export function base64ToBuffer(data: string) {
    //去掉url的头，并转换为byte
    const split = data.split(',');
    const bytes = window.atob(split[1]);
    //处理异常,将ascii码小于0的转换为大于0
    const ab = new ArrayBuffer(bytes.length);
    const ia = new Uint8Array(ab);
    for (let i = 0; i < bytes.length; i++) {
        ia[i] = bytes.charCodeAt(i);
    }
    const match = split[0].match(/^data:(.*);base64/)
    const contentType = match && match.length == 2 ? match[1] : ''
    //return new Blob([ab], {type: split[0]});
    return {
        buffer: [ab],
        contentType
    }
}

export function base64ToFile(data: string, fileName: string) {
    const _data = base64ToBuffer(data);
    return new File(_data.buffer, fileName, {type:_data.contentType})
}