riot-web/res/css/views/rooms/_VoiceRecordComposerTile.scss

/*
Copyright 2021 The Matrix.org Foundation C.I.C.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

.mx_VoiceRecordComposerTile_stop {
    // 28px plus a 2px border makes this a 32px square (as intended)
    width: 28px;
    height: 28px;
    border: 2px solid $voice-record-stop-border-color;
    border-radius: 32px;
    margin-right: 16px; // between us and the send button
    position: relative;

    &::after {
        content: '';
        width: 14px;
        height: 14px;
        position: absolute;
        top: 7px;
        left: 7px;
        border-radius: 2px;
        background-color: $voice-record-stop-symbol-color;
    }
}

.mx_VoiceRecordComposerTile_waveformContainer {
    padding: 5px;
    padding-right: 4px; // there's 1px from the waveform itself, so account for that
    padding-left: 15px; // +10px for the live circle, +5px for regular padding
    background-color: $voice-record-waveform-bg-color;
    border-radius: 12px;
    margin-right: 12px; // isolate from stop button

    // Cheat at alignment a bit
    display: flex;
    align-items: center;

    position: relative; // important for the live circle

    color: $voice-record-waveform-fg-color;
    font-size: $font-14px;

    &::before {
        animation: recording-pulse 2s infinite;

        content: '';
        background-color: $voice-record-live-circle-color;
        width: 10px;
        height: 10px;
        position: absolute;
        left: 8px;
        top: 16px; // vertically center
        border-radius: 10px;
    }

    .mx_Waveform_bar {
        background-color: $voice-record-waveform-fg-color;
    }

    .mx_Clock {
        padding-right: 8px; // isolate from waveform
        padding-left: 10px; // isolate from live circle
        width: 42px; // we're not using a monospace font, so fake it
    }
}

// The keyframes are slightly weird here to help make a ramping/punch effect
// for the recording dot. We start and end at 100% opacity to help make the
// dot feel a bit like a real lamp that is blinking: the animation ends up
// spending a lot of its time showing a steady state without a fade effect.
// This lamp effect extends into why the 0% opacity keyframe is not in the
// midpoint: lamps take longer to turn off than they do to turn on, and the
// extra frames give it a bit of a realistic punch for when the animation is
// ramping back up to 100% opacity.
//
// Target animation timings: steady for 1.5s, fade out for 0.3s, fade in for 0.2s
// (intended to be used in a loop for 2s animation speed)
@keyframes recording-pulse {
    0% {
        opacity: 1;
    }
    35% {
        opacity: 0;
    }
    65% {
        opacity: 1;
    }
}