How to distinguish between CUT and COPY

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When GetClipboardData() is used to access the data captured by the Clipboard, is there an API call or flag to distinguish between a Copy action (CTRL+C) and a Cut action (CTRL+X)?

What I have tried:

Searching the web. Generally speaking, I couldn't find any documentation about the difference between Cut and Copy when it comes to data captured by the Clipboard

Posted 23-Apr-18 7:59am

Michael Haephrati

Updated 23-Apr-18 23:38pm

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[no name] 23-Apr-18 14:48pm

A very good question. I just tried the follwing, to check wheter a cut Operation works between applications:
a.) Cut a text file in the Windows Explorer
b.) Paste it in a Word document

Result:
The file is copied into the word document, but _not_ deleted in the file System by explorer.

[Edit]
While vice versa, cut the file from WinWord doc and paste it with Explorer, the file disapears from the word doc....

Richard MacCutchan 24-Apr-18 3:48am

That is a totally different test and will not do what you expect. Cut & Paste of files will only work within Explorer, as that is the application that deletes the original when it pastes it to the new location. Pasting it into Word means that explorer never sees the Paste operation.

Michael Haephrati 23-Apr-18 15:50pm

This may be a different limitations but let's say you develop App1 and a user running App2 is cutting text and pasting it to the same app (App2). There are ways to capture this text but I wonder how can one determine whether it was a Copy or a Cut...

[no name] 23-Apr-18 16:02pm

My thinking was more that the cuting app (owner of the clipboard (?)) receives finally something like a "paste_executed" Event. But it seems not to be like this. And I also recognized, word imediatelly shows "cuted" while Explorer Shows it something like "marked as cut". Sorry for my english :-)

Anyway your question was interesting and started me to think about some Details

Jochen Arndt 24-Apr-18 5:48am

You had the right idea.

See my answer below. It explains why the Explorer shows such files marked.

There is something similar to the "paste_executed" event. The target creates two clipboard objects CFSTR_PASTESUCCEEDED and CFSTR_PERFORMEDDROPEFFECT that are read by the source (the Explorer). So it knows when a paste has succeded and can delete the file or update the display depending on the action performed by the target.

[no name] 24-Apr-18 6:04am

Thank you very much for your hint.

Richard MacCutchan 24-Apr-18 3:51am

You cannot determine the difference. Cut and Copy perform exactly the same, they send some information to the clipboard. It is up to the application that performs the Cut, to decide when to delete the original data.

[no name] 24-Apr-18 6:04am

See the comment of Jochen above

Richard MacCutchan 24-Apr-18 6:09am

Yes, but that still does not tell you whether the original operation was a Cut or a Copy.

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OriginalGriff · Answer 1 · 2018-04-23T08:08:00

Solution 1

No. You can't tell, because the application which places it on the clipboard:
1) Doesn't tell the clipboard anything other than "here is some data, it's this type"
2) Doesn't have to obey "normal" cut or copy rules at all: it could for example move text to an archive, and copy it to the clipboard.
3) Doesn't have to have a user input of any kind in order to load data to the clipboard - it could be automated via a timer to load data from an RSS feed onto the clipboard in order to issue a "paste" instruction message to a different app.

So, no. No way to tell at all.

Posted 23-Apr-18 8:08am

OriginalGriff

Comments

Michael Haephrati 23-Apr-18 14:39pm

You got my 5 stars! I wonder if there is a creative solution to capture the CUT or COPY actions

Dave Kreskowiak 23-Apr-18 15:31pm

No, there isn't. The application that is putting the data in the clipboard knows, but never the receiving application. The "sending" application handles the Cut or Copy operation, but that is only to tell the application what to do with its own document data. The data that's being put on the clipboard is completely independent of the cut or copy operation. The "receiving" application how no way on knowing what happened in the "sending" application.

[no name] 23-Apr-18 15:40pm

~~Please see my comment to the question. How you explain the Experiment?~~

Michael Haephrati 23-Apr-18 15:38pm

I meant some sort of "global hooking" to capture the Copy or Cut events

Dave Kreskowiak 23-Apr-18 16:14pm

There are no such things as a "cut event" or a "copy event". Also, stuff can get on the clipboard without ever having been cut or copied. For example, running your app in a virtual machine and cutting something to the clipboard from the host machine.

Global Keyboard hook? Nope. First, there's no way to tell where those keystrokes were going. You have no idea what app was doing the cut/copy. Also, There's more than one way to Cut/Copy something in an app besides Ctrl-X and Ctrl-C.

You will also have to handle the alternate key combinations and sequences, such as the ever popular, not not required!, Alt-E, Alt-C or Alt-T to do the same things.

You will also miss context menus. Select a range of text in the "sender" app, right-click the selection and click Copy/Cut.

There really isn't any way to do what you're thinking about in any consistent manner. There are no such things as "global events" for these operations.

Michael Haephrati 25-Apr-18 6:29am

There is http://winapi.freetechsecrets.com/win32/WIN32WMCUT.htm

OriginalGriff 25-Apr-18 6:41am

Yes there is a message for WM_CUT, but it doesn't have to be used:

        private void button1_Click(object sender, EventArgs e)
            {
            Clipboard.SetText(myTextBox.Text);
            myTextBox.Text = "";
            }

That is a cut operation, but it doesn't trigger a WM_CUT message to be generated anywhere in the system. And the clipboard (indeed the whole system) can't tell the difference between that and this:

        private void button1_Click(object sender, EventArgs e)
            {
            Clipboard.SetText(myTextBox.Text);
            }

Dave Kreskowiak 25-Apr-18 10:19am

There is also a WM_COPY message. Both are sent to the target window (control) to tell it to perform that operation. It's not sent in response to that operation actually occurring.

There are also other ways to do the Cut and Copy operations to the clipboard without those messages being used at all.

Jochen Arndt · Answer 2 · 2018-04-23T23:39:00

As said in solution 1 and the comments:
There is no general way to know what had happened on the source side.

But there is one exception: Delete-on-Paste Operations
These are used when cutting files (e.g. from within the Windows Explorer).

With those the source requests the target to get informed when a paste operation has been performed by adding an additional object to the clipboard data. When a target detects such requests, it knows that there was a cut operation at the source side (and that it should act acordingly).

See the section Handling Delete-on-Paste Operations at Handling Shell Data Transfer Scenarios (Windows)[^] for how it works.

How to distinguish between CUT and COPY

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