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陈杨
陈杨

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Hong Mong 5 Development Treasure Case Sharing Performance Analysis Introduction

Here is a sharing article organized based on the HarmonyOS development resources you provided, combined with practical cases and code analysis. The style is relaxed but the content is full of valuable information 👇

"Hey, HarmonyOS developers! You would never guess how many hidden gem cases the official docs contain!"

Recently, I dug up a "hidden copy" in the HarmonyOS documentation—the official team actually quietly provides 100+ scenario-based development cases, covering performance optimization, UI design, device adaptation, and more! These practical resources are 10 times more useful than the basic docs, yet are hidden in the "Best Practices" section that few people notice. Today, let's go treasure hunting!

🔥 1. Why Are These Cases Hidden Gems?

The cases in the official docs are all real-world, code-level solutions for scenarios, such as:

  • Foldable screen hover interaction (e.g., hovering video player)
  • Smooth scrolling for ten-thousand-item lists (deep optimization of LazyForEach)
  • Real-time refresh for service cards (stock card updates in seconds)
  • Cross-device flow (start editing a photo on your phone, continue on your tablet)

👉 Direct Path: Official Docs → Best Practices → Core Technical Concepts/Domain Cases (with path illustration)

Note: The docs are updated frequently. Some cases are in subdirectories like "Device Scenarios" and "Seamless Flow".

🛠 2. Three Selected God-Level Case Analyses (with Code)

Case 1: Foldable Screen "Hover Mode" Development

Pain Point: Ordinary layouts get squeezed and deformed in hover state

Official Solution: Use displayMode to respond to screen form changes

// Listen for screen fold status
display.on('foldStatusChange', (newStatus) => {
  if (newStatus === display.FoldStatus.FOLD_STATUS_HALF) {
    // Hover mode layout
    this.topHeight = '40%'
    this.bottomHeight = '60%'
  } else {
    // Full screen mode
    this.topHeight = '100%'
  }
})
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Key Tips:

  • Use ConstraintLayout to constrain layout and avoid absolute positioning
  • Add the clip property to the bottom area in hover mode to prevent content overflow

Case 2: Ultimate Optimization for Ten-Thousand-Item Lists

Official Performance Data: 10,000 items scroll at ≥55fps

Core Code:

LazyForEach(this.dataArray, (item) => {
  ListItem() {
    Text(item.name)
      .fontSize(16)
      // ✅ Key optimization: fixed height to avoid repeated calculation
      .height(48) 
  }
  // ✅ Reuse strategy: same type component reuse pool
}, item => item.id)
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Pitfall Guide:

  • Do not bind complex logic inside itemGenerator
  • For image loading, use AsyncImage + memory cache

Case 3: Real-Time Refresh for Service Cards

Stock Card Update Code:

// Card provider
onUpdateForm(formId) {
  let stockData = fetchNewData() // Get latest stock price
  let formData = {
    "price": stockData.price,
    "delta": stockData.changeRate
  }
  // Dynamically update card
  formProvider.updateForm(formId, formData)
}
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Supporting Config (form_config.json):

{
  "data": {
    "price": "$price",
    "delta": "$delta"
  },
  "updateEnabled": true, // Enable updates
  "scheduledUpdateTime": "08:00" // Daily trigger time
}
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💡 3. What Problems Can These Cases Solve?

Scenario Case Path Highlighted Technology
List scroll lag Performance Optimization > Long List Loading Frame-splitting rendering + component reuse pool
Cross-device flow failure Seamless Flow > App Continuation Distributed data management
Camera preview artifacts Media > Camera Artifact Solution Double-buffered textures
Dark mode adaptation difficulty UI Framework > Dark Mode Adaptation Dynamic resource replacement

🚀 4. How to Use These Cases Efficiently?

  1. Precise Search: On the docs page, use Ctrl+F to search keywords
    • Example: Directly search for "waterfall flow", "WebView memory"
  2. Code Migration:
    • 90% of cases come with complete demo projects (search HarmonyOS-Codelabs on GitHub)
    • Just modify the business logic in entry/src/main/ets
  3. Debugging Tips: Use DevEco Profiler to capture performance data for the cases: 
hdc shell hilog | grep "RenderFrame"
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💎 Final Words

These cases are basically official "cheat codes"! Especially for foldable screen adaptation and cross-device flow, directly reusing the official solutions saves 80% of the trial-and-error time. I recommend reading through the "Domain Cases" section—code design varies greatly for e-commerce, finance, social, and other scenarios.

🌟 Easter Egg: In "Best Practices > App Quality > Performance" there is a Douyin-level short video smoothness optimization solution, even with GPU instruction optimization!
Discussion: Have you found any god-level cases? See you in the comments 👇

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