uni-app 图片切割

// 	this.cropImageTListBase64(item.covers, 1)
							// 		.then((croppedBase64Img) => {
							// 			// 在这里处理切割后的图片的 base64 数据
							// 			this.List[index].covers = croppedBase64Img;
							// 			console.log(croppedBase64Img)
							// 		})
							// 		.catch((error) => {
							// 			console.log(33444)
							// 			// 处理错误情况
							// 			console.error(error);
							// 		});





cropImageTListBase64(url, ratio, startX = 0, startY = 0) {
				return new Promise((resolve, reject) => {
					const canvas = document.createElement('canvas');
					const ctx = canvas.getContext('2d');
					const img = new Image();
					img.crossOrigin = 'anonymous';
					img.onload = function() {
						const originalWidth = img.width;
						const originalHeight = img.height;
						const targetHeight = 1000; // 将目标高度改为 900
						const targetWidth = Math.round(targetHeight * ratio); // 根据比例计算目标宽度

						canvas.width = targetWidth;
						canvas.height = targetHeight;

						// 在画布上绘制网络图片的指定区域
						ctx.drawImage(
							img,
							startX,
							startY,
							originalWidth - startX,
							(originalWidth - startX) / ratio,
							0,
							0,
							targetWidth,
							targetHeight
						);

						try {
							const base64 = canvas.toDataURL('image/png');
							resolve(base64);
						} catch (error) {
							reject(error);
						}
					};

					img.onerror = function() {
						reject(new Error('Failed to load image'));
					};

					img.src = url;
				});
			},