Get selected text from Label

[eleanor-em]

This seems simple, but I can't find any information on this: suppose I have a Label:

ui.add(egui::Label::new("here is some text")
    .selectable(true));

How do I get the text that has been selected from this label? The returned Response object does not seem to have anything useful in it, unless I can somehow use another API to "look up" the label from the Id or similar. (The goal here is to support copying selected text to the clipboard.)

[rustbasic]

If you do selectable(true), you can select the contents of the label with the mouse.
And you can copy it with Ctrl + C (in Windows).

Since this is a new feature, it seems that there will be additional features in the future.

[eleanor-em]

Thanks! You're right that copying works with selectable(true), I was not correctly applying the platform_output when I tried it.

However I'd still like to know if it is possible to access the selected text more directly. It seems you are saying it isn't?

[YgorSouza]

As rustbasic said, the selected text is already copied to the clipboard when a Copy event is received. I don't think it is possible to copy or access the selected text under different circumstances. The text to be copied is stored in this private field:

egui/crates/egui/src/text_selection/label_text_selection.rs

Lines 122 to 123 in d856f7b

	/// Accumulated text to copy.
	text_to_copy: String,

This field is normally empty, as it is not needed on every frame. When a copy event arrives, every label appends its selected text to the accumulated selection as it is painted:

egui/crates/egui/src/text_selection/label_text_selection.rs

Lines 510 to 512 in d856f7b

	if got_copy_event(ui.ctx()) {
	self.copy_text(galley_pos, galley, &cursor_range);
	}

Then, at the end of the frame, the accumulated text is moved to the clipboard (using a public method that you can also call from your code):

egui/crates/egui/src/text_selection/label_text_selection.rs

Lines 228 to 231 in d856f7b

	let text_to_copy = std::mem::take(&mut state.text_to_copy);
	if !text_to_copy.is_empty() {
	ctx.copy_text(text_to_copy);
	}

So you can put arbitrary strings in the clipboard using copy_text, and egui will put the selected text in the clipboard automatically when the user presses Ctrl+C (or the Copy shortcut in their system), but you can't retrieve the selected text to put it in the clipboard yourself.

On the other hand, you can use a TextEdit with a non-mut string (which makes it look like a label), and then you can access the selected text like this:

#[derive(Default)]
struct MyApp {}

impl eframe::App for MyApp {
    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        egui::CentralPanel::default().show(ctx, |ui| {
            use egui::TextBuffer as _;
            let text = "The quick brown fox jumps over the lazy dog";
            let response = TextEdit::multiline(&mut text.as_str()).show(ui);
            let selection = response
                .cursor_range
                .as_ref()
                .map(|c| text.char_range(c.as_sorted_char_range()));
            if let Some(selection) = selection {
                ui.label(selection);
            }
        });
    }
}

But if you plan on copying it to the clipboard when the user clicks a button on something similar, be aware that clicking the button will clear the selection before you have a chance to copy it to the clipboard, so you have to store it and get the selection from a previous frame when the button is clicked.

[eleanor-em]

Thank you very much for the detailed response!