5 files changed, 167 insertions, 0 deletions
diff --git a/frontend/src/components/lobby/radial-list/RadialList.css b/frontend/src/components/lobby/radial-list/RadialList.css
new file mode 100644
index 00000000..3b0f3a79
--- /dev/null
+++ b/frontend/src/components/lobby/radial-list/RadialList.css
@@ -0,0 +1,23 @@
+.radial-list-container {
+    margin: 0;
+    padding: 0;
+    position: relative;
+}
+
+.radial-list {
+    margin: 0;
+    padding: 0;
+    transition: all 500ms ease-in-out;
+    z-index: 1;
+}
+
+.radial-list-center {
+    z-index: 0;
+}
+
+.absolute-center {
+    position: absolute;
+    left: 50%;
+    top: 50%;
+    transform: translate(-50%, -50%);
+}
diff --git a/frontend/src/components/lobby/radial-list/RadialList.jsx b/frontend/src/components/lobby/radial-list/RadialList.jsx
new file mode 100644
index 00000000..95ed8d17
--- /dev/null
+++ b/frontend/src/components/lobby/radial-list/RadialList.jsx
@@ -0,0 +1,65 @@
+//@flow
+import * as React from 'react';
+import type { CartesianCoords, RadialConfig } from './radial-math';
+import { cartesianOffsets, CLOCKWISE, COUNTERCLOCKWISE } from './radial-math';
+import './RadialList.css';
+import { RadialListItem } from './RadialListItem';
+
+type RadialListProps = {
+  items: Array<React.Node>,
+  centerElement?: React.Node,
+  diameter?: number, // 240px by default
+  offsetDegrees?: number, // defaults to 0 = 12 o'clock
+  arc?: number, // defaults to 360 (full circle)
+  clockwise?: boolean, // defaults to 360 (full circle)
+  itemWidth?: number,
+  itemHeight?: number,
+};
+
+export const RadialList = ({items, centerElement, diameter = 240, offsetDegrees = 0, arc = 360, clockwise = true, itemWidth = 20, itemHeight = 20}: RadialListProps) => {
+  const containerStyle = {
+    width: diameter + itemWidth,
+    height: diameter + itemHeight,
+  };
+  const radius = diameter / 2;
+  const direction = clockwise ? CLOCKWISE : COUNTERCLOCKWISE;
+  const radialConfig: RadialConfig = {radius, arc, offsetDegrees, direction};
+
+  return <div className='radial-list-container' style={containerStyle}>
+    <RadialListItems items={items} radialConfig={radialConfig}/>
+    <RadialListCenter centerElement={centerElement}/>
+  </div>;
+};
+
+type RadialListItemsProps = {
+  items: Array<React.Node>,
+  radialConfig: RadialConfig,
+};
+
+const RadialListItems = ({items, radialConfig}: RadialListItemsProps) => {
+  const diameter = radialConfig.radius * 2;
+  const ulStyle = {
+    width: diameter,
+    height: diameter,
+  };
+  const itemOffsets: Array<CartesianCoords> = cartesianOffsets(items.length, radialConfig);
+
+  return <ul className='radial-list absolute-center' style={ulStyle}>
+    {items.map((item, i) => (<RadialListItem
+            key={i}
+            item={item}
+            offsets={itemOffsets[i]}
+    />))}
+  </ul>;
+};
+
+type RadialListCenterProps = {
+  centerElement?: React.Node,
+};
+
+const RadialListCenter = ({centerElement}: RadialListCenterProps) => {
+  if (!centerElement) {
+    return null;
+  }
+  return <div className='radial-list-center absolute-center'>{centerElement}</div>;
+};
diff --git a/frontend/src/components/lobby/radial-list/RadialListItem.css b/frontend/src/components/lobby/radial-list/RadialListItem.css
new file mode 100644
index 00000000..65bb9661
--- /dev/null
+++ b/frontend/src/components/lobby/radial-list/RadialListItem.css
@@ -0,0 +1,11 @@
+.radial-list-item {
+    display: block;
+    position: absolute;
+    top: 50%;
+    left: 50%;
+    margin: 0;
+    padding: 0;
+    list-style: unset;
+    transition: all 500ms ease-in-out;
+    z-index: 1;
+}
diff --git a/frontend/src/components/lobby/radial-list/RadialListItem.jsx b/frontend/src/components/lobby/radial-list/RadialListItem.jsx
new file mode 100644
index 00000000..1d5df7f5
--- /dev/null
+++ b/frontend/src/components/lobby/radial-list/RadialListItem.jsx
@@ -0,0 +1,18 @@
+//@flow
+import * as React from 'react';
+import type { CartesianCoords } from './radial-math';
+import './RadialListItem.css';
+
+type RadialListItemProps = {
+  item: React.Node,
+  offsets: CartesianCoords,
+};
+
+export const RadialListItem = ({item, offsets}: RadialListItemProps) => {
+  // Y-axis points down, hence the minus sign
+  const liStyle = {
+    transform: `translate(${offsets.x}px, ${-offsets.y}px) translate(-50%, -50%)`,
+  };
+
+  return <li className='radial-list-item' style={liStyle}>{item}</li>;
+};
diff --git a/frontend/src/components/lobby/radial-list/radial-math.js b/frontend/src/components/lobby/radial-list/radial-math.js
new file mode 100644
index 00000000..4091a270
--- /dev/null
+++ b/frontend/src/components/lobby/radial-list/radial-math.js
@@ -0,0 +1,50 @@
+//@flow
+
+export type CartesianCoords = {
+  x: number,
+  y: number,
+}
+type CylindricalCoords = {
+  radius: number,
+  thetaDegrees: number,
+}
+
+const toRad = (deg) => deg * (Math.PI / 180);
+const roundedProjection = (radius, theta, trigFn) => Math.round(radius * trigFn(theta));
+const xProjection = (radius, theta) => roundedProjection(radius, theta, Math.cos);
+const yProjection = (radius, theta) => roundedProjection(radius, theta, Math.sin);
+
+const toCartesian = ({radius, thetaDegrees}: CylindricalCoords): CartesianCoords => ({
+  x: xProjection(radius, toRad(thetaDegrees)),
+  y: yProjection(radius, toRad(thetaDegrees)),
+});
+
+export type Direction = -1 | 1;
+export const CLOCKWISE: Direction = -1;
+export const COUNTERCLOCKWISE: Direction = 1;
+
+export type RadialConfig = {|
+  radius: number,
+  arc: number,
+  offsetDegrees: number,
+  direction: Direction,
+|}
+const DEFAULT_CONFIG: RadialConfig = {
+  radius: 120,
+  arc: 360,
+  offsetDegrees: 0,
+  direction: CLOCKWISE,
+};
+
+const DEFAULT_START = 90; // Up
+
+export function cartesianOffsets(nbItems: number, radialConfig: RadialConfig = DEFAULT_CONFIG): Array<CartesianCoords> {
+  return Array.from({length: nbItems}, (v, i) => itemCartesianOffsets(i, nbItems, radialConfig));
+}
+
+function itemCartesianOffsets(index: number, nbItems: number, {radius, arc, direction, offsetDegrees}: RadialConfig): CartesianCoords {
+  const startAngle = DEFAULT_START + direction * offsetDegrees;
+  const angleStep = arc / nbItems;
+  const itemAngle = startAngle + direction * angleStep * index;
+  return toCartesian({radius, thetaDegrees: itemAngle});
+}