[eframe native-windows] Entire program crashes when eframe viewport is resized fast from a corner

[AvinashPrajapati]

use eframe::{self};
use eframe::egui::{self, CentralPanel, Sense, UiBuilder, ViewportCommand, RichText};

struct MyApp {
    window_size: egui::Vec2,
}

impl Default for MyApp {
    fn default() -> Self {
        MyApp {
            window_size: egui::vec2(400.0, 300.0),
        }
    }
}

impl eframe::App for MyApp {
    fn clear_color(&self, _visuals: &egui::Visuals) -> [f32; 4] {
        egui::Rgba::TRANSPARENT.to_array() // Make sure we don't paint anything behind the rounded corners
    }

    fn update(&mut self, ctx: &egui::Context, frame: &mut eframe::Frame) {
        custom_window_frame(ctx, frame, "Custom Window", &mut self.window_size, |ui| {
            ui.label(RichText::new("This is bold").strong());
        });
    }
}

fn custom_window_frame(
    ctx: &egui::Context,
    frame: &mut eframe::Frame,
    title: &str,
    window_size: &mut egui::Vec2,
    add_contents: impl FnOnce(&mut egui::Ui),
) {
    let panel_frame = egui::Frame {
        fill: ctx.style().visuals.window_fill(),
        rounding: 5.0.into(),
        stroke: ctx.style().visuals.widgets.noninteractive.fg_stroke,
        outer_margin: 0.5.into(), // so the stroke is within the bounds
        ..Default::default()
    };
    // panel_frame.

    CentralPanel::default().frame(panel_frame).show(ctx, |ui| {
        let mut app_rect = ui.max_rect();

        let title_bar_height = 25.0;
        let title_bar_rect = {
            let mut rect = app_rect;
            rect.max.y = rect.min.y + title_bar_height;
            rect
        };

        title_bar_ui(ui, title_bar_rect, title);

        // Add the contents:
        let content_rect = {
            let mut rect = app_rect;
            rect.min.y = title_bar_rect.max.y;
            rect
        }
        .shrink(4.0);
        let mut content_ui = ui.new_child(UiBuilder::new().max_rect(content_rect));
        add_contents(&mut content_ui);

        // Visual indicator for resizing
        // Resize interaction on bottom-right corner
        let resize_area_size = 10.0;
        let resize_rect = egui::Rect {
            min: app_rect.right_bottom() - egui::vec2(resize_area_size, resize_area_size),
            max: app_rect.right_bottom(),
        };

        let resize_response =
            ui.interact(resize_rect, egui::Id::new("resize_handle"), Sense::drag());
        if resize_response.dragged() {
            if let Some(pointer_pos) = resize_response.hover_pos() {
                let delta = pointer_pos - app_rect.right_bottom();

                // Update window size
                window_size.x = (window_size.x + delta.x).max(200.0); // Min width
                window_size.y = (window_size.y + delta.y).max(150.0); // Min height

                // Update the application rectangle

                // Update the app rectangle based on the new window size
                ctx.send_viewport_cmd(egui::ViewportCommand::InnerSize(*window_size));
                


                // ui.ctx().request_repaint();
            }
        }

        if resize_response.hovered() {
            ui.painter()
                .rect_filled(resize_rect, 1.0, egui::Color32::from_white_alpha(128));
        }
    });
}

fn title_bar_ui(ui: &mut egui::Ui, title_bar_rect: eframe::epaint::Rect, title: &str) {
    use egui::{vec2, Align2, FontId, Id, PointerButton, Sense, UiBuilder};

    let painter = ui.painter();

    let title_bar_response = ui.interact(
        title_bar_rect,
        Id::new("title_bar"),
        Sense::click_and_drag(),
    );

    // Paint the title:
    painter.text(
        title_bar_rect.center() - egui::vec2(title_bar_rect.width() / 3.0, 0.0),
        Align2::CENTER_CENTER,
        title,
        FontId::proportional(15.0),
        ui.style().visuals.text_color(),
    );

    // Paint the line under the title:
    painter.line_segment(
        [
            title_bar_rect.left_bottom() + vec2(1.0, 0.0),
            title_bar_rect.right_bottom() + vec2(-1.0, 0.0),
        ],
        ui.visuals().widgets.noninteractive.bg_stroke,
    );

    // Interact with the title bar (drag to move window):
    if title_bar_response.double_clicked() {
        let is_maximized = ui.input(|i| i.viewport().maximized.unwrap_or(false));
        ui.ctx()
            .send_viewport_cmd(ViewportCommand::Maximized(!is_maximized));
    }

    if title_bar_response.drag_started_by(PointerButton::Primary) {
        ui.ctx().send_viewport_cmd(ViewportCommand::StartDrag);
    }

    // Close button for the window
    ui.allocate_new_ui(
        UiBuilder::new()
            .max_rect(title_bar_rect)
            .layout(egui::Layout::right_to_left(egui::Align::Center)),
        |ui| {
            ui.spacing_mut().item_spacing.x = 0.0;
            ui.visuals_mut().button_frame = false;
            ui.add_space(8.0);
            close_button(ui);
        },
    );
}

fn close_button(ui: &mut egui::Ui) {
    use egui::{Button, RichText};

    let button_height = 12.0;

    let close_response = ui
        .add(Button::new(RichText::new("❌").size(button_height)))
        .on_hover_text("Close the window");
    if close_response.clicked() {
        ui.ctx().send_viewport_cmd(egui::ViewportCommand::Close);
    }
}

fn main() -> eframe::Result {
    let options = eframe::NativeOptions {
        viewport: egui::ViewportBuilder::default()
            .with_decorations(false) // Hide the OS-specific "chrome" around the window
            .with_inner_size([400.0, 600.0]) // Set the initial size
            .with_min_inner_size([200.0, 300.0]) // Minimum size for the window
            .with_transparent(true), // To have rounded corners we need transparency
        ..Default::default()
    };

    eframe::run_native(
        "Custom Window with Close Button",
        options,
        Box::new(|_cc| Ok(Box::<MyApp>::default())),
    )
}

** i got the same issue here**

• My toml file code

[package]
name = "egui-ui"
version = "0.1.0"
edition = "2021"

[dependencies]
eframe = "0.29.1"
egui = "0.29.1"

When i resize it very fast then the application just crashes.

I am guessing sending the command to resize the viewport on fast resize(each change in dimensional unit sends the command to viewport to resize) the application can not process and get crashes.

// Update the app rectangle based on the new window size
                ctx.send_viewport_cmd(egui::ViewportCommand::InnerSize(*window_size));

Any solution??