HarmonyOS 如何实现可拖动、可停留的悬浮按钮

可以通过子窗口来实现，参考文档：https://developer.huawei.com/consumer/cn/doc/harmonyos-guides-V5/application-window-stage-V5#设置应用子窗口

EntryAbility.ets文件

onWindowStageCreate(windowStage: window.WindowStage) {
  // 将自定义数据变量“data”存入AppStorage
  AppStorage.setOrCreate('data', 1);
  AppStorage.setOrCreate('window', windowStage);
}

主窗口界面

//Index
import window from '@ohos.window';

@Entry
@Component
struct Index {
  // 使用@StorageLink将"mainData"与AppStorage中的变量"data"进行双向绑定
  @StorageLink('data') mainData: number = 1;
  @StorageLink('window') storWindow: window.WindowStage | null = null
  private windowStage = this.storWindow
  private sub_windowClass: window.Window | null = null
  showSubWindow() {
    // 创建应用子窗口。
    if (this.windowStage == null) {
      console.error('Failed to create the subwindow. Cause: windowStage_ is null');
    } else {
      this.windowStage.createSubWindow("hiSubWindow", (err, data) => {
        if (err.code) {
          console.error('Failed to create the subwindow. Cause: ' + JSON.stringify(err));
          return;
        }
        this.sub_windowClass = data;
        console.info('Succeeded in creating the subwindow. Data: ' + JSON.stringify(data));
        // 子窗口创建成功后，设置子窗口的位置、大小及相关属性等。
        this.sub_windowClass.moveWindowTo(500, 500, (err) => {
          if (err.code) {
            console.error('Failed to move the window. Cause:' + JSON.stringify(err));
            return;
          }
          console.info('Succeeded in moving the window.');
        });
        this.sub_windowClass.resize(800, 800, (err) => {
          if (err.code) {
            console.error('Failed to change the window size. Cause:' + JSON.stringify(err));
            return;
          }
          console.info('Succeeded in changing the window size.');
        });
        // 为子窗口加载对应的目标页面。
        this.sub_windowClass.setUIContent("pages/SubWindow", (err) => {
          if (err.code) {
            console.error('Failed to load the content. Cause:' + JSON.stringify(err));
            return;
          }
          console.info('Succeeded in loading the content.');
          // 显示子窗口。
          (this.sub_windowClass as window.Window).showWindow((err) => {
            let errCode: number = err.code;
            if (errCode) {
              console.error('Failed to show the window. Cause: ' + JSON.stringify(err));
              return;
            }
            console.info('Succeeded in showing the window.');
          });
          if (this.sub_windowClass == null) {
            console.error('Failed to create the subwindow. Cause: windowStage_ is null');
          } else {
            this.sub_windowClass.setWindowBackgroundColor('#E8A027')
          }
        });
      })
    }
  }

  destroySubWindow() {
    if (this.sub_windowClass == null) {
      console.error('Failed to create the subwindow. Cause: windowStage_ is null');
    } else {
      this.sub_windowClass.destroyWindow((err) => {
        if (err.code) {
          console.error('Failed to destroy the window. Cause: ' + JSON.stringify(err));
          return;
        }
        console.info('Succeeded in destroying the window.');
      });
    }

  }

  build() {
    Row() {
      Column() {
        Text(`数据传输：${this.mainData}`)
          .margin({ bottom: 30 })
        Button('子窗口数据+1')
          .backgroundColor('#ff8599cd')
          .margin({ bottom: 30 })
          .onClick(() => {
            // 点击，storData的值加1
            this.mainData += 1
          })
        Button('创建子窗口')
          .backgroundColor('#ff8599cd')
          .onClick(() => {
            // 点击弹出子窗口
            this.showSubWindow()
          })
          .margin({ bottom: 30 })
        Button('消除子窗口')
          .backgroundColor('#ff8599cd')
          .onClick(() => {
            // 点击消除子窗口
            this.destroySubWindow()
          })
      }
      .width('100%')
    }
    .height('100%')
  }
}

子窗口界面

// SubWindow.ets
import window from '@ohos.window';

interface Position {
  x: number,
  y: number
}

@Entry
@Component
struct SubWindow {
  @State offsetX: number = 0
  @State offsetY: number = 0
  // 使用@StorageLink将"subData"与AppStorage中的变量"data"进行双向绑定
  @StorageLink('data') subData: number = 1;
  // 创建位置变量，并使用@Watch监听，变量发生变化调用moveWindow方法移动窗口
  @State @Watch("moveWindow") windowPosition: Position = { x: 500, y: 500 };
  private panOption: PanGestureOptions = new PanGestureOptions({ direction: PanDirection.All });
  private subWindow: window.Window | null = null
  // 通过悬浮窗名称“hiSubWindow”获取到创建的悬浮窗
  aboutToAppear() {
    this.subWindow = window.findWindow("hiSubWindow")
  }

  // 将悬浮窗移动到指定位置
  moveWindow() {
    if (this.subWindow == null) {
      console.info('Faild in destroying the window.');
    } else {
      this.subWindow.moveWindowTo(this.windowPosition.x, this.windowPosition.y);
    }
  }

  build() {
    Column() {
      Text(`传输的数据：${this.subData}`)
        .fontSize(12)
        .margin({ bottom: 10 })
      Button('主窗口数据+1')
        .fontSize(12)
        .backgroundColor('#ff8599cd')
        .onClick(() => {
          // 点击，subData的值加1
          this.subData += 1
        })
    }
    .height('100%')
    .width('100%')
    .alignItems(HorizontalAlign.Center)
    .justifyContent(FlexAlign.Center)
    .gesture(
      PanGesture(this.panOption)//手势识别成功回调。
        .onActionStart((event: GestureEvent) => {
          console.info('Pan start');
        })// 手势移动过程中回调。发生拖拽时，获取到触摸点的位置，并将位置信息传递给windowPosition
        .onActionUpdate((event: GestureEvent) => {
          this.windowPosition.x += event.offsetX;
          this.windowPosition.y += event.offsetY;
        })//手势识别成功，手指抬起后触发回调。
        .onActionEnd(() => {
          console.info('Pan end');
        })
    )
  }
}