非常的强大，但是国内的资源教程很少，最近想加个功能给元素添加辅助参考线（类似 ）。这样某个元素移动缩放都会根据其他元素有个参考，就行ps里面的功能一样。虽然类似的功能我其他的项目有单独实现过，但是我本着能懒就懒的原则，于是乎我google了一下，官方的bug里有提到，安利给大家。

首先下载这个文件到你的项目中，

然后你想import可以稍微加一句

export default initAligningGuidelines;

原文件（为了防止有一天上面文件链接失效，原谅我这么粗俗的贴出下面这么长的原代码，呃呃呃。。：）

function initAligningGuidelines(canvas) {	var ctx = canvas.getSelectionContext(),		aligningLineOffset = 5,		aligningLineMargin = 4,		aligningLineWidth = 1,		aligningLineColor = 'rgb(255,255,0)',		viewportTransform,		zoom = 1;	function drawVerticalLine(coords) {		drawLine(			coords.x + 0.5,			coords.y1 > coords.y2 ? coords.y2 : coords.y1,			coords.x + 0.5,			coords.y2 > coords.y1 ? coords.y2 : coords.y1);	}	function drawHorizontalLine(coords) {		drawLine(			coords.x1 > coords.x2 ? coords.x2 : coords.x1,			coords.y + 0.5,			coords.x2 > coords.x1 ? coords.x2 : coords.x1,			coords.y + 0.5);	}	function drawLine(x1, y1, x2, y2) {		ctx.save();		ctx.lineWidth = aligningLineWidth;		ctx.strokeStyle = aligningLineColor;		ctx.beginPath();		ctx.moveTo(((x1+viewportTransform[4])*zoom), ((y1+viewportTransform[5])*zoom));		ctx.lineTo(((x2+viewportTransform[4])*zoom), ((y2+viewportTransform[5])*zoom));		ctx.stroke();		ctx.restore();	}	function isInRange(value1, value2) {		value1 = Math.round(value1);		value2 = Math.round(value2);		for (var i = value1 - aligningLineMargin, len = value1 + aligningLineMargin; i <= len; i++) {			if (i === value2) {				return true;			}		}		return false;	}	var verticalLines = [],		horizontalLines = [];	canvas.on('mouse:down', function () {		viewportTransform = canvas.viewportTransform;		zoom = canvas.getZoom();	});	canvas.on('object:moving', function(e) {		var activeObject = e.target,			canvasObjects = canvas.getObjects(),			activeObjectCenter = activeObject.getCenterPoint(),			activeObjectLeft = activeObjectCenter.x,			activeObjectTop = activeObjectCenter.y,			activeObjectBoundingRect = activeObject.getBoundingRect(),			activeObjectHeight = activeObjectBoundingRect.height / viewportTransform[3],			activeObjectWidth = activeObjectBoundingRect.width / viewportTransform[0],			horizontalInTheRange = false,			verticalInTheRange = false,			transform = canvas._currentTransform;		if (!transform) return;		// It should be trivial to DRY this up by encapsulating (repeating) creation of x1, x2, y1, and y2 into functions,		// but we're not doing it here for perf. reasons -- as this a function that's invoked on every mouse move		for (var i = canvasObjects.length; i--; ) {			if (canvasObjects[i] === activeObject) continue;			var objectCenter = canvasObjects[i].getCenterPoint(),				objectLeft = objectCenter.x,				objectTop = objectCenter.y,				objectBoundingRect = canvasObjects[i].getBoundingRect(),				objectHeight = objectBoundingRect.height / viewportTransform[3],				objectWidth = objectBoundingRect.width / viewportTransform[0];			// snap by the horizontal center line			if (isInRange(objectLeft, activeObjectLeft)) {				verticalInTheRange = true;				verticalLines.push({					x: objectLeft,					y1: (objectTop < activeObjectTop)						? (objectTop - objectHeight / 2 - aligningLineOffset)						: (objectTop + objectHeight / 2 + aligningLineOffset),					y2: (activeObjectTop > objectTop)						? (activeObjectTop + activeObjectHeight / 2 + aligningLineOffset)						: (activeObjectTop - activeObjectHeight / 2 - aligningLineOffset)				});				activeObject.setPositionByOrigin(new fabric.Point(objectLeft, activeObjectTop), 'center', 'center');			}			// snap by the left edge			if (isInRange(objectLeft - objectWidth / 2, activeObjectLeft - activeObjectWidth / 2)) {				verticalInTheRange = true;				verticalLines.push({					x: objectLeft - objectWidth / 2,					y1: (objectTop < activeObjectTop)						? (objectTop - objectHeight / 2 - aligningLineOffset)						: (objectTop + objectHeight / 2 + aligningLineOffset),					y2: (activeObjectTop > objectTop)						? (activeObjectTop + activeObjectHeight / 2 + aligningLineOffset)						: (activeObjectTop - activeObjectHeight / 2 - aligningLineOffset)				});				activeObject.setPositionByOrigin(new fabric.Point(objectLeft - objectWidth / 2 + activeObjectWidth / 2, activeObjectTop), 'center', 'center');			}			// snap by the right edge			if (isInRange(objectLeft + objectWidth / 2, activeObjectLeft + activeObjectWidth / 2)) {				verticalInTheRange = true;				verticalLines.push({					x: objectLeft + objectWidth / 2,					y1: (objectTop < activeObjectTop)						? (objectTop - objectHeight / 2 - aligningLineOffset)						: (objectTop + objectHeight / 2 + aligningLineOffset),					y2: (activeObjectTop > objectTop)						? (activeObjectTop + activeObjectHeight / 2 + aligningLineOffset)						: (activeObjectTop - activeObjectHeight / 2 - aligningLineOffset)				});				activeObject.setPositionByOrigin(new fabric.Point(objectLeft + objectWidth / 2 - activeObjectWidth / 2, activeObjectTop), 'center', 'center');			}			// snap by the vertical center line			if (isInRange(objectTop, activeObjectTop)) {				horizontalInTheRange = true;				horizontalLines.push({					y: objectTop,					x1: (objectLeft < activeObjectLeft)						? (objectLeft - objectWidth / 2 - aligningLineOffset)						: (objectLeft + objectWidth / 2 + aligningLineOffset),					x2: (activeObjectLeft > objectLeft)						? (activeObjectLeft + activeObjectWidth / 2 + aligningLineOffset)						: (activeObjectLeft - activeObjectWidth / 2 - aligningLineOffset)				});				activeObject.setPositionByOrigin(new fabric.Point(activeObjectLeft, objectTop), 'center', 'center');			}			// snap by the top edge			if (isInRange(objectTop - objectHeight / 2, activeObjectTop - activeObjectHeight / 2)) {				horizontalInTheRange = true;				horizontalLines.push({					y: objectTop - objectHeight / 2,					x1: (objectLeft < activeObjectLeft)						? (objectLeft - objectWidth / 2 - aligningLineOffset)						: (objectLeft + objectWidth / 2 + aligningLineOffset),					x2: (activeObjectLeft > objectLeft)						? (activeObjectLeft + activeObjectWidth / 2 + aligningLineOffset)						: (activeObjectLeft - activeObjectWidth / 2 - aligningLineOffset)				});				activeObject.setPositionByOrigin(new fabric.Point(activeObjectLeft, objectTop - objectHeight / 2 + activeObjectHeight / 2), 'center', 'center');			}			// snap by the bottom edge			if (isInRange(objectTop + objectHeight / 2, activeObjectTop + activeObjectHeight / 2)) {				horizontalInTheRange = true;				horizontalLines.push({					y: objectTop + objectHeight / 2,					x1: (objectLeft < activeObjectLeft)						? (objectLeft - objectWidth / 2 - aligningLineOffset)						: (objectLeft + objectWidth / 2 + aligningLineOffset),					x2: (activeObjectLeft > objectLeft)						? (activeObjectLeft + activeObjectWidth / 2 + aligningLineOffset)						: (activeObjectLeft - activeObjectWidth / 2 - aligningLineOffset)				});				activeObject.setPositionByOrigin(new fabric.Point(activeObjectLeft, objectTop + objectHeight / 2 - activeObjectHeight / 2), 'center', 'center');			}		}		if (!horizontalInTheRange) {			horizontalLines.length = 0;		}		if (!verticalInTheRange) {			verticalLines.length = 0;		}	});	canvas.on('before:render', function() {		canvas.clearContext(canvas.contextTop);	});	canvas.on('after:render', function() {		for (var i = verticalLines.length; i--; ) {			drawVerticalLine(verticalLines[i]);		}		for (var i = horizontalLines.length; i--; ) {			drawHorizontalLine(horizontalLines[i]);		}		verticalLines.length = horizontalLines.length = 0;	});	canvas.on('mouse:up', function() {		verticalLines.length = horizontalLines.length = 0;		canvas.renderAll();	});}export default initAligningGuidelines;

引入这个js，然后

import initAligningGuidelines from '@/libs/guidelines.js';	let canvas = new fabric.Canvas('canvas');	initAligningGuidelines(canvas)

然后

看到没各位。。。一根黄色的辅助线就有了，辅助线的颜色,宽度等都可以调节，具体看代码aligningLineColor 等变量。

有个有趣的事情说一下：这个竟然价值美元。Google一下，迎娶白富美靠你了。 我下一篇会写一下有关添加背景表格的方法，如上图的表格。最近一直在用Fabricjs做相关项目，如果有Fabricjs的问题的小伙伴，可以留下你的问题，我们一起探讨。么么哒。：）