Babylon.js/inspector/src/components/actionTabs/tabs/propertyGrids/animations/svgDraggableArea.tsx

import * as React from "react";
import { Vector2 } from 'babylonjs/Maths/math.vector';
import { KeyframeSvgPoint, IKeyframeSvgPoint } from './keyframeSvgPoint';

interface ISvgDraggableAreaProps {
    keyframeSvgPoints: IKeyframeSvgPoint[];
    updatePosition: (updatedKeyframe: IKeyframeSvgPoint, index: number) => void;
}

export class SvgDraggableArea extends React.Component<ISvgDraggableAreaProps>{

    private _active: boolean;
    private _isCurrentPointControl: string;
    private _currentPointIndex: number;
    private _draggableArea: React.RefObject<SVGSVGElement>;
    private _panStart: Vector2;
    private _panStop: Vector2;

    constructor(props: ISvgDraggableAreaProps) {
        super(props);
        this._currentPointIndex = -1;
        this._isCurrentPointControl = "";
        this._draggableArea = React.createRef();
        this._panStart = new Vector2(0, 0);
        this._panStop = new Vector2(0, 0);
    }

    componentDidMount() {
        this._draggableArea.current?.addEventListener("keydown", this.keyDown.bind(this));
        this._draggableArea.current?.addEventListener("keyup", this.keyUp.bind(this));
    }  

    dragStart(e: React.TouchEvent<SVGSVGElement>): void;
    dragStart(e: React.MouseEvent<SVGSVGElement, MouseEvent>): void;
    dragStart(e: any): void {
        e.preventDefault();
        if (e.target.classList.contains("draggable")) {
            this._active = true;
            this._currentPointIndex = parseInt(e.target.getAttribute('data-id'));

            if (e.target.classList.contains("control-point")) {
                this._isCurrentPointControl = e.target.getAttribute("type");
            }
        }

        if (e.target.classList.contains("pannable")) {
            if (e.buttons === 1 && e.ctrlKey) {
                this._panStart.set(e.clientX, e.clientY);
            }
        }
    }

    drag(e: React.TouchEvent<SVGSVGElement>): void;
    drag(e: React.MouseEvent<SVGSVGElement, MouseEvent>): void;
    drag(e: any): void {
        if (this._active) {

            e.preventDefault();

            var coord = this.getMousePosition(e);

            if (coord !== undefined) {

                var newPoints = [...this.props.keyframeSvgPoints];

                if (this._isCurrentPointControl === "left") {
                    newPoints[this._currentPointIndex].leftControlPoint = coord;
                } else if (this._isCurrentPointControl === "right") {
                    newPoints[this._currentPointIndex].rightControlPoint = coord;
                } else {
                    newPoints[this._currentPointIndex].keyframePoint = coord;
                }

                this.props.updatePosition(newPoints[this._currentPointIndex], this._currentPointIndex);

            }
        }
    }

    dragEnd(e: React.TouchEvent<SVGSVGElement>): void;
    dragEnd(e: React.MouseEvent<SVGSVGElement, MouseEvent>): void;
    dragEnd(e: any): void {
        e.preventDefault();
        this._active = false;
        this._currentPointIndex = -1;
        this._isCurrentPointControl = "";

        if (e.target.classList.contains("pannable")) {
            if (this._panStart.x !== 0 && this._panStart.y !== 0) {
                this._panStop.set(e.clientX, e.clientY);
                this.panDirection();
            }
        }
    }

    getMousePosition(e: React.TouchEvent<SVGSVGElement>): Vector2 | undefined;
    getMousePosition(e: React.MouseEvent<SVGSVGElement, MouseEvent>): Vector2 | undefined;
    getMousePosition(e: any): Vector2 | undefined {

        if (e.touches) { e = e.touches[0]; }

        if (this._draggableArea.current) {
            var svg = this._draggableArea.current as SVGSVGElement;
            var CTM = svg.getScreenCTM();
            if (CTM) {
                return new Vector2((e.clientX - CTM.e) / CTM.a, (e.clientY - CTM.f) / CTM.d);
            } else {
                return undefined;
            }
        } else {
            return undefined;
        }
    }

    panDirection() {

        // Movement Right to Left
        if (this._panStart.x > this._panStop.x) {
            console.log("right to left");
            this.panTo("right", Math.abs(this._panStart.x - this._panStop.x));
        }

        // Movement Right to Left
        if (this._panStart.x < this._panStop.x) {
            this.panTo("left", Math.abs(this._panStart.x - this._panStop.x));
            console.log("left to right");
        }

        // Movement Bottom to Up
        if (this._panStart.y > this._panStop.y) {
            console.log("down up");
        }

        // Movement Up to Bottom
        if (this._panStart.y < this._panStop.y) {
            console.log("up down");
        }

        this._panStart.set(0, 0);
        this._panStop.set(0, 0);

    }

    panTo(direction: string, value: number) {

        switch (direction) {
            case "left":
                (this._draggableArea.current?.parentElement as HTMLDivElement).scrollLeft -= (value * 1);
                break;
            case "right":
                (this._draggableArea.current?.parentElement as HTMLDivElement).scrollLeft += (value * 1);
                break;
            case "top":
                break;
            case "down":
                break;
        }
    }

    keyDown(e: KeyboardEvent) {
        e.preventDefault();
        if (e.keyCode === 17) {
            this._draggableArea.current?.style.setProperty("cursor", "grab");
        }
    }

    keyUp(e: KeyboardEvent) {
        e.preventDefault();
        if (e.keyCode === 17) {
            this._draggableArea.current?.style.setProperty("cursor", "initial");
        }
    }

    focus(e: React.MouseEvent<SVGSVGElement>) {
        e.preventDefault();
        this._draggableArea.current?.focus();
    }

    render() {
        return (
            <>
                <svg className="linear pannable" ref={this._draggableArea}  tabIndex={0}

                    onMouseMove={(e) => this.drag(e)}
                    onTouchMove={(e) => this.drag(e)}
                    onTouchStart={(e) => this.dragStart(e)}
                    onTouchEnd={(e) => this.dragEnd(e)}

                    onMouseDown={(e) => this.dragStart(e)}
                    onMouseUp={(e) => this.dragEnd(e)}
                    onMouseLeave={(e) => this.dragEnd(e)}
                    // Add way to add new keyframe
                    onClick={(e) => this.focus(e)}

                    viewBox="0 0 200 100">

                    {this.props.children}
                    {this.props.keyframeSvgPoints.map((keyframe, i) =>
                        <KeyframeSvgPoint key={i} id={i.toString()} keyframePoint={keyframe.keyframePoint} leftControlPoint={keyframe.leftControlPoint} rightControlPoint={keyframe.rightControlPoint} />
                    )}
                </svg>
            </>)
    }
}