you open read-only files and will also let you modify their contents, but when you try to save you will get a warning dialog telling you that the file is write-protected; you need to confirm if you want to actually save changes or not; (other software may not prompt with such a dialog and may just fail):
If you choose to save, you will remove the read-only attribute and make the file normal again.
If you want to make a file completely un-editable so that you can't even accidentally change the file, you can achieve that with a simple plugin in combination with making the file read-only (see this video if you're not sure how to apply a plugin):
import sublime
import sublime_plugin
import os
class ReadOnlyListener(sublime_plugin.EventListener):
def on_load(self, view):
if (os.path.exists(view.file_name())
and not os.access(view.file_name(), os.W_OK)):
view.set_read_only(True)
EDIT: The internal View Package Files command will open package resources from sublime-package files transparently and give them a filename that represents where they would exist on disk if they were not in the package file.
The plugin from the original answer would stop you from being able to use this command by noting that the file is not writable (because it does not exist on disk) and make the view read-only, which stops the file content from being displayed because the view can't be modified.
This is rectified in the edit above by only taking action if the file actually exists on disk (the View Package File command already makes files it loads in this manner read-only if they do not exist on disk).
This makes an event listener that checks every time you open a file to see if the file is writable, and if it's not it makes the view read-only. This distinction is Sublime specific; regardless of the underlying state of the file, you just can't make any changes to such a file at all. That doesn't stop you from saving the file even if you haven't made any changes, which would have the same effect as the above.
Disclaimer: I'm new to using Rumba to access IBM Mainframe.
I have currently set up a library for personal use and I have some code that I want to store in a member of this library, how can I copy/paste from a .txt file on my desktop into this program??? As of right now I can successfully copy/paste one line at a time from documents outside of Rumba.
There are various ways. The best one will depend upon the size of the file/amount of data to be transferred.
If it's only a few lines, block copy and paste should work, but you might have to play with Rumba's 'paste' edit settings such as how to handle new lines, etc.
Bigger files can be transferred with the TSO file transfer program ind£file (maybe ind$file on your system) which essentially copies a file to the screen and then Rumba 'scrapes' the screen for data to put into a file (this is for a mainframe-to-PC transfer; for going the other way the operation is reversed). This can be surprisingly quick.
Lastly there's FTP - either from the command line or via a program such as WinSCP.
Edit:
Based on your comment that the files are about 300 lines long, I'd look into using Rumba's file-transfer option using the ind$file utility. Once you have the files on one system, speak to your mainframe tech support team about the best way to get them to the other systems.
If you need help uploading the files, then the tech support team should be your first point of call.
What mainframe editor are you running? TSO/ISPF?
I copy and and paste from ".txt" files into ISPS all the time with no problem.
Select the text you want to copy (in the ".txt" file)
Press CTRL-C
Open the mainframe file using ISPF Edit (option 2).
Enter line command "Inn" at the line where where you want the copy to start.
(This inserts "nn" empty lines to receive the copied data. Personally, I usually use "nn"=20)
Position your cursor at the first character of the first empty line.
Press CTRL-V
I work on a custom project system and I have an issue with renaming items. The project system implementation is based on MPF and renaming items via the solution explorer worked more or less without any problems, but...
When an item gets renamed, I also update information which are stored in the file itself. In case the document is opened by the code editor, the text in the editor doesn´t get refreshed (only the document window´s caption changes to the new filename). If I save the open document all changes applied by the rename operation are overriden, of course.
How can I force the editor to reload the document, so that the automatic changes will be shown?
Assuming it's a text file versus some custom designer, use the IVsRunningDocumentTable interfaces to get the text buffer for the file that's currently open. The fourth iteration of the interface is the easiest one to use from managed code. You can call IsMonikerValid (where the "moniker" is the file name) to see if the file is open, and if so then call GetDocumentData to get the IVsTextBuffer for the file. That type itself is fairly annoying to work with, so if you're only supporting Visual Studio 2010 or later, then pass that to this function to get the newer editor APIs version of it.
As far as they "why" it's a good idea to do this: if you edit the file on disk and then try to force a reload, there are various problems you might run into. If the file wasn't saved before the rename, you might accidentally lose those unsaved edits. The reload might cause the undo history of the file to be lost, and any other extensions/features that were tracking points in the file with editor tracking spans or markers might lose the points they're tracking. Performance should be a bit better too if the file is a large file.
Any tips on how to store large amounts of text, such as programming code. So I need to retain the tabs, spaces, etc?
Also how could i keep versions like say someone edits one line, i can see the changes that have been made?
That's what various revision control systems are for.
Any of git, cvs, rcs, subversion and a host of others will work.
I agree with other posters that you probably want to use what has already been done. Sometimes rolling your own can be fun.
You could write a wrapper for the command line diff utils. Each user could have their own config to choose their preferred editor. The script would made a copy of the file, so you would have an orig and new. When done editing the script would kick off a diff and store that to disk and delete the original backup of the file. This way, you would only store the latest versions plus all diffs so you can revert back and also see the changes.
I would keep a log of all diffs created and tag them in a csv with the userid of the person who modified the file and the timestamp of the modification.
I want to use a algorithm to reduce memory used to save the particular text file.I don't really know how text is stored but i have an idea in mind.
Would it be better to extend a open source text editor (if yes than which one) or write a text editor myself.
It would be nice if someone could also give me a link or tutorial to some basics on how text editors work and the way data is stored.
Edited to add
To clarify, what I wanted to do is instead of saving duplicates of a word make a hash table and store the address where it needs to be placed.
That way I wouldn't be storing the duplicates.
This would have become specific to a particular text editor.
Update
thanks everyone I got what all of you'll are trying to say. Anyways all i wanted to do is instead of saving duplicates of a word make a hash table and store the address where it needs to be placed.
This was i wouldn't be storing the duplicates.
Yes and this would have become specific to a particular text editor. never realized that.
I want to use a algorithm to reduce memory used to save the particular text file
If you did this you would no longer have a text editor, but instead you would have created some sort of binary file editor.
The whole point of the text file format is that it is universal, meaning any text file can be open in any other text editor.
Emacs handles compression transparently. Just create a text file with .gz extension. Emacs will automatically compress contents of the file during save operation, and decompress when you open the file next time.
Text is basically stored as-is. i.e., every character takes up a byte or two (wide chars), and there is no conversion done on it when it's saved. It might add an end-of-file character or something though. Don't try coming up with your own algorithm to compress these files. That's why zip-files and other archives were created. They're really good at compressing text. If you wanted to add these feature to your text-editor, you'd have to add some sort of post-save hook to zip it, and then put a hook on the open command to unzip it. Unless you wanted to do it by hand every time. Don't try writing the text editor yourself from scratch, unless (maybe) you're writing notepad. Text editors with syntax highlighting aren't very easy to make, even with the proper libraries. I'd say write a plugin for something like Visual Studio or what have you. Or find an open-source text editor.