aida_front/src/component/Canvas/CanvasEditor/utils/objectHelper.js

import { fabric } from "fabric-with-all";

/**
 * 将序列化对象恢复为 fabric 对象
 * @param {Object} serializedObject - toObject() 生成的对象
 * @param {fabric.Canvas} canvas - 目标画布
 * @returns {Promise<fabric.Object>} 恢复的 fabric 对象
 */
export async function restoreFabricObject(serializedObject, canvas) {
	return new Promise((resolve, reject) => {
		const objectType = serializedObject.type;
		// 定义恢复后的处理函数
		const handleRestoredObject = (fabricObject) => {
			if (!fabricObject) {
				reject(new Error(`无法恢复 ${objectType} 类型的对象`));
				return;
			}
			// 恢复自定义属性
			if (serializedObject.id) fabricObject.id = serializedObject.id;
			if (serializedObject.layerId) fabricObject.layerId = serializedObject.layerId;
			if (serializedObject.layerName) fabricObject.layerName = serializedObject.layerName;

			// 更新坐标
			fabricObject.setCoords();

			// 添加到画布
			//   canvas.add(fabricObject);

			resolve(fabricObject);
		};

		// 根据类型选择恢复方法
		switch (objectType) {
			case "rect":
				fabric.Rect.fromObject(serializedObject, handleRestoredObject);
				break;
			case "circle":
				fabric.Circle.fromObject(serializedObject, handleRestoredObject);
				break;
			case "path":
				fabric.Path.fromObject(serializedObject, handleRestoredObject);
				break;
			case "image":
				fabric.Image.fromObject(serializedObject, handleRestoredObject);
				break;
			case "group":
				fabric.Group.fromObject(serializedObject, handleRestoredObject);
				break;
			default:
				// 使用通用方法
				fabric.util.enlivenObjects([serializedObject], (objects) => {
					if (objects && objects[0]) {
						handleRestoredObject(objects[0]);
					} else {
						reject(new Error("对象恢复失败"));
					}
				});
		}
	});
}

/**
 * 获取对象黑白通道画布
 * @param {fabric.Object} object - 要处理的 fabric 对象
 * @param {ImageData} revData - 相反的ImageData，白通道的相同位置是否为透明，revData为白色为透明，黑色为不透明
 * @param {number} diff - 差值，默认 25
 * @param {Object} rgba - 自定义 rgba 值，默认 { r: 255, g: 255, b: 255, a: 255 }
 * @returns {HTMLCanvasElement|null} 包含黑白通道的画布，或 null 如果失败
*/
export function getObjectAlphaToCanvas(object, revData, diff = 30, rgba = { r: 255, g: 255, b: 255, a: 255 }) {
	const image = object.getElement();
	const { width, height } = image;
	if (!width || !height) {
		console.warn("对象没有元素");
		return null;
	}
	const canvas = document.createElement("canvas");
	canvas.width = width;
	canvas.height = height;
	const ctx = canvas.getContext("2d");
	ctx.drawImage(image, 0, 0, width, height);
	const data = ctx.getImageData(0, 0, width, height);
	for (let i = 0; i < data.data.length; i += 4) {
		const r = data.data[i + 0];
		const g = data.data[i + 1];
		const b = data.data[i + 2];
		const a = data.data[i + 3];
		const revR = revData?.data[i + 0] || 0;
		const revG = revData?.data[i + 1] || 0;
		const revB = revData?.data[i + 2] || 0;
		const revA = revData?.data[i + 3] || 0;
		if (r || g || b || a) {
			if (revR > diff || revG > diff || revB > diff || revA > diff) {
				data.data[i + 0] = 0;
				data.data[i + 1] = 0;
				data.data[i + 2] = 0;
				data.data[i + 3] = 0;
			} else {
				data.data[i + 0] = rgba.r;
				data.data[i + 1] = rgba.g;
				data.data[i + 2] = rgba.b;
				data.data[i + 3] = rgba.a;
			}
		} else {
			data.data[i + 0] = 0;
			data.data[i + 1] = 0;
			data.data[i + 2] = 0;
			data.data[i + 3] = 0;
		}
	}
	ctx.clearRect(0, 0, width, height);
	ctx.putImageData(data, 0, 0);
	return canvas;
}