HarmonyOS NEXT Development Case: Randomized 9-Cell Grid

[Lomanu4]

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This article demonstrates a lottery system implementation using HarmonyOS NEXT's reactive programming capabilities and component-based architecture. The solution features a dynamic 9-cell grid with configurable prizes and smooth animation effects.

Implementation Highlights

1. Reactive Data Model


// Observable Prize class with traceable properties
@ObservedV2
class Prize {
@Trace title: string // Prize title with reactive tracking
@Trace color: string // Color property for UI styling
@Trace description: string // Prize description

constructor(title: string, color: string, description: string = "") {
this.title = title
this.color = color
this.description = description
}
}
2. State Management Components


// Prize editor component with shared state
@Component
struct MyPrizeUpdate {
@Consume selectedIndex: number // Currently selected index
@Consume private selectionOrder: number[] // Lottery sequence
@Consume private prizeArray: Prize[] // Prize collection

build() {
Column({ space: 20 }) {
// UI elements for editing prize properties
}
}
}
3. Core Lottery Logic


@Entry
@Component
struct LotteryPage {
@Provide private selectedIndex: number = 0
private isAnimating: boolean = false
@Provide private selectionOrder: number[] = [0, 1, 2, 5, 8, 7, 6, 3]
// ...other properties

// Multi-stage animation control
startLottery(speed: number = 500) {
// Acceleration phase
}

runAtConstantSpeed() {
// Constant-speed phase with random duration
}

slowDown(speed = 50) {
// Deceleration phase with result display
}
}
Key Features

1. Dynamic Grid Layout

Flex({ wrap: FlexWrap.Wrap }) {
ForEach(this.prizeArray, (item: Prize, index: number) => {
// Responsive cell rendering with click effects
})
}

1. Three-Phase Animation
2. Acceleration: Gradual speed increase (500ms → 50ms)
3. Constant Speed: Random duration (40ms + n×50ms)
4. 
   Deceleration: Progressive slowdown until stop
   
   
5. 
   Interactive Configuration
   

TextInput({ text: this.prizeArray[...].title })
.onChange((value) => {
// Directly update reactive properties
})

1. Visual Feedback
2. Dynamic color schemes
3. Click effects with scaling
4. Real-time selection highlighting
5. Shadow effects for depth perception

Complete Implementation

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Conclusion


This implementation showcases HarmonyOS NEXT's powerful capabilities in:

• Reactive state management (@ObservedV2/
  
  

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  )
• Component-based architecture
• Smooth animation control
• Responsive UI updates

The solution can be extended with additional features like network synchronization or prize probability configurations, demonstrating the flexibility of HarmonyOS application development.

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