moonfire-nvr/ui/src/Live/Multiview.tsx

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// This file is part of Moonfire NVR, a security camera network video recorder.
// Copyright (C) 2021 The Moonfire NVR Authors; see AUTHORS and LICENSE.txt.
// SPDX-License-Identifier: GPL-v3.0-or-later WITH GPL-3.0-linking-exception
import Select from "@material-ui/core/Select";
import MenuItem from "@material-ui/core/MenuItem";
import React, { useReducer, useState } from "react";
import { Camera } from "../types";
import { makeStyles } from "@material-ui/core/styles";
import useResizeObserver from "@react-hook/resize-observer";
export interface Layout {
className: string;
cameras: number;
}
// These class names must match useStyles rules (below).
const LAYOUTS: Layout[] = [
{ className: "solo", cameras: 1 },
{ className: "main-plus-five", cameras: 6 },
{ className: "two-by-two", cameras: 4 },
{ className: "three-by-three", cameras: 9 },
];
const MAX_CAMERAS = 9;
const useStyles = makeStyles((theme) => ({
root: {
flex: "1 0 0",
color: "white",
marginTop: theme.spacing(2),
overflow: "hidden",
"& .mid": {
position: "relative",
aspectRatio: "16 / 9",
display: "inline-block",
},
// Set the width based on the height.
"& .mid.wider": {
height: "100%",
},
// Set the height based on the width.
"& .mid.taller": {
width: "100%",
},
},
inner: {
// match parent's size without influencing it.
position: "absolute",
width: "100%",
height: "100%",
backgroundColor: "#000",
overflow: "hidden",
display: "grid",
gridGap: "0px",
// These class names must match LAYOUTS (above).
"&.solo": {
gridTemplateColumns: "100%",
gridTemplateRows: "100%",
},
"&.two-by-two": {
gridTemplateColumns: "repeat(2, calc(100% / 2))",
gridTemplateRows: "repeat(2, calc(100% / 2))",
},
"&.main-plus-five, &.three-by-three": {
gridTemplateColumns: "repeat(3, calc(100% / 3))",
gridTemplateRows: "repeat(3, calc(100% / 3))",
},
"&.main-plus-five > div:nth-child(1)": {
gridColumn: "span 2",
gridRow: "span 2",
},
},
}));
export interface MultiviewProps {
cameras: Camera[];
layoutIndex: number;
renderCamera: (camera: Camera | null, chooser: JSX.Element) => JSX.Element;
}
export interface MultiviewChooserProps {
/// An index into <tt>LAYOUTS</tt>.
layoutIndex: number;
onChoice: (selectedIndex: number) => void;
}
/**
* Chooses the layout for a Multiview.
* Styled for placement in the app menu bar.
*/
export const MultiviewChooser = (props: MultiviewChooserProps) => {
return (
<Select
id="layout"
value={props.layoutIndex}
onChange={(e) => props.onChoice(e.target.value)}
size="small"
sx={{
// Hacky attempt to style for the app menu.
color: "inherit",
"& svg": {
color: "inherit",
},
}}
>
{LAYOUTS.map((e, i) => (
<MenuItem key={e.className} value={i}>
{e.className}
</MenuItem>
))}
</Select>
);
};
/**
* The cameras selected for the multiview.
* This is always an array of length <tt>MAX_CAMERAS</tt>; only the first
* LAYOUTS[layoutIndex].cameras are currently visible. There are no duplicates;
* setting one element to a given camera unsets any others pointing to the same
* camera.
*/
type SelectedCameras = Array<number | null>;
interface SelectOp {
selectedIndex: number;
cameraIndex: number | null;
}
function selectedReducer(old: SelectedCameras, op: SelectOp): SelectedCameras {
let selected = [...old]; // shallow clone.
if (op.cameraIndex !== null) {
// de-dupe.
for (let i = 0; i < selected.length; i++) {
if (selected[i] === op.cameraIndex) {
selected[i] = null;
}
}
}
selected[op.selectedIndex] = op.cameraIndex ?? null;
return selected;
}
/**
* Presents one or more camera views in one of several layouts.
*
* The parent should arrange for the multiview's outer div to be as large
* as possible. Internally, multiview uses the largest possible aspect
* ratio-constrained section of it. It uses a ResizeObserver to determine if
* the outer div is wider or taller than 16x9, and then sets an appropriate CSS
* class to constrain the width or height respectively. The goal is to have the
* smoothest resizing by changing the DOM/CSS as little as possible.
*/
const Multiview = (props: MultiviewProps) => {
const [selected, updateSelected] = useReducer(
selectedReducer,
Array(MAX_CAMERAS).fill(null)
);
const [widerOrTaller, setWiderOrTaller] = useState("");
const outerRef = React.useRef<HTMLDivElement>(null);
const midRef = React.useRef<HTMLDivElement>(null);
// Keep a constant 16x9 aspect ratio. Chrome 89.0.4389.90 supports the
// "aspect-ratio" CSS property and seems to behave in a predictable way.
// Intuition suggests using that is more performant than extra DOM
// manipulations. Firefox 87.0 doesn't support aspect-ratio. Emulating it
// with an <img> child doesn't work well either for using a (flex item)
// ancestor's (calculated) height to compute
// the <img>'s width and then the parent's width. There are some open bugs
// that look related, eg:
// https://bugzilla.mozilla.org/show_bug.cgi?id=1349738
// https://bugzilla.mozilla.org/show_bug.cgi?id=1690423
// so when there's no "aspect-ratio", just calculate everything here.
const aspectRatioSupported = CSS.supports("aspect-ratio: 16 / 9");
useResizeObserver(outerRef, (entry: ResizeObserverEntry) => {
const w = entry.contentRect.width;
const h = entry.contentRect.height;
const hFromW = (w * 9) / 16;
if (aspectRatioSupported) {
setWiderOrTaller(hFromW > h ? "wider" : "taller");
return;
}
const mid = midRef.current;
if (mid === null) {
return;
}
if (hFromW > h) {
mid.style.width = `${(h * 16) / 9}px`;
mid.style.height = `${h}px`;
} else {
mid.style.width = `${w}px`;
mid.style.height = `${hFromW}px`;
}
});
const classes = useStyles();
const layout = LAYOUTS[props.layoutIndex];
const monoviews = selected.slice(0, layout.cameras).map((e, i) => {
// When a camera is selected, use the camera's index as the key.
// This allows swapping cameras' positions without tearing down their
// WebSocket connections and buffers.
//
// When no camera is selected, use the index within selected. (Actually,
// its negation, to disambiguate between the two cases.)
const key = e ?? -i;
return (
<Monoview
key={key}
cameras={props.cameras}
cameraIndex={e}
renderCamera={props.renderCamera}
onSelect={(cameraIndex) =>
updateSelected({ selectedIndex: i, cameraIndex })
}
/>
);
});
return (
<div className={classes.root} ref={outerRef}>
<div className={`mid ${widerOrTaller}`} ref={midRef}>
<div className={`${classes.inner} ${layout.className}`}>
{monoviews}
</div>
</div>
</div>
);
};
interface MonoviewProps {
cameras: Camera[];
cameraIndex: number | null;
onSelect: (cameraIndex: number | null) => void;
renderCamera: (camera: Camera | null, chooser: JSX.Element) => JSX.Element;
}
/** A single pane of a Multiview, including its camera chooser. */
const Monoview = (props: MonoviewProps) => {
const chooser = (
<Select
value={props.cameraIndex == null ? undefined : props.cameraIndex}
onChange={(e) => props.onSelect(e.target.value ?? null)}
displayEmpty
size="small"
sx={{
// Restyle to fit over the video (or black).
backgroundColor: "rgba(255, 255, 255, 0.5)",
"& svg": {
color: "inherit",
},
}}
>
<MenuItem value={undefined}>(none)</MenuItem>
{props.cameras.map((e, i) => (
<MenuItem key={i} value={i}>
{e.shortName}
</MenuItem>
))}
</Select>
);
return props.renderCamera(
props.cameraIndex === null ? null : props.cameras[props.cameraIndex],
chooser
);
};
export default Multiview;