splineui.js

// Copyright 2018 Raph Levien

// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! UI for drawing splines

/// Fancy name for something that just detects double clicks, but might expand.
class GestureDet {
	constructor(ui) {
		this.ui = ui;
		this.lastEv = null;
		this.lastPt = null;
		this.clickCount = 0;
	}

	onPointerDown(ev) {
		let dblClickThreshold = 550; // ms
		let radiusThreshold = 5;
		let pt = this.ui.getCoords(ev);
		if (this.lastEv !== null) {
			if (ev.timeStamp - this.lastEv.timeStamp > dblClickThreshold
				|| Math.hypot(pt.x - this.lastPt.x, pt.y - this.lastPt.y) > radiusThreshold) {
				this.clickCount = 0;
			}
		}
		this.lastEv = ev;
		this.lastPt = pt;
		this.clickCount++;
	}
}

// Dimensions of the tangent target
// Inside this radius, convert to corner point
let tanR1 = 5;
// Radius of drawn tangent marker
let tanR2 = 15;
// Outside this radius, remove explicit tangent
let tanR3 = 45;

/// State and UI for an editable spline
class SplineEdit {
	constructor(ui) {
		this.ui = ui;
		this.knots = [];
		this.isClosed = false;
		this.bezpath = new BezPath;
		this.selection = new Set();
		this.mode = "start";
		this.grid = 20;
		this.shiftOnDrag = false;
	}

	renderGrid(visible) {
		let grid = document.getElementById("grid");
		this.ui.removeAllChildren(grid);
		if (!visible) return;
		let w = 640;
		let h = 480;
		for (let i = 0; i < w; i += this.grid) {
			let line = this.ui.createSvgElement("line");
			line.setAttribute("x1", i);
			line.setAttribute("y1", 0);
			line.setAttribute("x2", i);
			line.setAttribute("y2", h);
			grid.appendChild(line);
		}
		for (let i = 0; i < h; i += this.grid) {
			let line = this.ui.createSvgElement("line");
			line.setAttribute("x1", 0);
			line.setAttribute("y1", i);
			line.setAttribute("x2", w);
			line.setAttribute("y2", i);
			grid.appendChild(line);
		}
	}

	setSelection(sel) {
		this.selection = sel;
	}

	roundToGrid(pt) {
		let g = this.grid;
		return new Vec2(g * Math.round(pt.x / g), g * Math.round(pt.y / g));
	}

	onPointerDown(ev, obj) {
		let pt = this.ui.getCoords(ev);
		if (obj === null) {
			let subdivideDist = 5;
			if (ev.shiftKey) {
				pt = this.roundToGrid(pt);
			}
			let ty = ev.altKey ? "smooth" : "corner";
			let hit = this.bezpath.hitTest(pt.x, pt.y);
			let insIx = this.knots.length;
			if (hit.bestDist < subdivideDist) {
				ty = "smooth";
				insIx = hit.bestMark + 1;
			}
			let knot = new Knot(this, pt.x, pt.y, ty);
			this.knots.splice(insIx, 0, knot);
			this.ui.attachReceiver(knot.handleEl, this, knot);
			// TODO: setter rather than state change?
			this.ui.receiver = this;
			this.setSelection(new Set([knot]));
			if (ty === "corner") {
				this.mode = "creating";
			} else {
				this.mode = "dragging";
			}
			this.initPt = pt;
		} else if (obj instanceof TanHandle) {
			this.mode = "tanhandle";
			this.isRight = obj.isRight;
			// This suggests maybe we should use selected point, not initPt
			this.initPt = new Vec2(obj.knot.x, obj.knot.y);
			this.updateTan(obj.knot, pt, ev);
			this.setSelection(new Set([obj.knot]));
		} else {
			if (this.selection.size == 1
				&& this.selection.has(this.knots[this.knots.length - 1])
				&& this.knots.length >= 3
				&& obj === this.knots[0])
			{
				this.isClosed = true;
			}
			this.mode = "dragging";
			if (this.ui.gestureDet.clickCount > 1) {
				if (obj.ty === "corner") {
					obj.setTy("smooth");
				} else {
					obj.setTy("corner");
				}
				obj.setTan(null);
			}
			let sel;
			this.shiftOnDrag = ev.shiftKey;
			if (ev.shiftKey) {
				// toggle point selection
				sel = new Set(this.selection);
				if (sel.has(obj)) {
					sel.delete(obj);
				} else {
					sel.add(obj);
				}
			} else {
				if (this.selection.has(obj)) {
					sel = this.selection;
				} else {
					sel = new Set([obj]);
				}
			}
			this.setSelection(sel);
		}
		this.render();
		this.lastPt = pt;
	}

	onPointerMove(ev) {
		let pt = this.ui.getCoords(ev);
		let dx = pt.x - this.lastPt.x;
		let dy = pt.y - this.lastPt.y;
		if (this.mode === "dragging") {
			for (let knot of this.selection) {
				if (ev.shiftKey && !this.shiftOnDrag && this.selection.size == 1) {
					pt = this.roundToGrid(pt);
					knot.updatePos(pt.x, pt.y);
				} else {
					knot.updatePos(knot.x + dx, knot.y + dy);
				}
			}
		} else if (this.mode === "creating") {
			let r = Math.hypot(pt.x - this.initPt.x, pt.y - this.initPt.y);
			let ty = r < tanR1 ? "corner" : "smooth";
			for (let knot of this.selection) {
				knot.setTy(ty);
			}
		} else if (this.mode === "tanhandle") {
			let r = Math.hypot(pt.x - this.initPt.x, pt.y - this.initPt.y);
			for (let knot of this.selection) {
				this.updateTan(knot, pt, ev);
			}
		}
		this.render();
		this.lastPt = pt;
	}

	onPointerUp(ev) {
		this.mode = "start";
		this.render();
	}

	onPointerHover(ev) {
		let pt = this.ui.getCoords(ev);
		// TODO: hover the knots and the visible tangent handles
		let hit = this.bezpath.hitTest(pt.x, pt.y);
		// TODO: display proposed knot
	}

	onKeyDown(ev) {
		if (ev.key === "Backspace" || ev.key === "Delete") {
			this.delete();
			return true;
		} else if (ev.key === "ArrowLeft") {
			this.nudge(-1, 0, ev);
			return true;
		} else if (ev.key === "ArrowRight") {
			this.nudge(1, 0, ev);
			return true;
		} else if (ev.key === "ArrowUp") {
			this.nudge(0, -1, ev);
			return true;
		} else if (ev.key === "ArrowDown") {
			this.nudge(0, 1, ev);
			return true;
		}
		return false;
	}

	delete() {
		for (let i = 0; i < this.knots.length; i++) {
			let knot = this.knots[i];
			if (this.selection.has(knot)) {
				this.knots.splice(i, 1);
				knot.handleEl.remove();
				i--;
			}
		}
		if (this.knots.length < 3) {
			this.isClosed = false;
		}
		this.selection = new Set();
		this.render();
	}


	nudge(dx, dy, ev) {
		if (ev && ev.shiftKey) {
			dx *= 10;
			dy *= 10;
		}
		for (let knot of this.selection) {
			knot.updatePos(knot.x + dx, knot.y + dy);
		}
		this.render();
	}

	updateTan(knot, pt, ev) {
		let dx = pt.x - this.initPt.x;
		let dy = pt.y - this.initPt.y;
		if (!this.isRight) {
			dx = -dx;
			dy = -dy;
		}
		let r = Math.hypot(dx, dy);
		let th = null;
		if (r < tanR3) {
			th = Math.atan2(dy, dx);
			if (ev.shiftKey) {
				th = Math.PI / 2 * Math.round(th * (2 / Math.PI));
			}
		}
		knot.setTan(th, this.isRight);
	}

	renderSpline() {
		let ctrlPts = [];
		for (let knot of this.knots) {
			let pt = new ControlPoint(new Vec2(knot.x, knot.y), knot.ty, knot.lth, knot.rth);
			ctrlPts.push(pt);
		}
		this.spline = new Spline(ctrlPts, this.isClosed);
		this.spline.solve();
		// Should this be bundled into solve?
		this.spline.computeCurvatureBlending();
		this.bezpath = this.spline.render();
		let path = this.bezpath.renderSvg();
		document.getElementById("spline").setAttribute("d", path);
	}

	renderSel() {
		for (let i = 0; i < this.knots.length; i++) {
			let knot = this.knots[i];
			knot.computedLTh = this.spline.pt(i, 0).lTh;
			knot.computedRTh = this.spline.pt(i, 0).rTh;
			knot.updateSelDecoration(this.selection.has(knot), this.mode);
		}
	}

	render() {
		this.renderSpline();
		this.renderSel();
	}

	/// Return a JSON object (suitable for stringify)
	serialize() {
		function r(x, adj) {
			return Math.round(x * adj) / adj;
		}
		let pts = [];
		for (let knot of this.knots) {
			let pt = {"x": r(knot.x, 100), "y": r(knot.y, 100)};
			if (knot.ty === "corner") {
				pt["c"] = 0;
				if (knot.lth !== null) {
					pt["l"] = r(knot.lth, 1000);
				}
				if (knot.rth !== null) {
					pt["r"] = r(knot.rth, 1000);
				}
			} else {
				pt["c"] = 1;
				if (knot.lth !== null) {
					pt["t"] = r(knot.lth, 1000);
				}
			}
			pts.push(pt);
		}
		let sp = {"closed": this.isClosed, "pts": pts};
		let result = {"subpaths": [sp]};
		return result;
	}


	/// Take either a JSON object or a string, and set UI state to it
	deserialize(data) {
		if (typeof data === 'string') {
			data = JSON.parse(data);
		}
		let sp = data.subpaths[0];
		let knots = [];
		for (let pt of sp.pts) {
			let ty = pt.c ? "smooth" : "corner";
			let knot = new Knot(this, pt.x, pt.y, ty);
			if (pt.c) {
				if ("t" in pt) {
					knot.lth = pt.t;
					knot.rth = knot.lth;
				}
			} else {
				if ("l" in pt) {
					knot.lth = pt.l;
				}
				if ("r" in pt) {
					knot.lth = pt.r;
				}
			}
			knots.push(knot);
		}
		// Hopefully for invalid data an exception would have occurred by here.

		for (let knot of this.knots) {
			knot.handleEl.remove();
		}
		this.knots = knots;
		for (let knot of knots) {
			this.ui.attachReceiver(knot.handleEl, this, knot);
		}
		this.isClosed = sp.closed;
		console.log(sp.closed);
		this.selection = new Set();
		this.render();
	}
}

class Knot {
	/// ty is one of 'corner', 'smooth'.
	constructor(se, x, y, ty) {
		this.se = se;
		this.x = x;
		this.y = y;
		this.ty = ty;
		this.lth = null;
		this.rth = null;
		this.selected = false;
		this.lthLine = null;
		this.rthLine = null;
		this.lthCircle = null;
		this.rthCircle = null;

		this.handleEl = this.createHandleEl();
	}

	createHandleEl() {
		let handle = this.se.ui.createSvgElement("g", true);
		handle.setAttribute("class", "handle");
		handle.setAttribute("transform", `translate(${this.x} ${this.y})`);
		// TODO: handles group should probably be variable in ui
		document.getElementById("handles").appendChild(handle);
		let inner = this.renderHandleEl();
		handle.appendChild(inner);
		return handle;
	}

	renderHandleEl() {
		let r = 4;
		let inner;
		if (this.ty === "corner") {
			inner = this.se.ui.createSvgElement("rect", true);
			inner.setAttribute("x", -r);
			inner.setAttribute("y", -r);
			inner.setAttribute("width", r * 2);
			inner.setAttribute("height", r * 2);
		} else {
			inner = this.se.ui.createSvgElement("circle", true);
			inner.setAttribute("cx", 0);
			inner.setAttribute("cy", 0);
			inner.setAttribute("r", r);
		}
		inner.setAttribute("class", "handle");
		return inner;			
	}

	setTan(th, isRight) {
		if (this.ty === "smooth" || !isRight) {
			this.lth = th;
		}
		if (this.ty === "smooth" || isRight) {
			this.rth = th;
		}
	}

	updateSelLine(th, el, r) {
		if (th === null && el !== null) {
			el.remove();
			el = null;
		} else if (th !== null && el === null) {
			el = this.se.ui.createSvgElement("line");
			el.setAttribute("x1", 0);
			el.setAttribute("y1", 0);
			el.setAttribute("class", "tan");
			this.handleEl.appendChild(el);
		}
		if (el !== null) {
			el.setAttribute("x2", r * Math.cos(th));
			el.setAttribute("y2", r * Math.sin(th));
		}
		return el;
	}

	updateSelCircle(th, el, r, computed) {
		if (th === null && el !== null) {
			el.remove();
			el = null;
		} else if (th !== null && el === null) {
			el = this.se.ui.createSvgElement("circle", true);
			el.setAttribute("r", 3);
			el.setAttribute("class", "tanhandle");
			this.handleEl.appendChild(el);
			let tanHandle = new TanHandle(this, r > 0);
			// To be more object oriented, receiver might be the knot or tanHandle. Ah well.
			this.se.ui.attachReceiver(el, this.se, tanHandle);
		}
		if (el !== null) {
			if (computed) {
				el.classList.add("computed");
			} else {
				el.classList.remove("computed");
			}
			el.setAttribute("cx", r * Math.cos(th));
			el.setAttribute("cy", r * Math.sin(th));
		}
		return el;
	}

	updateSelDecoration(selected, mode) {
		if (!selected && this.selected) {
			this.handleEl.classList.remove("selected");
		} else if (selected && !this.selected) {
			this.handleEl.classList.add("selected");
		}
		let lComputed = this.lth === null;
		let rComputed = this.rth === null;
		let drawCirc = selected && (mode !== "creating" && mode !== "dragging");
		let drawLTan = !lComputed || drawCirc;
		let drawRTan = !rComputed || drawCirc;
		let lth = null;
		if (drawLTan && this.lth != null) {
			lth = this.lth;
		} else if (drawLTan && this.computedLTh !== undefined) {
			lth = this.computedLTh;
		}
		let rth = null;
		if (drawRTan && this.rth != null) {
			rth = this.rth;
		} else if (drawRTan && this.computedRTh !== undefined) {
			rth = this.computedRTh;
		}
		this.rthLine = this.updateSelLine(rth, this.rthLine, tanR2 - 3);
		this.lthLine = this.updateSelLine(lth, this.lthLine, -tanR2 + 3);
		if (!drawCirc) {
			lth = null;
			rth = null;
		}
		this.lthCircle = this.updateSelCircle(lth, this.lthCircle, -tanR2, lComputed);
		this.rthCircle = this.updateSelCircle(rth, this.rthCircle, tanR2, rComputed);
		this.selected = selected;
	}

	setTy(ty) {
		if (ty !== this.ty) {
			this.ty = ty;
			let oldHandle = this.handleEl.querySelector(".handle");
			this.handleEl.replaceChild(this.renderHandleEl(), oldHandle);
		}
	}

	updatePos(x, y) {
		this.x = x;
		this.y = y;
		this.handleEl.setAttribute("transform", `translate(${x} ${y})`);
	}
}

class TanHandle {
	constructor(knot, isRight) {
		this.knot = knot;
		this.isRight = isRight;
	}
}

// TODO: create UI base class rather than cutting and pasting.
class Ui {
	constructor() {
		this.svgNS = "http://www.w3.org/2000/svg";
		this.setupHandlers();
		this.controlPts = [];
		this.se = new SplineEdit(this);
		this.gestureDet = new GestureDet(this);
		this.showGrid = true;
		this.se.renderGrid(this.showGrid);
		this.setupDialogs();
		this.keyHandlerActive = true;
	}

	setupHandlers() {
		let svg = document.getElementById("s");

		if ("PointerEvent" in window) {
			svg.addEventListener("pointermove", e => this.pointerMove(e));
			svg.addEventListener("pointerup", e => this.pointerUp(e));
			svg.addEventListener("pointerdown", e => this.pointerDown(e));
		} else {
			// Fallback for ancient browsers
			svg.addEventListener("mousemove", e => this.mouseMove(e));
			svg.addEventListener("mouseup", e => this.mouseUp(e));
			svg.addEventListener("mousedown", e => this.mouseDown(e));
			// TODO: add touch handlers
		}
		window.addEventListener("keydown", e => this.keyDown(e));
		this.mousehandler = null;
		this.receiver = null;
	}

	attachHandler(element, handler) {
		let svg = document.getElementById("s");
		if ("PointerEvent" in window) {
			element.addEventListener("pointerdown", e => {
				svg.setPointerCapture(e.pointerId);
				this.mousehandler = handler;
				e.preventDefault();
				e.stopPropagation();
			});
		} else {
			element.addEventListener("mousedown", e => {
				this.mousehandler = handler;
				e.preventDefault();
				e.stopPropagation();
			});
			// TODO: add touch handlers
		}
	}

	/// This is the pattern for the new object-y style.

	// Maybe just rely on closures to capture obj?
	attachReceiver(element, receiver, obj) {
		let svg = document.getElementById("s");
		if ("PointerEvent" in window) {
			element.addEventListener("pointerdown", e => {
				this.gestureDet.onPointerDown(e);
				svg.setPointerCapture(e.pointerId);
				this.receiver = receiver;
				receiver.onPointerDown(e, obj);
				e.preventDefault();
				e.stopPropagation();
			});
		} else {
			element.addEventListener("mousedown", e => {
				this.gestureDet.onPointerDown(e);
				this.receiver = receiver;
				receiver.onPointerDown(e, obj);
				e.preventDefault();
				e.stopPropagation();
			});
			// TODO: add touch handlers
		}
	}

	pointerDownCommon(e) {
		this.gestureDet.onPointerDown(e);
		this.se.onPointerDown(e, null);
		e.preventDefault();
	}

	pointerDown(e) {
		let svg = document.getElementById("s");
		svg.setPointerCapture(e.pointerId);
		this.pointerDownCommon(e);
	}

	mouseDown(e) {
		this.pointerDownCommon(e);
	}

	pointerMove(e) {
		if (this.receiver !== null) {
			this.receiver.onPointerMove(e);
		} else if (this.mousehandler !== null) {
			this.mousehandler(e);
		} else {
			this.se.onPointerHover(e);
		}
		e.preventDefault();
	}

	mouseMove(e) {
		this.pointerMove(e);
	}

	pointerUpCommon(e) {
		if (this.receiver !== null) {
			this.receiver.onPointerUp(e);
		}
		this.mousehandler = null;
		this.receiver = null;
		e.preventDefault();
	}

	pointerUp(e) {
		e.target.releasePointerCapture(e.pointerId);
		this.pointerUpCommon(e);
	}

	mouseUp(e) {
		this.pointerUpCommon(e);
	}

	keyDown(e) {
		// Maybe would be better to use focus instead of explicit logic...
		if (!this.keyHandlerActive) { return; }
		let handled = this.se.onKeyDown(e);
		if (handled) {
			e.preventDefault();
		}
	}

	// On Chrome, just offsetX, offsetY work, but on FF it takes the group transforms
	// into account. We always want coords relative to the SVG.
	getCoords(e) {
		let svg = document.getElementById("s");
		let rect = svg.getBoundingClientRect();
		let x = e.clientX - rect.left;
		let y = e.clientY - rect.top;
		return new Vec2(x, y);
	}

	createSvgElement(tagName, isRaw = false) {
		let element = document.createElementNS(this.svgNS, tagName);
		if (!isRaw) {
			element.setAttribute("pointer-events", "none");
		}
		return element;
	}

	resetPlots() {
		this.removeAllChildren(document.getElementById("plots"));
	}

	plotCircle(x, y, r = 2, color = "black", isRaw = false) {
		let circle = this.createSvgElement("circle", isRaw);
		circle.setAttribute("cx", x);
		circle.setAttribute("cy", y);
		circle.setAttribute("r", r);
		if (color !== null) {
			circle.setAttribute("fill", color);
		}
		document.getElementById("plots").appendChild(circle);
		return circle;
	}

	tangentMarker(x, y, th) {
		let len = 8;
		let dx = len * Math.cos(th);
		let dy = len * Math.sin(th);
		let line = this.createSvgElement("line");
		line.setAttribute("x1", x - dx);
		line.setAttribute("y1", y + dy);
		line.setAttribute("x2", x + dx);
		line.setAttribute("y2", y - dy);
		line.setAttribute("stroke", "green");
		document.getElementById("plots").appendChild(line);
	}

	redraw() {
		this.resetPlots();
		let path = "";
		let cmd = "M";
		for (let pt of this.controlPts) {
			path += `${cmd}${pt.x} ${pt.y}`;
			cmd = " L";
		}
		document.getElementById("ctrlpoly").setAttribute("d", path);

		let showMyCurve = true;
		let showBiParabola = true;
		let spline2Offset = 200;
		let nIter = 10;

		if (showMyCurve) {
			let spline = new TwoParamSpline(new MyCurve, this.controlPts);
			let ths = spline.initialThs();
			for (let i = 0; i < nIter; i++) {
				spline.iterDumb(i);
			}
			let splinePath = spline.renderSvg();
			document.getElementById("spline").setAttribute("d", splinePath);
		}

		if (showBiParabola) {
			let pts = [];
			for (let pt of this.controlPts) {
				pts.push(new Vec2(pt.x + spline2Offset, pt.y));
			}
			let spline2 = new TwoParamSpline(new BiParabola, pts);
			spline2.initialThs();
			for (let i = 0; i < nIter; i++) {
				let absErr = spline2.iterDumb(i);
				if (i == nIter - 1) {
					console.log(`biparabola err: ${absErr}`);
				}
			}
			let spline2Path = spline2.renderSvg();
			document.getElementById("spline2").setAttribute("d", spline2Path);
		}

		/*
		for (let i = 0; i < ths.length; i++) {
			let pt = this.controlPts[i]
			this.tangentMarker(pt.x, pt.y, -ths[i]);
		}
		*/
	}

	// TODO: extend so it can insert at an arbitrary location
	addPoint(x, y) {
		let ix = this.controlPts.length;
		this.controlPts.push(new Vec2(x, y));

		let handle = this.createSvgElement("circle", true);
		handle.setAttribute("cx", x);
		handle.setAttribute("cy", y);
		handle.setAttribute("r", 4);
		handle.setAttribute("class", "handle");
		document.getElementById("handles").appendChild(handle);
		this.attachHandler(handle, e => {
			this.movePoint(handle, ix, e.offsetX, e.offsetY);
		});
		this.mousehandler = e => this.movePoint(handle, ix, e.offsetX, e.offsetY);
	}

	movePoint(handle, ix, x, y) {
		handle.setAttribute("cx", x);
		handle.setAttribute("cy", y);
		this.controlPts[ix] = new Vec2(x, y);
		this.redraw();
	}

	updateShowGrid(showGrid) {
		if (showGrid) {
			document.getElementById("show-grid-check").classList.remove("invisible");
		} else {
			document.getElementById("show-grid-check").classList.add("invisible");
		}
		this.se.renderGrid(showGrid);
		this.showGrid = showGrid;
	}

	addMenuHandler(id, handler) {
		document.getElementById(id).addEventListener("click", e => {
			handler(e);
			let el = e.target;
			while (el.nodeName != "UL") {
				el = el.parentNode;
			}
			// Hacks like this make me think we should just control the menu logic with
			// JS instead of trying to leverage CSS. Oh well, it works...
			el.classList.add("off");
			window.setTimeout(() => el.classList.remove("off"), 50);
		});
	}

	saveToJson() {
		document.getElementById("save-json-modal").style.display = "block";
		let jsonStr = JSON.stringify(this.se.serialize());
		let el = document.getElementById("save-json-content");
		this.removeAllChildren(el);
		el.appendChild(document.createTextNode(jsonStr));
	}

	/// This displays the load dialog, doesn't do the load action.
	loadFromJson() {
		document.getElementById("load-json-modal").style.display = "block";
		document.getElementById("load-text").focus();
		this.keyHandlerActive = false;
	}

	doLoadAction(data) {
		// TODO: error handling
		this.se.deserialize(data);
		document.getElementById("load-json-modal").style.display = "none";
		this.keyHandlerActive = true;
	}

	setupDialogs() {
		this.addMenuHandler("menu-save", e =>
			this.saveToJson());
		this.addMenuHandler("menu-load", e =>
			this.loadFromJson());
		this.addMenuHandler("menu-show-grid", e =>
			this.updateShowGrid(!this.showGrid));
		this.addMenuHandler("menu-delete", e =>
			this.se.delete());
		this.addMenuHandler("menu-help", e =>
			document.getElementById("help-modal").style.display = "block");

		document.getElementById("help-close").addEventListener("click", e =>
			document.getElementById("help-modal").style.display = "none");
		document.getElementById("save-json-close").addEventListener("click", e =>
			document.getElementById("save-json-modal").style.display = "none");
		document.getElementById("load-json-close").addEventListener("click", e => {
			document.getElementById("load-json-modal").style.display = "none";
			this.keyHandlerActive = true;
		});
		document.getElementById("load-button").addEventListener("click", e =>
			this.doLoadAction(document.getElementById("load-text").value));
	}

	removeAllChildren(el) {
		while (el.firstChild) {
			el.removeChild(el.firstChild);
		}
	}
}

let ui = new Ui();