fix(prejoin): Make avatar resizable

css/_premeeting-screens.scss

@@ -197,16 +197,9 @@
         text-align: center;
     }
 
-    .preview-avatar-container {
-        width: 100%;
-        height: 80%;
-        display: flex;
-        align-items: center;
-        justify-content: center;
-    }
-
     .avatar {
         background: #A4B8D1;
+        margin: 0 auto;
     }
 
     video {

react/features/base/premeeting/components/web/Avatar.js

@@ -0,0 +1,61 @@
+// @flow
+
+import React from 'react';
+
+import { Avatar } from '../../../avatar';
+import { connect } from '../../../redux';
+import { calculateAvatarDimensions } from '../../functions';
+
+type Props = {
+
+   /**
+    * The height of the window.
+    */
+    height: number,
+
+   /**
+    * The name of the participant (if any).
+    */
+    name: string
+}
+
+/**
+ * Component displaying the avatar for the premeeting screen.
+ *
+ * @param {Props} props - The props of the component.
+ * @returns {ReactElement}
+ */
+function PremeetingAvatar({ height, name }: Props) {
+    const { marginTop, size } = calculateAvatarDimensions(height);
+
+    if (size <= 5) {
+        return null;
+    }
+
+
+    return (
+        <div style = {{ marginTop }}>
+            <Avatar
+                className = 'preview-avatar'
+                displayName = { name }
+                participantId = 'local'
+                size = { size } />
+        </div>
+    );
+}
+
+/**
+ * Maps (parts of) the redux state to the React {@code Component} props.
+ *
+ * @param {Object} state - The redux state.
+ * @returns {{
+ *    height: number
+ * }}
+ */
+function mapStateToProps(state) {
+    return {
+        height: state['features/base/responsive-ui'].clientHeight
+    };
+}
+
+export default connect(mapStateToProps)(PremeetingAvatar);

react/features/base/premeeting/components/web/Preview.js

@@ -2,11 +2,12 @@
 
 import React from 'react';
 
-import { Avatar } from '../../../avatar';
 import { Video } from '../../../media';
 import { connect } from '../../../redux';
 import { getLocalVideoTrack } from '../../../tracks';
 
+import PreviewAvatar from './Avatar';
+
 export type Props = {
 
     /**
@@ -54,13 +55,7 @@ function Preview(props: Props) {
             <div
                 className = 'no-video'
                 id = 'preview'>
-                <div className = 'preview-avatar-container'>
+                <PreviewAvatar name = { name } />
-                    <Avatar
-                        className = 'preview-avatar'
-                        displayName = { name }
-                        participantId = 'local'
-                        size = { 200 } />
-                </div>
             </div>
         );
     }

react/features/base/premeeting/functions.js

@@ -1,3 +1,5 @@
+// @flow
+
 import { findIndex } from 'lodash';
 
 import { CONNECTION_TYPE } from './constants';
@@ -8,6 +10,75 @@ const LOSS_VIDEO_THRESHOLDS = [ 0.33, 0.1, 0.05 ];
 const THROUGHPUT_AUDIO_THRESHOLDS = [ 8, 20 ];
 const THROUGHPUT_VIDEO_THRESHOLDS = [ 60, 750 ];
 
+/**
+ * The avatar size to container size ration.
+ */
+const ratio = 1 / 3;
+
+/**
+ * The max avatar size.
+ */
+const maxSize = 190;
+
+/**
+ * The window limit hight over which the avatar should have the default dimension.
+ */
+const upperHeightLimit = 760;
+
+/**
+ * The window limit hight under which the avatar should not be resized anymore.
+ */
+const lowerHeightLimit = 460;
+
+/**
+ * The default top margin of the avatar.
+ */
+const defaultMarginTop = '10%';
+
+/**
+ * The top margin of the avatar when its dimension is small.
+ */
+const smallMarginTop = '5%';
+
+/**
+ * Calculates avatar dimensions based on window height and position.
+ *
+ * @param {number} height - The window height.
+ * @returns {{
+ *   marginTop: string,
+ *   size: number
+ * }}
+ */
+export function calculateAvatarDimensions(height: number) {
+    if (height > upperHeightLimit) {
+        return {
+            size: maxSize,
+            marginTop: defaultMarginTop
+        };
+    }
+
+    if (height > lowerHeightLimit) {
+        const diff = height - lowerHeightLimit;
+        const percent = diff * ratio;
+        const size = Math.floor(maxSize * percent / 100);
+        let marginTop = defaultMarginTop;
+
+        if (height < 600) {
+            marginTop = smallMarginTop;
+        }
+
+        return {
+            size,
+            marginTop
+        };
+    }
+
+    return {
+        size: 0,
+        marginTop: '0'
+    };
+}
+
 /**
  * Returns the level based on a list of thresholds.
  *
@@ -121,7 +192,7 @@ function _getConnectionDataFromTestResults({ fractionalLoss: l, throughput: t })
  *   connectionDetails: string[]
  * }}
  */
-export function getConnectionData(state) {
+export function getConnectionData(state: Object) {
     const { precallTestResults } = state['features/prejoin'];
 
     if (precallTestResults) {