Create icons for users without an avatar in desktop notifications (#305)

* Add notifications icon for users without an avatar

* Render icon at higher resolution

* Use scale to render at higher resolution

src/app/atoms/avatar/Avatar.jsx

@@ -8,6 +8,7 @@ import Text from '../text/Text';
 import RawIcon from '../system-icons/RawIcon';
 
 import ImageBrokenSVG from '../../../../public/res/svg/image-broken.svg';
+import { avatarInitials } from '../../../util/common';
 
 function Avatar({
   text, bgColor, iconSrc, iconColor, imageSrc, size,
@@ -40,7 +41,7 @@ function Avatar({
                   ? <RawIcon size={size} src={iconSrc} color={iconColor} />
                   : text !== null && (
                     <Text variant={textSize} primary>
-                      {twemojify([...text][0])}
+                      {twemojify(avatarInitials(text))}
                     </Text>
                   )
               }

src/app/atoms/avatar/render.js

@@ -0,0 +1,61 @@
+import { avatarInitials } from '../../../util/common';
+
+function cssVar(name) {
+  return getComputedStyle(document.body).getPropertyValue(name);
+}
+
+// renders the avatar and returns it as an URL
+export default async function renderAvatar({
+  text, bgColor, imageSrc, size, borderRadius, scale,
+}) {
+  try {
+    const canvas = document.createElement('canvas');
+    canvas.width = size * scale;
+    canvas.height = size * scale;
+
+    const ctx = canvas.getContext('2d');
+
+    ctx.scale(scale, scale);
+
+    // rounded corners
+    ctx.beginPath();
+    ctx.moveTo(size, size);
+    ctx.arcTo(0, size, 0, 0, borderRadius);
+    ctx.arcTo(0, 0, size, 0, borderRadius);
+    ctx.arcTo(size, 0, size, size, borderRadius);
+    ctx.arcTo(size, size, 0, size, borderRadius);
+
+    if (imageSrc) {
+      // clip corners of image
+      ctx.closePath();
+      ctx.clip();
+
+      const img = new Image();
+      img.crossOrigin = 'anonymous';
+      const promise = new Promise((resolve, reject) => {
+        img.onerror = reject;
+        img.onload = resolve;
+      });
+      img.src = imageSrc;
+      await promise;
+
+      ctx.drawImage(img, 0, 0, size, size);
+    } else {
+      // colored background
+      ctx.fillStyle = cssVar(bgColor);
+      ctx.fill();
+
+      // centered letter
+      ctx.fillStyle = '#fff';
+      ctx.font = `${cssVar('--fs-s1')} ${cssVar('--font-primary')}`;
+      ctx.textBaseline = 'middle';
+      ctx.textAlign = 'center';
+      ctx.fillText(avatarInitials(text), size / 2, size / 2);
+    }
+
+    return canvas.toDataURL();
+  } catch (e) {
+    console.error(e);
+    return imageSrc;
+  }
+}