canvas缩放图片

最新推荐文章于 2026-01-08 23:29:03 发布

原创最新推荐文章于 2026-01-08 23:29:03 发布 · 197 阅读

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#javascript #前端 #vue

上菜！

/**
 *
 * @param {string} source 图片资源
 * @param {number} scale 缩放倍率 0-1
 * @param {string} responseType base64,blob
 * @returns {Promise<string||File>}
 */
export const zipImage=(source,scale=0.5,responseType='base64')=>{
	return new Promise((resolve, reject) => {
		try {
			const img = new Image()
			img.src = source
			img.onload =function () {

				const canvas = document.createElement("canvas");
				const ctx = canvas.getContext('2d');
				const radio = img.width/img.height;
				canvas.width = img.width * scale;
				canvas.height = img.width * scale*radio;
				ctx.drawImage(this, 0, 0, canvas.width, canvas.height)

				responseType ==='base64'&&resolve(canvas.toDataURL('png', 1))
				if (responseType === 'blob') {
					canvas.toBlob((v)=>{
						resolve(v)
					},'png',1)
				}
			}
		}catch (e){
			reject(e)
		}
	})

}

const src = "data img src"

// 返回base64
zipImage(src,0.5,'base64').then(base64=>{
	console.log(base64)
})

// 返回 File对象
zipImage(src,0.5,'blob').then(file=>{
	console.log(file)
})