🍳 Zoom

🍳 and 🔍. Space + drag to pan, Z to zoom, and shift + Z to reset
当前为 2020-07-28 提交的版本，查看最新版本。
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// ==UserScript==
// @name        🍳 Zoom
// @namespace   https://gf.qytechs.cn/users/281093
// @match       https://sketchful.io/
// @grant       none
// @version     1.0
// @author      Bell
// @description 🍳 and 🔍. Space + drag to pan, Z to zoom, and shift + Z to reset
// @run-at      document-end
// ==/UserScript==

const canvas = document.querySelector("#canvas");
const zoomContainer = document.createElement("div");
const sheet = window.document.styleSheets[window.document.styleSheets.length - 1];
const resetObserver = new MutationObserver(resetCanvas);

let panning = false;
let startPos = {};
let canvasOffset = {};
let cursor = "default";
let zoomed = false;

(function init() {
	canvas.style.position = "relative";
	canvas.style.transition = "transform 0.1s ease";
	zoomContainer.style.overflow = "hidden";
  	zoomContainer.id = "zoomContainer";
	sheet.insertRule(".dark #zoomContainer { background: #2C2F33}");
	sheet.insertRule("#zoomContainer { background: #c8c8c8}")
  
  	wrap(canvas, zoomContainer);
	resetCanvas();
  
  	resetObserver.observe(document.querySelector("#gameSticky"), { childList: true });
	document.addEventListener("keydown", keyDown, false);
	document.addEventListener("keyup", stopPanning, false);
	canvas.addEventListener("pointerdown", getStartPos, true);
	canvas.addEventListener("pointermove", moveCanvas, true);
	document.addEventListener("pointerup", stopMoving, false);
})();

function wrap(toWrap, wrapper) {
    toWrap.parentNode.appendChild(wrapper);
    wrapper.appendChild(toWrap);
};

function stopPanning(e) {
  	if (e.code !== "Space" || !panning) return;
  	e.preventDefault();
  	canvas.style.cursor = cursor;
  	panning = false;
}

function keyDown(e) {
  	if (!isDrawing()) return;
  	switch (e.code) {
	case "Space":
		startPanning();
		e.preventDefault();
		break;
	case "KeyZ":
		if (e.ctrlKey) return;
		else if (e.shiftKey) {
		  	resetCanvas();
			e.stopImmediatePropagation();
		  	return;
		}
		toggleZoom();
		e.stopImmediatePropagation();
	}
}

function toggleZoom() {
  	canvas.style.transform = zoomed ? "": "scale(2)";
	zoomed = !zoomed;
} 

function startPanning() {
  	if (panning) return;
	cursor = canvas.style.cursor;
	canvas.style.cursor = "grab";
	panning = true;
}

function moveCanvas(e) {
  	if (!panning || !e.buttons) return;
  	let offset = {};
  	offset.x = e.clientX - startPos.x;
  	offset.y = e.clientY - startPos.y;
  	canvas.style.left = `${(canvasOffset.x + offset.x)}px`;
  	canvas.style.top = `${(canvasOffset.y + offset.y)}px`;
    e.preventDefault();
  	e.stopImmediatePropagation();
}

function getStartPos(e) {
  	if (!panning) return;
	startPos.x = e.clientX;
	startPos.y = e.clientY;  
  	canvas.style.cursor = "grabbing";
    e.preventDefault();
    e.stopImmediatePropagation();
}

function stopMoving(e) {
  	canvasOffset.x = parseInt(canvas.style.left.match(/-?\d+/)[0]);
  	canvasOffset.y = parseInt(canvas.style.top.match(/-?\d+/)[0]);
  	if (panning) {
		canvas.style.cursor = "grab";
		e.stopImmediatePropagation();
	}
}

function resetCanvas() {
	canvas.style.left = "0px";
	canvas.style.top = "0px";
	canvas.style.transform = "";
	zoomed = false;
	canvasOffset = { x: 0, y: 0 };
}

function isDrawing() {
    return document.querySelector("#gameTools").style.display !== "none" &&
           document.querySelector("body > div.game").style.display !== "none" &&
           document.activeElement !== document.querySelector("#gameChatInput");
}
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