如何滑动页面时，让滑动速度变慢

@Component
struct ScrollViewExample {
  @State translateY: number = 0
  private startY: number = 0
  private lastTime: number = 0
  private velocity: number = 0
  private damping: number = 0.8 // 阻尼系数(0-1)

  build() {
    Stack() {
      // 主内容区...
      
      // 二楼区域
      Column() {
        // 二楼内容...
      }
      .translate({ y: this.translateY })
      .gesture(
        PanGesture({
          onActionStart: (event: GestureEvent) => {
            this.startY = event.offsetY
            this.lastTime = new Date().getTime()
          },
          onActionUpdate: (event: GestureEvent) => {
            const now = new Date().getTime()
            const deltaTime = now - this.lastTime
            this.lastTime = now
            
            // 计算速度并应用阻尼
            this.velocity = (event.offsetY - this.startY) / deltaTime
            this.translateY += event.offsetY * this.damping
            
            this.startY = event.offsetY
          },
          onActionEnd: () => {
            // 惯性滑动(带衰减)
            let inertia = this.velocity
            const decay = () => {
              inertia *= 0.95 // 衰减系数
              this.translateY += inertia
              
              if (Math.abs(inertia) > 0.5) {
                requestAnimationFrame(decay)
              }
            }
            decay()
          }
        })
      )
    }
  }
}
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// 引入鸿蒙动画系统
import curve from '@ohos.animator'

// 在build方法中添加：
.gesture(
  PanGesture({
    onActionEnd: () => {
      const options: curve.IAnimationOptions = {
        duration: 500,
        curve: curve.springMotion(100, 10, 0) // 刚度/阻尼/质量
      }
      animateTo(options, () => {
        this.translateY = this.calculateTargetPosition()
      })
    }
  })
)
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// 添加边界判断
onActionUpdate: (event: GestureEvent) => {
  const newY = this.translateY + event.offsetY * this.damping
  
  // 上边界检测
  if (newY < 0) {
    this.translateY = newY * 0.3 // 越界时增加阻力
    return
  }
  
  // 下边界检测(二楼最大展开位置)
  const maxHeight = 500
  if (newY > maxHeight) {
    const overshoot = newY - maxHeight
    this.translateY = maxHeight + overshoot * 0.2
    return
  }
  
  this.translateY = newY
}
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private lastUpdate: number = 0
private updateInterval: number = 16 // 60fps

onActionUpdate: (event: GestureEvent) => {
  const now = Date.now()
  if (now - this.lastUpdate < this.updateInterval) return
  this.lastUpdate = now
  // 正常处理逻辑...
}
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// 根据设备DPI调整参数
import display from '@ohos.display'

const displayInfo = display.getDefaultDisplaySync()
const density = displayInfo.densityPixels

// 高分辨率设备需要更强的阻尼
this.damping = density > 3 ? 0.7 : 0.85
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@Component
export struct SecondFloorComponent {
  @State translateY: number = 0
  private startY: number = 0
  private damping: number = 0.75
  private maxHeight: number = 600
  
  // 动态计算边界阻力
  private getDynamicDamping(currentY: number): number {
    const threshold = this.maxHeight * 0.8
    if (currentY > threshold) {
      const overflowRatio = (currentY - threshold) / (this.maxHeight - threshold)
      return this.damping * (1 - overflowRatio * 0.5)
    }
    return this.damping
  }

  build() {
    Column() {
      // 二楼内容...
    }
    .height('100%')
    .backgroundColor('#f5f5f5')
    .translate({ y: this.translateY })
    .gesture(
      PanGesture({
        onActionStart: (event: GestureEvent) => {
          this.startY = event.offsetY
        },
        onActionUpdate: (event: GestureEvent) => {
          const deltaY = event.offsetY - this.startY
          const currentDamping = this.getDynamicDamping(this.translateY)
          this.translateY += deltaY * currentDamping
          this.startY = event.offsetY
        },
        onActionEnd: () => {
          // 自动定位到最近边界
          const targetY = this.translateY > this.maxHeight / 2 ? this.maxHeight : 0
          animateTo({
            duration: 300,
            curve: curve.cubicBezier(0.2, 0.8, 0.1, 1.0)
          }, () => {
            this.translateY = targetY
          })
        }
      })
    )
  }
}
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// 添加调试滑块
Slider({
  value: this.damping,
  min: 0.1,
  max: 0.9,
  onChange: (value: number) => { this.damping = value }
})
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# 使用DevEco Profiler监控
hdc shell hilog | grep ScrollPerformance
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import device from '@ohos.deviceInfo'

const deviceType = device.deviceType
if (deviceType === 'phone') {
  // 手机设备使用更强阻尼
  this.damping = 0.8
} else if (deviceType === 'tablet') {
  // 平板设备降低阻尼
  this.damping = 0.6
}
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