【每日学点HarmonyOS Next知识】折叠屏状态判断、H5选择图片、组件刷新、点击图片放大缩小、界面无法更新问题

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1、HarmonyOS 折叠屏手机如何判断当前是展开还是折叠状态？

请参考API获取当前可折叠设备的折叠状态：developer.huawei.com/consumer/cn…

FoldStatus 当前可折叠设备的折叠状态枚举。

名称值说明
FOLD_STATUS_UNKNOWN0表示设备当前折叠状态未知。
FOLD_STATUS_EXPANDED1表示设备当前折叠状态为完全展开。
FOLD_STATUS_FOLDED2表示设备当前折叠状态为折叠。
FOLD_STATUS_HALF_FOLDED3表示设备当前折叠状态为半折叠。半折叠指完全展开和折叠之间的状态。

2、HarmonyOS H5页面选择图片可以从onShowFileSelector 监听到，但是H5页面选择视频的时候，从onShowFileSelector监听不到。请问是从别的方法中监听吗？

H5页面选择图片可以从onShowFileSelector 监听到，但是H5页面选择视频的时候，从onShowFileSelector监听不到。请问是从别的方法中监听吗？

H5页面选择视频的时候onShowFileSelector可以监听，参考如下文档和例子。

文档：developer.huawei.com/consumer/cn…

onShowFileSelector(callback: Callback<OnShowFileSelectorEvent, boolean>) 调用此函数以处理具有“文件”输入类型的HTML表单。如果不调用此函数或返回false，Web组件会提供默认的“选择文件”处理界面。如果返回true，应用可以自定义“选择文件”的响应行为。

例子：

@Entry
@Component
export struct WebComponent {
  controller: webview.WebviewController = new webview.WebviewController()

  build() {
    Column() {
      Web({ src: $rawfile('index.html'), controller: this.controller })
        .onShowFileSelector((event) => {
          if (event) {
            let photoSelectOptions = new photoAccessHelper.PhotoSelectOptions();
            let photoPicker = new photoAccessHelper.PhotoViewPicker();
            // 过滤选择媒体文件类型为IMAGE
            photoSelectOptions.MIMEType = photoAccessHelper.PhotoViewMIMETypes.IMAGE_VIDEO_TYPE;
            // 设置最大选择数量
            photoSelectOptions.maxSelectNumber = 5;
            // let chooseFile: picker.PhotoSelectResult = await photoPicker.select(photoSelectOptions);
            photoPicker.select(photoSelectOptions).then((res)=>{

              console.log('asd===',JSON.stringify(res.photoUris))

            }).catch((err:Error)=>{

            })
            console.log('res ===',JSON.stringify(event))
          }
          return true;
        })
    }
  }
}

3、HarmonyOS 点击图片放大缩小？

请问下有没有图片大图浏览的组件，可双击点击放大缩小。

当前并无相关组件可用于查看大图，具体实现方式可参考图库查看大图、左右切换浏览图片源码：gitee.com/openharmony…

或者参考如下代码：

1.Page页面：
// xxx.ets
import router from '@ohos.router'

@Entry
@Component
struct SharedTransitionExample {
  @State active: boolean = false
  @State imageNames: Resource[] = [$r('app.media.image1'), $r('app.media.image2'), $r('app.media.image3')]
  @StorageLink('currentIndex') currentIndex: number = 0

  build() {
    Row() {
      ForEach(this.imageNames, (res: Resource, index: number) => {
        Column() {
          Image(res)
            .width('100%')
            .height('100%')
            .objectFit(ImageFit.Contain) // 在组件上绑定缩放比例，可以通过修改缩放比例来实现组件的缩小或者放大
        }
        .width(100)
        .height(100)
        .clip(true)
        .sharedTransition('sharedImage' + res.id, {
          duration: 200,
          curve: Curve.Linear,
          zIndex: this.currentIndex === index ? 10 : -10
        })
        .onClick(() => {
          this.currentIndex = index
          router.pushUrl({ url: 'pages/Index', params: {
            data: this.imageNames,
          } })
        })
      })

    }.width('100%')
    .height('100%')
  }

  pageTransition() {
    PageTransitionEnter({ duration: 0, curve: Curve.Linear })
      .onEnter((type?: RouteType, progress?: number) => {

      }) // 进场过程中会逐帧触发onEnter回调，入参为动效的归一化进度(0% -- 100%)
    PageTransitionExit({ duration: 0, curve: Curve.Ease })
      .onExit((type?: RouteType, progress?: number) => {

      }) // 退场过程中会逐帧触发onExit回调，入参为动效的归一化进度(0% -- 100%)
  }
}
//2.Index页面
import window from '@ohos.window';
import router from '@ohos.router';

interface Data {
  data: Resource[];
}

enum Direction {
  None,
  Left,
  Right,
}

@Entry
@Component
struct Index {
  private swiperController: SwiperController = new SwiperController();
  @State imageNames: Resource[] = []
  @StorageLink('currentIndex') currentIndex: number = 0
  @State screenWidth: number = 0;
  @State op: number = 0

  aboutToAppear() {
    const data = (router.getParams() as Data)
    this.imageNames = data.data
    window.getLastWindow(getContext(this)).then(currentWindow => {

      let property = currentWindow.getWindowProperties();
      this.screenWidth = property.windowRect.width;
    })
  }

  build() {
    Stack({ alignContent: Alignment.Center }) {
      Swiper(this.swiperController) {
        ForEach(this.imageNames, (name: Resource, index: number) => {
          Column() {
            ImageComponent({
              image: name,
              viewWidth: this.screenWidth,
              isCurrent: this.currentIndex === index,
              onNeedGoNext: (dire: Direction) => {
                if (dire === Direction.Right) {
                  this.swiperController.showNext()
                } else if (dire === Direction.Left) {
                  this.swiperController.showPrevious()
                }
              }
            }).zIndex(index == this.currentIndex ? 2 : 1)
          }.width('100%')
          .height('100%')
          .justifyContent(FlexAlign.Center)
        })
      }
      .index(this.currentIndex)
      .indicator(false)
      .disableSwipe(true)
      .itemSpace(10)
      .onChange((index: number) => {
        this.currentIndex = index
      })
    }.width('100%').height('100%')
    .backgroundColor(`rgba(0,0,0,${this.op})`)
  }

  pageTransition() {
PageTransitionEnter({ duration: 200, curve: Curve.Linear })
.onEnter((type?: RouteType, progress?: number) => {
if (progress) {
this.op = progress
}

}) // 进场过程中会逐帧触发onEnter回调，入参为动效的归一化进度(0% -- 100
@Component
struct ImageComponent {
private image: Resource = $r('app.media.icon')
private preGeometryScale: number = 1
@State geometryScale: number = 1
private preOffsetX: number = 0
private preOffsetY: number = 0
@State geometryOffsetX: number = 0
@State geometryOffsetY: number = 0
@State imageWidth: number = 0
@State imageHeight: number = 0
@Prop viewWidth: number = 0
@Prop isCurrent: boolean = false
private dire: Direction = Direction.None
private goNext: boolean = true
private pinching: boolean = false
private onNeedGoNext: (dire: Direction) => void = () => {
}

  reset(): Promise<void> | undefined {
    this.preGeometryScale = 1
    this.preOffsetX = 0
    this.preOffsetY = 0
    this.dire = Direction.None
    this.goNext = true
    if (this.geometryScale === 1) return
    return new Promise<void>(res => {
      animateTo({ duration: 200, onFinish: res }, () => {
        this.geometryScale = 1
        this.geometryOffsetX = 0
        this.geometryOffsetY = 0
      })
    })
  }

  build() {
    Column() {
      Image(this.image)
        .onComplete((e) => {
          this.imageWidth = (e?.width || 0)
          this.imageHeight = (e?.height || 0)
        })
        .objectFit(ImageFit.Cover)
        .width(this.imageWidth + 'px')
        .height(this.imageHeight + 'px')
        .scale({
          x: this.geometryScale,
          y: this.geometryScale
        })
        .offset({
          x: this.geometryOffsetX,
          y: this.geometryOffsetY
        })
        .focusable(true)
        .objectFit(ImageFit.Cover)
        .autoResize(false)
        .sharedTransition('sharedImage' + this.image.id, {
          duration: 200,
          curve: Curve.Linear,
          zIndex: this.isCurrent ? 10 : -10
        })
    }
    .clip(true)
    .width('100%')
    .height('100%')
    .justifyContent(FlexAlign.Center)
    .hitTestBehavior(HitTestMode.Default)
    .parallelGesture( // 在组件上绑定二指触发的捏合手势
      GestureGroup(GestureMode.Parallel,
        PinchGesture({ fingers: 2 })
          .onActionStart((event: GestureEvent) => {
            this.pinching = true
            this.goNext = false
          })// 当捏合手势触发时，可以通过回调函数获取缩放比例，从而修改组件的缩放比例
          .onActionUpdate((event: GestureEvent) => {
            const s = this.preGeometryScale * event.scale;
            this.geometryScale = Math.max(0.6, Math.min(2, s))
          })
          .onActionEnd(async () => {
            this.preGeometryScale = this.geometryScale
            if (this.preGeometryScale < 1) {
              await this.reset()
            }
            this.pinching = false
          }),
        PanGesture()
          .onActionStart((event?: GestureEvent) => {
          })
          .onActionUpdate((event?: GestureEvent) => {
            let offsetX = this.preOffsetX + (event?.offsetX || 0)
            let offsetY = this.preOffsetY + (event?.offsetY || 0)
            if (((this.imageWidth * this.geometryScale - this.viewWidth) / 2 - Math.abs(vp2px(offsetX))) <= 0) {
              if (!this.pinching) {
                this.dire = offsetX < 0 ? Direction.Right : Direction.Left
              }
              return;
            }
            this.goNext = false
            this.geometryOffsetX = offsetX
            this.geometryOffsetY = offsetY
          })
          .onActionEnd((event?: GestureEvent) => {
            if ((this.dire !== Direction.None)) {
              if (this.goNext) {
                this.onNeedGoNext(this.dire)
                this.reset()
              }
              this.goNext = true
            }
            this.preOffsetX = this.geometryOffsetX
            this.preOffsetY = this.geometryOffsetY
          }),
      )
    )
  }
}

4、HarmonyOS 组件刷新问题？

struct MyFoldPage {
  @State filePaths: FolderModel[] = []
   build() {
      Column(){
            Grid() {
            ForEach(this.filePaths, (item: FolderModel, index: number) => {
              GridItem() {
                this.ItemBuilder(index)
              }
            }, (item: FolderModel) => item.fileName)
          }
         }
     }
}
export class FolderModel {
  filePath: string = ''
  fileName: string = ''
  isScreenshot: boolean = true
  thumbnailPath?: string = ''   //当文件是视频的时候，抓视频的缩略图pixelMap
  isSelect?: boolean = false
}

现在有个问题是修改了数组内部item类里面isSelect的值，整个列表不会自动刷新，必须要新new一个item并重新赋值给filepaths才能更新，有没有比较好的实现方式

请使用@Observed装饰器和@ObjectLink装饰器实现该场景，具体使用方法请参考文档。文档链接：developer.huawei.com/consumer/cn…

5、HarmonyOS 自定义组件，数据更新时，界面无法重新渲染？

@Component
export struct CardView {
  @State title: string | undefined = undefined
  @State moreText: string = '更多'

  @Builder
  tempBuilder() {
  };

  @BuilderParam contentBuilder: () => void = this.tempBuilder

  build() {
    this.contentBuilder()
  }
}

//组件被调用

@Component
export struct NoticeCardView {
  @State noticeList: Notice[] = []

  aboutToAppear(): void {
    new NoticeRepository().getNoticeList().then((result) => {
      this.noticeList = result
    })
  }

  @Builder
  ContentBuilder() {
    ForEach(this.noticeList, (notice: Notice) => {
      Row() {
        Image($r('app.media.wb_ic_notice_tip')).height(11).width(9)
        Text(notice.title)
          .margin({ left: 11 })
          .fontColor($r('app.color.cm_text_primary'))
          .fontSize('14fp')
          .maxLines(1)
          .textOverflow({ overflow: TextOverflow.Ellipsis })
      }.padding(8)
    })
  }

  build() {
    CardView({
      title: '',
      contentBuilder: this.ContentBuilder
    })
  }
}

自定义组件noticeList更新时，无法触发界面更新，无法渲染出列表展示

参考以下代码：

@Component
struct CardView  {
  @Prop header: string = '';
  @Builder tempBuilder(){}

  @BuilderParam contentBuilder: () => void = this.tempBuilder
  build() {
    Column() {
      this.contentBuilder()
    }
  }
}
@Entry
@Component
struct CustomContainerUser {
  @State text: string = 'header';
  @State list: string[] = []
  aboutToAppear(): void {
    this.list.push("1");
    this.list.push("2");
    this.list.push("3");
    console.log('&#25171;&#21360;&#19968;&#19979;',this.list)

  }
  build() {
    Column() {
      Text(this.text)
      CardView ({ header: this.text }) {
        Column() {
          this.ContentBuilder('testA', 'testB')
        }.backgroundColor(Color.Yellow)
      }
    }

  }
  @Builder  ContentBuilder(label1: string, label2: string) {
    Column() {
      Text('test')
      ForEach(this.list, (text: string) => {
        Text(text)
      })
    }
  }
}
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