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// @flow
import * as React from 'react';
const CLICK_TIMEOUT = 1000;
const MOVE_THRESHOLD = 10;
export type SwitchProps = {
className?: string,
isOn: boolean,
onChange: ?(isOn: boolean) => void,
};
type State = {
ignoreChange: boolean,
initialPos: { x: number, y: number },
startTime: ?number,
};
export default class Switch extends React.Component<SwitchProps, State> {
static defaultProps: SwitchProps = {
isOn: false,
onChange: null,
};
state = {
ignoreChange: false,
initialPos: { x: 0, y: 0 },
startTime: (null: ?number),
};
isCapturingMouseEvents = false;
ref: ?HTMLInputElement;
onRef = (e: ?HTMLInputElement) => (this.ref = e);
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() {
// eslint-disable-next-line no-unused-vars
const { isOn, onChange, ...otherProps } = this.props;
const 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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