TextCursorState.set_char_range() interacts wrongly with user click

[abey79]

Considering the repro code below, regardless of how the text edit gains focus, I'm expecting all of the text to be selected. It works as expected when Tabing, or clicking in the text edit whitespace.

However, when clicking on the text itself, only the text up to the mouse cursor is selected.

set_cursor_bug.mp4

use eframe::egui;

fn main() -> Result<(), eframe::Error> {
    env_logger::init(); // Log to stderr (if you run with `RUST_LOG=debug`).
    let options = eframe::NativeOptions {
        viewport: egui::ViewportBuilder::default().with_inner_size([320.0, 240.0]),
        ..Default::default()
    };
    eframe::run_native(
        "My egui App",
        options,
        Box::new(|cc| {
            // This gives us image support:
            egui_extras::install_image_loaders(&cc.egui_ctx);

            Box::<MyApp>::default()
        }),
    )
}

struct MyApp {
    name: String,
}

impl Default for MyApp {
    fn default() -> Self {
        Self {
            name: "Arthur".to_owned(),
        }
    }
}

impl eframe::App for MyApp {
    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        egui::CentralPanel::default().show(ctx, |ui| {
            ui.heading("My egui Application");
            ui.horizontal(|ui| {
                ui.label("Your name: ");

                let mut output = egui::TextEdit::singleline(&mut self.name).show(ui);

                if output.response.gained_focus() {
                    output.response.request_focus();
                    let min = egui::text::CCursor::new(0);
                    let max = egui::text::CCursor::new(self.name.len());
                    let new_range = egui::text::CCursorRange::two(min, max);
                    output.state.cursor.set_char_range(Some(new_range));
                    output.state.store(ui.ctx(), output.response.id);
                }
            });
        });
    }
}

[emilk]

This is because the TextEdit gains focus as soon as the mouse pressed down on it, but the frame after the mouse button is still down, and now TextEdit treats it as a drag-to-select sort of situation.

Not sure how to proceed here

[abey79]

I guess a workaround would then be a mini state machine to trigger select on the frame after gain_focus...

[abey79]

This work-around sort-of-works. Nothing is selected so long as the mouse is down and the selection becomes correct on mouse release.

Some/all of these request repaint might be superfluous as mouse state change would trigger the draw anyways.

use eframe::egui;

fn main() -> Result<(), eframe::Error> {
    env_logger::init(); // Log to stderr (if you run with `RUST_LOG=debug`).
    let options = eframe::NativeOptions {
        viewport: egui::ViewportBuilder::default().with_inner_size([320.0, 240.0]),
        ..Default::default()
    };
    eframe::run_native(
        "My egui App",
        options,
        Box::new(|cc| {
            // This gives us image support:
            egui_extras::install_image_loaders(&cc.egui_ctx);

            Box::<MyApp>::default()
        }),
    )
}

struct MyApp {
    name: String,
    focus_gained: bool,
}

impl Default for MyApp {
    fn default() -> Self {
        Self {
            name: "Arthur".to_owned(),
            focus_gained: false,
        }
    }
}

impl eframe::App for MyApp {
    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        egui::CentralPanel::default().show(ctx, |ui| {
            ui.heading("My egui Application");
            ui.horizontal(|ui| {
                ui.label("Your name: ");

                let mut output = egui::TextEdit::singleline(&mut self.name).show(ui);

                if output.response.gained_focus() {
                    self.focus_gained = true;
                    ctx.request_repaint();
                }

                if self.focus_gained {
                    // wait for the mouse to be released before selecting all
                    if ui.input(|i| !i.pointer.any_down()) {
                        self.focus_gained = false;

                        output.response.request_focus();
                        let min = egui::text::CCursor::new(0);
                        let max = egui::text::CCursor::new(self.name.len());
                        let new_range = egui::text::CCursorRange::two(min, max);
                        output.state.cursor.set_char_range(Some(new_range));
                        output.state.store(ui.ctx(), output.response.id);
                    } else {
                        ctx.request_repaint();
                    }
                }
            });
        });
    }
}