HarmonyOS 自定义相机怎样实现拍照，并且拿到照片 uri 并且转换成base

let base64Str = buffer.from(arrayBuffer).toString('base64')
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"requestPermissions": [ 
{ 
  "name": "ohos.permission.READ_IMAGEVIDEO", 
"reason": "$string:camera_reason", 
"usedScene": { 
  "when":"inuse" 
} 
}, 
{ 
  "name": "ohos.permission.WRITE_IMAGEVIDEO", 
"reason": "$string:camera_reason", 
"usedScene": { 
  "when":"inuse" 
} 
}, 
 
{ 
  "name": "ohos.permission.CAMERA", 
"reason": "$string:camera_reason", 
"usedScene": { 
  "when":"inuse" 
} 
}, 
{ 
  "name": "ohos.permission.INTERNET", 
"reason":  "$string:inter_reason", 
"usedScene": { 
  "when":"inuse" 
} 
}, 
],
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