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// @flow
import React, { Component } from 'react';
import type { Point2d } from '../types';
const CLICK_TIMEOUT = 1000;
const MOVE_THRESHOLD = 10;
export type SwitchProps = {
isOn: boolean;
onChange: ?((isOn: boolean) => void);
};
export default class Switch extends Component {
props: SwitchProps;
static defaultProps: SwitchProps = {
isOn: false,
onChange: null
}
isCapturingMouseEvents = false;
ref: ?HTMLInputElement;
onRef = (e: HTMLInputElement) => this.ref = e;
state = {
ignoreChange: false,
initialPos: ({x: 0, y: 0}: Point2d),
startTime: (null: ?number)
}
handleMouseDown = (e: MouseEvent) => {
const { clientX: x, clientY: y } = e;
this.startCapturingMouseEvents();
this.setState({
initialPos: { x, y },
startTime: e.timeStamp
});
}
handleMouseMove = (e: MouseEvent) => {
const inputElement = this.ref;
const { x: x0 } = this.state.initialPos;
const { clientX: x, clientY: y } = e;
const dx = Math.abs(x0 - x);
if(dx < MOVE_THRESHOLD) {
return;
}
const isOn = !!this.props.isOn;
let nextOn = isOn;
if(x < x0 && isOn) {
nextOn = false;
} else if(x > x0 && !isOn) {
nextOn = true;
}
if(isOn !== nextOn) {
this.setState({
initialPos: { x, y },
ignoreChange: true
});
if(inputElement) {
inputElement.checked = nextOn;
}
this.notify(nextOn);
}
}
handleMouseUp = () => {
this.stopCapturingMouseEvents();
}
handleChange = (e: Event) => {
const startTime = this.state.startTime;
const eventTarget: Object = e.target;
if(typeof(startTime) !== 'number') {
throw new Error('startTime must be a number.');
}
const dt = e.timeStamp - startTime;
if(this.state.ignoreChange) {
this.setState({ ignoreChange: false });
e.preventDefault();
} else if(dt > CLICK_TIMEOUT) {
e.preventDefault();
} else {
this.notify(eventTarget.checked);
}
}
notify(isOn: boolean) {
const onChange = this.props.onChange;
if(onChange) {
onChange(isOn);
}
}
startCapturingMouseEvents() {
if(this.isCapturingMouseEvents) {
throw new Error('startCapturingMouseEvents() is called out of order.');
}
document.addEventListener('mousemove', this.handleMouseMove);
document.addEventListener('mouseup', this.handleMouseUp);
this.isCapturingMouseEvents = true;
}
stopCapturingMouseEvents() {
if(!this.isCapturingMouseEvents) {
throw new Error('stopCapturingMouseEvents() is called out of order.');
}
document.removeEventListener('mousemove', this.handleMouseMove);
document.removeEventListener('mouseup', this.handleMouseUp);
this.isCapturingMouseEvents = false;
}
componentWillUnmount() {
// guard from abrupt programmatic unmount
if(this.isCapturingMouseEvents) {
this.stopCapturingMouseEvents();
}
}
render(): React.Element<*> {
const { isOn, onChange, ...otherProps } = this.props; // eslint-disable-line no-unused-vars
let className = ('switch' + ' ' + (otherProps.className || '')).trim();
return (
<input { ...otherProps }
type="checkbox"
ref={ this.onRef }
className={ className }
checked={ isOn }
onMouseDown={ this.handleMouseDown }
onChange={ this.handleChange } />
);
}
}
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