一、學習筆記

HarmonyOS NEXT API 12

二、代碼實例

1、base64 格式圖片 轉 FilePath（文件路徑）

/**
 * base64Img 轉 FilePath
 * @param context
 * @param base64Str
 * @returns
 */
export async function base64ImgConvertFilePath(context: Context, base64Str: string): Promise<string | undefined> {
  try {
    const filePath = context.cacheDir + "/xxx_" + new Date().getTime() + '.png';

    let file = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
    const reg = new RegExp("data:image/\\w+;base64,")
    const base64 = base64Str.replace(reg, "");
    const dataBuffer = buffer.from(base64, 'base64').buffer;
    const size = fs.writeSync(file.fd, dataBuffer);
    //關閉文件
    fs.closeSync(file);
    return filePath
  } catch (error) {
    return undefined
  }
}

2、圖片uri 轉 base64 格式

export async function uriConvertBase64(uri: string): Promise<string> {

  let pixelMap = await uriOrPathConvertPixelMap(uri)
  if (pixelMap == undefined) {
    throw new Error(" uriConvertBase64 轉換失敗")
    return ''
  }
  const packOptions: image.PackingOption = {
    format: 'image/jpeg',
    quality: 99 // 圖片質量
  }
  let arrayBuffer = await image.createImagePacker().packing(pixelMap, packOptions)

  let base64Str = buffer.from(arrayBuffer).toString('base64')
  let resultBase64Str = "data:image/png;base64," + base64Str
  return resultBase64Str
}

3、圖片 pixMap 轉 base64 格式

export async function pixMapConvertBase64(pixelMap: image.PixelMap): Promise<string> {
 const packOptions: image.PackingOption = {
    format: 'image/jpeg',
    quality: 99 // 圖片質量
  }
  let arrayBuffer = await image.createImagePacker().packing(pixelMap, packOptions)
  let base64Str = buffer.from(arrayBuffer).toString('base64')
  let resultBase64Str = "data:image/png;base64," + base64Str
  return resultBase64Str
}

4、FilePath(文件路徑) 轉 uri

export async function filePathConvertUri(filePath:string): Promise<string | undefined>{

  try {
    let uri = fileUri.getUriFromPath(filePath)
    return uri
  } catch (err) {
    return undefined
  }
}

5、uri/filePath 轉 pixelMap

export async function uriOrPathConvertPixelMap(path:string): Promise<image.PixelMap|undefined>{
  try {
    let file = fs.openSync(path, fs.OpenMode.READ_ONLY)
    const imageSource: image.ImageSource = image.createImageSource(file.fd)
    fs.closeSync(file)
    let decodingOptions: image.DecodingOptions = {
      editable: true,
      desiredPixelFormat: 3,
    }
    let pixelMap = await imageSource.createPixelMap(decodingOptions)
    return pixelMap
  } catch (e) {
    return undefined
  }
}