#366: add loader for qr code and remove layout jumps after content was loaded

src/components/profile/multiFactorAuth/keyForm/KeyForm.js

@@ -5,6 +5,7 @@ import classNames from 'classnames';
 
 import { FormattedMessage as Message } from 'react-intl';
 
+import { ImageLoader } from 'components/ui/loader';
 import profileForm from 'components/profile/profileForm.scss';
 import messages from '../MultiFactorAuth.intl.json';
 
@@ -14,7 +15,8 @@ export default function KeyForm({secret, qrCodeSrc}: {
     secret: string,
     qrCodeSrc: string
 }) {
-    const formattedSecret = formatSecret(secret);
+    // we are using invisible symbol (\u2063) as a placeholder till we get actual secret
+    const formattedSecret = formatSecret(secret) || '\u2063';
 
     return (
         <div className={profileForm.formBody}>
@@ -26,7 +28,7 @@ export default function KeyForm({secret, qrCodeSrc}: {
 
             <div className={profileForm.formRow}>
                 <div className={styles.qrCode}>
-                    <img src={qrCodeSrc} alt={secret} />
+                    <ImageLoader ratio={1} src={qrCodeSrc} alt={secret} />
                 </div>
             </div>
 

src/components/profile/multiFactorAuth/keyForm/key-form.scss

@@ -1,5 +1,7 @@
 .qrCode {
     text-align: center;
+    width: 242px;
+    margin: 0 auto;
 
     img {
         width: 242px;

src/components/ui/loader/ComponentLoader.js

@@ -1,14 +1,13 @@
-import PropTypes from 'prop-types';
+// @flow
+import type { Skin } from 'components/ui';
 import React from 'react';
-
 import classNames from 'classnames';
 
-import { skins, SKIN_DARK } from 'components/ui';
-
 import styles from './componentLoader.scss';
 
-export default function ComponentLoader(props) {
-    const {skin} = props;
+export default function ComponentLoader({ skin }: {
+    skin: Skin,
+}) {
     return (
         <div className={classNames(styles.componentLoader, styles[`${skin}ComponentLoader`])}>
             <div className={styles.spins}>
@@ -20,11 +19,6 @@ export default function ComponentLoader(props) {
     );
 }
 
-
-ComponentLoader.propTypes = {
-    skin: PropTypes.oneOf(skins),
-};
-
 ComponentLoader.defaultProps = {
-    skin: SKIN_DARK
+    skin: 'dark'
 };

src/components/ui/loader/ImageLoader.js

@@ -0,0 +1,64 @@
+// @flow
+import React from 'react';
+import classNames from 'classnames';
+import { ComponentLoader } from 'components/ui/loader';
+
+import styles from './imageLoader.scss';
+
+export default class ImageLoader extends React.Component<{
+    src: string,
+    alt: string,
+    ratio: number, // width:height ratio
+    onLoad?: Function,
+}, {
+    isLoading: bool
+}> {
+    state = {
+        isLoading: true
+    };
+
+    componentWillMount() {
+        this.preloadImage();
+    }
+
+    preloadImage() {
+        const img = new Image();
+        img.onload = () => this.imageLoaded();
+        img.onerror = () => this.preloadImage();
+        img.src = this.props.src;
+    }
+
+    imageLoaded() {
+        this.setState({ isLoading: false });
+
+        if (this.props.onLoad) {
+            this.props.onLoad();
+        }
+    }
+
+    render() {
+        const { isLoading } = this.state;
+        const { src, alt, ratio } = this.props;
+
+        return (
+            <div className={styles.container}>
+                <div style={{
+                    height: 0,
+                    paddingBottom: `${ratio * 100}%`
+                }} />
+
+                {isLoading && (
+                    <div className={styles.loader}>
+                        <ComponentLoader />
+                    </div>
+                )}
+
+                <div className={classNames(styles.image, {
+                    [styles.imageLoaded]: !isLoading
+                })}>
+                    <img src={src} alt={alt} />
+                </div>
+            </div>
+        );
+    }
+}

src/components/ui/loader/imageLoader.scss

@@ -0,0 +1,25 @@
+.container {
+    position: relative;
+    z-index: 1;
+}
+
+.loader {
+    position: absolute;
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%);
+}
+
+.image {
+    position: absolute;
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%);
+
+    opacity: 0;
+    transition: 0.4s ease-in;
+}
+
+.imageLoaded {
+    opacity: 1;
+}

src/components/ui/loader/index.js

@@ -1,5 +1,4 @@
-import ComponentLoader from './ComponentLoader';
+// @flow
 
-export {
-    ComponentLoader
-};
+export {default as ImageLoader} from './ImageLoader';
+export {default as ComponentLoader} from './ComponentLoader';