element-web/res/css/views/audio_messages/_SeekBar.pcss

/*
Copyright 2024 New Vector Ltd.
Copyright 2021 The Matrix.org Foundation C.I.C.

SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only
Please see LICENSE files in the repository root for full details.
*/

/* CSS inspiration from: */
/* * https://www.w3schools.com/howto/howto_js_rangeslider.asp */
/* * https://stackoverflow.com/a/28283806 */
/* * https://css-tricks.com/styling-cross-browser-compatible-range-inputs-css/ */

.mx_SeekBar {
    /* default, overridden in JS */
    --fillTo: 1;

    /* Dev note: we deliberately do not have the -ms-track (and friends) selectors because we don't */
    /* need to support IE. */

    appearance: none; /* default style override */

    width: 100%;
    height: 1px;
    background: $quaternary-content;
    outline: none; /* remove blue selection border */
    position: relative; /* for before+after pseudo elements later on */

    cursor: pointer;

    &::-webkit-slider-thumb {
        appearance: none; /* default style override */

        /* Dev note: This needs to be duplicated with the -moz-range-thumb selector */
        /* because otherwise Edge (webkit) will fail to see the styles and just refuse */
        /* to apply them. */
        width: 8px;
        height: 8px;
        border-radius: 8px;
        background-color: $tertiary-content;
        cursor: pointer;
    }

    &::-moz-range-thumb {
        width: 8px;
        height: 8px;
        border-radius: 8px;
        background-color: $tertiary-content;
        cursor: pointer;

        /* Firefox adds a border on the thumb */
        border: none;
    }

    /* This is for webkit support, but we can't limit the functionality of it to just webkit */
    /* browsers. Firefox responds to webkit-prefixed values now, which means we can't use media */
    /* or support queries to selectively apply the rule. An upside is that this CSS doesn't work */
    /* in firefox, so it's just wasted CPU/GPU time. */
    &::before {
        /* ::before to ensure it ends up under the thumb */
        content: "";
        background-color: $tertiary-content;

        /* Absolute positioning to ensure it overlaps with the existing bar */
        position: absolute;
        top: 0;
        left: 0;

        /* Sizing to match the bar */
        width: 100%;
        height: 1px;

        /* And finally dynamic width without overly hurting the rendering engine. */
        transform-origin: 0 100%;
        transform: scaleX(var(--fillTo));
    }

    /* This is firefox's built-in support for the above, with 100% less hacks. */
    &::-moz-range-progress {
        background-color: $tertiary-content;
        height: 1px;
    }

    &:disabled {
        opacity: 0.5;
    }

    /* Increase clickable area for the slider (approximately same size as browser default) */
    /* We do it this way to keep the same padding and margins of the element, avoiding margin math. */
    /* Source: https://front-back.com/expand-clickable-areas-for-a-better-touch-experience/ */
    &::after {
        content: "";
        position: absolute;
        top: -6px;
        bottom: -6px;
        left: 0;
        right: 0;
    }
}