uniapp 图片相关（压缩、转base64）

// 压缩图片
export function compressImage(url,qa) {
  return new Promise((resolve, reject) => {
    const filenames = url.split('/')
    const name = "_doc/upload/" + filenames[filenames.length-1];
    plus.zip.compressImage(
      {
        src: url, //src: (String 类型 )压缩转换原始图片的路径
        dst: name, //压缩转换目标图片的路径
        quality: qa, //quality: (Number 类型 )压缩图片的质量.取值范围为1-100
        overwrite: true, //overwrite: (Boolean 类型 )覆盖生成新文件
      },
      function (zip) {
        //页面显示图片
        resolve(zip);
      },
      function (error) {
        reject(error);
      }
    );
  });
}

// 缩小图片
export function scaleimg(url,filename,width,height) {
  return new Promise((resolve, reject) => {
    const filenames = url.split('/')
    const name = "_doc/upload/" + filenames[filenames.length-1];
    plus.zip.compressImage(
      {
        src: url, //src: (String 类型 )压缩转换原始图片的路径
        dst: name, //压缩转换目标图片的路径
        overwrite: true, //overwrite: (Boolean 类型 )覆盖生成新文件
        width,
        height,
      },
      function (zip) {
        //页面显示图片
        resolve(zip);
      },
      function (error) {
        reject(error);
      }
    );
  });
}


// 转base64
export function toBase64(url) {
  return new Promise((resolve, reject) => {
    //根据路径读取到文件
    plus.io.resolveLocalFileSystemURL(url, function (entry) {
      entry.file(function (file) {
        let fileReader = new plus.io.FileReader();
        fileReader.readAsDataURL(file);
        fileReader.onloadend = function (e) {
            const picUrl = e.target.result.toString();
            resolve(picUrl);
        };
      });
    });
  });
}