Files
element-call/src/video-grid/NewVideoGrid.tsx
Robin Townsend 1207ecc9d7 Decouple video grid from video tile components
This is an attempt to address the feedback in https://github.com/vector-im/element-call/pull/1099#discussion_r1226863404 that the video grid and video tile components have become too tightly coupled. After this change, the only requirements that the video grid makes of its child components are:

- They accept ref, style, and item props
- They attach the ref and styles to a react-spring animated element

Note: I removed the video grid Storybook file, because I'm not aware of anyone using Storybook for development of Element Call beyond Robert, and it would take some effort to fix to work with these changes.
2023-06-12 18:21:45 -04:00

472 lines
14 KiB
TypeScript

/*
Copyright 2023 New Vector Ltd
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.
*/
import { SpringRef, TransitionFn, useTransition } from "@react-spring/web";
import { EventTypes, Handler, useScroll } from "@use-gesture/react";
import React, {
Dispatch,
FC,
ReactNode,
SetStateAction,
useCallback,
useEffect,
useMemo,
useRef,
useState,
} from "react";
import useMeasure from "react-use-measure";
import { zipWith } from "lodash";
import styles from "./NewVideoGrid.module.css";
import { TileDescriptor } from "./TileDescriptor";
import { VideoGridProps as Props, TileSpring } from "./VideoGrid";
import { useReactiveState } from "../useReactiveState";
import { useMergedRefs } from "../useMergedRefs";
import {
Grid,
Cell,
row,
column,
fillGaps,
forEachCellInArea,
cycleTileSize,
appendItems,
} from "./model";
import { TileWrapper } from "./TileWrapper";
interface GridState extends Grid {
/**
* The ID of the current state of the grid.
*/
generation: number;
}
const useGridState = (
columns: number | null,
items: TileDescriptor[]
): [GridState | null, Dispatch<SetStateAction<Grid>>] => {
const [grid, setGrid_] = useReactiveState<GridState | null>(
(prevGrid = null) => {
if (prevGrid === null) {
// We can't do anything if the column count isn't known yet
if (columns === null) {
return null;
} else {
prevGrid = { generation: 0, columns, cells: [] };
}
}
// Step 1: Update tiles that still exist, and remove tiles that have left
// the grid
const itemsById = new Map(items.map((i) => [i.id, i]));
const grid1: Grid = {
...prevGrid,
cells: prevGrid.cells.map((c) => {
if (c === undefined) return undefined;
const item = itemsById.get(c.item.id);
return item === undefined ? undefined : { ...c, item };
}),
};
// Step 2: Backfill gaps left behind by removed tiles
const grid2 = fillGaps(grid1);
// Step 3: Add new tiles to the end of the grid
const existingItemIds = new Set(
grid2.cells.filter((c) => c !== undefined).map((c) => c!.item.id)
);
const newItems = items.filter((i) => !existingItemIds.has(i.id));
const grid3 = appendItems(newItems, grid2);
return { ...grid3, generation: prevGrid.generation + 1 };
},
[columns, items]
);
const setGrid: Dispatch<SetStateAction<Grid>> = useCallback(
(action) => {
if (typeof action === "function") {
setGrid_((prevGrid) =>
prevGrid === null
? null
: {
...(action as (prev: Grid) => Grid)(prevGrid),
generation: prevGrid.generation + 1,
}
);
} else {
setGrid_((prevGrid) => ({
...action,
generation: prevGrid?.generation ?? 1,
}));
}
},
[setGrid_]
);
return [grid, setGrid];
};
interface Rect {
x: number;
y: number;
width: number;
height: number;
}
interface Tile extends Rect {
item: TileDescriptor;
}
interface DragState {
tileId: string;
tileX: number;
tileY: number;
cursorX: number;
cursorY: number;
}
/**
* An interactive, animated grid of video tiles.
*/
export const NewVideoGrid: FC<Props> = ({
items,
disableAnimations,
children,
}) => {
// Overview: This component lays out tiles by rendering an invisible template
// grid of "slots" for tiles to go in. Once rendered, it uses the DOM API to
// get the dimensions of each slot, feeding these numbers back into
// react-spring to let the actual tiles move freely atop the template.
// To know when the rendered grid becomes consistent with the layout we've
// requested, we give it a data-generation attribute which holds the ID of the
// most recently rendered generation of the grid, and watch it with a
// MutationObserver.
const [slotGrid, setSlotGrid] = useState<HTMLDivElement | null>(null);
const [slotGridGeneration, setSlotGridGeneration] = useState(0);
useEffect(() => {
if (slotGrid !== null) {
setSlotGridGeneration(
parseInt(slotGrid.getAttribute("data-generation")!)
);
const observer = new MutationObserver((mutations) => {
if (mutations.some((m) => m.type === "attributes")) {
setSlotGridGeneration(
parseInt(slotGrid.getAttribute("data-generation")!)
);
}
});
observer.observe(slotGrid, { attributes: true });
return () => observer.disconnect();
}
}, [slotGrid, setSlotGridGeneration]);
const [gridRef1, gridBounds] = useMeasure();
const gridRef2 = useRef<HTMLDivElement | null>(null);
const gridRef = useMergedRefs(gridRef1, gridRef2);
const slotRects = useMemo(() => {
if (slotGrid === null) return [];
const slots = slotGrid.getElementsByClassName(styles.slot);
const rects = new Array<Rect>(slots.length);
for (let i = 0; i < slots.length; i++) {
const slot = slots[i] as HTMLElement;
rects[i] = {
x: slot.offsetLeft,
y: slot.offsetTop,
width: slot.offsetWidth,
height: slot.offsetHeight,
};
}
return rects;
// The rects may change due to the grid being resized or rerendered, but
// eslint can't statically verify this
// eslint-disable-next-line react-hooks/exhaustive-deps
}, [slotGrid, slotGridGeneration, gridBounds]);
const [columns] = useReactiveState<number | null>(
// Since grid resizing isn't implemented yet, pick a column count on mount
// and stick to it
(prevColumns) =>
prevColumns !== undefined && prevColumns !== null
? prevColumns
: // The grid bounds might not be known yet
gridBounds.width === 0
? null
: Math.max(2, Math.floor(gridBounds.width * 0.0045)),
[gridBounds]
);
const [grid, setGrid] = useGridState(columns, items);
const [tiles] = useReactiveState<Tile[]>(
(prevTiles) => {
// If React hasn't yet rendered the current generation of the grid, skip
// the update, because grid and slotRects will be out of sync
if (slotGridGeneration !== grid?.generation) return prevTiles ?? [];
const tileCells = grid.cells.filter((c) => c?.origin) as Cell[];
const tileRects = new Map<TileDescriptor, Rect>(
zipWith(tileCells, slotRects, (cell, rect) => [cell.item, rect])
);
return items.map((item) => ({ ...tileRects.get(item)!, item }));
},
[slotRects, grid, slotGridGeneration]
);
// Drag state is stored in a ref rather than component state, because we use
// react-spring's imperative API during gestures to improve responsiveness
const dragState = useRef<DragState | null>(null);
const [tileTransitions, springRef] = useTransition(
tiles,
() => ({
key: ({ item }: Tile) => item.id,
from: ({ x, y, width, height }: Tile) => ({
opacity: 0,
scale: 0,
shadow: 1,
shadowSpread: 0,
zIndex: 1,
x,
y,
width,
height,
immediate: disableAnimations,
}),
enter: { opacity: 1, scale: 1, immediate: disableAnimations },
update: ({ item, x, y, width, height }: Tile) =>
item.id === dragState.current?.tileId
? {}
: {
x,
y,
width,
height,
immediate: disableAnimations,
},
leave: { opacity: 0, scale: 0, immediate: disableAnimations },
config: { mass: 0.7, tension: 252, friction: 25 },
})
// react-spring's types are bugged and can't infer the spring type
) as unknown as [TransitionFn<Tile, TileSpring>, SpringRef<TileSpring>];
// Because we're using react-spring in imperative mode, we're responsible for
// firing animations manually whenever the tiles array updates
useEffect(() => {
springRef.start();
}, [tiles, springRef]);
const animateDraggedTile = (endOfGesture: boolean) => {
const { tileId, tileX, tileY, cursorX, cursorY } = dragState.current!;
const tile = tiles.find((t) => t.item.id === tileId)!;
springRef.start((_i, controller) => {
if ((controller.item as Tile).item.id === tileId) {
if (endOfGesture) {
return {
scale: 1,
zIndex: 1,
shadow: 1,
x: tile.x,
y: tile.y,
width: tile.width,
height: tile.height,
immediate: disableAnimations || ((key) => key === "zIndex"),
// Allow the tile's position to settle before pushing its
// z-index back down
delay: (key) => (key === "zIndex" ? 500 : 0),
};
} else {
return {
scale: 1.1,
zIndex: 2,
shadow: 15,
x: tileX,
y: tileY,
immediate:
disableAnimations ||
((key) => key === "zIndex" || key === "x" || key === "y"),
};
}
} else {
return {};
}
});
const overTile = tiles.find(
(t) =>
cursorX >= t.x &&
cursorX < t.x + t.width &&
cursorY >= t.y &&
cursorY < t.y + t.height
);
if (overTile !== undefined && overTile.item.id !== tileId) {
setGrid((g) => ({
...g!,
cells: g!.cells.map((c) => {
if (c?.item === overTile.item) return { ...c, item: tile.item };
if (c?.item === tile.item) return { ...c, item: overTile.item };
return c;
}),
}));
}
};
// Callback for useDrag. We could call useDrag here, but the default
// pattern of spreading {...bind()} across the children to bind the gesture
// ends up breaking memoization and ruining this component's performance.
// Instead, we pass this callback to each tile via a ref, to let them bind the
// gesture using the much more sensible ref-based method.
const onTileDrag = (
tileId: string,
{
tap,
initial: [initialX, initialY],
delta: [dx, dy],
last,
}: Parameters<Handler<"drag", EventTypes["drag"]>>[0]
) => {
if (tap) {
setGrid((g) => cycleTileSize(tileId, g!));
} else {
const tileSpring = springRef.current
.find((c) => (c.item as Tile).item.id === tileId)!
.get();
if (dragState.current === null) {
dragState.current = {
tileId,
tileX: tileSpring.x,
tileY: tileSpring.y,
cursorX: initialX - gridBounds.x,
cursorY: initialY - gridBounds.y + scrollOffset.current,
};
}
dragState.current.tileX += dx;
dragState.current.tileY += dy;
dragState.current.cursorX += dx;
dragState.current.cursorY += dy;
animateDraggedTile(last);
if (last) dragState.current = null;
}
};
const onTileDragRef = useRef(onTileDrag);
onTileDragRef.current = onTileDrag;
const scrollOffset = useRef(0);
useScroll(
({ xy: [, y], delta: [, dy] }) => {
scrollOffset.current = y;
if (dragState.current !== null) {
dragState.current.tileY += dy;
dragState.current.cursorY += dy;
animateDraggedTile(false);
}
},
{ target: gridRef2 }
);
const slotGridStyle = useMemo(() => {
if (grid === null) return {};
const areas = new Array<(number | null)[]>(
Math.ceil(grid.cells.length / grid.columns)
);
for (let i = 0; i < areas.length; i++)
areas[i] = new Array<number | null>(grid.columns).fill(null);
let slotId = 0;
for (let i = 0; i < grid.cells.length; i++) {
const cell = grid.cells[i];
if (cell?.origin) {
const slotEnd = i + cell.columns - 1 + grid.columns * (cell.rows - 1);
forEachCellInArea(
i,
slotEnd,
grid,
(_c, j) => (areas[row(j, grid)][column(j, grid)] = slotId)
);
slotId++;
}
}
return {
gridTemplateAreas: areas
.map(
(row) =>
`'${row
.map((slotId) => (slotId === null ? "." : `s${slotId}`))
.join(" ")}'`
)
.join(" "),
gridTemplateColumns: `repeat(${columns}, 1fr)`,
};
}, [grid, columns]);
const slots = useMemo(() => {
const slots = new Array<ReactNode>(items.length);
for (let i = 0; i < items.length; i++)
slots[i] = (
<div className={styles.slot} key={i} style={{ gridArea: `s${i}` }} />
);
return slots;
}, [items.length]);
// Render nothing if the grid has yet to be generated
if (grid === null) {
return <div ref={gridRef} className={styles.grid} />;
}
return (
<div ref={gridRef} className={styles.grid}>
<div
style={slotGridStyle}
ref={setSlotGrid}
className={styles.slotGrid}
data-generation={grid.generation}
>
{slots}
</div>
{tileTransitions((spring, tile) => (
<TileWrapper
key={tile.item.id}
id={tile.item.id}
onDragRef={onTileDragRef}
targetWidth={tile.width}
targetHeight={tile.height}
item={tile.item}
{...spring}
>
{children}
</TileWrapper>
))}
</div>
);
};