cclipboardwinforms
I have a Windows Forms TreeView (node, subnodes). Each node contains some additional information in its Tag. Also, each nodes maps a file on the disk. What's the easiest way copy/cut/paste nodes/files in C#?
It would be nice to have some sample code.
There are three primary browser APIs for copying to the clipboard:
Async Clipboard API [navigator.clipboard.writeText]
document.execCommand('copy') (deprecated) 👎
Overriding the copy event
Don't expect clipboard related commands to work whilst you are testing code in the console. Generally, the page is required to be active (Async Clipboard API) or requires user interaction (e.g. a user click) to allow (document.execCommand('copy')) to access the clipboard see below for more detail.
Note that since this post was originally written deprecation of permissions in cross-origin IFRAMEs and other IFRAME "sandboxing" prevents the embedded demos "Run code snippet" buttons and "codepen.io example" from working in some browsers (including Chrome and Microsoft Edge).
To develop create your own web page, serve that page over an HTTPS connection to test and develop against.
Here is a test/demo page which demonstrates the code working: https://deanmarktaylor.github.io/clipboard-test/
Due to the level of browser support for the new Async Clipboard API, you will likely want to fall back to the document.execCommand('copy') method to get good browser coverage.
Here is a simple example (may not work embedded in this site, read "important" note above):
function fallbackCopyTextToClipboard(text) {
var textArea = document.createElement("textarea");
textArea.value = text;
// Avoid scrolling to bottom
textArea.style.top = "0";
textArea.style.left = "0";
textArea.style.position = "fixed";
document.body.appendChild(textArea);
textArea.focus();
textArea.select();
try {
var successful = document.execCommand('copy');
var msg = successful ? 'successful' : 'unsuccessful';
console.log('Fallback: Copying text command was ' + msg);
} catch (err) {
console.error('Fallback: Oops, unable to copy', err);
}
document.body.removeChild(textArea);
}
function copyTextToClipboard(text) {
if (!navigator.clipboard) {
fallbackCopyTextToClipboard(text);
return;
}
navigator.clipboard.writeText(text).then(function() {
console.log('Async: Copying to clipboard was successful!');
}, function(err) {
console.error('Async: Could not copy text: ', err);
});
}
var copyBobBtn = document.querySelector('.js-copy-bob-btn'),
copyJaneBtn = document.querySelector('.js-copy-jane-btn');
copyBobBtn.addEventListener('click', function(event) {
copyTextToClipboard('Bob');
});
copyJaneBtn.addEventListener('click', function(event) {
copyTextToClipboard('Jane');
});<div style="display:inline-block; vertical-align:top;">
<button class="js-copy-bob-btn">Set clipboard to BOB</button><br /><br />
<button class="js-copy-jane-btn">Set clipboard to JANE</button>
</div>
<div style="display:inline-block;">
<textarea class="js-test-textarea" cols="35" rows="4">Try pasting into here to see what you have on your clipboard:
</textarea>
</div>(codepen.io example may not work, read "important" note above) Note that this snippet is not working well in Stack Overflow's embedded preview you can try it here: https://codepen.io/DeanMarkTaylor/pen/RMRaJX?editors=1011
Note that there is an ability to "request permission" and test for access to the clipboard via the permissions API in Chrome 66.
var text = "Example text to appear on clipboard";
navigator.clipboard.writeText(text).then(function() {
console.log('Async: Copying to clipboard was successful!');
}, function(err) {
console.error('Async: Could not copy text: ', err);
});
The rest of this post goes into the nuances and detail of the document.execCommand('copy') API.
The JavaScript (deprecated) 👎document.execCommand('copy') support has grown, see the links below for browser updates:
(may not work embedded in this site, read "important" note above)
var copyTextareaBtn = document.querySelector('.js-textareacopybtn');
copyTextareaBtn.addEventListener('click', function(event) {
var copyTextarea = document.querySelector('.js-copytextarea');
copyTextarea.focus();
copyTextarea.select();
try {
var successful = document.execCommand('copy');
var msg = successful ? 'successful' : 'unsuccessful';
console.log('Copying text command was ' + msg);
} catch (err) {
console.log('Oops, unable to copy');
}
});<p>
<button class="js-textareacopybtn" style="vertical-align:top;">Copy Textarea</button>
<textarea class="js-copytextarea">Hello I'm some text</textarea>
</p>The above simple example works great if there is a textarea or input element visible on the screen.
In some cases, you might wish to copy text to the clipboard without displaying an input / textarea element. This is one example of a way to work around this (basically insert an element, copy to clipboard, remove element):
Tested with Google Chrome 44, Firefox 42.0a1, and Internet Explorer 11.0.8600.17814.
(may not work embedded in this site, read "important" note above)
function copyTextToClipboard(text) {
var textArea = document.createElement("textarea");
//
// *** This styling is an extra step which is likely not required. ***
//
// Why is it here? To ensure:
// 1. the element is able to have focus and selection.
// 2. if the element was to flash render it has minimal visual impact.
// 3. less flakyness with selection and copying which **might** occur if
// the textarea element is not visible.
//
// The likelihood is the element won't even render, not even a
// flash, so some of these are just precautions. However in
// Internet Explorer the element is visible whilst the popup
// box asking the user for permission for the web page to
// copy to the clipboard.
//
// Place in the top-left corner of screen regardless of scroll position.
textArea.style.position = 'fixed';
textArea.style.top = 0;
textArea.style.left = 0;
// Ensure it has a small width and height. Setting to 1px / 1em
// doesn't work as this gives a negative w/h on some browsers.
textArea.style.width = '2em';
textArea.style.height = '2em';
// We don't need padding, reducing the size if it does flash render.
textArea.style.padding = 0;
// Clean up any borders.
textArea.style.border = 'none';
textArea.style.outline = 'none';
textArea.style.boxShadow = 'none';
// Avoid flash of the white box if rendered for any reason.
textArea.style.background = 'transparent';
textArea.value = text;
document.body.appendChild(textArea);
textArea.focus();
textArea.select();
try {
var successful = document.execCommand('copy');
var msg = successful ? 'successful' : 'unsuccessful';
console.log('Copying text command was ' + msg);
} catch (err) {
console.log('Oops, unable to copy');
}
document.body.removeChild(textArea);
}
var copyBobBtn = document.querySelector('.js-copy-bob-btn'),
copyJaneBtn = document.querySelector('.js-copy-jane-btn');
copyBobBtn.addEventListener('click', function(event) {
copyTextToClipboard('Bob');
});
copyJaneBtn.addEventListener('click', function(event) {
copyTextToClipboard('Jane');
});<div style="display:inline-block; vertical-align:top;">
<button class="js-copy-bob-btn">Set clipboard to BOB</button><br /><br />
<button class="js-copy-jane-btn">Set clipboard to JANE</button>
</div>
<div style="display:inline-block;">
<textarea class="js-test-textarea" cols="35" rows="4">Try pasting into here to see what you have on your clipboard:
</textarea>
</div>All document.execCommand('copy') calls must take place as a direct result of a user action, e.g. click event handler. This is a measure to prevent messing with the user's clipboard when they don't expect it.
See the Google Developers post here for more info.
Note the full Clipboard API draft specification can be found here: https://w3c.github.io/clipboard-apis/
document.queryCommandSupported('copy') should return true if the command "is supported by the browser".document.queryCommandEnabled('copy') return true if the document.execCommand('copy') will succeed if called now. Checking to ensure the command was called from a user-initiated thread and other requirements are met.However, as an example of browser compatibility issues, Google Chrome from ~April to ~October 2015 only returned true from document.queryCommandSupported('copy') if the command was called from a user-initiated thread.
Note compatibility detail below.
Whilst a simple call to document.execCommand('copy') wrapped in a try/catch block called as a result of a user click will get you the most compatibility use the following has some provisos:
Any call to document.execCommand, document.queryCommandSupported or document.queryCommandEnabled should be wrapped in a try/catch block.
Different browser implementations and browser versions throw differing types of exceptions when called instead of returning false.
Different browser implementations are still in flux and the Clipboard API is still in draft, so remember to do your testing.
There are a wealth of clipboards you could be dealing with. I expect you're probably a Linux user who wants to put stuff in the X Windows primary clipboard. Usually, the clipboard you want to talk to has a utility that lets you talk to it.
In the case of X, there's xclip (and others). xclip -selection c will send data to the clipboard that works with Ctrl + C, Ctrl + V in most applications.
If you're on Mac OS X, there's pbcopy. E.g., cat example.txt | pbcopy
If you're in Linux terminal mode (no X) then look into gpm or Screen which has a clipboard. Try the Screen command readreg.
Under Windows 10+ or Cygwin, use /dev/clipboard or clip.
Best Answer
Consider using the Clipboard class. It features all the methods necessary for putting data on the Windows clipboard and to retrieve data from the Windows clipboard.
The code above will put the files test.txt and test2.txt for copy on the Windows Clipboard. After executing the code you can navigate to any folder and Paste (Ctrl+V) the files. This is equivalent to selecting both files in Windows Explorer and selecting copy (Ctrl+C).