slint/internal/compiler/widgets/common/tabwidget-base.slint

// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-1.2 OR LicenseRef-Slint-commercial

export component TabBarBase inherits TouchArea {
    // injected properties:
    // The currently selected tab
    in-out property <int> current;
    // The total number of tabs
    in-out property <int> num-tabs;

    // Returns the index of the previous tab
    protected pure function previous-tab() -> int {
        return Math.max(root.current - 1,  0);
    }

    // Returns the index of the next tab
    protected pure function next-tab() -> int {
        return Math.min(root.current + 1, root.num-tabs - 1);
    }

    private property <length> scroll-delta: 2px;

    // Allows scrolling through the tabs
    scroll-event(event) => {
        if (event.delta-y < -root.scroll-delta) {
            root.current = next-tab();
            return accept;
        }
        if (event.delta-y > -root.scroll-delta) {
            root.current = previous-tab();
            return accept;
        }
        reject
    }
}