纯血鸿蒙APP实战开发——图片选择和下载保存案例

async getFileAssetsFromType(){
  const photoSelectOptions = new picker.PhotoSelectOptions(); // 创建图库对象实例
  photoSelectOptions.MIMEType = picker.PhotoViewMIMETypes.IMAGE_TYPE; // 选择媒体文件类型为Image
  photoSelectOptions.maxSelectNumber = 2; // 选择媒体文件的最大数目
 }

  async getFileAssetsFromType(){  
    photoViewPicker.select(photoSelectOptions)
      .then((photoSelectResult) => { 
        this.uris = photoSelectResult.photoUris; // select返回的uri权限是只读权限，需要将uri写入全局变量@State中即可根据结果集中的uri进行读取文件数据操作。
      })
      .catch((err: BusinessError) => {
       console.info('Invoke photoViewPicker.select failed, code is ${err.code},message is ${err.message}');
      })
  }

http.createHttp()
  .request('https://gitee.com/openharmony/applications_app_samples/raw/master/code/Solutions/Shopping/OrangeShopping/feature/navigationHome/src/main/resources/base/media/product002.png',
    (error: BusinessError, data: http.HttpResponse) => {
      if (error) {
        promptAction.showToast({
          message: $r("app.string.photopickandsave_image_request_fail"),
          duration: 2000
        })
        return
      }
      this.transcodePixelMap(data);
      if (data.result instanceof ArrayBuffer) {
        this.imageBuffer = data.result as ArrayBuffer;
      }
    })

// 将ArrayBuffer类型的图片装换为PixelMap类型
transcodePixelMap(data: http.HttpResponse) {
  let code: http.ResponseCode | number = data.responseCode;
  if (ResponseCode.ResponseCode.OK === code) {
    let imageData: ArrayBuffer = data.result as ArrayBuffer;
    let imageSource: image.ImageSource = image.createImageSource(imageData);

    class tmp {
      height: number = 100;
      width: number = 100;
    };

    let options: Record<string, number | boolean | tmp> = {
      'alphaType': 0, // 透明度
      'editable': false, // 是否可编辑
      'pixelFormat': 3, // 像素格式
      'scaleMode': 1, // 缩略值
      'size': { height: 100, width: 100 }
    }; // 创建图片大小

    imageSource.createPixelMap(options).then((pixelMap: PixelMap) => {
      this.image = pixelMap;
      this.isShow = true
    });
  }
}

1.OpenHarmony开发基础
2.OpenHarmony北向开发环境搭建
3.鸿蒙南向开发环境的搭建
4.鸿蒙生态应用开发白皮书V2.0 & V3.0
5.鸿蒙开发面试真题（含参考答案） 
6.TypeScript入门学习手册
7.OpenHarmony 经典面试题(含参考答案)
8.OpenHarmony设备开发入门【最新版】
9.沉浸式剖析OpenHarmony源代码
10.系统定制指南
11.【OpenHarmony】Uboot 驱动加载流程
12.OpenHarmony构建系统--GN与子系统、部件、模块详解
13.ohos开机init启动流程
14.鸿蒙版性能优化指南
.......

     async saveImage(buffer: ArrayBuffer | string): Promise<void> {
       let context = getContext(this) as common.UIAbilityContext;
       let helper = photoAccessHelper.getPhotoAccessHelper(context);
       let uri = await helper.createAsset(photoAccessHelper.PhotoType.IMAGE, 'jpg');
       let file = await fs.open(uri, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
       await fs.write(file.fd, buffer);
       await fs.close(file.fd);
     }

     async pickerSave(buffer: ArrayBuffer | string): Promise<void> {
       const photoSaveOptions = new picker.PhotoSaveOptions(); // 创建文件管理器保存选项实例
       photoSaveOptions.newFileNames = ['PhotoViewPicker ' + new Date().getTime() + 'jpg'] // 保存文件名（可选）
       const photoViewPicker = new picker.PhotoViewPicker;
       photoViewPicker.save(photoSaveOptions)
         .then(async (photoSvaeResult) => {
           console.info('PhotoViewPicker.save successfully,photoSvaeResult uri:' + JSON.stringify(photoSvaeResult));
           let uri = photoSvaeResult[0];
           let file = await fs.open(uri, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
           await fs.write(file.fd, buffer);
           await fs.close(file.fd);
           promptAction.showToast({
             message: $r("app.string.photopickandsave_save_picture"),
             duration: 2000
           })
         })
     }

   picturemanage                                   // har类型
   |---src/main/ets/components
   |   |---SelectPictures.ets                      // 场景一：访问手机相册图片预览并选择 
   |   |---SaveNetWorkPictures.ets                 // 场景二：下载网络图片并保存到手机相册或用户选择的文件夹
   |   |---PictureManage.ets                       // 视图层-主页面，三个场景入口