Iced: What is the intended use of text_input::State::cursor()?

[mtkennerly]

I'm trying to get the selection of a TextInput. I see that there is a public text_input::State::cursor() returning a Cursor, which has a public state() method. However, I can't call Cursor::state() because it takes a text_input::value::Value, which doesn't seem to be exposed, and even if I could call it, I don't think text_input::cursor::State is exposed in order to match on the return value. I can understand why cursor::State and Value would be kept private if users are supposed to go through text_input::State as a wrapper around them, but then I'm not sure why text_input::State::cursor() would ever be used as a public method, since everything else on Cursor is private. Am I missing something?

[hecrj]

iced_graphics uses the Cursor API to draw a TextInput:

https://github.com/hecrj/iced/blob/5c4f5ae5ecb36703a95cafb2cd58692529c9466d/graphics/src/widget/text_input.rs#L127-L132

[mtkennerly]

Ah, so it supports cases where you're working directly with the iced_native crate rather than just the iced crate. Thanks for the quick response! (This made me realize that I can just add iced_native as an additional dependency to accomplish what I'm trying to do.)

Would you be open to adding methods to text_input::State for accessing the cursor selection (similar to how move_cursor_to_end works)?

[hecrj]

Would you be open to adding methods to text_input::State for accessing the cursor selection (similar to how move_cursor_to_end works)?

Maybe! What are the use cases you have in mind?

[Imberflur]

Might be unrelated, but when working with input field tabbing I noticed a select_all method would be useful.

[mtkennerly]

My particular use case is that I'm using a Subscription to implement my own copy/cut/undo/redo shortcuts (I'd like to figure out how to contribute them back if possible, but for now I just need to get something working). For copy/cut, I need to know what's currently selected, and for cut, I also need to delete the selected part of the text and clear the selection:

// in update()
match shortcut {
    // backup_target_input is a text_input::State, and backup_target_history is my own TextHistory
    Shortcut::ClipboardCut => {
        self.config.backup.path = crate::shortcuts::cut_to_clipboard_from_iced(&self.config.backup.path, &self.backup_screen.backup_target_input.cursor());
        self.backup_screen.backup_target_history.push(&self.config.backup.path);
    },
}

pub fn cut_to_clipboard_from_iced(text: &str, cursor: &iced_native::text_input::Cursor) -> String {
    let value = iced_native::text_input::Value::new(text);
    match cursor.state(&value) {
        iced_native::text_input::cursor::State::Selection { start, end } => {
            match cut_to_clipboard(&text, std::cmp::min(start, end), std::cmp::max(start, end)) {
                Ok(remaining) => {
                    // TODO: Clear the selection?
                    remaining.to_owned(),
                }
                Err(_) => text.to_owned(),
            }
        }
        _ => text.to_owned(),
    }
}

Incidentally, cutting and then immediately pasting causes a panic in iced_native::widget::text_input::value::Value::remove_many, called by iced_native::widget::text_input::editor::Editor::paste. The TextInput doesn't seem to realize that the text has changed, so it's still working based on the previous length. I'm still trying to figure out how to make a fix for that. Here's a simple gist, and here's the main part of the backtrace based on latest master code:

thread 'main' panicked at 'end drain index (is 28) should be <= len (is 8)', src\liballoc\vec.rs:1331:13
[...]
  15: iced_native::widget::text_input::value::Value::remove_many
             at C:\Users\mtken\.cargo\git\checkouts\iced-2bccc042db34f88f\3172bd3\native\src\widget\text_input\value.rs:120
  16: iced_native::widget::text_input::editor::Editor::paste
             at C:\Users\mtken\.cargo\git\checkouts\iced-2bccc042db34f88f\3172bd3\native\src\widget\text_input\editor.rs:36
  17: iced_native::widget::text_input::{{impl}}::on_event<paste_panic::Message,iced_graphics::renderer::Renderer<iced_wgpu::backend::Backend>>
             at C:\Users\mtken\.cargo\git\checkouts\iced-2bccc042db34f88f\3172bd3\native\src\widget\text_input.rs:448
[...]